ENERGY ABSORPTION UNIT FOR PREVENTING SHOCK INJURY

[0001 ] The present application claims the filing date of international patent application Nr. PCT/SG2019/050277 as its priority date, which was filed with WIPO via RO/IPOS (Intellectual Property Office of Singapore) on 28 May 2019. The present application claims a filing date of international patent application Nr. PCT/SG2019/050577 as its priority date, which was filed with WIPO via RO/IPOS on 26 November 2019. All relevant content and/or subject matter of the earlier priority patent applications is hereby incorporated by reference wherever appropriate, possible or relevant.

[0002] The present application relates to an energy absorption unit for absorbing external shocks in order to prevent head injury, such as concussion. The present application also discloses some applications of the energy absorption unit, such as head protection devices, impact attenuators for vehicles and apparel and footwear.

[0003] Traumatic injury is a major cause of death and disability. Extent and severity of the traumatic injuries incurred largely depend on the energy imparted to the victim. A protective system (e.g. device, apparatus) thus should be installed for absorbing the energy to a maximum degree in order to minimize the traumatic injury incurred to the victim. Traditionally, various protective systems have been developed for resisting external shocks, including hydraulic devices, pneumatic devices or friction-based devices. However, these protective systems do not efficiently absorb the tremendous magnitude of energy imparted in a traumatic situation.

[0004] An external shock transmits kinetic energy from a colliding object to the victim upon impact. Therefore, the subject application discloses an energy absorption unit for absorbing the kinetic energy from an external shock in order to minimize the traumatic injury imparted to the victim. The kinetic energy may be absorbed in three ways by the energy absorption unit. Firstly, the kinetic energy is converted into elastic potential energy due to elastic deformation of the energy absorption unit. Secondly, the kinetic energy is converted into internal dissipated energy due to plastic deformation of the energy absorption unit. Thirdly, the kinetic energy is converted into thermal energy due to the friction generated between different components of the energy absorption unit.

[0005] As a first aspect, the present application discloses an energy absorption unit for absorbing kinetic energy from a colliding object. The energy absorption unit comprises a tensile system configured to undergo elastic deformation for converting a first portion of the kinetic energy into tensile elastic potential energy; and a compression system configured to undergo compressive deformation for converting a second portion of the kinetic energy into compressive elastic potential energy and thermal energy. The tensile system is configured to respond to the colliding object earlier than the compression system. In other words, the tensile system absorbs the kinetic energy first and then followed by the compression system. The tensile system optionally comprises a linear tensile mechanism for storing a first portion of the elastic potential energy.

[0006] The linear tensile mechanism of the energy absorption unit optionally comprises a plurality of elastic fibres (cords, cables, threads, or the like) for absorbing the first elastic potential energy. The elastic fibres are configured within an intermediate layer (also known as gap layer) of the energy absorption unit (such as a three-layer (trilaminar) energy absorption system). The energy absorption unit may have various designs according to specific requirements. In some implementations, the energy absorption unit has an inner shell, an outer shell and an intermediate layer in-between. The elastic fibres are configured to span the intermediate layer between the inner shell and the outer shell of the energy absorption unit. In the intermediate layer, the elastic fibres may be configured to cross diagonally to form a matrix configuration in order to absorb forces exerted in opposing directions (such as anteroposterior directions or lateral directions). The diagonal orientation thus may help optimize force resistance or energy absorption by recruiting multiple elastic fibres. In particular, the intermediate layer may have a minimum width required to enable the outer shell to translate relative to the inner shell depends on the degree of relative rotation needed as well as the dimensions of both elliptical shells. According to preliminary calculations for a, the minimum width required would be substantially 15 millimetres (mm). [0007] The inner shell and the outer shell are configured to be segregated and move independently. Both the inner and outer shells are composed of rigid materials (e.g. Polystyrene; carbon fibre) in order to prevent the linear tension system being compromised if either or both of the inner and outer shells collapse.

[0008] The elastic fibres may comprise a material having a high elastic modulus (or also known as modulus of elasticity). The higher the elastic modulus is, the more elastic potential energy the elastic fibres could store; and thus the more kinetic energy the elastic fibres could absorb. The elastic modulus is measured as a slope of a stress-strain curve in the elastic deformation region where permanent deformation does not occur yet. According to direction of the stress, the elastic modulus may be categorized as Young’s modulus, shear modulus and bulk modulus. In particular, the Young’s modulus determines elastic deformation (measured as tensile strain) along an axis of the material when opposing forces (measured as tensile stress) are applied along the axis. Thus the Young’s modulus is defined as a ratio of the tensile stress to the tensile strain along the axis. The elastic fibres are configured to be under moderate tension in a resting state in order to minimize any motion between the inner shell and the outer shell during non significant natural movements of the head. The elastic fibre may also have a high hysteresis. In a force-extension plot of a material, an area of a hysteresis loop represents energy dissipated due to internal friction of the material. The larger the hysteresis is, the more energy could be dissipated in a cycle of loading and unloading; and the more kinetic energy the elastic fibres could absorb. The elastic fibre may be made of a natural material, a synthetic material or a combination thereof. The natural materials include collagen, and natural rubber or the alike. While the synthetic materials include viscoelastic polymers - e.g. Sorbothane, synthetic rubbers (e.g. Silicon rubber, neoprene, butyl rubber, polyurethane), Akton polymer; gels (including hydrogels) and foams (polyethylene, polypropylene and expanded polystyrene foam) and equivalent materials.

[0009] The tensile system comprises a radial tensile mechanism configured to expand radially for storing a second portion of the tensile elastic potential energy. In particular, the radial tensile mechanism is actuated by the compression system which is moved by compression due to the colliding object. The compression system and the radial tensile mechanism may have various designs according to specific requirements, as long as they have complementary structures such that the compression system could convert compression force under impact of the colliding object to expanding force to the radial tensile mechanism. The compression system optionally comprises a tapering component movably coupled to the radial tensile mechanism. Before the impact of the colliding object, the tapering component is arranged to align with the radial tensile mechanism but does not apply the expanding force to the radial tensile mechanism. During the impact of the colliding object, the tapering component move into the radial tensile mechanism for providing the expanding force to the radial tensile mechanism to expand radially. Preferably, the tapering component and the radial tensile mechanism have symmetrical structures for expanding homogenously under the impact of the colliding object.

[0010] In some implementations, the radial tensile mechanism comprises an expandable component, and the tapering component is configured to insert into the expandable component. An external force of the colliding object is applied onto the tapering component which then transmits a radial expansion force to the expandable component for expanding the expandable component; and thus the second portion of the tensile elastic potential energy is stored in the expandable component in the expanded state. In addition to the radial expansion force, the expandable component is also subjected to a compression force from the tapering component. In other words, the expandable component is forced to expand in a radial direction and meanwhile be compressed vertically to the radial direction by the tapering component; while the tapering component is pushed to move relatively to the expandable component under the external force of the colliding object. Therefore, the kinetic energy of the external force is partially converted to the second portion of the tensile elastic potential energy stored in the expandable component. The expandable component may be made of an elastomeric material, such as rubber (either natural rubber or synthetic rubber) or elastomeric synthetic materials (e.g. sorbothane). The elastomeric material optionally undergoes an elastic deformation before the external force reaches a maximum value of the tensile strength. Therefore, the larger the tensile strength is, the more energy could be absorbed during the radial expansion. Meanwhile, the tapering component has a compressive strength larger than the maximum value of the tensile strength of the expandable component for ensuring that the radial expansion of the expandable component happens before the tapering component is squeezed to collapse by the expandable component. In addition, the expandable component optionally has a large cross-sectional area for increasing the tensile strength. The expandable component is thus forced simultaneously to expand and to be compressed by the tapering component. The expandable component optionally has a maximum force to limit radial expansion larger than an initial force to induce compression for achieving greater radial expansion.

[001 1 ] The expandable component may have various cross-sectional architectures according to specific requirements. The expandable component optionally comprises a single large cable. Alternatively, the expandable component comprises a plurality of small cords.

[0012] The tapering component and the expandable component may be configured in direct contact to generate a frictional force at the direct contact point for converting a portion of the kinetic energy into thermal energy. For converting more kinetic energy into thermal energy, the tapering component and the expandable component optionally comprise a material having a high frictional coefficient at the contact point for increasing the frictional force. In some implementations, the frictional force and the radial expansion force form a contact angle between the tapering component and the expandable component. The contact angle would influence the magnitude of the expansion force and the frictional force.

[0013] The radial tensile mechanism is optionally supported in the energy absorption unit. In some implementations, the radial tensile mechanism can span over the gap between the inner shell and the outer shell; and thus the tapering component or the expandable component is supported by the inner shell and the outer shell. The inner shell and the outer shell are optionally composed of lightweight, sturdy materials such as carbon fibre, Kevlar, fibre glass and polycarbonate. In some implementations, the energy absorption unit may have a multi-laminated configuration, with one or more intermediate plates for attaching the tapering component or the expandable components. The intermediate plates are optionally positioned in the gap between the inner shell and the outer shell. [0014] The expandable component may have various designs according to specific requirements. The expandable component may have a donut-like structure with a central cavity; and the tapering component is configured to enter into the central cavity for pushing the expandable component to expand radially. Accordingly, the tapering component optionally comprises a wedge-like structure. The wedge-like structure comprises a first end larger than the central cavity and a second end smaller than the central cavity. The wedge-like structure thus partially stays in the central cavity at the second end when the radial tensile mechanism is in a resting state. In particular, the wedge-like structure has a tip angle which determines the ratio of the radial expansion force and the vertical compression force. The larger the tip angle is, the larger the ratio would be. Therefore, the tip angle should be greater than 45 degrees for enhancing the expansion force and meanwhile suppressing the compression force.

[0015] The wedge-like structure optionally comprises a top wedge and a bottom wedge. Both the top wedge and the bottom wedge partially stay in the central cavity from a top surface and a bottom surface of the donut-like structure respectively. Accordingly, the expandable component optionally comprises two or more expandable sub-components stacked together, wherein at least a top expandable sub-component and a bottom expandable sub-component have a top cavity and a bottom cavity for the top wedge and the bottom wedge of the wedge-like structure to partially stay in respectively. The top wedge and/or the bottom wedge may comprise two or more sub-wedges stacked together. The stacked sub-wedges have a bottommost sub-wedge for the top wedge or a topmost sub-wedge for the bottom wedge. The bottommost sub-wedge stays in the top cavity partially or completely; while the topmost sub-wedge stays in the bottom cavity partially or completely.

[0016] The expandable sub-components may have an elliptical cross-section with a large diameter and a short height (i.e. a low centre of gravity) preventing the expandable component from collapsing or toppling on compression. The circular aerial profile enables each of the expandable sub-components to circumferentially expand evenly in all directions. In addition, more expansion force is needed to expand the expandable sub-components if they have a larger width and a larger height proportionately. And thus more kinetic energy would be converted to the second elastic potential energy stored in the expandable sub-components.

[0017] The board optionally comprises a top plate and a bottom plate for attaching the top wedge and the bottom wedge respectively. The top plate and the bottom plate may be also positioned in the gap between the inner shell and the outer shell. The board comprises one or more intermediate plates for separating the stacked expandable sub-components and the stacked sub-wedges. In particular, the sub wedges are attached onto the intermediate plates between the top plate and bottom plate for preventing the expandable component from collapsing on compression.

[0018] The energy absorption unit may further comprise a frame for restricting compression of the expandable component, since the frame substantially encloses the expandable component and thus confines the expansion of the expandable component. In some implementations, the frame optionally comprises an external frame enclosing the expandable component externally. In particular, the external frame optionally comprises two sub-frames partially overlapping for enclosing the expandable component. In some implementations, the frame comprises an internal frame embedded in the expandable component. Either in the form of the external frame or the internal frame, the frame comprises a rigid material which does not deform and thus minimizes compression when the expandable component expands radially.

[0019] The radial tensile mechanism may have various designs according to specific requirements. In some implementations, the radial tensile mechanism comprises a base for stabilizing the radial tensile mechanism; a plurality of arms movably coupled to the base; and a plurality of elastic threads passing through perforations (also known as holes) of the arms at each level. The radial tensile mechanism optionally has a symmetrical configuration. In particular, the arms are configured to be equidistant in relation to the base. In other words, the arms have a same length and a same angle to the base. The base optionally has a plurality of hinges for movably coupling the arms. For example, the base has an octagonal shape with four hinges configured to be coupled to four arms. [0020] An alternative model for energy absorption through a radial tensile mechanism may include the following components: a board having a top plate and a bottom plate; a central telescoping axle fixed to an octagonal base (from aerial view) between the top plate and the bottom plate; a plurality of arms movably coupled to the octagonal base; and a plurality of elastic threads which traverse perforations of each arm at a particular level. In particular, each of the arms has a first sub-arm movably coupled to a top portion of the central telescoping axle; and a second sub-arm movably coupled to a bottom portion of the central telescoping axle. The first sub-arm and the second sub-arm are movably coupled together for forming the arm. For example, the first sub-arm and the second sub-arm have a first hole and a second hole respectively, wherein a peg, pin, or bolt is configured to be inserted into the first hole and the second hole for movably coupling the first sub arm and the second sub-arm. Each of the sub-arms optionally has a plurality of perforations for the elastic threads to pass through. The radial tensile mechanism optionally has a symmetrical configuration to the central telescoping axle. On one hand, all the arms are configured to be equidistant; and on other hand, the first sub arm and the second sub-arm are also configured to be equidistant for each arm.

[0021 ] The energy absorption unit may further comprise a dissipative system configured to undergo plastic deformation for converting a portion of the kinetic energy into internal dissipated energy. The plastic deformation is structural in nature, involving shearing, creep, and molecular rearrangement. Energy required to achieve the plastic deformation is absorbed by the dissipative system and then dispersed as heat. The plastic deformation optionally comprises permanent deformation to the deformable system. The dissipative system comprises a plurality of elastic wires, wherein the wires undergo permanent deformation. The wires may have an elastic nature but undergo plastic deformation after the wires reach a per- determined tension threshold. The wire may have various designs according to specific requirements. In some implementations, the wire comprises a rigid material primarily undergoing plastic deformation. In some implementations, the wire may be composed of a hybrid material or composite with both viscoelastic and plastic deformative properties, such as viscoelastic polymeric materials. The viscoelastic material may provide additional protection from impact of the colliding object. The wire comprise a dissipative portion which undergoes the plastic deformation after the wire reaches a pre-determined tension threshold. The dissipative portion may comprise the rigid material or the viscoelastic material.

[0022] The radial tensile mechanism (e.g. expandable component) of the energy absorption unit may comprises a plurality of circumferential bands distributed in a circular configuration around a central telescoping axle or the central cavity where the tapering component resides; and a plurality of elastomeric tension bands for assembling the circumferential bands together. Under the external impact, the radial tensile mechanism transforms from a resting state to a stretched state by stretching the elastomeric tension bands away from the centre (in an aerial perspective). The elastomeric tension bands may be compressed together in cross-sectional view may have either a single thick cable or multiple small cables bound together by a peripheral strap. The multiple small cables may be further cross-linked for enhancing their structural integrity within the peripheral strap.

[0023] The circumferential bands may be evenly distributed in the circular configuration. For example, the radial tensile mechanism comprises eight circumferential bands; and every two immediately neighbouring circumferential bands have a same angle of 45 degrees. Each of the elastic bands forms a substantially concentric configuration around the imaginary centre. Since the perforations of each circumferential band have different distances away from the imaginary centre, the elastic bands have different diameter measured from the imaginary centre which are equal to the different distances, respectively. In particular, the perforations may be evenly distributed in each circumferential band; and accordingly all the elastic bands are configured to be evenly spaced apart. For example, the radial tensile mechanism comprises four elastic bands which forms four circular configurations with four different diameters from the imaginary centre, respectively.

[0024] As a second aspect, the present application discloses a head protector for absorbing the impact sustained from a colliding object. Energy transmitted from an externally applied force is absorbed in two phases utilizing an entire intermediate layer of the head protector, rather than a compression phase at the point or region of impact. Only. The two phases comprise an initial linear tensile phase and a secondary compressive phase along with a radial tensile phase. The linear tensile model exerted on elements lateral or distal to the region of impact has been previously described earlier. During the secondary compressive phase, the inner and outer shells are pulled closer together. The head protector comprises a helmet having a tri-laminar (trilaminar) configuration; and one or more energy absorption units of the first aspect. The energy absorption unit is configured to be integrated into the intermediate layer of the helmet. The helmet of the trilaminar configuration has an inner shell, an outer shell and an intermediate layer between the inner shell and the outer shell. Energy transferred to the helmet from the colliding object is absorbed throughout the whole circumference of the helmet in 2 phases: 1 . An initial linear tensile phase where elastic fibres lateral to and distal to the region of impact are pulled into tension; 2. A secondary compressive phase (radial tensile phase) where the proposed concave and/or convex units interact at the region of impact. The linear tensile mechanism optionally comprises a plurality of elastic fibres in a matrix configuration in order to absorb the external force exerted in opposing directions (i.e. anteroposterior directions or lateral directions). In addition, the elastic fibres may also traverse diagonally across the intermediate layer of the helmet for absorbing the external force from any direction.

[0025] The radial tensile mechanism may further comprise a dome coupled to the first end of the tapering component for transmitting an external force to the underlying rings (as the expandable components). The dome optionally has a four- leaf clover configuration with four lobes and four grooves between every two lobes. In particular, the dome has a curved profile in a cross-sectional view. These structures collectively form a peg-dome-ring construct (convex unit). If the dome is inverted, it will form a concave receiver unit. The internal aspect of each shell is lined with either a dome-peg-ring construct (convex unit) or concave receiver unit. During the secondary compression phase, the inner and outer shells at the region of impact are pulled closer together. Depending on the format and distribution of the energy absorption units (i.e. concave and convex units) and the alignment of the 2 shells (i.e. any rotational component), the following interactions may occur: 1 . convex unit impacting with complementary concave receiver unit; 2. concave- concave unit 3. convex-convex unit; 4. concave or convex unit impacting with a plain inner or outer shell surface. In all these instances, the compression will result in the radial expansion of an individual unit’s expandable components (i.e. elastomeric rings in direct tangential contact with the peg or the elastomeric ring running within the circumferential groove of the dome.

[0026] One or more of the elastic fibres optionally traverses into the dome through a first slit, the expandable component of the radial tensile mechanism, and out of the dome through a second slit aligned with the first slit. The radial tensile mechanism may further comprise one or more elastomeric rings running along a groove within the circumference of the dome. In order to minimize elastic recoil within the intermediate layer from a linear tensile model, the following methods have been proposed:

1 . Choice of material:

i) material with inherent good stretch and resistant compressive qualities

ii) hysteresis of elastomer - absorbing energy required to stretch material and releasing in form of thermal energy, resulting in less elastic recoil;

Using elastomers or materials with high elastic hysteresis enable some of the energy to be absorbed or released as the thermal energy when unloaded, thereby reducing elastic recoil potential

iii) damping coefficient of elastomer

2. counteracting tension fibres diagonally opposite expanded side - recoil of expanded fibres is counteracted by diagonally opposite fibres which will automatically stretch

3. crossing fibres will resist recoil of their opposing fibres

4. buffers interspersed within intermediate layer to dampen elastic recoil - compressive shock absorbers consisting of interspersed rubber/sorbothane/other flexible/shock-absorbable pylons running transversely and longitudinally will cushion impact of elastic recoil from tension cords/cables/fibres in coronal and sagittal planes, respectively. Alternatively, these pylons may be filled with circulating fluid which redistributes to the opposing side of impact, so that the redistributed fluid will cushion the elastic recoil 5. integrated fine springs or coils of elastomer wrapped around or integrated with the middle third of the tension cord (ie. cord-spring coil-cord configuration) will resist compression during recoil phase as the cords either side slacken

6. a bond or link between diagonally traversing cord/fibres can help to retard elastic recoil potential

7. twisting fibres or sets of fibres into an helical configuration so that they stretch easily but are more resistant to recoil

8. applying cords on maximal tension so that when stretched further, they will snap and release the stored elastic potential energy

9. tension reiease mechanism

10. hybrid wires/cords/cables composed of two or more integrated materials that undergoes plastic deformation beyond specific tension threshold (i.e. point of plastic deformation) or are stretch-compliant but resistant to compression.

[0027] The head protector optionally further comprises a tension release mechanism coupled to the at least one energy absorption unit for minimizing an elastic recoil of the linear tensile mechanism. In some implementations, the tension release mechanism further comprises a rotating disc and a clutch device coupled together. In a helmet, the rotating disc is integrated underneath the convex or concave units. Two elastic fibres diagonally traverse the intermediate layer, cover on one convex or concave unit, pass through the grooves of the dome and run partly (90-180 degrees) along the circumference of the rotating disc in opposite directions before anchoring to the rotating disc on diametrically opposing sides. When the elastic fibres are pulled into tension, the rotating disc is forced to rotate in one direction. When a specific tension threshold is exceeded, the clutch mechanism is overcome, forcing the rotating disc to rotate and then to release tension on the fibres. For example, the clutch mechanism comprises two tabs coupled to two ends of a spring housed within the rotating disc, respectively.

[0028] As a third aspect, the present application discloses a vehicle attenuator for resisting a colliding object. The vehicle attenuator comprises a plurality of the energy absorption units of the first aspect which can be stacked into padding. The padding is optionally distributed in appropriate impact regions of a vehicle, including the peripheral framework of the vehicle. The longitudinal axis of stacked energy absorption units are configured to be in alignment with the direction of travel of the colliding object in order to maximize absorption of the kinetic energy of the colliding object.

[0029] The stacked energy absorption units are optionally configured into one or more loading cylinders. In some implementations, the loading cylinder is configured to be integrated into a chassis of the vehicle for transmitting impact of the colliding object away from the internal body work of the vehicle.

[0030] As a fourth aspect, the present application discloses a footwear for absorbing a shock from the ground. The footwear comprises a plurality of the energy absorption units of the first aspect. In particular, the energy absorption units are configured between a superior base and an inferior base of the footwear. The energy absorption unit optionally has a variable thickness to match the contour of a sole. The superior base and the inferior base optionally comprise a firm and resilient material.

[0031 ] The tapering component of the energy absorption unit optionally comprises a first lightweight material. The first lightweight material also has a high compressive strength, including but not limited to metallic or rigid plastic material. The expandable component of the energy absorption unit optionally comprises a second lightweight material. The second lightweight material also has a low friction coefficient, including but not limited to rubber or gel.

[0032] The energy absorption units are optionally configured in a parallel configuration. The immediately adjacent energy absorption units may be spaced apart for accommodating the radial expansion. The footwear may further comprise one or more elastic devices coupled between the superior platform and the inferior platform for facilitating the energy absorption units. In some implementations, the elastic device comprises one or more coil springs. In some implementations, the energy absorption units and the elastic devices are configured in an alternating configuration. In other words, a single energy absorption unit is surrounded by multiple elastic devices; while a single elastic device is also surrounded by multiple energy absorption units. In some implementations, the expandable component of the energy absorption unit optionally has a concertina-like configuration with staggered intervening elastomeric rings encircling the recesses of the concertina structure. This design enables the elastomeric rings to be pulled into tension when the concertina is compressed during an axial compression phase (i.e. application of foot on the ground). Furthermore, it provides better structural integrity by preventing the whole structure from collapsing on compression and minimising overheating due to excessive frictional rub created by 2 surfaces constantly rubbing against each other during axial loading and unloading phases.

[0033] The accompanying figures (Figs.) illustrate embodiments and serve to explain principles of the disclosed embodiments. It is to be understood, however, that these figures are presented for purposes of illustration only, and not for defining limits of relevant applications.

Fig. 1 illustrates a cross-sectional view (a) and a top view (b) of a first embodiment of energy absorption unit;

Fig. 2 illustrates a spectrum of forces at a contact area in the first embodiment of energy absorption unit;

Fig. 3 illustrates a radial expansion rate of an expandable component of the first embodiment of absorption unit;

Fig. 4 illustrates a radial tension gain of the expandable component of the first embodiment of absorption unit;

Fig. 5 illustrates another spectrum of forces at a contact area in the first embodiment of energy absorption unit;

Fig. 6 illustrates a cross-sectional view of a second embodiment of energy absorption unit in a resting state (a) and an expansion state (b);

Fig. 7 illustrates a cross-sectional view of a third embodiment of energy absorption unit in a resting state;

Fig. 8 illustrates a cross-sectional view of an expandable sub-component;

Fig. 9 illustrates a cross-sectional view of a fourth embodiment of energy absorption unit in a resting state;

Fig. 10 illustrates a cross-sectional view of a fifth embodiment of energy absorption unit with a first external frame; Fig. 1 1 illustrates a cross-sectional view of a sixth embodiment of energy absorption unit with a second external frame;

Fig. 12 illustrates a cross-sectional view (a) and an overview (b) of a seventh embodiment of energy absorption unit with an internal frame;

Fig. 13 illustrates a spectrum of forces exerted on an expandable sub component;

Fig. 14 illustrates a cross-sectional view (a) and a top view (b) of an energy absorption system having a series of energy absorption units;

Fig. 15 illustrates a top view of an eighth embodiment of energy absorption unit;

Fig. 16 illustrates a cross-sectional view of the eighth embodiment of energy absorption unit;

Fig. 17 illustrates a cross-sectional view of a ninth embodiment of energy absorption unit;

Fig. 18 illustrates a top view (a) and a cross-sectional view (b) of one level of a tenth embodiment of energy absorption unit in a resting state;

Fig. 19 illustrates the top view (a) and a cross-sectional view (b) of one level of a tenth embodiment of energy absorption unit in a stretched state;

Fig. 20 illustrates (a) a top view of a helmet before an external force is applied;

and (b) a top view of the helmet after the external force is applied;

Fig. 21 illustrate a side view of a first head protector construct;

Fig. 22 illustrates a cross-sectional view of a first embodiment of the first head protector construct (a) before an axial loading stress is applied; and (b) during the axial loading stress is applied;

Fig. 23 illustrates a cross-sectional view of a second embodiment of the first head protector construct (a) before an axial loading stress is applied; and (b) during the axial loading stress is applied;

Fig. 24 illustrates a cross-sectional view of a third embodiment of the first head protector construct (a) before an axial loading stress is applied; and (b) during the axial loading stress is applied;

Fig. 25 illustrates a cross-sectional view of a fourth embodiment of the first head protector construct (a) before an axial loading stress is applied; and (b) during the axial loading stress is applied; Fig. 26 illustrates a cross-sectional view of a fifth embodiment of the first head protector construct (a) before an axial loading stress is applied; and (b) during the axial loading stress is applied;

Fig. 27 illustrates a cross-sectional view of the first head protector construct with an elastic fibre in a resting state.

Fig. 28 illustrates a cross-sectional view of the second head protector construct with the elastic fibre in an expansion state;

Fig. 29 illustrates a cross-sectional view (a) and a top view (b) of a third head protector construct;

Fig. 30 illustrates a cross-sectional view of a first energy absorption system of head protector;

Fig. 31 illustrates a cross-sectional view of a second energy absorption system of head protector;

Fig. 32 illustrates a cross-sectional view of a third energy absorption system of head protector;

Fig. 33 illustrates a cross-sectional view of a fourth energy absorption system of head protector;

Fig. 34 illustrates a top view of a vehicle having the energy absorption unit;

Fig. 35 illustrates a cross-sectional view of a first energy absorption system of vehicle in a resting state (a) and in a compression state (b);

Fig. 36 illustrates a bottom view of the first energy absorption system;

Fig. 37 illustrates a cross-sectional view (a) and a top view (b) of a second energy absorption system of vehicle;

Fig. 38 illustrates a cross-sectional view of a first stacked model; and

Fig. 39 illustrates a cross-sectional view of a second stacked model.

[0034] As a first variation of the subject application, seven embodiments of the energy absorption unit are shown from Fig. 1 to Fig. 13. Fig. 1 illustrates a first embodiment 100 of energy absorption unit. Fig. 1 (a) and Fig. 1 (b) show a cross- sectional view and a top view of first embodiment 100 respectively. The first embodiment 100 of energy absorption unit comprises a wedge 102 and an expandable component 104. The expandable component 104 has a donut-like structure having an outer rim 106 and an inner rim 108 defining an outside boundary and an inside boundary of the donut-like structure. A central cavity 1 10 is thus formed inside the inner rim 108. The expandable component 104 is imaginatively divided into two identical halves, i.e. a left half 1 12 and a right half 1 14. The wedge 102 has a top end 1 16 and a bottom end 1 18 opposed to the top end 1 16. The bottom end 1 18 is smaller than the top end 1 16; and thus the bottom end 1 18 and the top end 1 16 stay in and out of the central cavity 1 10 respectively. In other words, the wedge 102 is surrounded at the bottom end 1 18 by the inner rim 108 of the donut-like structure. Thus the wedge 102 and the donut-like structure has a circular contact area 120 shown in the Fig. 1 (b). The contact area 120 is shown as a left contact area 122 for the left half and a right contact area 124 for the right half in the Fig. 1 (a).

[0035] When an external force (F) 130 (shown as an arrow 130) is applied perpendicularly to the top end 1 16 of the wedge 102, the wedge 102 would advances into the central cavity 1 10 and meanwhile distributes a contact force (Fc) 132 evenly to the inner rim 108 of the donut-like structure. The contact force (Fc) is perpendicular to the contact area 120. Meanwhile, a frictional force (Ff) 134 is also generated between the wedge 102 and the inner rim 108 of the donut-like structure. The frictional force (Ff) is tangent to the contact area 120 and thus is perpendicular to the contact force (Fc). The contact force (Fc) would push the expandable component 104 to expand radially and thus convert kinetic energy brought by the external force (F) into elastic potential energy of the expandable component. For example, a left arrow 136, a right arrow 137, a front arrow 138 and a rear arrow 139 show the expansion in a left direction, a right direction, a front direction and a rear direction, respectively. Therefore, the wedge 102 is made of a natural material, a synthetic material or a combination thereof. The natural materials include collagen, and natural rubber or the alike. While the synthetic materials include viscoelastic polymers - e.g. Sorbothane, synthetic rubbers (e.g. Silicon rubber, neoprene, butyl rubber, polyurethane), Akton polymer; gels (including hydrogels) and foams (polyethylene, polypropylene and expanded polystyrene foam) and equivalent materials that is strong enough to resist collapse; in other words, the wedge 102 has a larger compressive strength than a maximum tensile strength of the expandable component. [0036] Fig. 2 to Fig. 4 show absorption of the external force F into the expansion force Fe can be optimized by modulating an angle a between the friction force (Ff) in the tangent direction and the contact force (Fc). Fig. 2 illustrates a spectrum of forces 150 at the contact area 120 in the first embodiment of energy absorption unit. As mentioned above, the external force (F) is decomposed into the contact force (Fc) and the frictional force (Ff) perpendicular and parallel to a tangent direction 152 at the contact area 120 between the wedge 102 and the inner rim 108 of the expandable component 104. The contact force (Fc) is further decomposed into a compression force (Fc) 154 and an expansion force (Fe) 156 which are perpendicular to each other. The compression force (Fc) 154 also has an angle a to the contact force (Fc) 132. Therefore, the formula is established as:

F = (n) Fc;

“n” refers to a number of individual shock absorption units from a combined assembly of stacked units.

Fc = Fc cos a; Fe = Fc sin a;

Thus: tan a = Fe/Fc.

[0037] The wedge 102 optionally has a deep profile (i.e. the angle a increases towards a right angle (90 degrees)) for increasing expansion force (Fe) and meanwhile decreasing the compression force (Fc). For example, if ratio of Fe/Fc > 1.0, then tan a > 1 and a > 45°; if ratio of Fe/Fc > 2.0, then a = 63°; if ratio of Fe/Fc > 3.0, then a = 72°.

[0038] In order to achieve greater expansion of the expandable component 104 in the radial expansion (also known as radial expansion), an initial force required to induce the radial expansion should be less than an initial force required to induce the compression of the expandable component 104, i.e. Fri < Fci, wherein Fri stands for the initial expansion force in the radial direction and Fci stands for the initial impression force. Optionally, the initial compression force Fci is still larger than a maximum force required up to limit the expansion in the radial direction before the expandable component 104 ruptures, i.e. Frm < Fci, wherein Frm stands for the maximum expansion force in the radial direction. [0039] Fig. 3 illustrates a radial expansion rate 160 of an expandable component 104 of the first embodiment 100 of energy absorption unit. The expandable component 104 has a velocity V and a radius R vertical to each other. Accordingly, the expandable component 104 has a change in velocity 5V which is reflective of change in momentum or force, and a change in radius 5R. Since tan a = 5V/ Ar, then 5R= 5V/Tan a.

[0040] Therefore, the radial expansion rate (5R) can be modulated by the angle a. The wedge 102 optionally has a deep profile (i.e. the angle a increases towards a right angel (90 degrees)) for resulting in a smaller compressive force and hence a slower rate of compression.

[0041 ] Fig. 4 illustrates a radial tension gain 170 of the expandable component 104 of the first embodiment 100 of energy absorption unit. The expandable component 104 has a tension T1 in a resting state 172 and a tension T2 in an expansion state 174 when the expansion force (Fe) is applied to the expandable component 104. Accordingly, the expandable component 104 has a radius R1 in the resting state and a radius R2 in the expansion state. A radial tension gain (dT) is then determined as dT= T2 - T1 ; while a radius gain (bR) is expressed as 6R- R2 -R1. Therefore, the radial tension gain dT = T1 + 2p 6R

= T1 + 2 bV/Tan a

[0042] The radial tension gain (dT) can be modulated by the angle a. The wedge 102 optionally has a deep profile (i.e. the angle a increases towards a right angel (90 degrees)) for resulting in a slower rate of radial tension gain (dT).

[0043] Fig. 5 illustrates another spectrum 180 of forces at the contact area 120 in the first embodiment 100 of energy absorption unit. The compression force (Fc) and expansion force (Fe) are influenced by the angle a at the contact area 120 between the wedge 102 and the inner rim 108 of the expandable component 104. The force exerted in the radial direction is a sum of a component of applied contact force and a fraction/component of the frictional resistive force. The expandable component 104 optionally has an elliptical configuration having a height larger than a width of the expandable component 104. By making the width larger which is accompanied by proportionately larger height, more radial expansion force is required to expand the expandable component 104. Hence, more kinetic energy brought by the larger external force (F) may be absorbed and attenuated by the expandable component 104.

[0044] In addition, a rougher contact area 120 between the wedge 102 and the expandable component 104 would result in a greater frictional force (Ff). The wedge 102 and/or the expandable component 104 at the contact area 120 may be made of a material having a high frictional coefficient. The frictional force (Ff) additionally contribute to the force exerted in the radial direction which is determined as

Fe = Fc sin a + (1/x)(Fc) wherein 1 /x stands for fraction or component of a force, i.e. frictional coefficient and angular component of the frictional force.

[0045] Fig. 6 illustrates a cross-sectional view of a second embodiment 200 of energy absorption unit in a resting state (a) and an expansion state (b). The second embodiment 200 of energy absorption unit comprises a wedge 202 and an expandable component 204. In particular, the expandable component 204 further comprises five expandable sub-components 206-214 stacked together for optimizing energy absorption, i.e. a first expandable sub-component 206, a second expandable sub-component 208, a third expandable sub-component 210, a fourth expandable sub-component 212 and a fifth expandable sub-component 214 sequentially stacked from the top to the bottom. According to specific requirements, the expandable component 204 may have any number of the expandable sub components (such as five expandable sub-components). Each of the expandable sub-components 206-214 has a central cavity (not shown); and thus the stacked expandable sub-components 206-214 have a concentric configuration such that their central cavities form a through cavity within the expandable component as a whole. Meanwhile, the wedge 202 comprises a top wedge 216 and a bottom wedge 218 which are opposed to each other and aligned along a single longitudinal axis through the through cavity of the expandable component 204. The second embodiment 200 of energy absorption unit is fixed inside a board 220. As shown in Fig. 6, the board comprises a top plate 222 and a bottom plate 224. The top wedge 216 and the bottom wedge 218 are thus fixed at a bottom surface of the top plate 222 and a top surface of the bottom plate 224, respectively.

[0046] In the resting state shown in Fig. 6(a), the expandable sub-components 206- 214 keeps an original profile with a larger height and a smaller radius; and the top wedge 216 and the bottom wedge 218 are inserted into the first expandable sub component 236 and the fifth expandable sub-component 244, respectively. After an external force 226 is applied to the top plate 222 and the bottom plate 224, the top wedge 216 and the bottom wedge 218 compress the first expandable sub component 236 and the fifth expandable sub-component 244, respectively; and then advance into the second expandable sub-component 238 and the fourth expandable sub-component 242, respectively while the expandable sub components 206-214 expand with a smaller height and a larger radius. The arrows show movement of the top wedge 216, the bottom wedge 218 and the expandable sub-components 206-214. In particular, the expandable sub-component 206-214 expand in a radial direction more than being compressed in the direction of the external force 226.

[0047] Fig. 7 illustrates a cross-sectional view of a third embodiment 230 of energy absorption unit in a resting state, which has a similar structure with the second embodiment 200. The third embodiment 230 comprises a wedge 232 and an expandable component 234, which are sandwiched between a top plate 266 and a bottom plate 268 of a board 264. The expandable component 234 has six expandable sub-components 236-246 sequentially from the top to the bottom; and wedge 232 has a top wedge 248 and a bottom wedge 250 opposed to each other. However, the top wedge 248 further comprises three stacked sub-wedges, i.e. a first sub-wedge 252 partially inside the first expandable sub-component 236; a second sub-wedge 254 inside the first expandable sub-component 236 and the second expandable sub-component 238; and a third sub-wedge 256 inside the second expandable sub-component 238 and the third expandable sub-component 240; while the bottom wedge 250 also further comprises three stacked sub-wedges, i.e. a fourth sub-wedge 258 inside the fourth expandable sub-component 242 and the fifth expandable sub-component 244; a fifth sub-wedge 260 inside the fifth expandable sub-component 244 and the sixth expandable sub-component 246; and a sixth sub-wedge 262 partially inside the sixth expandable sub-component 246. The wedge 232 has a higher efficiency of force absorption by creating the stacked sub-wedges for the top wedge and 248 the bottom wedge 250, since the external force applied to the wedge 232 would permit radial expansion of all the sixth expandable sub-components 236-246 of the expandable component 234 simultaneously and also generate greater frictional force.

[0048] The expandable component 204 in Fig. 6 or 234 in Fig. 7 may collapse due to the stacked expandable sub-components 206-212 in Fig. 6 or 236-246 in Fig. 7. Various designs may be adopted according to specific requirements. For example, Fig. 8 illustrates a cross-sectional view of an expandable sub-component 270 which has a smaller height 272 and a larger diameter 274 for lowering down its centre of gravity 276.

[0049] For another example, Fig. 9 illustrates a cross-sectional view of a fourth embodiment 280 of energy absorption unit in a resting state. The fourth embodiment 280 is separated into three compartments, i.e. a first compartment 282, a second compartment 283 and a third compartment 284, each of which has a similar structure with the second embodiment 200 in Fig. 6. The first compartment 282 comprises a first set of expandable sub-components 288 between a top plate 286 and a first intermediate plate 288. Compared with the expandable component 204, the expandable sub-component 288 has fewer stacked expandable sub components (such as two stacked expandable sub-components in Fig. 9). The first compartment 286 also comprises a first sub-wedge 293 fixed to the top plate 286 and a second sub-wedge 294 fixed to the first intermediate plate 288, which are inserted into the first set of expandable sub-component from a top direction and from a bottom direction respectively. Similarly, the second compartment 283 comprises a second set of expandable sub-components 291 between the first intermediate plate 288 and a second intermediate plate 289. [0050] The second compartment 283 also comprises a third sub-wedge 295 fixed to the first intermediate plate 288 and a fourth sub-wedge 296 fixed to the second intermediate plate 289, which are inserted into the second set of expandable sub components from a top direction and from a bottom direction respectively. The third compartment 284 comprises a third set of expandable sub-components 292 between the second intermediate plate 289 and a bottom plate 287. The third compartment 284 also comprises a fifth sub-wedge 297 fixed to the second intermediate plate 289 and a sixth sub-wedge 298 fixed to the bottom plate 287, which are inserted into the third set of expandable sub-components from a top direction and from a bottom direction respectively. Both the second expandable sub components 291 and the third expandable sub-components 292 also have two stacked expandable sub-components. In this way, the first intermediate plate 288 and the second intermediate plate 289 separate the fourth embodiment 280 into smaller compartments 282-284 for preventing collapse of the energy absorption unit.

[0051 ] Fig. 10 illustrates a cross-sectional view of a fifth embodiment 300 of energy absorption unit with a first external frame 302 composed of a rigid material construct resistant to compression. The fifth embodiment 300 has a similar structure with one of the compartments 282-284 in the Fig. 9 with two stacked expandable sub components sandwiched between a top plate 306 and a bottom plate 308. The first external frame 302 has a cylindrical shape for encompassing stacked expandable sub-components of an expandable component 304 and thus vertically supports the expandable component 304 to resist the compression force (Fc). In particular, the first external frame 302 leaves enough space in the radial direction for the permitting radial expansion of the expandable component 304 while minimizing the vertical compression.

[0052] Fig. 1 1 illustrates a cross-sectional view of a sixth embodiment 320 of energy absorption unit with a second external frame 322. The sixth embodiment 320 has a similar structure with the fifth embodiment 300 with an expandable component 324. In contrast to the first external frame 302, the second external frame 322 has two sub-frames, i.e. a first sub-frame 326 and a second sub-frame 328 for supporting a top portion and a bottom portion of the expandable component 324, respectively. The first sub-frame 326 has a first cover 330 and a first sidewall 332 connected together; while the second sub-frame 328 has a second cover 334 and a second sidewall 336 connected together. In particular, the first sidewall 332 of the frame sub-frame 326 and the second sidewall 336 of the second sub-frame 328 may move relatively to each other and thus become overlapped at an overlapping zone 338. The greater the external force 340 is applied on the first cover 330 and the second cover 334, the larger compression deformation the expandable component 324 would have in the vertical direction, and thus the larger the overlapping zone 330 would become. The sixth embodiment 320 is preferably applicable when the expandable component 324 has a larger number of expandable sub-components which would lead to a large compression deformation. The second external frame 332 also leaves enough space in the radial direction for the expandable component 324 to expand radially.

[0053] Fig. 12 illustrates a cross-sectional view (a) and an overview (b) of a seventh embodiment 350 of energy absorption unit with an internal frame 352. The seventh embodiment 350 comprises an expandable component 354 with four stacked expandable sub-components. In particular, the internal frame 352 has a bottom cover 360 and a cylindrical sidewall 362 connected together. The cylindrical sidewall 362 is embedded between an inner rim 364 and an outer rim 368 and thus would not limit radial expansion of the expandable component 354. The expandable component 354 is positioned on and thus supported by the bottom cover 360. Therefore, the expandable component 354 is sandwiched between a top plate 356 and the bottom cover 360. The seventh embodiment 350 has a top wedge 358 only which advances into a central cavity 368 of the expandable component 354 from the top direction.

[0054] Fig. 13 illustrates a spectrum of forces 380 exerted on an expandable sub component 382. The expandable sub-component 382 needs to be more resistant to compression force 384 than radial tension 386 in order for the expandable sub component 382 to absorb the external force by radial tension 386. Therefore, a maximum radial tension must be less than a maximum compression force required such that the external force would be absorbed through radial stress/tension phase before compressive phase of the expandable sub-component 382. The requirement of the expandable sub-component is briefly expressed as:

Fri < Fci; and Frm < Fern, wherein,

Fri stands for an initial expansion force required to induce the radial expansion;

Frm stands for the maximum expansion force required for a maximum radial expansion;

Fci stands for an initial compression force to induce the compression; and Fern stands for the maximum force to limit the compression.

[0055] Fig. 14 illustrates a cross-sectional view (a) and a top view (b) of an energy absorption system 400 having a series of energy absorption units arranged in a pattern. For example, the energy absorption system 400 has nine energy absorption units 402-418, i.e. a first energy absorption unit 402, a second energy absorption unit 404, a third energy absorption unit 406, a fourth energy absorption unit 408, a fifth energy absorption unit 410, a sixth energy absorption unit 412, a seventh energy absorption unit 414, an eighth energy absorption unit 416 and a ninth energy absorption unit 418 which are arranged into a square pattern 420. The energy absorption system 400 has a top tray 422 and a bottom tray 424, both of which has a square shape in alignment with the square pattern 420. The nine energy absorption units 402-418 are sandwiched between the top tray 422 and the bottom tray 424. In addition, intervening spaces 426 are configured between every two adjacent energy absorption units 402-418 for accommodating radial expansion of the energy absorption units 402-418. The energy absorption system 400 may evenly distribute an external force from all directions such that absorption of kinetic energy of the external force is amplified between the top tray 422 and the bottom tray 424. Arrows and circular dash lines show radial expansion of the fifth energy absorption unit 410 in the middle position of the square pattern 420. And straight dash lines show the intervening space 426. [0056] As a second variation of the subject application, two embodiments of energy absorption unit are shown from Fig. 15 to Fig. 17. Fig. 15 illustrates a top view of an eighth embodiment 500 of energy absorption unit. The eighth embodiment 500 comprises an octagonal base 502 with four hinges 504-510 (i.e. a first hinge 504, a second hinge 506, a third hinge 508 and a fourth hinge 510), and four equidistant arms 512-518 (i.e. a first arm 512, a second arm 514, a third arm 516 and a fourth arm 518) movably coupled to the octagonal base 502 via the hinges 504-510, respectively. The four arms 512-518 are evenly distributed around the octagonal base 502; in other words, the first arm 512 and the third arm 516 are aligned and perpendicular to the second arm 514 and the fourth arm 518. The four arms 512- SI 8 are assembled together by four elastic threads (i.e. a first elastic thread 520, a second elastic thread 522, a third elastic thread 524 and a fourth elastic thread 526) which are arranged concentrically around and sequentially away from the octagonal base 502 through the four arms 512-518. Therefore, the four elastic threads 520- 526 form four concentric rings 528-534 (i.e. a first concentric ring 528, a second concentric ring 530, a third concentric ring 532 and a fourth concentric ring 534) around the octagonal base 502, respectively. When a compression force (not shown) is applied vertically downwards onto any of the equidistant arms 512-518, the equidistant arms 512-518 are pulled apart, resulting in the concentric rings being pulled into radial tension 536.

[0057] Fig. 16 illustrates a cross-sectional view of the eighth embodiment 500 of energy absorption unit. The octagonal base 502 is supported by a central axle 538 which is inserted into a centre of the octagonal base 502. The four equidistant arms 512-518 are inclined at an angle in a range of 30-45 degrees relative to the base 502. Each of the equidistant arms 512-518 has four evenly-spaced holes. For example, the first arm 512 has a first left hole 540, a second left hole 542, a third left hole 544 and a fourth left hole 546 from the bottom to the top; and the third arm 516 has a first right hole 548, a second right hole 550, a third right hole 552 and a fourth right hole 554 from the bottom to the top. In particular, the third left hole 544 and the first right hole 548, the second left hole 542 and the second right hole 550, the third left hole 544 and the third right hole 552, and the fourth left hole 546 and the fourth right hole 554 are aligned at a first level 556, a second level 558, a third level 560 and a fourth level 562, respectively. Similarly, four rear holes (i.e. a first rear hole, a second rear hole, a third rear hole and a fourth rear hole from the bottom to the top (not shown)) of the second arm 514 and four front holes (a first front hole, a second front hole, a third front hole and a fourth front hole from the bottom to the top (not shown)) of the fourth arm 518 are also aligned at the first level 556, the second level 558, the third level 560 and the fourth level 562, respectively. The first elastic thread 520 is arranged through the first left hole 540, the first rear hole (not shown), the first right hole 548 and the first front hole (not shown) at the first level 556 for forming the first concentric ring 528. Similarly, the second elastic thread 522, the third elastic thread 524 and fourth elastic thread 526 are arranged through the second holes (including the second left hole 542, the second rear hole (not shown), the second right hole 550 and the second front hole (not shown) at the second level), the third holes (including the third left hole 544, the third rear hole (not shown), the third right hole 552 and the third front hole (not shown) at the third level) and the fourth holes (including the fourth left hole 546, the fourth rear hole (not shown), the fourth right hole 554 and the fourth front hole (not shown) at the fourth level) for forming the second concentric right 530, the third concentric hole 532 and the fourth concentric hole 534, respectively. When a compression force 564 is applied downwards onto each of the arms 512-518, the arms 512-518 are pulled apart which leads the concentric rings 528-534 to be pulled into the radial tension 536.

[0058] Fig. 17 illustrates a cross-sectional view of a ninth embodiment 600 of energy absorption unit. The ninth embodiment 600 comprises a radial tensile mechanism 602 sandwiched between a top plate 604 and a bottom plate 606. The radial tensile mechanism 602 further comprises a central telescoping axle 608 fixed between the top plate 604 and the bottom plate 606, four arms 610-616 (i.e. a left arm 610, a rear arm 612 (not shown), a right arm 614 and a front arm 616 (not shown)) movably coupled to the central telescoping axle 608. Each of the four arms 610-616 has two sub-arms connected together. For example, the left arm 610 has a first left sub-arm 618 having a first left end 620 and a second left end 622; and a second left sub-arm 624 having a third left end 626 and a fourth left end 628. The first left end 620 and the four left end 628 are connected to the central telescoping axle 608 at the top plate 604 and the bottom plate 606, respectively; while the second left end 622 and the third left end 624 are connected at an angle in a range of 60-90 degrees. Similarly, the right arm 614 has a first right sub-arm 630 having a first right end 632 and a second right end 634; and a second right sub-arm 636 having a third right end 638 and a fourth right end 640. The first right end 632 and the four right end 640 are connected to the central telescoping axle 608 at the top plate 604 and the bottom plate 606, respectively; while the second right end 634 and the third right end 636 are connected at an angle in a range of 60-90 degrees. The rear arm 612 has a first rear sub-arm 642 and a second rear sub-arm 644 connected together similarly; while the front arm 616 has a first front sub-arm 646 and a second front sub-arm 648 connected together similarly.

[0059] The first left sub-arm 618 has four holes (i.e. a first left hole 650, a second left hole 652, a third left hole 654 and a fourth left hole 656 from the first left end to the second left end); while the second left sub-arm 624 has four holes (i.e. a fifth left hole 658, a sixth left hole 660, a seventh left hole 662 and an eighth left hole 664 from the third left end to the fourth left end). The fourth left hole 656 and the fifth left hole 658 are overlapped for connecting the first left sub-arm 618 and the second left sub-arm 624 at the second left end and the third left end. The first right sub-arm has four holes (i.e. a first right hole 666, a second right hole 668, a third right hole 670 and a fourth right hole 672 from the first right end to the second right end); while the second right sub-arm has four holes (i.e. a fifth right hole 674, a sixth right hole 676, a seventh right hole 678 and an eighth right hole 680 from the third right end to the fourth right end). The fourth right hole 672 and the fifth right hole 674 are overlapped for connecting the first right sub-arm and the second right sub arm at the second right end and the third right end. In a similar manner, the first rear sub-arm 642 has four rear holes (i.e. a first rear hole to a fourth rear hole (not shown)); and the second rear sub-arm 644 also has four rear holes (i.e. a fifth rear hole to an eighth rear hole (not shown)). The first front sub-arm 646 has four front holes (i.e. a first front hole to a fourth front hole (not shown)); and the second front sub-arm 648 also has four front holes (i.e. a fifth front hole to an eighth front hole (not shown)). In particular, the first holes (including the first left hole 650, the first rear hole (not shown), the first right hole 666 and the first front hole (not shown)) are aligned at a first level 682. Similarly, the second holes (including the first second hole 652, the second rear hole (not shown), the second right hole 668 and the second front hole (not shown)) to the eighth holes (including the left eighth hole 664, the eighth rear hole (not shown), the eighth right hole 680 and the eighth front hole (not shown)) are aligned at a second level 683 to an eighth level 689 (along with the third level 684, the fourth level 685, the fifth level 686, the sixth level 687, and the seventh 688), respectively. In particular, the fourth level 685 and the fifth level 688 are overlapped in accordance with the overlapped fourth holes and fifth holes.

[0060] Seven elastic threads 690-696 (i.e. a first elastic thread 690, a second elastic thread 691 , a third elastic thread 692, a fourth elastic thread 693, a fifth elastic thread 694, a sixth elastic thread 695 and a seventh elastic thread 696) are arranged through the first holes to the eight holes at the first level 682 to the eighth level 689, respectively. In particular, the fourth elastic thread 693 is arranged through the fourth holes and the fifth holes which are overlapped. The seven elastic threads 690-696 thus form seven concentric rings (not shown) around the elastic axle 608 respectively for assembling the arms 610-616 together. Therefore, the ninth embodiment 600 has a symmetrical configuration to the fourth level 685 or the fifth level 686. When a compressive force 698 is applied to any of the arms 610-616, the central telescoping axle 608 telescopically collapses to shorten in height and simultaneously the concentric rings are pulled out with greater radial tension 699. Hence, the kinetic energy of the compression force 698 is transmitted to the ninth embodiment 600 and converted into elastic potential energy when the concentric rings are forced to expand radially.

[0061 ] As a third variation of the subject application, Fig. 18 illustrates a top view (a) and a cross-sectional view (b) of one level of a tenth embodiment 700 of energy absorption unit in a resting state. As shown in Fig. 18 (a), the tenth embodiment 700 comprises eight elastomeric tension bands 702-716 (i.e. a first elastomeric tension band 702, a second elastomeric tension band 704, a third elastomeric tension band 706, a fourth elastomeric tension band 708, a fifth elastomeric tension band 710, a sixth elastomeric tension band 712, a seventh elastomeric tension band 714 and an eighth elastomeric tension band 716), each of which has a cylindrical profile. The eight elastomeric tension bands 702-716 are evenly distributed in a circular configuration around an imaginary centre 718. The tenth embodiment 700 further comprises circumferential bands 720-726 passing through the elastomeric tension bands 702-716 respectively for connecting the eight elastomeric tension bands 702- 716 together. The four circumferential bands 720-726 comprises a first circumferential band 720, a second circumferential band 722, a third circumferential band 724 and a fourth circumferential band 726 distributed sequentially away from the imaginary centre 718. The four circumferential bands 720-726 form a first concentric configuration 721 , a second concentric configuration 723, a third concentric configuration 725 and a fourth concentric configuration 727, respectively around the imaginary centre 718. In addition, substantially same distances are configured between every two immediately neighbouring concentric configurations 721 -727. As shown in Fig. 18(b), a cross section of the marked region of Fig 18(a) demonstrates the composition of the elastomeric tension bands 702-716. Each of the elastomeric tension bands 702-716 may consist of either a single thick cable or multiple small cables bound together by a peripheral strap 764. As shown in Fig. 18(b), the small cables comprise seven identical small cables 750-762, i.e. a first small cable 750, a second small cable 752, a third small cable 754, a fourth small cable 756, a fifth small cable 758, a sixth small cable 760 and a small seventh cable 762, all of which are bound together by the peripheral strap 764. In particular, the six small cables 750-760 are arranged around the seventh small cable 762.

[0062] Fig. 19 illustrates a top view (a) and a cross-sectional view (b) of one level of the tenth embodiment 700 of energy absorption unit in a stretched state. When a radial expansive force 740 (indicated by the arrows) is exerted on the tenth embodiment 700 of energy absorption unit, the elastomeric tension bands 702-716 moves away from the imaginary centre 718 and meanwhile each of the elastomeric tension bands 702-716 is compressed with a substantially same shorter length than that of the resting state. The circumferential bands 720-726 are stretched accordingly away from the imaginary centre 718. The distances configured between every two immediately neighbouring concentric configurations 721 -727 are also compressed shorter than those of the resting state. The small cables 750-762 and the peripheral strap 764 are also deformed under the radial expansive force 740.

[0063] The energy absorption unit of the subject application may have other variations which are conceived to be not deviated from the inventive concept shown above. The energy absorption may have many applications and three examples will be illustrated below. Although all the variations of the subject application are applicable to the applications, only the first variation above is used as a fundamental unit of shock absorption for showing principles of the applications.

[0064] As a first example, the energy absorption unit is applicable to a head protector (such as a helmet 780). Fig. 20 illustrates (a) a top view of the helmet 780 before an external force 790 is applied; and (b) a top view of the helmet 780 after the external force 790 is applied. The helmet 780 comprises an outer shell 782, an inner shell 784 and an intermediate layer 786 sandwiched between the outer shell 782 and the inner shell 784. In particular, the intermediate layer 786 comprises a plurality of matrix fibres. A dashline frame 788 indicates a region of impact onto the helmet 780 by the external force 790. As shown in Fig. 20(b), the matrix fibres within the intermediate layer 786 and distal to the region of impact are pulled into tension while the outer shell 782 and the inner shell 784 proximal to the region of impact are pulled closer together. Energy absorption is conducted as a two-phase process for the head protector, i.e. a first tension phase and a second compression phase. The first tension phase of shock absorption can be applied using the helmet of trilaminar configuration disclosed earlier. In the patent application, the matrix fibres traverse diagonally across the intermediate layer and are anchored to meshwork forming the base of the inner and outer shells. Hence, the tension cables/cords/fibres will function effectively like seat belts, thereby increasing time interval over momentum reduction. [F=mv-mu/t]. In order to minimise elastic recoil from the matrix fibres pulled under tension, various strategies have been enumerated above, including the tension release mechanism described below:

(1 ) If a continuous stream of interweaving cable is used, both ends of the cable can be connected to a release mechanism which helps to minimise elastic recoil.

(2) The cables run to a disc with cables attaching round the circumference of the disc .

(3) The disc rotates in one direction to increase tension which may be adjusted manually to achieve specific threshold tension.

(4) Slack can be released on cables when specific threshold is reached.

[0065] In some implementations, the intermediate layer 786 between the inner shell 784 and outer shell 782 are lined with a first head protector construct 800 for absorbing kinetic energy applied to the head protector. Fig. 21 illustrates a side view of the first head protector construct 800 which comprises a peg 802 having a top end 804 and a bottom end 806; and a dome-peg-ring construct 808 integrated onto the top end 804. The dome-peg-ring construct 808 has a curved profile which has a concave side in contact with the peg 802. In particular, the dome -peg-ring construct 808 has a four-leave configuration with a first leave 810, a second leave 812, a third leave 814 and a fourth leave 816. Every two of the leaves 810-814 are separated apart by four crevices 818-824, i.e. the first leave 810 and the second leave 812 are separated by a first crevice 818, the second leave 812 and the third leave 814 are separated by a second crevice 820, the third leave 814 and the fourth leave 816 are separated by a third crevice 822, and the fourth leave 816 and the first leave 810 by a fourth crevice 824. The four leaves 810-816 are assembled together by a central anchor 826 at which the four crevices 818-824 terminate. The peg 802 is inserted into an expandable component 828 (not shown) under the concave side of the dome -peg-ring construct 808. The expandable component 828 is integrated within or supported by the inner or outer shell to which it is attached.

[0066] During the second compression phase, an axial loading stress 832 is exerted on the dome-peg-ring construct (convex unit) on one shell 808 by the complementary concave receiver unit on opposing shell which causes the peg 802 to be driven into the expandable component 828 and leads to radial expansion of the expandable component 828. Meanwhile, the dome-peg-ring construct 808 is made of a flexible material and thus is flattened under the axial loading stress 832. But the four leaves do not collide with each other during the compression phase due to the crevices 818-824.

[0067] Fig. 22 illustrates a cross-sectional view of a first embodiment 836 of the first head protector construct 800 (a) in a resting state before the axial loading stress 832 is applied; and (b) in a compression state during the axial loading stress 832 is applied. The first embodiment 836 is arranged as a convex unit which is attached to an top plate 842 (either as the outer shell 782 or the inner shell 784) and faces an bottom plate 843 (either as the inner shell 784 or the outer shell 782 accordingly) of the first head protector (such as the helmet 780). The expandable component 828 has two stacked expandable sub-components. When the axial loading stress 832 is applied on the top plate 842, the top plate 842 is compressed to move towards the dome-peg-ring construct 808. The expandable component 828 are then expanded radially by the peg 802 of the dome-peg-ring construct 808. The radial arrows in the Fig. 22(b) shows expansion of both the expandable sub-components of the expandable component 828.

[0068] Fig. 23 illustrates a cross-sectional view of a second embodiment 837 of the first head protector construct 800 (a) before the axial loading stress 832 is applied; and (b) during the axial loading stress 832 is applied. The second embodiment 837 comprises two convex units in Fig. 22 which face each other. The two convex units are attached to the top plate 842 and the bottom plate 843 respectively. Similar to the first embodiment 836, the expandable component 828 has two stacked expandable sub-components. When the axial loading stress 832 is applied on the top plate 842 or the bottom plate 843, the top plate 842 or the bottom plate 843 is compressed to move towards the dome-peg-ring construct 808. In contrast to the first embodiment 836, the two convex units collide with each other during the compression. The expandable component 828 are then expanded radially by the peg 802 of the dome-peg-ring construct 808. The radial arrows in the Fig. 23(b) shows expansion of both the expandable sub-components of the expandable component 828.

[0069] Fig. 24 illustrates a cross-sectional view of a third embodiment 838 of the first head protector construct (a) before the axial loading stress 832 is applied; and (b) during the axial loading stress 832 is applied. In contrast to the first embodiment 836 and the second embodiment 837, the third embodiment 838 is arranged as a concave receiver unit in which the dome-peg-ring construct 808 is positioned upside-down with the concave side facing away from the expandable component 828. In other words, the convex side of the dome-peg-ring construct 808 is in contact with the peg 802. The dome-peg-ring construct 808 is attached to the top plate 842 and faces the bottom plate 843. When the axial loading force 832 is applied to the bottom plate 843, the outer plate 843 moves towards the dome-peg-ring construct 808. The dome-peg-ring construct 808 is then compressed from the concave side, and the expandable component 828 are expanded radially against the top plate 842. The radial arrows in the Fig. 24(b) shows expansion of the expandable components 828.

[0070] Fig. 25 illustrates a cross-sectional view of a fourth embodiment 839 of the first head protector construct 800 (a) before the axial loading stress 832 is applied; and (b) during the axial loading stress 832 is applied. The fourth embodiment 839 comprises two concave receiver units in Fig. 24 which face each other. The two concave receiver units are attached to the top plate 842 and the bottom plate 843 respectively. When the axial loading stress 832 is applied on the top plate 842 or the bottom plate 843, the top plate 842 or the bottom plate 843 is compressed to move towards the dome-peg-ring construct 808. In contrast to the third embodiment 838, the two concave receiver units collide with each other during the compression. The expandable component 828 are then expanded radially by the peg 802 of the dome-peg-ring construct 808. The radial arrows in the Fig. 25(b) shows expansion of both the expandable sub-components of the expandable component 828.

[0071 ] Fig. 26 illustrates a cross-sectional view of a fifth embodiment 840 of the first head protector construct 800 (a) before the axial loading stress 832 is applied; and (b) during the axial loading stress 832 is applied. The fifth embodiment 840 comprises a concave receiver unit attached to the top plate 842 and a convex unit attached to the bottom plate 843. The concave receiver unit and the convex unit are arranged to face each other. When the axial loading stress 832 is applied on the top plate 842 or the bottom plate 843, the top plate 842 or the bottom plate 843 is compressed to move towards the dome-peg-ring construct 808. In contrast to the second embodiment 837 or the fourth embodiment 839, the concave receiver units and the convex unit match each other when collide with each other during the compression. The expandable component 828 are then expanded radially by the peg 802 of the dome-peg-ring construct 808. The radial arrows in the Fig. 26(b) shows expansion of both the expandable sub-components of the expandable component 828.

[0072] Fig. 27 illustrates cross-sectional view of the first head protector construct 800 in Fig. 22 with an elastic fibre 844 in a resting state. The elastic fibre 844 firstly diagonally spans from one side of the intermediate layer, traverses the crevices 818-824 of the dome -peg-ring construct 808, passes between the peg 802 and expandable component 828, and anchors to the meshwork 846 of the helmet. The fibre then passes back from the meshwork 846 and through the expandable component 828 and the crevices 818-824 in an opposite side before returning to the intermediate layer and crossing diagonally to the next opposite energy absorption unit.

[0073] Fig. 28 illustrates a cross-sectional view of the first head protector construct 800 in Fig. 24 with the elastic fibre 844 in an expansion state. Similar to the Fig. 27, the elastic fibre 844 spans diagonally from one side, transgresses the energy absorption unit, and passes to the opposite side before returning to the intermediate layer and crossing diagonally to the next opposing energy absorption unit. When axial loading stress 832 is applied to the dome -peg-ring construct 808, the dome - peg-ring construct 808 is flattened which further forces the expandable component 828 to expand radially for providing additional energy absorption.

[0074] Fig. 29 illustrates cross-sectional view (a) and a top view (b) of a second head protector construct 850. The second head protector construct 850 has a similar structure to the Fig. 28, but the expandable component 844 is replaced by a rotating disc 852. The rotating disc is also attached to a peg 854 under a concave dome 856. An elastic fibre 858 passes through the dome 856 and runs along a circumference of the rotating disc 852 for reducing an elastic recoil of the elastic fibre 854. In particular, the elastic fibre 858 is tethered to a front tethering point 860 and a rear tethering point 861 on a rim 862 of the rotating disc 852. The rotating disc 852 is connected to a clutch mechanism 864, which essentially acts as a tension-release mechanism on the cables when a specific tension threshold is exceeded When a tensile force 866 is applied to the elastic fibre 858 and reaches a predetermined tension threshold, the clutch mechanism 864 is released which causes the rotating disc 852 to rotate and slacken tension on the elastic fibre 858. The clutch mechanism 864 is composed of a spring mechanism 868 connected between a left tab 870 and a right tab 872 which are attached to the rotating disc 852. When the rotating disc 852 is forced to rotate (by the application of elastic fibre tension to opposing ends of the disc), the left tab 870 and the right tab 872 are pulled in and thus create slack on the elastic fibre 858. The pre-determined tension threshold may be adjusted by modulating the tensile force 866 applied to the spring mechanism 868.

[0075] Fig. 30 illustrates a cross-sectional view of a first energy absorption system of head protector 900 which is located in an intermediate layer 902 between an outer shell 904 and an inner shell 906. The first energy absorption system of head protector 900 has a radial tension system by adopting multiple first head protector constructs 800 or second head protector constructs 840. As shown in Fig. 30(a), the first energy absorption system of head protector 900 has a first set 908 and a second set 910 of the first head protector constructs 800. The first set 908 has two first head protector constructs 800 (i.e. a first construct 912 and a second construct 914) connected to the outer shell 904; while the second set 910 has three first head protector constructs 800 (i.e. a third construct 916, a fourth construct 918 and a fifth construct 920) connected to the inner shell 906. In particular, the first set 908 and the second set are alternatively arranged. In other words, the first construct 912 is arranged between the third construct 916 and the fourth construct 918; and the second construct 914 is arranged between the fourth construct 918 and the fifth construct 920. The first energy absorption system of head protector 900 may have a different number of the constructs (also known as density of construct) in the first set 908 and the second set 910 within the intermediate layer 902. The density of construct may be modulated to achieve variation in capacity of shock absorption capacity, as well as the degree of airflow through the first energy absorption system of head protector 900. The higher the density is, the more efficiently the first energy absorption system of head protector 900 would absorb energy, but the less the degree of airflow would become.

[0076] The first energy absorption system of head protector 900 also has a linear tensile system by adopting an elastic fibre 922 traversing diagonally through the alternatively arranged first set 908 and the second set 910. Therefore, an air gap 924 is left in the intermediate layer 902 among the first energy absorption system of head protector 900. The air gap 924 permits air to circulate freely within the intermediate layer 902 for facilitating airflow through the helmet for cooling head of a user. Therefore, the first energy absorption system of head protector 900 has a radial tension system and a linear tensile system simultaneously. [0077] The first energy absorption system of head protector 900 in Fig. 30(a) has a similar structure, except that the first head protector constructs 800 is replaced by the second head protector constructs 840. In addition, the first set 908 has three second head protector constructs 840 (i.e. a first inverted construct 926, a second inverted construct 928 and a third inverted construct 930) connected to the outer shell 904; and the second set 910 has two second head protector constructs 840 (i.e. a fourth inverted construct 932 and a fifth inverted construct 934). The first set 908 and the second set 910 are also alternatively arranged for forming the air gap 924. Inverted constructs are the concave units.

[0078] Fig. 31 illustrates cross-sectional view of a second energy absorption system of head protector 940 which is constructed by superimposing the two types of the first energy absorption system of head protectors 900 in Fig. 31 (a) and Fig. 31 (b). The second energy absorption system of head protector 940 has a first set 942 and a second set 944 of the first head protector constructs 800 fixed at an outer shell 946 and an inner shell 948, respectively. Both the first set 942 and the second set 944 have five first head protector constructs 800, i.e. a first construct to a fifth construct 950-954 for the first set 942 and a sixth construct to tenth construct 955- 959 for the second set 944, where every construct in the first set 942 has an opposite counterpart in the second set 944. Therefore, the second energy absorption system of head protector 940 has two radial tension systems. In particular, the constructs 950-959 are categorized into a first group 960 and a second group 962 represented in solid line and in dash line, respectively. As shown in Fig. 31 , the first group 960 has the second construct 951 , the fourth construct 953, the sixth construct 955, the eighth construct 957 and the tenth construct 959 which are connected by a first elastic fibre 964 as a first linear tensile system; while the second group 962 has the first construct 950, the third construct 952, the fifth construct 954, the seventh construct 956 and the ninth construct 958 which are connected by a second elastic fibre 966 as the second linear tensile system. In summary, the second energy absorption system of head protector 940 has two radial tension systems and two linear tensile systems and thus has a much higher efficiency for absorbing kinetic energy of the external force. [0079] Fig. 32 illustrates a cross-sectional view of a third energy absorption system of head protector 970 having a similar structure with the second energy absorption system of head protector 940. The third energy absorption system of head protector 970 has a first set 972 connected to an outer shell 973 and a second set 974 connected to an inner shell 975. However, each construct of a first group 976 has one expandable sub-component; while each construct of a second group 978 has two stacked expandable sub-components. The constructs of the second group 978 are connected by an elastic fibre 980 as a linear tensile system; while the constructs of the first group 976 are not connected.

[0080] Fig. 33 illustrates a cross-sectional view of a fourth energy absorption system of head protector 990 having a similar structure with the third energy absorption system of head protector 970. However, the constructs of the first group 976 are connected by an elastic fibre 992 as a linear tensile system; while the constructs of the second group 978 are not connected.

[0081 ] As a second example, the energy absorption unit is applicable to a vehicle 1000 as shown in Fig. 34 with any of the energy absorption units described above. The Vehicle 1000 has an external body framework 1002 and an internal body framework 1004 (also known as safety cell) enclosed inside the external body framework 1002. The vehicle 1000 also has a crumple zone 1006 and a rear bonnet 1008 at the front and the rear of the vehicle 1000. The crumple zone 1006 and the rear bonnet have a front bumper 1010 and a rear bumper for resisting any external shock from a front direction and a rear direction, respectively. The energy absorption unit is arranged at the crumple zone 1006 (particularly the front bumper 1010), the rear bonnet (particularly the rear bumper 1012), a side panel 1014 at the external body framework 1002 and any other region of impact. The vehicle 1000 also has four wheels 1016-1022, i.e. a left front wheel 1016 and a right front wheel 1018 under the crumple zone 1006; and a left rear wheel 1020 and a right rear wheel 1022 under the rear bonnet 1008. The crumple zone 1006 and the rear bonnet 1008 are subjected to external shocks from both an anteroposterior direction 1024 and a lateral direction 1026. [0082] The energy absorption unit may be arranged in the form of packaging or padding. The energy absorption unit may be constructed by any of the above embodiments dome -peg-ring construct 808The packaging or padding made of the energy absorption unit may be distributed along a periphery of the vehicle 1000, such as an inner lining of the external body framework 1002 and an outer lining of the internal framework 1004 or even bridging an entire interface of the vehicle 1000. In particular, the packaging or padding should be so orientated such that the long axis of the model is in alignment to the direction of the external force. In addition, the energy absorption unit can be constructed into a cylindrical configuration for traversing the crumple zone 1006 and the rear bonnet 1008 in both longitudinal and transverse directions in alignment with the direction of the external force. The internal body framework 1008 may be resilient enough to resist intrusion and also provide a firm base for the energy absorption unit to absorb the external force. Moreover, the vehicle 1000 may have a chassis 1028 (not shown) integrated with the energy absorption unit in order to transmit the external force away from the internal body framework 1004.

[0083] Fig. 35 illustrates a cross-sectional view of a first energy absorption system 1 100 of vehicle in a resting state (a) and in a compression state (b). As shown in Fig. 35(a), the first energy absorption system 1 100 has four energy absorption units 1 102-1 108 (i.e. a first energy absorption unit 1 102, a second energy absorption unit 1 104, a third energy absorption unit 1 106 and a fourth energy absorption unit 1 108 from the left to the right) between a top plate 1 1 10 and a bottom plate 1 1 12. The first energy absorption unit 1 102 and the third energy absorption unit 1 106 respectively have a first wedge 1 1 14 and a third wedge 1 1 18 connected to the bottom plate 1 1 12; while the second energy absorption unit 1 104 and the fourth energy absorption unit 1 108 respectively have a second wedge 1 1 16 and a fourth wedge 1 120 connected to the top plate 1 1 10. The energy absorption units 1 102- 1 108 have a first expandable component 1 122, a second expandable component 1 124, a third expandable component 1 126 and a fourth expandable component 1 128 for the wedges 1 1 14-1 120 to move through, respectively. Accordingly, the top plate 1 1 10 has a first opening 1 130 and a third opening 1 134 aligned with the first wedge 1 1 14 and the third wedge 1 1 18, respectively; while the bottom plate 1 1 12 has a second opening 1 134 and a fourth opening 1 136 aligned with the second wedge 1116 and the fourth wedge 1120, respectively. As shown in Fig.35(b), when a compression force 1170 is applied to the top plate 1110 and the bottom plate 1112, the top plate 1110 moves relatively to the bottom plate 1112 since the four expandable components 1122-1128 are compressed. Since the wedges 1114-1120 are almost not compressed, the first wedge 1114 and the third wedge 1118 intrude out of the top plate 1110 via the first opening 1130 and the third opening 1134 respectively; while the second wedge 1116 ad the fourth wedge 1120 intrude out of the bottom plate 1112 via the second opening 1132 and the fourth opening 1136. In addition, an intervening space 1172 is left between every two adjacent energy absorption units, 1102-1108 for allowing the energy absorption units 1102-1108 to expand laterally.

[0084] Fig.36 illustrates a bottom view of the first energy absorption system 1100 of vehicle. The first energy absorption system 1100 has a rectangular configuration 1138 with twelve energy absorption units arranged into three rows (i.e. a first row 1140, a second row 1142 and a third row 1144) of energy absorption units. Fig.36 shows the cross-sectional view of the four energy absorption units 1102-1108 in the first row 1140. The first wedge 1114, the second opening 1132, the third wedge 1118 and the fourth opening 1136 are alternatively exposed from the bottom plate 1112. If viewed from the top plate 1110, the first row 1140 would have an inverted structure where the first opening 1130, the second wedge 1116, the third opening 1134 and the fourth wedge 1120 are exposed. There are also four energy absorption units in the second row 1142 which has the inverted structure with the fifth opening 1154, the sixth wedge 1146, the seventh opening 1156 and the eighth wedge 1148 alternatively arranged from the left to the right. There are also four energy absorption units in the third row 1144 which has a similar structure with the first row 1140 with a ninth wedge 1150, a tenth opening 1158, an eleventh wedge 1152 and a twelfth opening 1160 alternatively arranged from the left to the right. The first energy absorption system 1000 is thus arranged into four parallel lines 1162-1168 (i.e. a first line 1162, a second line 1164, a third line 1166 and a fourth line 1168 from the left to the right). Therefore, the twelve energy absorption units are alternatively and evenly distributed in the first energy absorption system 1000. [0085] Fig. 37 illustrates a cross-sectional view (a) and a top view (b) of a second energy absorption system (shock absorption cylinder) 1200 of vehicle. As shown in Fig. 37(a), the second energy absorption system 1200 has an expandable component 1202 between a top plate 1204 and a bottom plate 1206. A top wedge 1208 and a bottom wedge 1210 are accommodated inside the expandable component 1202 and connected to the top plate 1204 and the bottom plate 1206, respectively. The second energy absorption system 1200 further has a drum 1212 on the bottom plate 1206 for enclosing the expandable component 1202, the top plate 1204, the top wedge 1208 and the bottom wedge 1210. An axle 1214 is connected onto the top plate 1204; and a disc 1216 is connected onto the axle 1214 and opposed to the top plate 1204. As shown in Fig. 37(b), the axle 1214, the drum 1212 and the disc 1216 form a concentric configuration. When a compression force 1218 is applied to the disc 1216, the expandable component 1202 is compressed longitudinally and meanwhile expands laterally; while the top wedge 1208 advances into the expandable component 1202. The axle 1214 and the disc 1216 also move downwardly along with the top wedge 1208. The small arrows show the movement of the axle 1214.

[0086] As a third example, the energy absorption unit is applicable to a garment and footwear. The energy absorption unit may have a stacked model of varying thickness to modulate the contours of a sole of a foot. The stacked model is supported by superior and inferior surfaces/platforms (which is made of a firm material resilient to compression. Both superior and inferior platforms are lined with fine wedges (such as studs) which is made of a lightweight and firm material with a high compressive strength and low friction coefficient with an expandable component of the energy absorption unit. Such materials may include metallic materials or rigid plastic materials. The expandable component is made of a light material but with a low friction coefficient, such as rubber or gel. The low friction coefficient between a wedge and the expandable component is required firstly for allowing the wedge to recoil smoothly when an applied pressure is removed when the foot is lifted from the ground; and secondly for preventing excessive thermal heating and melting with repetitive loading and unloading. In addition, an adequate intervening space is also required between adjacent expandable components in order to accommodate for radial expansions of the expandable components. [0087] Fig. 38 illustrates a cross-sectional view of a first stacked model 2000 of garments and footwear. The first stacked model 2000 has four concertina rings 2002-2008 (i.e. a first concertina ring 2002, a second concertina ring 2004, a third concertina ring 2006 and a fourth concertina ring 2008 from the top to the bottom) and three elastic rings 2010-2014 (i.e. a first elastic ring 2010, a second elastic ring 2012 and a third elastic ring 2014 from the top to the bottom) between a top base 2016 and a bottom base 2018. In particular, the four concertina rings 2002-2008 and the three elastic rings 2010-2014 are arranged in a staggered configuration. A top stud 2020 and a bottom stud 2022 are connected to the top base 2016 and the bottom base 2018, respectively. The top stud 2020 intrudes throughout the first concertina ring 2002 and further into the first elastic ring 2010; while the bottom stud 2022 intrudes throughout the fourth concertina ring 2008 and further into the third elastic ring 2014. The concertina rings 2002-2008 are made of a low-friction material (such as gel) for creating a low-frictional interface between the studs 2020, 2022 and the elastic rings 2010-2014 to prevent overheating of the first stacked model 2000 during cycles of loading and unloading processes against the ground.

[0088] Fig. 39 illustrates a cross-sectional view of a second stacked model 2100 of garments and footwear. The second stacked model 2100 has a first energy absorption units 2102, a second energy absorption unit 2104, a first spring coil 2106 and a second spring coil 2108 from the left to the right between a top base 21 10 and a bottom base 21 12. The first energy absorption unit 2102 has a first stud 21 14 connected on the bottom base 21 12 on one end and intruded into a first expandable ring 21 18 on the other end; and a second stud 21 16 connected on the bottom base 21 12 on one end and intruded into a second expandable ring 2120 on the other end. The spring coils 2106, 2108 provide elastic recoil to the second stacked model 2000 when the foot is elevated from the ground.

[0089] The stacked models of garments and footwear (such as the first stacked model 2000 and the second stacked model 2100) are tested to determine if they work well. Force is applied to the stacked model is compared with a standard model of a same material and thickness for the stacked model. An efficiency of force absorption is primarily determined by two factors: 1 . width/diameter at a given time interval; and

2. reduction in thickness of the material at given time interval.

[0090] Alternatively, graphs demonstrating diameter or thickness per unit time may be plotted, wherein a shallower gradient of thickness change or steeper gradient of diameter increase indicates the material is more efficient in shock absorption.

[0091 ] In the application, unless specified otherwise, the terms "comprising", "comprise", and grammatical variants thereof, intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, non-explicitly recited elements.

[0092] As used herein, the term "about", in the context of concentrations of components of the formulations, typically means +/- 5% of the stated value, more typically +/- 4% of the stated value, more typically +/- 3% of the stated value, more typically, +/- 2% of the stated value, even more typically +/- 1 % of the stated value, and even more typically +/- 0.5% of the stated value.

[0093] Throughout this disclosure, certain embodiments may be disclosed in a range format. The description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1 , 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0094] It will be apparent that various other modifications and adaptations of the application will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the application and it is intended that all such modifications and adaptations come within the scope of the appended claims. Reference Numerals

100 first embodiment of energy absorption unit;

102 wedge;

104 expandable component;

106 outer rim;

108 inner rim;

1 10 central cavity;

1 12 left half;

1 14 right half;

1 16 top end;

1 18 bottom end;

120 contact area;

122 left contact area;

124 right contact area;

130 external force (F);

132 contact force (Fc);

134 frictional force (Ff);

136 left arrow;

137 right arrow;

138 front arrow;

139 rear arrow;

150 spectrum of forces;

152 tangent direction;

154 compression force (Fc);

156 expansion force (Fe);

160 radial expansion rate;

170 radial tension gain;

172 resting state;

174 expandable state;

180 spectrum of forces;

182 tangent direction;

184 compression force (Fc);

186 expansion force (Fe); 200 second embodiment of energy absorption unit;

202 wedge;

204 expandable component;

206 first expandable sub-component;

208 second expandable sub-component;

210 third expandable sub-component;

212 fourth expandable sub-component;

214 fifth expandable sub-component;

216 top wedge;

218 bottom wedge;

220 board;

222 top plate;

224 bottom plate;

226 external force;

230 third embodiment of energy absorption unit;

232 wedge;

234 expandable component;

236 first expandable sub-component;

238 second expandable sub-component;

240 third expandable sub-component;

242 fourth expandable sub-component;

244 fifth expandable sub-component;

246 sixth expandable sub-component;

248 top wedge;

250 bottom wedge;

252 first sub-wedge;

254 second sub-wedge;

256 third sub-wedge;

258 fourth sub-wedge;

260 fifth sub-wedge;

262 sixth sub-wedge;

264 board;

266 top plate; 268 bottom plate;

270 expandable sub-component;

272 height;

274 diameter;

276 centre of gravity;

280 fourth embodiment of energy absorption unit;

282 first compartment;

283 second compartment;

284 third compartment;

286 top plate;

287 bottom plate;

288 first intermediate plate;

289 second intermediate plate;

290 first set of expandable sub-components;

291 second set of expandable sub-components;

292 third set of expandable sub-components;

293 first sub-wedge;

294 second sub-wedge;

295 third sub-wedge;

296 fourth sub-wedge;

297 fifth sub-wedge;

298 sixth sub-wedge;

300 fifth embodiment of energy absorption unit; 302 first external frame;

304 expandable component;

306 top plate;

308 bottom plate;

320 sixth embodiment of energy absorption unit; 322 second external frame;

324 expandable component;

326 first sub-frame;

328 second sub-frame;

330 first cover;

332 first sidewall; 334 second cover;

336 second sidewall;

338 overlapping zone;

340 external force;

350 seventh embodiment of energy absorption unit;

352 internal frame;

354 expandable component;

356 top plate;

358 top wedge;

360 bottom cover;

362 sidewall;

364 inner rim;

366 outer rim;

368 central cavity;

380 spectrum of forces;

382 expandable sub-component;

384 compression force;

386 radial tension;

400 energy absorption system;

402 first energy absorption unit;

404 second energy absorption unit;

406 third energy absorption unit;

408 fourth energy absorption unit;

410 fifth energy absorption unit;

412 sixth energy absorption unit;

414 seventh energy absorption unit;

416 eight energy absorption unit;

418 ninth energy absorption unit;

420 square pattern;

422 top tray;

424 bottom tray;

426 intervening space;

500 eighth embodiment of energy absorption unit;

502 octagonal base; 504 first hinge;

506 second hinge;

508 third hinge;

510 fourth hinge;

512 first arm;

514 second arm;

516 third arm;

518 fourth arm;

520 first elastic thread;

522 second elastic thread;

524 third elastic thread;

526 fourth elastic thread;

528 first concentric ring;

530 second concentric ring;

532 third concentric ring;

534 fourth concentric ring;

536 radial tension;

538 central axle;

540 first left hole;

542 second left hole;

544 third left hole;

546 fourth left hole;

548 first right hole;

550 second right hole;

552 third right hole;

554 fourth right hole;

556 first level;

558 second level;

560 third level;

562 fourth level;

564 compression force;

600 ninth embodiment of energy absorption unit;

602 radial tensile mechanism;

604 top plate; 606 bottom plate;

608 central telescoping axle;

610 left arm;

612 rear arm;

614 right arm;

616 front arm;

618 first left sub-arm;

620 first left end;

622 second left end;

624 second left sub-arm;

626 third left end;

628 fourth left end;

630 first right sub-arm;

632 first right end;

634 second right end;

636 second right sub-arm;

638 third right end;

640 fourth right end;

642 first rear sub-arm;

644 second rear sub-arm;

646 first front sub-arm;

648 second front sub-arm;

650 first left hole;

652 second left hole;

654 third left hole;

656 fourth left hole;

658 fifth left hole;

660 sixth left hole;

662 seventh left hole;

664 eighth left hole;

666 first right hole;

668 second right hole;

670 third right hole;

672 fourth right hole; 674 fifth right hole;

676 sixth right hole;

678 seventh right hole;

680 eighth right hole;

682 first level;

683 second level;

684 third level;

685 fourth level;

686 fifth level;

687 sixth level;

688 seventh level;

689 eight level;

690 first elastic thread;

691 second elastic thread;

692 third elastic thread;

693 fourth elastic thread;

694 fifth elastic thread;

695 sixth elastic thread;

696 seventh elastic thread;

698 compression force;

699 radial tension;

700 tenth embodiment of energy absorption unit;

702 first elastomeric tension band;

704 second elastomeric tension band;

706 third elastomeric tension band;

708 fourth elastomeric tension band;

710 fifth elastomeric tension band;

712 sixth elastomeric tension band;

714 seventh elastomeric tension band;

716 eighth elastomeric tension band;

718 imaginary centre;

720 first circumferential band;

721 first concentric configuration;

722 second circumferential band; 723 second concentric configuration;

724 third circumferential band;

725 third concentric configuration

726 fourth circumferential band;

727 fourth concentric configuration

740 circumferential tension;

742 radial expansive force;

750 first small cable;

752 second small cable;

754 third small cable;

756 fourth small cable;

758 fifth small cable;

760 sixth small cable;

762 seventh small cable;

764 peripheral strap;

800 first head protector construct;

802 peg;

804 top end;

806 bottom end;

808 dome-peg-ring construct;

810 first leave;

812 second leave;

814 third leave;

816 fourth leave;

818 first crevice;

820 second crevice;

822 third crevice;

824 fourth crevice;

826 central anchor;

828 expandable component;

832 axial loading stress;

836 first embodiment of the first head protector construct;

837 second embodiment of the first head protector construct;

838 third embodiment of the first head protector construct; 839 fourth embodiment of the first head protector construct;

840 fifth embodiment of the first head protector construct;

842 top plate;

843 bottom plate;

844 elastic fibre;

846 meshwork;

850 second head protector construct;

852 rotating disc;

854 peg;

856 dome;

858 elastic fibre;

860 front tethering point;

861 rear tethering point

862 rim;

864 clutching mechanism;

866 tensile force;

868 spring mechanism;

870 left tab;

872 right tab;

900 energy absorption system of head protector;

902 intermediate layer;

904 outer shell;

906 inner shell;

908 first set;

910 second set;

912 first construct;

914 second construct;

916 third construct;

918 fourth construct;

920 fifth construct;

922 elastic fibre;

924 air gap;

926 first inverted construct;

928 second inverted construct; 930 third inverted construct;

932 fourth inverted construct;

934 fifth inverted construct;

940 second energy absorption system of head protector;

942 first set;

944 second set;

946 outer shell;

948 inner shell;

950 first construct;

951 second construct;

952 third construct;

953 fourth construct;

954 fifth construct;

955 sixth construct;

956 seventh construct;

957 eighth construct;

958 ninth construct;

959 tenth construct;

960 first group;

962 second group;

964 first elastic fibre;

966 second elastic fibre;

970 third energy absorption system of head protector;

972 first set;

973 outer shell;

974 second set;

975 inner shell;

976 first group;

978 second group;

980 elastic fibre;

990 fourth energy absorption system of head protector;

992 elastic fibre;

1000 vehicle;

1002 external body framework; 1004 internal body framework (safety cell);

1006 crumple zone;

1008 rear bonnet;

1010 front bumper;

1012 rear bumper;

1014 side panel;

1016 left front wheel;

1018 right front wheel;

1020 left rear wheel;

1022 right rear wheel;

1024 anteroposterior direction;

1026 lateral direction;

1028 chassis;

1 100 first energy absorption system;

1 102 first energy absorption unit;

1 104 second energy absorption unit;

1 106 third energy absorption unit;

1 108 fourth energy absorption unit;

1 1 10 top plate;

1 1 12 bottom plate;

1 1 14 first wedge;

1 1 16 second wedge;

1 1 18 third wedge;

1 120 fourth wedge;

1 122 first expandable component;

1 124 second expandable component;

1 126 third expandable component;

1 128 fourth expandable component;

1 130 first opening;

1 132 second opening;

1 134 third opening;

1 136 fourth opening;

1 138 rectangular configuration;

1 140 first row; 1142 second row;

1144 third row;

1146 sixth wedge;

1148 eighth wedge;

1150 ninth wedge;

1152 eleventh wedge;

1154 fifth opening;

1156 seventh opening;

1158 tenth opening;

1160 twelfth opening;

1162 first line;

1164 second line;

1166 third line;

1168 fourth line;

1170 compression force;

1172 intervening space;

1200 second energy absorption system;

1202 expandable component;

1204 top plate;

1206 bottom plate;

1208 top wedge;

1210 bottom wedge;

1212 drum;

1214 axle;

1216 disc;

1218 compression force;

2000 first stacked model;

2002 first concertina ring;

2004 second concertina ring;

2006 third concertina ring;

2008 fourth concertina ring;

2010 first elastic ring;

2012 second elastic ring;

2014 third elastic ring; 2016 top base;

2018 bottom base;

2020 top stud;

2022 bottom stud;

2100 second stacked model;

2102 first energy absorption unit; 2104 second energy absorption unit; 2106 first spring coil;

2108 second spring coil;

21 10 top base;

21 12 bottom base;

21 14 first stud;

21 16 second stud;

21 18 first expandable ring;

2120 second expandable ring;