PEDESTRIAN SAFETY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 62/690,562 filed on June 27, 2018 the content of which is relied upon and incorporated herein by reference in its entirety.

FIELD

[0002] The present disclosure relates generally to glass laminates, and more particularly to laminates with chemically-strengthened glass layers having low weight, high strength and an optimized breakage performance using an active breakage mechanism in the event of a pedestrian impact.

BACKGROUND

[0003] Glass laminates can be used as windows and glazing in architectural and vehicle or transportation applications, including automobiles, rolling stock, locomotives, watercraft, and airplanes. As used herein, a glazing or a laminated glass structure is a transparent, semi transparent, translucent or opaque part of a window, panel, wall, enclosure, cover, sign or other structure. Common types of glazing that are used in appliance, architectural and vehicle applications include clear and tinted laminated glass structures.

[0004] Conventional automotive glazing constructions may consist of two plies of soda lime glass (heat treated or annealed) with a thickness of 2 mm or more and with a polyvinyl butyral PVB interlayer between the two plies. These laminate constructions have certain advantages, including low cost, and a sufficient impact resistance for automotive and other applications. However, because of their limited impact resistance, these laminates usually have a poor behavior and a higher probability of breakage when getting struck by roadside stones, vandals and other impacts. In addition, fuel economy is a function of vehicle weight in many vehicles. It is desirable, therefore, to reduce the weight of glazings for such applications without compromising their strength and sound-attenuating properties.

[0005] In view of the foregoing, so-called hybrid glazings or glass laminates have been introduced that use a chemically-strengthened glass layer in place of at least one of the soda lime glass layers of conventional glazings or glass laminates. These hybrid laminates possess or exceed the durability, sound-damping and breakage performance properties associated l with thicker, heavier glazings, and can be lighter due to using a thinner chemically- strengthened glass layer in place of the relatively thick soda lime layer in conventional laminates.

[0006] However, another important factor in considering vehicle glazing is the safety and protection of not only the vehicle occupants, but also pedestrians and cyclists— so-called vulnerable road users (VRU)— who may be involved in pedestrian-vehicle collisions. As used herein,“pedestrian” may refer to any type of VRU, whether they are persons on-foot or on a bicycle, for example. During most pedestrian-vehicle collisions, the front of the vehicle (e.g., front bumper or grill) first collides with the pedestrian, and the body of the pedestrian wraps around the front shape of the vehicle (e.g., the shape defined by the bumper, hood or bonnet, and front windshield). This wrapping of the body around the shape of the vehicle results in a high probability that the head of the pedestrian will strike one or more particular areas of the vehicle, including the windshield. In some cases, this wrapping of the body results in a head impact at high velocity to a whiplash effect of the body around the shape of the vehicle. The severity and location of impact is determined by many factors, including vehicle shape and height of the pedestrian, which are used to determine a so-called wrap around distance (WAD). The WAD is used to determine likely areas of head impact in a pedestrian-vehicle collision, and these areas may include, for example, at least part of the windshield, particularly the lower part of the windshield nearest the hood or the sides of the windshield.

[0007] While the above-discussed hybrid glazings or laminates can have improved durability and breakage properties with respect to, for example, impacts between hail or stones and the windshield, the toughness of such laminates can have undesirable breakage performance in the event of a collision between a pedestrian and a windshield, for example. Even conventional windshields can improve in breakage performance during pedestrian collisions.

[0008] So-called“pedestrian protection” or“ped-pro” considerations demand that the energy of a collision between a pedestrian and the vehicle is dissipated to a degree so that the risk of injury to the pedestrian is reduced. For example, energy could be dissipated when a windshield breaks upon impact with the pedestrian. To encourage pedestrian safety, the EURO-NCAP (European New Car Assessment Programme) encourages automotive OEMs commercializing their vehicles in Europe to pass pedestrian protection tests, which measure performance in terms of a Head Injury Criterion (HIC) value. While pedestrian protection tests may not be part of standard regulations at this time, it is believed that they likely will be by 2024. Furthermore, automotive OEMs still need to comply to targets to achieve high ratings with insurers, as the testing is part of determining the“5 star” safety rating of a vehicle.

[0009] Conventional windshields made of two plies of relatively thick annealed soda- lime glass (ASLG) may yield and break accomplishing this goal; however, their performance is highly variable and the industry has struggled to consistently achieve the desired HIC targets, which can result in reduced safety ratings for the vehicle. On the other hand, hybrid glazings that include a chemically strengthened glass layer may not yield or break quickly enough (or at all) in the event of a pedestrian impact. For all windshields, a region within 165 cm of the periphery is particularly difficult to achieve this target due to the rigidity of the laminate in those areas (due to curvature and edge effects). The primary approach to achieve low HIC values is to have both plies of the glass fracture and then the PVB inter-layer stretches to absorb the impact. The challenge is that sometimes one or both plies of glass do not reliably fracture or do not fracture quickly enough to safely dissipate the impact energy, and thus result in high HIC values.

[0010] Other existing solutions include deploying airbags on the exterior of a vehicle, such as on or beneath the hood or from within the gap between the hood and windshield, to protect a pedestrian falling onto the hood or windshield. These airbags can be deployed based on sensors within the car detecting a collision. However, such airbag systems are complex and require proper deployment of the airbag, and may not result in better vehicle safety ratings based on the established parameters of ped-pro safety testing, particularly for ped-pro testing of the windshield.

[0011] In view of the foregoing, improved glazing or glass laminate systems using laminates that are thin, light, and durable against certain impacts but that have optimized breakage for pedestrian safety in the event of a pedestrian impact are desired.

SUMMARY

[0012] In certain applications, it is desirable for glass laminates having a high or maximized impact resistance to impacts on an external side of the laminate (external impacts), in order to resist breaking upon impacts from stones, hail or vandals, for example, while safely minimizing or dissipating the energy of a pedestrian striking the windshield to reduce risk of injury to the pedestrian in a vehicular accident.

[0013] According to an aspect of the present disclosure, a vehicle glazing system is provided. The vehicle glazing system has a glass laminate including: an outer glass substrate with a first outer surface, a second inner surface, and a first minor surface separating the first outer surface and the second inner surface; an inner glass substrate with a third outer surface, a fourth inner surface, and a second minor surface separating the third outer surface and the fourth inner surface; and a polymer interlayer between the outer glass substrate and the inner glass substrate. The vehicle glazing system also includes a sensor to detect an impact upon a vehicle in which the vehicle glazing system is installed, and a fracture mechanism to receive a signal from the sensor based on the impact. In the event that the signal indicates a predetermined type of impact, the fracture mechanism is configured to fracture the laminate. Some aspects of this embodiment may include at least one of the inner glass substrate and the outer glass substrate having a thickness of about 2 mm or less. In a further aspect, the inner glass substrate may have a thickness not exceeding 1.5 mm, not exceeding 1.0 mm, or not exceeding 0.7 mm. The inner glass substrate may also be chemically strengthened. In some embodiments, the predetermined type of impact is a collision between a vehicle and a pedestrian or between a vehicle and a headform used in safety testing. According to various embodiments, the vehicle glazing system provides a glazing that achieves low HIC values, which may be lower than 650.

[0014] According to an aspect of one or more other embodiments, a method of actively breaking a windshield of a vehicle is provided. The method includes providing a sensor capable of detecting an impact on the vehicle; providing a fracture mechanism in

communication with the sensor; detecting a predetermined type of impact based on data from the sensor detecting the impact; and fracturing the windshield with the fracture mechanism in response to the predetermined type of impact.

[0015] According to an aspect of one or more other embodiments, a pedestrian protection vehicle system is provided that includes a sensor to detect an impact upon a vehicle in which the vehicle glazing system is installed; and a fracture mechanism to receive a signal from the sensor based on the impact. The fracture mechanism is capable of breaking a glazing of the vehicle in response the signal indicating a predetermined type of impact.

[0016] Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description present embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Fig. 1 is a schematic cross-sectional illustration of a portion of a laminated glass structure according to an embodiment of this disclosure;

[0018] Fig. 2 is a schematic cross-sectional illustration of a portion of a laminated glass structure experiencing an impact according to an embodiment of this disclosure;

[0019] Fig. 3 is a plan view of the laminated glass structure of Fig. 2 according to an embodiment of this disclosure;

[0020] Fig. 4 is a schematic illustration of a glazing system with an active breakage mechanism according to an embodiment of this disclosure;

[0021] Fig. 5 is a schematic illustration of a vehicle glazing system with an active breakage mechanism according to some embodiments of this disclosure;

[0022] Fig. 6 is an illustration of a vehicle including a glazing according to some embodiments of this disclosure;

[0023] Fig. 7 is an illustration of a windshield having regions with a high probability of a pedestrian head strike, according to some embodiments of this disclosure;

[0024] Fig. 8A is a vehicle glazing system, according to some embodiments of this disclosure, before active breaking of the glass laminate has been triggered; [0025] Fig. 8B is the vehicle glazing system of Fig. 8A during or after triggering of active breakage of the glass laminate;

[0026] Fig. 9A is a vehicle glazing system, according to some embodiments of this disclosure, before active breaking of the glass laminate has been triggered;

[0027] Fig. 9B is the vehicle glazing system of Fig. 9A during or after triggering of active breakage of the glass laminate;

[0028] Fig. 10 is a schematic cross-sectional illustration of a section of a vehicle with a vehicle glazing system according to some embodiments of this disclosure;

[0029] Fig. 11 is a schematic illustration of points on a vehicle for which HIC values are tested;

[0030] Fig. 12 is a schematic illustration of the hood and windshield of a vehicle showing wrap around distances for measuring HIC values;

[0031] Fig. 13 is a schematic illustration of vehicle showing the boundaries of an area for which HIC values are tested;

[0032] Fig. 14 is a schematic illustration of a vehicle windshield for which a boundary region is tested for HIC performance;

[0033] Fig. 15 is a schematic illustration of a headform impact used in testing HIC performance; and

[0034] Fig. 16 is a graphical representation of a typical Ped-Pro impact response.

DETAILED DESCRIPTION

[0035] Embodiments disclosed herein are directed to laminated glass articles for vehicular glazings or windshields having controlled glass breakage in response to certain types impacts, and methods of making the same. In particular, embodiments disclosed herein are directed to glass laminates having controlled glass breakage in the event of a vehicular collision with a pedestrian to reduce or minimize the risk of injury to the pedestrian resulting from the pedestrian impacting the glazing or windshield. Some embodiments disclosed herein are directed to systems that result in or actively cause controlled breakage of a vehicle glazing resulting from an active breakage mechanism triggered by a collision with a pedestrian. The controlled breakage may also be triggered by an impact from a dummy or headform used in vehicular safety testing. Aspects of some embodiments include sensing such pedestrian collisions with sensors in the vehicle. The systems and methods disclosed herein can provide glass laminates or vehicles that achieve improved safety ratings, such as lower HIC values than would otherwise be achieved. For example, embodiments of this disclosure can achieve a HIC value of less than 650 for some or all testing points on a glazing or windshield. At least some embodiments herein are applicable to conventional vehicle or automotive glazings. Some embodiments are directed to laminates that are thinner than the laminates used in conventional automotive glazing, and may include one or more strengthened glass substrates.

[0036] As used herein, the phrase“laminates,” which may also be referred to as“laminate structures,” laminate glass structures, or“glazings,” relates to a transparent, semitransparent, translucent or opaque glass-based material. Aspects of this invention pertain to laminates and vehicles and architectural panels that incorporate such structures. Laminates according to one or more embodiments comprise at least two glass substrates. In vehicle applications such as automotive glazings, the internal glass substrate is exposed to a vehicle or automobile interior and the external glass substrate faces an outside environment of the automobile. In one or more embodiments, the external glass substrate and internal glass substrate are bonded together by an interlayer.

[0037] During use, it is desirable that the glass laminate resist fracture in response to most types of external impact events. In addition, in response to internal impact events, such as the glass laminates being struck by a vehicle’s occupant, it is desirable that the glass laminate retain the occupant in the vehicle yet dissipate energy upon impact in order to minimize injury. However, in certain types of external impact events, such as a vehicular collision with a pedestrian, it is desirable for the glass laminate to fracture in a way that dissipates energy from an impact between the pedestrian and the glass laminate. This energy dissipation is a measure to increase pedestrian safety by reducing risk or severity of injury to the pedestrian. Accordingly, embodiments herein include vehicle glazing systems that include glass articles or laminates and an active fracture mechanism to cause such breakage in response to predetermined type of impact, such as a collision with a headform or a pedestrian, while the glass articles resist breakage for other types of impact, such as a stone strike or hail impact.

[0038] According to some embodiments, the glazing system may be designed so that the glazing breaks within a certain time from the specified impact (i.e., a pedestrian or headform impact). By causing breakage within a certain time, the risk of injury to a pedestrian can be decreased. Generally, it is desirable for breakage to occur as soon as possible upon a head impact event to maximize energy dissipation via, for example, glass cracking and stretching of the polymer interlayer. For example, the glass substrate of a laminate may fracture within about 5 ms of detection of the specified type of impact. In some embodiments, the glass substrate may fracture within about 3 ms, within about 2 ms, or within about 1 ms of detection of the specified type of impact. In various embodiments, these time frames may be measured from a time of the specified impact on the glazing itself. In some embodiments, these time frames may be measured from a time that a sensor, which may or may not be located on the glazing itself, detects the specified type of impact. Alternatively, these time frames may be measured from a time that the fracture mechanism is triggered based on a detection of the specified type of impact.

[0039] According to some embodiments, the glass laminate includes two sheets of relatively thin annealed glass. In some embodiments, the glass laminate includes a thin inner glass sheet of strengthened glass. The outer glass sheet can be non-strengthened or annealed glass. In some embodiments, the strengthened inner glass sheet is chemically strengthened via an ion exchange process as described in more detail hereinafter. In some embodiments, the glass may be strengthened through a glass laminate process whereby coefficient of thermal expansion (“CTE”) mismatch from the core of the glass to the surface of the glass creates a compressive zone at the surfaces. However, embodiments may also include monolithic glazing formed from a single glass substrate, or may include laminates with more than two glass substrates.

[0040] As shown in Figure 1, a glass laminate 10 includes an outer glass sheet 11 having a first outer surface (a surface 1) and a second inner surface (a surface 2), an inner glass sheet 13 having a third outer surface (a surface 3) and a fourth inner surface (a surface 4), and a polymer interlayer 15, such as a polyvinyl butyral (PVB) interlayer, between the outer glass sheet 11 and the inner glass sheet 13.

[0041] Figure 2 shows a schematic of the glass laminate 10 when impacted on surface 1 by a headform H, representing the head of a pedestrian or a headform used in safety testing, with a force of impact in the direction shown by the arrow F. The bending of the glass laminate 10 is not necessarily drawn to scale, but illustrates how surface 1 may be put into compression, while surface 4 may be put into tension. Figure 3 shows a plan view of the glass laminate 10 in Figure 2, where the point of impact P with the headform H is shown. In addition, the circle HS represents a region of hoop stress induced in the glass laminate from the impact. Hoop stress can be understood as a normal stress in the tangential direction of circle HS.

[0042] Figure 4 illustrates a schematic arrangement of components of a glazing system 20, according to some embodiments of this disclosure. The system 20 includes a sensor 22, and an active fracture mechanism 24 where the sensor 22 is capable of sending a signal 23 to the active fracture mechanism 24. It is contemplated that the active fracture mechanism 24 can take many forms. In some embodiments, the system 20 further includes the glazing 28, which is to be fractured when the specified impact occurs on the vehicle and/or glazing 28.

[0043] As shown in Figure 4, the active fracture mechanism can include a sharp implement 26, which, when triggered by the active fracture mechanism 24, is driven against or into the glazing 28 to fracture the glazing 28. However, the implement may take other forms, such as a hammer or indenter. The implement may include a material of sufficient hardness or sharpness to ensure fracture of the glazing. In an aspect of some embodiments, the implement 26 is a diamond-tipped indenter. The implement 26 may be spring-loaded, or propelled pneumatically, hydraulically, or electrical, or fired by a chemical or thermo-chemical reaction. The fracture mechanism can use a very small impactor or indenter to achieve glass breakage. For example, in some embodiments, the indenter can have a length of less than 5mm, less than 4 mm, less than 3 mm, less than 2 mm, or less than 1 mm.

[0044] The signal 23 can be sent from the sensor 22 to the active fracture mechanism by any of a number of communication pathways for sending a signal. For example, the signal 23 can be transmitted by an electrically conductive cable or wire, an optical fiber, or other mechanism for carrying a signal along a physical medium. In addition, the signal 23 can be sent via any of a number of wireless communication technologies, including Bluetooth® or other wireless transmission protocol. These are examples only, and not intended to limit embodiments of this disclosure. A person of ordinary skill in the art may appreciate that there are various ways of transmitting such a signal that are known in the art and could be applicable.

[0045] According to some embodiments, the glazing system can include a processor in communication with the sensor and the active fracture mechanism. Figure 5 shows an example of such an embodiment, where the processor 32 is arranged to receive a signal from the sensor 22 and to send a signal to the active fracture mechanism 24. Other features of Figure 5 may correspond to the features of Figure 4 with the corresponding reference numerals, the descriptions of which can be found above and will not be repeated here. The processor 32 can be a microprocessor, computer, or logical circuit capable of determining whether the predetermined type of impact has occurred based on one or more signals received from at least one sensor 22.

[0046] Although only one sensor 22 is shown in Figures 4 and 5, it is contemplated that embodiments may include a plurality of sensors. For example, in Figure 5, multiple sensors 22 may send signals to the processor 32 for determining the type of impact. The processor 32 may receive a number of different inputs and determine whether to trigger the active fracture mechanism 24 based on one or a combination of these inputs. For example, the processor may consider one or more of the following factors: the speed or velocity of the vehicle and/or the pedestrian at the time of collision, the size of the pedestrian (which, for example, may be measured as the distance between the head of the pedestrian and the ground), the height of the vehicle’s bumper from the ground, the height of the vehicle’s hood or bonnet from the ground or from the bumper, the length of the hood or bonnet (as measured from the bumper- side of the hood to the windshield-side of the hood), the shape or incline of the hood or bonnet, the shape of the windshield, the wrap-around distance (WAD) of the vehicle, and the location of impact on the vehicle. Some of these factors may be stored in a computer- readable, non-transitory memory within or in communication with the processor 32, while others may be detected by the sensor 22 or other sensors installed in the vehicle.

[0047] In some embodiments, based on the various inputs received, the processor 32 may calculate a probability of the pedestrian coming into contact with the windshield and/or probability of a certain the type of impact with the windshield that is likely to injure the pedestrian, and, if the probability is above a predetermined threshold, the processor may signal the active fracture mechanism to break the windshield. The predetermined threshold may be above 0 %, but in some instances it may be appropriate for the threshold to be higher, such as above 1 %, above 2 %, above 5 %, above 10 %, or above 50 %, for example.

[0048] The sensor 22 may include different types of sensors or combinations of sensors, according to various embodiments. For example, the sensor may be at least one of a pressure sensor, a resistivity-based sensor, a light detection and ranging (“LiDAR”) sensor, radar, a camera, acoustic sensor, ultrasound sensor, line sensor, or piezoelectric sensor. As an aspect of some embodiments, the sensor may include a pressure sensor that includes a resistivity based sensor, or a fluid filled tube or bladder that detects an increase in pressure of the fluid upon impact. Cameras or other sensors may operate in visual, near-infrared, or infrared (IR) wavelengths. A line sensor may include a pressure-sensitive variable resistance film, tape, or wire. The sensor used in some embodiments may be the same sensor currently used in vehicles to detect a collision and deploying the vehicle’s interior or exterior airbags.

[0049] In addition, according to various embodiments, the sensor 22 can be positioned in various configurations. For example, with reference to Figure 6, sensor position can include at least one of on the exterior or interior of the vehicle bumper 40; mounted to the front facing surface 41 of the vehicle, including on or in a lighting system 42 or front grill 43; the exterior surface of the vehicle hood 44; beneath the vehicle hood (not pictured); in a frame surrounding the vehicle windshield 45; on an exterior or interior side of the windshield 46; within the vehicle glazing (not pictured); or on a left or right side panel 47 of the vehicle 48. For example, in embodiments with a vehicle glazing made from a laminate such as that shown in Figure 1, the sensor may be within the interlayer 15, between the outer glass sheet 11 and the interlayer 15, between the interlayer 15 and the inner glass sheet 13, within the outer glass sheet 11, or within the inner glass sheet 13. In some embodiments, the sensor may be disposed on at least one of surface 1, surface 2, surface 3, and surface 4. For example, the sensor may include a wire mesh sensor, such as a silver grid, in the outer glass substrate or on the second inner surface. The type of mesh sensor is not particularly limited, but in some embodiments may include nano- or micro-scale wire.

[0050] In embodiments where the sensor is positioned on or in the glazing itself, one or more sensors, such as a distributed mesh or grid sensor, may be placed throughout the entire area of the glazing, or may be positioned strategically in one or more areas of the glazing that have a higher probability of being impacted by a pedestrian’s head. These areas may also correspond to the areas of the windshield that are subjected to ped-pro safety testing. Figure 7 shows, with a dashed outline, a region 52 along the bottom and left and right side of glazing 50. The region 52 roughly corresponds to the areas of the glazing 50 that would be subjected to ped-pro testing according to the EURO-NCAP testing protocols to determine HIC values. The region 52 may not extend to the top of a windshield due to specifications related to the maximum Wrap Around Distance (or“WAD”) of a pedestrian or bicyclist in a vehicular collision, as specified by EURO-NCAP for a given vehicle. Accordingly, the region 52 in Figure 7 only extends vertically up the center area of glazing 50 for a short distance and does not include most of the upper border of the glazer. In some embodiments, the region 52 may extend up to height of the maximum WAD.

[0051] Depending on the type of impact on the vehicle or glazing, the sensors may register a different signal response that can be used to differentiate between the predetermined type (e.g., an impact from a pedestrian or headform), and other impacts (e.g., impacts from hail, stones, or other roadside debris) that ideally should not trigger the active fracture mechanism. In some embodiments, this differentiation between types of impacts can be based on the stress induced in the glass from the impact. A head or headform is relatively large compared to other objects (e.g., hail, stones) that more frequently strike a windshield. Due to the size and weight, the resulting force of impact and stress field induced in the windshield will be different from a headform as compared to a small stone, for example. Accordingly, embodiments of this disclosure include a system that triggers an active fracture mechanism in response to a sensor detecting a stress in the glazing that is characteristic of a stress induced by a head or headform. For example, one or more sensors may detect a hoop stress in the glazing, as shown in Figure 3, that has a diameter and/or magnitude corresponding to the predetermined impact type. In another example, a sensor or sensor array may detect a change in stress in the glazing at two or more separate locations on the laminate where the shape of the detected stress field, the magnitudes of the stresses detected, or the timing of the separate detections indicate an impact from a head or headform.

[0052] Figures 8A and 8B illustrate an embodiment of an active fracture mechanism 64 including an indenter or punch 66 for fracturing an inner glass layer 13 of a laminate 10, according to some embodiments. As shown in Figure 8A, the impactor 66 is disposed near surface 4 of the inner glass layer 13 when the active fracture mechanism 64 is in an un triggered state. In other words, in Figure 8A, the active fracture mechanism 64 is shown in a state before the predetermined type of impact has been detected and the impactor 66 has not yet been impacted and fractured the laminate 10. Figure 8B, on the other hand, shows the impactor 66 in a state during or after fracturing of the laminate 10. Specifically, the active fracture mechanism 64 has received a signal indicating that the predetermined type of impact has occurred, and the active fracture mechanism 64 has caused the impactor 66 to impact surface 4 of the inner glass sheet 13. The cracks 68 indicate that the inner glass sheet 13 has fractured, although the cracks 68 are not intended to necessarily depict an actual mode of failure or crack propagation in the inner glass sheet 13.

[0053] Figures 9A and 9B illustrate an aspect of some embodiments where the impactor 66 is disposed near a minor surface 5, or edge, of the inner glass sheet 13, the minor surface 5 separating surfaces 3 and 4. In Figure 9B, the impactor 66 has been driven into the edge 5 by the active fracture mechanism 64.

[0054] In some embodiments, the region of the inner glass sheet 13 that is impacted by the impactor 66 in Figures 8A-9B may have different mechanical properties than other regions of the inner glass sheet 13. In particular embodiments, the region of the glass sheet 13 that is impacted by the impactor may be a locally weakened region. The local weakening of the region can be a result of local annealing, using a heat source or laser, for example. In some embodiments where the inner glass sheet 13 is chemically strengthened, the region may be locally weakened during an ion exchange process, such as weakening by localized masking during the ion exchange process. Using localized masking during ion exchange, low-strength areas may be formed on at least surface 4 of the laminate 10. However, the low-strength areas may also be formed on surface 3, or surface 3 and surface 4. Embodiments are not limited to any specific material or coating for masking, but the masking should be able to sustain the ion exchange bath conditions to be effective, and be removed after the ion exchange. The localized weakening can be applied to only a very small area of the inner glass sheet 13 to minimize the chance of the weakened region being fractured unintentionally (e.g., from a stone strike). In an aspect of some embodiments, the weakened region is hidden within a frame around the glazing so that the weakened region is protected from external impacts, and only susceptible to intentional fracturing by the active fracture mechanism.

[0055] The strength and mechanical impact performance of a glass sheet or laminate can be affected by defects or flaws in the glass, including both surface and internal defects. For this reason, accidental or naturally occurring defects and flaws in the glass are normally undesirable as the flaws may limit strength and initiate failure of a glass substrate due to stress concentrations at or around the flaw. However, embodiments of this disclosure include glass articles or laminates with flaws formed in the glass to assist in fracturing the glass substrate. The types of flaws include the locally weakened regions discussed above, but are not limited thereto. Referring to Figure 1, the flaws may be located within at least one of the inner glass sheet 13 and the outer glass sheet 11 ; or on at least one of the first outer surface (surface 1), the second inner surface (surface 2), the third outer surface (surface 3), or the fourth inner surface (surface 4). The flaws may be intentionally formed in an area of the glass which will be subjected to stress or fracture from the active fracture mechanism discussed herein. For example, the active fracture mechanism may induce a stress field in the internal glass substrate upon impacting one of the external or internal glass substrates. That stress field may cause a stress concentration at or near the flaw that exceeds the fracture stress of the glass substrate. A stress concentration at or near the flaw may be influenced by the size and/or shape of the flaw. For example, the flaw may be shaped to have one or more sharp comers, or aspects with a small radius of curvature around which a high stress field is induced.

[0056] An aspect of some embodiments includes a plurality of flaws formed in a predetermined pattern to contribute to or hasten failure along a certain path within the substrate. The arrangement of flaws can be located in one or more specific areas of the laminate, such as areas corresponding to areas of a windshield likely to be struck by a pedestrian in a collision, or areas of a windshield that are tested to measure HIC values.

[0057] The defects or flaws are designed so that the risk of breakage due to other types of impacts on an exterior of the laminate, such as a rock strike or hail, is minimized. The risk of such unwanted breakage is minimized by controlling aspects of the points of fracture initiation, including size, spacing, shape of individual points, pattern of multiple points, depth, or location on or in a glass sheet. The defects or flaws according to some embodiments can be formed in or on a glass sheet through local annealing, laser ablation, scratches formed on a surface of the glass sheet, localized weakening during an ion exchange (“IOX”) process, or hard contact indentations. The terms“flaw” and“defect” may be used interchangeably herein, but unless otherwise noted are not intended to refer to natural or accidental flaws or defects resulting from typical manufacturing or handling processes, or from damage created during normal use, but rather refer to designed or engineered features formed on or in glass articles to achieve the desired breakage performance. [0058] As shown in Figure 10, a glazing 70 separates a hood 72 on the exterior of a vehicle from a dashboard or frame 73 on the interior of the vehicle. An active fracture mechanism 74 may be positioned on the interior side of the glazing 70 and within the dashboard or frame 73. The active fracture mechanism 74 includes an impactor 76 and a source of stored potential energy, such as a spring 75, capable of causing the impactor 76 to break the glazing 70 when triggered by the active fracture mechanism 74. In some embodiments, the impactor 76 may impact the interior surface of the glazing 70, as shown in Figure 10. However, the impactor 76 may also impact an edge or minor surface of the glazing 70, as discussed above.

[0059] The depiction of the impactor 66 in Figures 8A-10 is not meant to limit the form or type of impactor that can be used in various embodiments disclosed herein. For example, the impactor can be a sharp implement such as a nail or spike, similar to what is shown in Figure 8A-10, or a blunt implement such as a hammer. Alternatively, the impactor may an inflatable body, such as an airbag, or may be a projectile that is fired at the glass substrate. In alternative embodiments, the impactor may be the force generated from a controlled explosion or chemical reaction designed to break the glazing. Without wishing to be bound by theory, the impactor may cause failure of the glass substrate by piercing or indenting a surface of the glass substrate (e.g., surface 4 or surface 5 of inner glass sheet 13). The indentation or flaw formed in the glass substrate as a result of the impact may reach to a region of central tension (CT), which causes the substrate to fail. In some embodiments, the impactor puts a region of the glass substrate into a state of tension that is beyond the tensile strength of the glass substrate at that point, causing the substrate to fail. In some

embodiments, the active fracture mechanism initiates breakage on the edge or minor surface of a glass substrate where the region of central tension is most exposed and the depth of compression on the edge is small or none existent. In addition, flaws formed during manufacturing, forming, shaping, or cutting of the glass substrate may be more prevalent near the edge of the glass substrate, and can contribute to breakage when it is initiated by the active fracture mechanism. In this way, the glass substrate may be more easily fractured by impacting the edge, according to some embodiments.

[0060] While the impactor in Figures 8A-10 is arranged to impact the inner glass sheet 13, the impactor may also be arranged to impact both the outer and inner glass sheets 11 and 13, either simultaneously or sequentially in any order. For example, the impactor may impact an edge of both the outer and inner glass sheets 11 and 13 at substantially the same time, or may be driven through one of the outer and inner glass sheets 11 and 13 and into the other of the outer and inner glass sheets 11 and 13. Alternatively, the impactor may be arranged to impact only the outer glass sheet 11.

[0061] According to embodiments of this disclosure, referring to Figure 1, the inner glass sheet 13 can be chemically strengthened glass having a thickness of 1.5 mm or less or 1.0 mm or less, for example 0.55 mm, 0.5 mm or 0.7 mm, that have been strengthened via an ion exchange process. For example, the inner glass sheet 11 may both be formed of Coming ^® Gorilla ^® glass from Coming Incorporated. As described in U.S. Patent Nos. 7666511, 4483700 and 5674790, Coming Gorilla glass is made by fusion drawing a glass sheet and then chemical strengthening the glass sheet. As described in more detail hereinafter, Coming Gorilla glass has a relatively deep depth of layer (DOL) of compressive stress, and presents surfaces having a relatively high flexural strength, scratch resistance and impact resistance.

[0062] Terms of orientation, such as“outer,”“external,”“internal,” and“inner” are used in certain embodiments described herein in relation to the inside and outside of a vehicle, device or building, but it will be appreciated that the laminate could be reversed in certain application such that the inner and outer surfaces of the laminate are reversed. As such, these terms as used in the present disclosure and in the appended claims should be interpreted as orienting the layers in the laminate and the surfaces of the layers in relation to each other, rather than in relation the inside or outside of a vehicle, device or structure unless specifically stated otherwise.

[0063] According to certain embodiments hereof, by way of example only, the inner glass sheet 13 is chemically strengthened to have a CS in a range of about 400 MPa to about 900 MPa, or from about 700 MPa to about 750 MPa and a depth of layer (DOL) of about 40 pm, or greater than or equal to 40 pm.

[0064] As previously described, suitable glass sheets may be chemically strengthened by an ion exchange process. In this process, typically by immersion of the glass sheet into a molten salt bath for a predetermined period of time, ions within the glass sheet at or near the surface of the glass sheet are exchanged for larger metal ions, for example, from the salt bath. In one embodiment, the temperature of the molten salt bath is about 430°C and the predetermined time period is about eight hours. The incorporation of the larger ions into the glass strengthens the sheet by creating a compressive stress in a near surface region. A corresponding tensile stress is induced within a central region of the glass sheet to balance the compressive stress.

[0065] Example ion-exchangeable glasses that are suitable for forming glass laminates are alkali aluminosilicate glasses or alkali aluminoborosilicate glasses, though other glass compositions are contemplated. As used herein,“ion exchangeable” means that a glass is capable of exchanging cations located at or near the surface of the glass with cations of the same valence that are either larger or smaller in size.

[0066] One example glass composition comprises SiCE, B2O3 and Na20, where (SiCE + B2O3) > 66 mol.%, and Na20 > 9 mol.%. In an embodiment, the glass sheets include at least 6 wt.% aluminum oxide. In a further embodiment, a glass sheet includes one or more alkaline earth oxides, such that a content of alkaline earth oxides is at least 5 wt.%. Suitable glass compositions, in some embodiments, further comprise at least one of K2O, MgO, and CaO. In a particular embodiment, the glass can comprise 61-75 mol.% SiCE; 7-15 mol.% AI2O3; 0-12 mol.% B2O3; 9-21 mol.% Na20; 0-4 mol.% K2O; 0-7 mol.% MgO; and 0-3 mol.% CaO.

[0067] A further example glass composition suitable for forming glass laminates comprises: 60-70 mol.% SiCE; 6-14 mol.% AI2O3; 0-15 mol.% B2O3; 0-15 mol.% LEO; 0-20 mol.% Na20; 0-10 mol.% K2O; 0-8 mol.% MgO; 0-10 mol.% CaO; 0-5 mol.% Z1O2; 0-1 mol.% Sn02; 0-1 mol.% Ce02; less than 50 ppm AS2O3; and less than 50 ppm Sb203; where 12 mol.% < (LEO + Na20 + K2O) < 20 mol.% and 0 mol.% < (MgO + CaO) < 10 mol.%.

[0068] A still further example glass composition comprises: 63.5-66.5 mol.% S1O2; 8-12 mol.% AI2O3; 0-3 mol.% B2O3; 0-5 mol.% LEO; 8-18 mol.% Na ₂ 0; 0-5 mol.% K2O; 1-7 mol.% MgO; 0-2.5 mol.% CaO; 0-3 mol.% Zr0 ₂ ; 0.05-0.25 mol.% Sn0 ₂ ; 0.05-0.5 mol.% Ce02; less than 50 ppm AS2O3; and less than 50 ppm Sb203; where 14 mol.% < (LEO + Na20 + K2O) < 18 mol.% and 2 mol.% < (MgO + CaO) < 7 mol.%.

[0069] In a particular embodiment, an alkali aluminosilicate glass comprises alumina, at least one alkali metal and, in some embodiments, greater than 50 mol.% S1O2, in other embodiments at least 58 mol.% S1O2, and in still other embodiments at least 60 mol.% S1O2,

, · , · AL0. + B ₇ 0. . .

wherein the ratio - > 1 , wherein the ratio the components are expressed in

mol.% and the modifiers are selected from alkali metal oxides. This glass, in particular embodiments, comprises, consists essentially of, or consists of: 58-72 mol.% SiC ; 9-17 mol.% AI2O3; 2-12 mol.% B2O3; 8-16 mol.% Na20; and 0-4 mol.% K2O, wherein the ratio

[0070] In another embodiment, an alkali aluminosilicate glass comprises, consists essentially of, or consists of: 61-75 mol.% S1O2; 7-15 mol.% AI2O3; 0-12 mol.% B2O3; 9-21 mol.% Na20; 0-4 mol.% K2O; 0-7 mol.% MgO; and 0-3 mol.% CaO.

[0071] In yet another embodiment, an alkali aluminosilicate glass substrate comprises, consists essentially of, or consists of: 60-70 mol.% S1O2; 6-14 mol.% AI2O3; 0-15 mol.% B2O3; 0-15 mol.% L12O; 0-20 mol.% Na ₂ 0; 0-10 mol.% K2O; 0-8 mol.% MgO; 0-10 mol.% CaO; 0-5 mol.% Zr02; 0-1 mol.% Sn02; 0-1 mol.% Ce02; less than 50 ppm AS2O3; and less than 50 ppm Sb203; wherein 12 mol.% < L12O + Na20 + K2O < 20 mol.% and 0 mol.% < MgO + CaO < 10 mol.%.

[0072] In still another embodiment, an alkali aluminosilicate glass comprises, consists essentially of, or consists of: 64-68 mol.% S1O2; 12-16 mol.% Na20; 8-12 mol.% AI2O3; 0-3 mol.% B2O3; 2-5 mol.% K2O; 4-6 mol.% MgO; and 0-5 mol.% CaO, wherein: 66 mol.% < S1O2 + B2O3 + CaO < 69 mol.%; Na ₂ 0 + K2O + B2O3 + MgO + CaO + SrO > 10 mol.%; 5 mol.% < MgO + CaO + SrO < 8 mol.%; (Na20 + B2O3) - AI2O3 < 2 mol.%; 2 mol.% < Na20 - AI2O3 < 6 mol.%; and 4 mol.% < (Na20 + K2O) - AI2O3 < 10 mol.%.

[0073] The glass, in some embodiments, is batched with 0-2 mol.% of at least one fining agent selected from a group that includes Na2S0 ₄ , NaCl, NaF, NaBr, K2SO4, KC1, KF, KBr, and Sn02.

[0074] In one example embodiment, sodium ions in the glass can be replaced by potassium ions from the molten bath, though other alkali metal ions having a larger atomic radius, such as rubidium or cesium, can replace smaller alkali metal ions in the glass. According to particular embodiments, smaller alkali metal ions in the glass can be replaced by Ag ⁺ ions. Similarly, other alkali metal salts such as, but not limited to, sulfates, halides, and the like may be used in the ion exchange process.

[0075] The replacement of smaller ions by larger ions at a temperature below that at which the glass network can relax produces a distribution of ions across the surface of the glass that results in a stress profile. The larger volume of the incoming ion produces a compressive stress (CS) on the surface and tension (central tension, or CT) in the center region of the glass. The compressive stress is related to the central tension by the following relationship:

where t is the total thickness of the glass sheet and DOL is the depth of exchange, also referred to as depth of layer.

[0076] According to various embodiments, thin glass laminates comprising one or more sheets of ion-exchanged glass and having a specified depth of layer versus compressive stress profile possess an array of desired properties, including low weight, high impact resistance, and improved sound attenuation.

[0077] In one embodiment, a chemically-strengthened glass sheet can have a surface compressive stress of at least 300 MPa, e.g., at least 400 MPa, at least 500 MPa, at least 600 MPa, or at least 700 MPa, a depth of at least about 20 pm (e.g., at least about 20, 25, 30, 35, 40, 45, or 50 pm) and/or a central tension greater than 40 MPa (e.g., greater than 40, 45, or 50 MPa) and less than 100 MPa (e.g., less than 100, 95, 90, 85, 80, 75, 70, 65, 60, or 55 MPa).

[0078] Independently of, or in conjunction with, the foregoing relationships, the chemically-strengthened glass can have depth of layer that is expressed in terms of the corresponding surface compressive stress. In one example, the near surface region extends from a surface of the first glass sheet to a depth of layer (in micrometers) of at least

65-0.06(CS), where CS is the surface compressive stress and has a value of at least 300 MPa.

[0079] In a further example, the near surface region extends from a surface of the first glass sheet to a depth of layer (in micrometers) having a value of at least B-M(CS), where CS is the surface compressive stress and is at least 300 MPa. In the foregoing expression, B can range from about 50 to 180 (e.g., 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160 ± 5), and

M can range independently from about -0.2 to -0.02 (e.g., -0.18, -0.16, -0.14, -0.12, -0.10, - 0.08, -0.06, -0.04 ± -0.01).

[0080] A modulus of elasticity of a chemically-strengthened glass sheet can range from about 60 GPa to 85 GPa (e.g., 60, 65, 70, 75, 80 or 85 GPa). The modulus of elasticity of the glass sheet(s) and the polymer interlayer can affect both the mechanical properties (e.g., deflection and strength) and the acoustic performance (e.g., transmission loss) of the resulting glass laminate. [0081] Glass laminates for automotive glazing and other applications can be formed using a variety of processes. In an example process, one or more sheets of chemically-strengthened glass sheets can be assembled in a pre-press with a polymer interlayer, tacked into a pre laminate, and finished into an optically clear glass laminate. A thermoplastic material such as PVB may be applied as a preformed polymer interlayer. The thermoplastic layer can, in certain embodiments, have a thickness of at least 0.125 mm (e.g., 0.125, 0.25, 0.375, 0.5,

0.75, 0.76 or 1 mm). The thermoplastic layer can cover most or, preferably, substantially all of the two opposed major faces of the glass. It may also cover the edge faces of the glass. The glass sheet(s) in contact with the thermoplastics layer may be heated above the softening point of the thermoplastic, such as, for example, at least 5°C or l0°C above the softening point, to promote bonding of the thermoplastic material to the glass. The heating can be performed with the glass ply in contact with the thermoplastic layers under pressure.

[0082] A modulus of elasticity of the polymer interlayer can range from about 1 MPa to 75 MPa (e.g., about 1, 2, 5, 10, 15, 20, 25, 50 or 75 MPa). At a loading rate of 1 Hz, a modulus of elasticity of a standard PVB interlayer can be about 15 MPa, and a modulus of elasticity of an acoustic grade PVB interlayer can be about 2 MPa.

[0083] One or more polymer interlayers may be incorporated into a glass laminate. A plurality of interlayers may provide complimentary or distinct functionality, including adhesion promotion, acoustic control, UV transmission control, and/or IR transmission control.

[0084] The glass laminates can be adapted for use, for example, as windows or glazings, and configured to any suitable size and dimension. In embodiments, the glass laminates have a length and width that independently vary from 10 cm to 1 m or more (e.g., 0.1, 0.2, 0.5, 1,

2, or 5 m). Independently, the glass laminates can have an area of greater than 0.1 m ² , e.g., greater than 0.1, 0.2, 0.5, 1, 2, 5, 10, or 25 m ² .

[0085] The glass laminates can be substantially flat or shaped for certain applications. For instance, the glass laminates can be formed as bent or shaped parts for use as windshields or cover plates. The structure of a shaped glass laminate may be simple or complex. In certain embodiments, a shaped glass laminate may have a complex curvature where the glass sheets have a distinct radius of curvature in two independent directions. Such shaped glass sheets may thus be characterized as having“cross curvature,” where the glass is curved along an axis that is parallel to a given dimension and also curved along an axis that is perpendicular to the same dimension. An automobile sunroof, for example, typically measures about 0.5 m by 1.0 m and has a radius of curvature of 2 to 2.5 m along the minor axis, and a radius of curvature of 4 to 5 m along the major axis.

[0086] Methods for bending and/or shaping glass laminates can include gravity bending, press bending and methods that are hybrids thereof. In a traditional method of gravity bending thin, flat sheets of glass into curved shapes such as automobile windshields, cold, pre-cut single or multiple glass sheets are placed onto the rigid, pre-shaped, peripheral support surface of a bending fixture. The bending fixture may be made using a metal or a refractory material. In an example method, an articulating bending fixture may be used. Prior to bending, the glass typically is supported only at a few contact points. The glass is heated, usually by exposure to elevated temperatures in a lehr, which softens the glass allowing gravity to sag or slump the glass into conformance with the peripheral support surface.

Substantially the entire support surface generally will then be in contact with the periphery of the glass.

[0087] A related technique is press bending where flat glass sheets are heated to a temperature corresponding substantially to the softening point of the glass. The heated sheets are then pressed or shaped to a desired curvature between male and female mold members having complementary shaping surfaces. In embodiments, a combination of gravity bending and press bending techniques can be used.

[0088] Applicants have shown that the glass laminate structures disclosed herein have excellent durability, impact resistance, toughness, and scratch resistance, while having improved breakage performance with respect to pedestrian safety. Due to chemical strengthening, one or both of the external surfaces of the glass laminates disclosed herein are under compression. In order for flaws to propagate and failure to occur, the tensile stress from an impact must exceed the surface compressive stress at the tip of the flaw. In embodiments, the high compressive stress and high depth of layer of chemically-strengthened glass sheets enable the use of thinner glass than in the case of non-chemically-strengthened glass.

[0089] In an embodiment hereof, a glass laminate can comprise inner and/or outer glass sheets such as chemically-strengthened glass sheets. In particular, the inner-facing glass sheet (e.g., an inner chemically-strengthened glass sheet) can have a surface compressive stress of from one-third to one-half the surface compressive stress of the outer chemically- strengthened glass sheet, or equal that of the outer glass sheet. Flaws may optionally be formed in the outer surface 3 or inner surface 4 of the inner glass sheet.

[0090] In other embodiments hereof the outer glass sheet 11 maybe formed of a non- chemically strengthened glass sheet, such as a soda lime glass sheet, having a thickness of about 1.5 mm or greater, about 2 mm or greater or about 2.5 mm or greater and the inner glass sheet 13 may be a thin chemically strengthened glass sheet having a thickness, CS, DOL. The CS of the inner glass sheet in these embodiments may be about 300 MPa or greater, or about 700 MPa or greater. The non-chemically strengthened external glass sheets may optionally be heat strengthened or thermally tempered.

[0091] In a further embodiments hereof, the the inner sheet 13 maybe formed of non- chemically strengthened glass sheet, such as a soda lime glass sheet, having a thickness of about 1.5 mm or greater, about 2 mm or greater, or about 2.5 mm or greater and the outer glass sheet 11 may be a thin chemically strengthened glass sheet having a thickness, CS and DOL as previously described herein. The CS of the inner glass sheet in these embodiments may be about 550 MPa. The non-chemically strengthened internal glass sheet may optionally be heat strengthened or thermally tempered.

[0092] Pedestrian Protection Criteria

[0093] Certain aspects of pedestrian protection testing and rating will be discussed below to inform the mechanical performance and advantages of embodiments of this disclosure. References herein to the EURO-NCAP protocol are to the EURO-NCAP Assessment Protocol v9.0.2, the EURO-NCAP Pedestrian Test Protocol v8.4, and the EURO-NCAP Autonomous Emergency Breaking (AEF) Vulnerable Road User (VRU) Test Protocol v2.0.2. While the EURO-NCAP protocols involve impact testing using headform, upper legform, and lower legform testing, as well as AEB test data, and include impacts to the bumper and bonnet/hood of vehicles, embodiments of this disclosure are primarily concerned with HIV values as they related to impacts to the glazing or windshield. However, as discussed above, embodiments of the systems and methods disclosed herein include sensors that detect impacts on other parts of a vehicle not necessarily limited to the glazing. [0094] According to the EURO-NCAP safety ratings system, the potential risk of head injury in the event of a vehicle striking a pedestrian is estimated using a series of impact tests is performed using a headform impactor traveling at up to 40 km/h. The tests include impacting the headform at several grid points on the bonnet/hood and on an installed windshield. In the headform impact area, as shown in Figure 11, a grid of points 154 is marked on the outer surface of the vehicle 150, including on the windshield 152, and some or all of the points are tested. The headform test area is bounded by the geometric trace of the 1000 mm wrap around line 156 (see Figures 12 and 13) in the front, the sides 160 and 162 of the bonnet/hood, and the 2100 mm wrap around distance (WAD) 158.

[0095] The impact points are then assessed and the protection offered is rated as“good,” “adequate,”“marginal,”“weak,” or“poor.” Specifically, each point of the grid points can be awarded up to one scoring point according to the measured Head Injury Criterion (HIC) value (HIC < 650 = 1.00 point; 650 < HIC < 1000 = 0.75 points; 1000 < HIC < 1350 = 0.50 points; 1350 < HIC < 1700 = 0.25 points; and 1700 < HIC = 0.00 points). The final score will define the number of safety stars that the vehicle will be granted (from 1 to 5). The data is often represented by color-coding the grid points according to the color codes shown in Table 1 below. EURO-NCAP rates each model of vehicle with its own test.

Table 1. HIC Vale Color Coding.

[0096] The vehicle manufacturer provides HIC values (or color data according to Table 1) to the EURO-NCAP testing facility detailing the predicted protection offered by the vehicle, and EURO-NCAP tests a random collection of those provided points. The actual protection or HIC values are then compared to the predicted values. Some of the grid points are defaulted to a green or red rating. For example, points on the windshield glazing may be defaulted to green except for (1) any grid points that are within 165 mm of the solid strip around the periphery of the windshield mounting frame, where the 165 mm is measured along the outer contour of the windshield, as shown in Figure 14; (2) any areas where there are structures mounted directly behind the windshield, such as sensor systems; and (3) grid points on the windshield that are within 100 mm of any underlying structures in the windshield base area, measured from the grid point in the impact direction of the relevant headform.

[0097] As shown in Figure 15, when impacting with the headform 164, a selected grid point 166 is treated as the aiming point for the headform 164, where the centerline 168 of the headform 164 is in the line of flight of the headform 164 toward the aiming point 166. The headform conforms to Regulation (EC) 78/2009 of the European Parliament and of the Council (l4 ^th January 2009) and annexed in Regulation (EC) 631/2009 (22 ^nd July 2009). Further details of the testing procedures and requirements can be found in the above- referenced EURO-NCAP protocols.

[0098] The Testing can also be performed with the headform travelling at less than 40 km/h, with a sliding scale used to adjust the score for lower velocity impacts. Test speeds higher than 40 km/h can also be assessed on a pass/fail basis.

[0099] Figure 16 shows a plot of a typical headform response during the above-described ped-pro testing, where acceleration of the headform during impact is plotted on the y-axis measured in units of g (1 g is approximately 9.8 m/s ² ), and time is plotted on the x-axis in milliseconds. The performance or success in this test can be measured in terms of the integral of the curve shown in Figure 16. For example, the following Equation 1 is used to calculate

HIC: * Equation 1.

In Equation 1, ti and h are the times marking the beginning of the head acceleration due to impact and the end of the head acceleration. The glass breakage of the windshield is indicated by the drop from the first, large spike in the curve. As discussed above, it is preferred that the windshield break quickly for pedestrian safety, and thus the area under this spike in the curve should preferably be small. [00100] According to an aspect (1) of the present disclosure, a vehicle glazing system is provided. The vehicle glazing system comprising: an outer glass substrate comprising a first outer surface, a second inner surface, and a first minor surface separating the first outer surface and the second inner surface, an inner glass substrate comprising a third outer surface, a fourth inner surface, and a second minor surface separating the third outer surface and the fourth inner surface, and a polymer interlayer between the outer glass substrate and the inner glass substrate; a sensor configured to detect an impact upon a vehicle in which the vehicle glazing system is installed; and a fracture mechanism configured to receive a signal from the sensor based on the impact, wherein, in the event that the signal indicates a predetermined type of impact, the fracture mechanism is configured to fracture the laminate.

[00101] According to an aspect (2) of the present disclosure, the vehicle glazing system of aspect (1) is provided, wherein at least one of the inner glass substrate and the outer glass substrate has a thickness of about 2 mm or less.

[00102] According to an aspect (3) of the present disclosure, the vehicle glazing system of any of aspects (l)-(2) is provided, wherein the fracture mechanism initiates fracture on at least one of the outer glass substrate and the inner glass substrate.

[00103] According to an aspect (4) of the present disclosure, the vehicle glazing system of any of aspects (l)-(3) is provided, wherein the sensor comprises at least one of a wire mesh sensor that detects an impact via resistivity-based sensing, a camera, a LiDAR motion sensor, radar, a piezoelectric sensor, or an acoustic sensor.

[00104] According to an aspect (5) of the present disclosure, the vehicle glazing system of aspect (4) is provided, wherein the glass laminate comprises the wire mesh sensor.

[00105] According to an aspect (6) of the present disclosure, the vehicle glazing system of aspect (5) is provided, wherein the wire mesh sensor comprises a silver grid in the outer glass substrate or on the second inner surface.

[00106] According to an aspect (7) of the present disclosure, the vehicle glazing system of aspect (5) is provided, wherein the polymer interlayer comprises the wire mesh sensor.

[00107] According to an aspect (8) of the present disclosure, the vehicle glazing system of any of aspects (l)-(7) is provided, wherein the fracture mechanism comprises an impactor configured to impact at least one of the outer glass substrate and the inner glass substrate to initiate fracture. [00108] According to an aspect (9) of the present disclosure, the vehicle glazing system of aspect (8) is provided, wherein the impactor comprises a sharp tip configured impact the outer glass substrate or the inner glass substrate.

[00109] According to an aspect (10) of the present disclosure, the vehicle glazing system of aspect (8) is provided, wherein the impactor comprises a diamond tip.

[00110] According to an aspect (11) of the present disclosure, the vehicle glazing system of any of aspects (1)-(10) is provided, wherein the impactor comprises a hammer or an indenter.

[00111] According to an aspect (12) of the present disclosure, the vehicle glazing system of any of aspects (l)-(l l) is provided, wherein the impactor comprises a spring-loaded punch mechanism.

[00112] According to an aspect (13) of the present disclosure, the vehicle glazing system of any of aspects (l)-(l2) is provided, wherein the inner glass substrate is strengthened.

[00113] According to an aspect (14) of the present disclosure, the vehicle glazing system of aspect (13) is provided, wherein the inner glass substrate is chemically strengthened.

[00114] According to an aspect (15) of the present disclosure, the vehicle glazing system of any of aspects (l)-(l4) is provided, wherein both the inner glass substrate and the outer glass substrate are chemically strengthened.

[00115] According to an aspect (16) of the present disclosure, the vehicle glazing system of any of aspects (l)-(l5) is provided, wherein the outer glass substrate is not chemically strengthened.

[00116] According to an aspect (17) of the present disclosure, the vehicle glazing system of any of aspects (l)-(l6) is provided, wherein the outer glass substrate is soda lime glass.

[00117] According to an aspect (18) of the present disclosure, the vehicle glazing system of any of aspects (l)-(l7) is provided, wherein the inner glass substrate comprises an alkali aluminosilicate glass or an alkali aluminoborosilicate glass.

[00118] According to an aspect (19) of the present disclosure, the vehicle glazing system of any of aspects (l)-(l8) is provided, wherein the vehicle glazing system further comprises an airbag, and wherein the sensor is configured to trigger the airbag and to initiate fracture via the fracture mechanism when the predetermined type of impact is detected by the sensor. [00119] According to an aspect (20) of the present disclosure, the vehicle glazing system of aspect (19) is provided, wherein the airbag comprises at least one of an internal airbag within the vehicle and an external airbag on the exterior of the vehicle.

[00120] According to an aspect (21) of the present disclosure, the vehicle glazing system of any of aspects (l)-(20) is provided, wherein the vehicle glazing system achieves a Head Impact Criteria (HIC) value of less than 650.

[00121] According to an aspect (22) of the present disclosure, the vehicle glazing system of any of aspects (l)-(2l) is provided, wherein the fracture mechanism is configured to impact the glass laminate on or near an edge of the glass laminate.

[00122] According to an aspect (23) of the present disclosure, the vehicle glazing system of any of aspects (l)-(22) is provided, wherein the fracture mechanism comprises an indenter having a length of less than 1 mm.

[00123] According to an aspect (24) of the present disclosure, the vehicle glazing system of any of aspects (l)-(23) is provided, wherein the fracture mechanism is configured to penetrate the inner glass substrate to a central tension region.

[00124] According to an aspect (25) of the present disclosure, the vehicle glazing system of aspect (4) is provided, wherein the wire mesh comprises nano- or micro-scale wire.

[00125] According to an aspect (26) of the present disclosure, the vehicle glazing system of any of aspects (l)-(25) is provided, wherein the fracture mechanism is configured to impact the glass laminate on at least one of the first and second minor surfaces.

[00126] According to an aspect (27) of the present disclosure, the vehicle glazing system of any of aspects (l)-(26) is provided, wherein the predetermined type of impact is an impact between a pedestrian and the vehicle, or between a headform and the vehicle.

[00127] According to an aspect (28) of the present disclosure, the vehicle glazing system of any of aspects (l)-(27) is provided, wherein the inner glass substrate has a thickness of 2 mm or less and is chemically strengthened.

[00128] According to an aspect (29) of the present disclosure, the vehicle glazing system of any of aspects (l)-(28) is provided, wherein the outer glass has a thickness of about 1.5 mm or greater and is not chemically strengthened. [00129] According to an aspect (30) of the present disclosure, the vehicle glazing system of any of aspects (l)-(29) is provided, wherein the outer glass substrate is thicker than the inner glass substrate.

[00130] According to an aspect (31) of the present disclosure, the vehicle glazing system of any of aspects (l)-(30) is provided, wherein the fracture mechanism is configured to impact the glass laminate on the fourth inner surface.

[00131] According to an aspect (32) of the present disclosure, the vehicle glazing system of any of aspects (l)-(3l) is provided, wherein the inner glass substrate has a thickness not exceeding 1.5 mm, not exceeding 1.0 mm, or not exceeding 0.7 mm.

[00132] According to an aspect (33) of the present disclosure, the vehicle glazing system of any of aspects (l)-(32) is provided, wherein the inner glass substrate is chemically strengthened with a depth of layer (DOL) of about 40 pm.

[00133] According to an aspect (34) of the present disclosure, the vehicle glazing system of any of aspects (l)-(32) is provided, wherein the inner glass substrate is chemically strengthened with a depth of layer (DOL) of at least 40 pm.

[00134] According to an aspect (35) of the present disclosure, the vehicle glazing system of any of aspects (l)-(34) is provided, wherein the inner glass sheet is chemically strengthened to a surface compressive stress (CS) of at least 300 MPa, or at least 500 MPa.

[00135] According to an aspect (36) of the present disclosure, the vehicle glazing system of any of aspects (l)-(35) is provided, wherein the vehicle glazing system is configured to break the glass laminate within a time of about 3 ms from the predetermined impact on the first surface.

[00136] According to an aspect (37) of the present disclosure, the vehicle glazing system of aspect (32) is provided, wherein the vehicle glazing system is configured to break the glass laminate within a time of about 2 ms from the predetermined impact on the first surface.

[00137] According to an aspect (38) of the present disclosure, the vehicle glazing system of any of aspects (l)-(37) is provided, wherein the sensor comprises a plurality of sensors.

[00138] According to an aspect (39) of the present disclosure, the vehicle glazing system of aspect (34) is provided, wherein any one sensor of the plurality of sensors is configured to detect the predetermined type of impact and send the signal to the fracture mechanism. [00139] According to an aspect (40) of the present disclosure, the vehicle glazing system of aspect (34) is provided, further comprising a processor operable to process data received from the plurality of sensors to determine whether the signal indicates that the impact detected is the predetermined type of impact.

[00140] According to an aspect (41) of the present disclosure, the vehicle glazing system of aspect (36) is provided, wherein the processor determines that the signal indicates the predetermined type of impact based on at least one of: a length of time that one or more sensors detects the impact; a spatial distribution of sensors that detect the impact from among the plurality of sensors; and a temporal distribution of data from the sensors that detect the impact.

[00141] According to an aspect (42) of the present disclosure, a method of actively breaking a windshield of a vehicle is provided. The method comprising: providing a sensor capable of detecting an impact on the vehicle; providing a fracture mechanism in communication with the sensor; detecting a predetermined type of impact based on data from the sensor detecting the impact; and fracturing the windshield with the fracture mechanism in response to the predetermined type of impact.

[00142] According to an aspect (43) of the present disclosure, the method of aspect (42) is provided, wherein the windshield comprises a laminate comprising: an outer glass substrate comprising a first outer surface, a second inner surface, and a first minor surface separating the first outer surface and the second inner surface; an inner glass substrate comprising a third outer surface, a fourth inner surface, and a second minor surface separating the third outer surface and the fourth inner surface; and a polymer interlayer between the outer glass substrate and the inner glass substrate.

[00143] According to an aspect (44) of the present disclosure, the method of aspect (43) is provided, wherein at least one of the inner glass substrate and the outer glass substrate has a thickness of about 2 mm or less.

[00144] According to an aspect (45) of the present disclosure, the method of any of aspects (43)-(44) is provided, wherein fracturing the windshield comprises the fracture mechanism initiating fracture on at least one of the outer glass substrate and the inner glass substrate.

[00145] According to an aspect (46) of the present disclosure, the method of any of aspects (43)-(45) is provided, wherein the inner glass substrate is chemically strengthened. [00146] According to an aspect (47) of the present disclosure, the method of any of aspects

(42)-(46) is provided, wherein the sensor comprises at least one of a wire mesh sensor that detects an impact via resistivity -based sensing, a camera, a LiDAR motion sensor, or an acoustic sensor.

[00147] According to an aspect (48) of the present disclosure, the method of aspect (47) is provided, wherein the laminate comprises the wire mesh sensor.

[00148] According to an aspect (49) of the present disclosure, the method of any of aspects

(43)-(48) is provided, wherein the fracture mechanism comprises an impactor, and fracturing the windshield comprises the impactor impacting at least one of the outer glass substrate or the inner glass substrate.

[00149] According to an aspect (50) of the present disclosure, the method of any of aspects

(42)-(49) is provided, wherein the sensor is configured to trigger an airbag.

[00150] According to an aspect (51) of the present disclosure, the method of any of aspects

(43)-(50) is provided, wherein the fracture mechanism is configured to impact the glass laminate on or near an edge of the glass laminate.

[00151] According to an aspect (52) of the present disclosure, the method of any of aspects (43)-(5l) is provided, wherein fracturing the windshield comprises penetrating the inner glass substrate, using the fracture mechanism, to a central tension region within the inner glass substrate.

[00152] According to an aspect (53) of the present disclosure, the method of any of aspects (43)-(52) is provided, wherein fracturing the windshield comprises impacting at least one of the first and second minor surfaces using the fracture mechanism.

[00153] According to an aspect (54) of the present disclosure, the method of any of aspects (43)-(53) is provided, wherein the predetermined type of impact is an impact between a pedestrian and the vehicle, or between a headform and the vehicle.

[00154] According to an aspect (55) of the present disclosure, the method of any of aspects (43)-(54) is provided, wherein fracturing the windshield comprises impacting the fourth inner surface using the fracture mechanism.

[00155] According to an aspect (56) of the present disclosure, the method of any of aspects (43)-(55) is provided, wherein the windshield fractures within a time of about 3 ms or within a time of about 2 ms from the predetermined impact. [00156] According to an aspect (57) of the present disclosure, the method of any of aspects (42)-(56) is provided, wherein the inner glass substrate has a thickness not exceeding 1.5 mm, not exceeding 1.0 mm, or not exceeding 0.7 mm.

[00157] According to an aspect (58) of the present disclosure, a pedestrian protection vehicle system is provided. The pedestrian protection vehicle system comprising: a sensor configured to detect an impact upon a vehicle in which the vehicle glazing system is installed; and a fracture mechanism configured to receive a signal from the sensor based on the impact, the fracture mechanism being configured to break a glazing of the vehicle in response the signal indicating a predetermined type of impact.

[00158] According to an aspect (59) of the present disclosure, the pedestrian protection vehicle system of aspect (58) is provided, wherein the glazing is a glass laminate, and the fracture mechanism is configured to fracture the glass laminate on a surface of the laminate facing the interior of the vehicle.

[00159] According to an aspect (60) of the present disclosure, the pedestrian protection vehicle system of any of aspects (58)-(59) is provided, wherein the sensor comprises at least one of a wire mesh sensor that detects an impact via resistivity-based sensing, a camera, a LiDAR motion sensor, or an acoustic sensor.

[00160] According to an aspect (61) of the present disclosure, the pedestrian protection vehicle system of aspect (60) is provided, wherein the wire mesh sensor comprises a silver wire grid.

[00161] According to an aspect (62) of the present disclosure, the pedestrian protection vehicle system of any of aspects (58)-(6l) is provided, wherein the fracture mechanism comprises an impactor configured to impact the glazing to break the glazing.

[00162] According to an aspect (63) of the present disclosure, the pedestrian protection vehicle system of any of aspects (58)-(62) is provided, wherein the sensor is configured to be disposed in or on at least one of the vehicle’s hood, engine compartment, front grill, or glazing.

[00163] According to an aspect (64) of the present disclosure, the pedestrian protection vehicle system of any of aspects (58)-(63) is provided, wherein the predetermined type of impact is an impact between a pedestrian and the vehicle, or between a headform and the vehicle. [00164] According to an aspect (65) of the present disclosure, the pedestrian protection vehicle system of any of aspects (58)-(64) is provided, wherein the sensor comprises a plurality of sensors.

[00165] According to an aspect (66) of the present disclosure, the pedestrian protection vehicle system of aspect (65) is provided, wherein any one sensor of the plurality of sensors is configured to detect the predetermined type of impact and send the signal to the fracture mechanism.

[00166] According to an aspect (67) of the present disclosure, the pedestrian protection vehicle system of aspect (65) is provided, further comprising a processor operable to process data received from the plurality of sensors to determine whether the signal is sent to the fracture mechanism.

[00167] According to an aspect (68) of the present disclosure, the pedestrian protection vehicle system of aspect (67) is provided, wherein the processor determines that the signal indicates the predetermined type of impact based on at least one of: a length of time that one or more sensors detects the impact; a spatial distribution of sensors that detect the impact from among the plurality of sensors; and a temporal distribution of data from the sensors that detect the impact.

[00168] As used herein, the singular forms“a,”“an,” and“the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a“metal” includes examples having two or more such“metals” unless the context clearly indicates otherwise.

[00169] Ranges can be expressed herein as from“about” one particular value, and/or to “about” another particular value. When such a range is expressed, examples include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[00170] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order.

Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred.

[00171] It is also noted that recitations herein refer to a component of the present invention being“configured” or“adapted to” function in a particular way. In this respect, such a component is“configured” or“adapted to” embody a particular property, or function in a particular manner, where such recitations are structural recitations as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is“configured” or“adapted to” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.

[00172] Reference throughout this specification to "one embodiment," "certain embodiments," "various embodiments," "one or more embodiments" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in various embodiments," "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment.

Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[00173] It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Since modifications combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and their equivalents.