The present invention relates to a material for resisting a cutting tool, and in particular but not exclusively to a material for resisting an abrasive cutting tool.

BACKGROUND

The powered two-wheeler (PTW) market, including vehicles such as motorcycles, is a growing sector. However, such vehicles are frequently the target of theft, being smaller and lighter than other vehicles such as cars. Motorcycles are seven times more likely to be stolen than any other vehicle, and in London 1 in 12 motorcycles are stolen. The impact of that theft affects not just the owner of the vehicle but the wider community, as stolen vehicles are often used to commit further crimes. For example, “snatch and grab” theft is often performed using stolen mopeds.

Research has shown any security measure at all on the vehicle can reduce the likelihood of theft by more than three times. Other factors such as location, vehicle value and the specific type of vehicle can also play a large part in determining a likelihood of vehicle theft.

The tools used to attack PTW security devices are many and varied and have evolved over time. For example, tools such as bolt croppers, club hammers, chisels, hacksaws and pliers have long been used in the theft of motorcycles. However, as handheld power tools have become more common place (due in part to a fall in Lithium-ion battery costs over time), the battery powered angle grinder has become cheaper and more easily concealed than other tools, such as a large pair of bolt croppers.

Conventional security measures are unable to resist angle grinder attacks. An angle grinder is able to cut through even the most heavy-duty conventional security measures, often in under one minute. Although some PTW security measures are allegedly designed to resist angle grinder attack, such devices often rely on sheer bulk, material hardness and weight. Those devices are typically so large and heavy as to cause to damage to the vehicle the owner is trying to protect, and are rarely used due to their excessive weight, size and difficulty.

The present invention has been devised with the foregoing in mind. SUMMARY OF INVENTION

According to a first aspect, there is provided a composite material for resisting a cutting tool. The material may comprise a hollow casing. The material may comprise a mixture disposed within the casing. The mixture may comprise an intumescent material and a ductile material. In response to heat generated during cutting, the intumescent material may be configured to expand. The expansion of the intumescent material may urge the ductile material against the cutting tool.

The composite material of the present invention uses the heat generated by the action of the cutting tool to cause material deformation that resists or prevents continued action of the cutting tool. Expansion of the intumescent material may force the ductile material against the cutting tool, causing an increase in friction and slowing the action of the cutting tool. Due to the force applied by the expanding intumescent material, the ductile material may yield and deform plastically to conform to a surface of the cutting tool, further increasing friction and further reducing the effectiveness of the cutting tool. That process may continue until the cutting tool is no longer able to cut effectively. The behaviour of the composite material may be particularly effective in resisting cutting by an abrasive cutting tool such as an angle grinder, which generates a substantial amount of heat during cutting. The composite material may therefore provide an adaptive response to the action of a cutting tool to resist or prevent continued action of the cutting tool, without simply increasing a size or hardness of the material as in many conventional materials and/or systems for resisting cutting. The inclusion of an intumescent material may significantly reduce a density of the material. A weight saving of approximately 60% may be obtained compared to a conventional all steel construction of equivalent dimensions. That may enable the composite material to be lightweight whilst simultaneously improving resistance to cutting. The use of a ductile material may also provide the composite material with better resistance to brittle fracture at lower temperatures compared to conventional materials used in security applications for resisting cutting. The ductile material may comprise a plurality of substantially planar structures, for example plates and/or discs. That may provide a greater surface area for the ductile material to contact the cutting tool and provide enhanced resistance to the action of the cutting tool.

One or more of the substantially planar structures may comprise a shape or configuration that at least partially deviates from a flat plane. One or more of the substantially planar structures comprises opposing concave and convex faces. Alternatively or additionally, one or more of the substantially planar structures may comprise a chevron or V-shaped configuration. That may prevent a direct cutting path through the composite material, providing additional resistance to cutting tools such as bolt croppers.

One or more of the substantially planar structures may have a thickness of between substantially 2mm and substantially 5mm. One or more of the substantially planar structures may have a thickness of substantially 3mm. That may provide a sufficient amount of ductile material to prevent the ductile material from wearing through under the action of the cutting tool, without introducing excessive weight to the composite material.

The ductile material may be or comprise a ductile metal or alloy. The ductile material may comprise one or more materials selected from aluminium, aluminium alloy such as Al-3003 or Al-6063, copper and a copper alloy such as 90/10 copper-nickel, aluminium bronze or nickel aluminium bronze 632. Those ductile materials are widely and readily available. The composite material may therefore make use of commonly available materials to provide enhanced resistance to or prevention of abrasive cutting without requiring specialist materials.

The intumescent material may comprise expanded graphite. The intumescent material may comprise expanded graphite mixed with a matrix material such as silicone.

The casing may comprise a metal or alloy. The casing may be or comprise a metal or alloy, for example a steel. The casing may be or comprise stainless steel, for example 316 stainless steel. That may allow the composite material to be used in outdoor applications without significant environmental degradation, for example oxidation (rust) which may compromise the integrity of the composite material.

The casing may be or comprise a hardened metal or alloy, for example a case-hardened metal or alloy. The casing may be or comprise a case-hardened steel such as case-hardened stainless steel. That may improve resistance of the composite material to cutting by tools such as angle grinders, saws (for example reciprocating saw or hacksaws) and bolt croppers, without increasing a weight of the composite material. The mixture may comprise alternating layers of intumescent material and ductile material. That may allow a simple construction that is easily manufactured whilst providing enhanced resistance to or prevention of abrasive cutting.

According to a second aspect, there is provided a chain link comprising the composite material of the first aspect.

According to a third aspect, there is provided a chain comprising one or more of the chain links of the second aspect.

According to a fourth aspect, there is provided a security device comprising the material of the first aspect, the chain link of the second aspect or the chain of the third aspect. The security device may be or comprise a vehicle lock.

The security device may comprise a plurality of interlinking or interconnected sections of the composite material forming a web, net or brace. The web, net or brace may provide a shield or cover for an object to be protected (for example, preventing access to the object or a part of the object) that is resistant to cutting by cutting tools without introducing excessive weight to the security device.

According to a fifth aspect, there is provided a method of manufacturing a composite material for resisting a cutting tool. The method may comprise disposing a mixture of an intumescent material and a ductile material in a hollow casing. The method may comprise disposing alternating layers of the intumescent material and the ductile material in the casing.

Features which are described in the context of separate aspects and embodiments of the invention may be used together and/or be interchangeable wherever possible. Similarly, where features are described in the context of a single embodiment for brevity, those features may also be provided separately or in any suitable sub-combination. Features described in connection with the composite material of the first aspect may have corresponding features definable with respect to the method of the fifth aspect, and vice versa, and these embodiments are specifically envisaged. BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 shows an embodiment of a composite material for resisting an abrasive cutting tool including substantially planar ductile structures comprising opposing concave and convex faces, in accordance with the invention; FIGs. 2A and 2B show the behaviour of the composite material of FIG. 1 in response to cutting by an abrasive cutting tool;

FIGs. 3 A, 3B and 3C show a schematic of a conventional cutting disc and examples of cutting discs that have failed during attempting cutting of the composite material shown in FIG. 1;

FIG. 4 shows an alternative embodiment of a composite material for resisting an abrasive cutting tool including substantially planar ductile structures comprising a chevron or V-shaped configuration, in accordance with the invention;

FIG. 5 shows an embodiment of a chain link comprising the composite material shown in FIG. 1, in accordance with the invention; and

FIG. 6 shows an embodiment of a method of manufacturing the chain link shown in FIG. 5;

FIG. 7 shows an alternative embodiment of the chain link of FIG. 5 comprising an olive or compression fitting to join the two ends of the tube; FIG. 8 shows an alternative embodiment of a chain link comprising the composite material shown in FIG. 1 comprising a pair of hollow, substantially U-shaped tubes joined together to form the chain link; and FIGs. 9A and 9B shows an embodiment of a security device comprising the composite material shown in FIG. 1 comprising a pair of interlinked sections or lengths of the composite material.

Like reference numerals in different Figures may represent like elements.

DETAILED DESCRIPTION

Figures 1 shows an embodiment of a composite material 100 for resisting a cutting tool in accordance with the invention. The composite material 100 comprises a hollow external casing 102. A mixture 104 is disposed within the casing 102. The mixture 104 comprises an intumescent material 104a and a ductile material 104b.

The composite material 100 is configured to exploit waste heat energy caused by cutting in order to resist or prevent further cutting of the composite material 100. The operational principle of the composite material 100 is described below and shown schematically in Figures 2A and 2B. In the example below, the cutting tool is an abrasive cutting disc (as typically used on an angle grinder). However, it will be appreciated from the description of the operational principle below the composite material 100 is configured not only to resist abrasive cutting, but to resist numerous different types of cutting tool that generate heat during cutting, for example cutting tools that rely on or utilise a rotational or oscillating action or mechanism. Such tools include drills and rotating or oscillating saws (whether driven by a power source or manually).

Heat is generated as an abrasive cutting disc of an angle grinder cuts into and/or penetrates the external casing 102 of the composite material 100. The heat generated is illustrated in the areas highlighted red in Figures 2A and 2B. The heat generated causes the intumescent material 104a to expand or dilate.

As the intumescent material 104a dilates in response to the heat generated by abrasive cutting, the casing 102 constrains the expansion of the intumescent material 104a. The only available space for expansion to take place is the cutting path where the cutting disc has already cut through the composite material 100. The expansion of the intumescent material 104a towards and into the cutting path therefore applies a force to the ductile material 104b that urges the ductile material 104b against the cutting disc, as shown in Figure 2B, with the applied force depicted by the blue arrows). That increases friction on the cutting disc, slowing rotation of the cutting disc and inhibiting further cutting.

The force applied to the ductile material 104b (resulting from the expanding intumescent material 104a urging the ductile material 104b against the cutting disc) subsequently causes the ductile material 104b to yield and deform. As the ductile material 104b yields and deforms under the applied force, the ductile material 104b conforms to the surface of the cutting disc (for example, fdling the asperities in the surface of the cutting disc). The mechanical keying or adhesion resulting from the ductile material 104b conforming to the surface of the cutting disc both reduces the cutting effectiveness of the cutting disc and increases the contact area between the ductile material 104b and the cutting disc. The increased contact area between the ductile material 104b and the cutting disc further increases friction on the cutting disc as the ductile material 104b is urged against the cutting disc by the expanding intumescent material 104a. The increased friction further slows rotation of the cutting disc. That process may continue to until the point where the rotation speed of the cutting is too slow to cut effectively and further cutting is unable to take place.

In the case of an abrasive cutting disc for an angle grinder, the conventional laminated structure of the cutting disc (shown in exploded view in Figure 3 A, comprising a disc core 150 comprising abrasive grains, a bonding agent and optionally additives, sandwiched between layers of fibreglass mesh 155, each of the disc core 150 and the layers of fibreglass mesh 155 comprising a central aperture supported by a metal ring 160) also means that if an operator roughly handles the angle grinder in an attempt to continue cutting, failure (e.g., delamination or structural failure) of the disc is likely to take place due to the reduced speed of the cutting disc. Figures 3B and 3C show examples of delamination and structural failure, respectively, of abrasive cutting discs caused by attempting to force continued cutting of the composite material 100 during slow rotation of the cutting disc.

In the embodiment shown in Figure 1, the mixture 104 comprises a plurality of substantially planar structures (referred to below as plates) of ductile material 104b, periodically arranged within a matrix of intumescent material 104a, although that is not essential. The mixture 104 may alternatively be thought of as alternating layers of intumescent material 104a and ductile material 104b. Each of the plates of ductile material 104b comprises opposing concave and convex faces. The convex and concave faces of adjacent plates of ductile material 104b spatially overlap with one another (along a longitudinal axis of the housing 102 in the embodiment shown), although that is not essential. For example, the convex face of one plate of ductile material 104b may be at least partially received within the space defined by the concave face of an adjacent plate of ductile material 104b. That arrangement may prevent a straight line of potentially soft intumescent material 104a from running directly through the composite material, along which alternative cutting tools such as bolt croppers could otherwise cut. The plates of ductile material 104b provide additional resistance to cutting by tools such as bolt croppers.

In the embodiment shown, the plates of ductile material 104b comprise a shape or configuration substantially corresponding or equal to an internal shape or configuration of the casing 102. The cross-sectional shape or configuration of the plates of ductile material 104b substantially corresponds to or fills the internal cross-sectional shape or configuration of the casing 102, throughout the casing. That may maximise a surface area of the ductile material 104b available to contact and conform to the surface of the cutting tool as the cutting tool enters the mixture 104 of the composite material. In the embodiment shown, the casing 102 comprises a 19mm stainless steel tube of circular cross-section having a wall thickness of 2mm. The plates of ductile material 104b comprise substantially circular discs having a diameter of approximately 15mm. However, that is not essential, and the plates of ductile material 104b may have a shape or configuration not substantially corresponding or equal to an internal shape or configuration of the casing 102. The plates of ductile material 104b may comprise a surface area less than an area of the internal shape or configuration of the casing 102, for example substantially 25% or more, substantially 50% or more or substantially 75% or more of an area of the internal shape or configuration of the casing 102.

In the embodiment shown, the plates of ductile material 104b have a thickness of substantially 3mm. Alternatively, the plates of ductile material 104b may have a thickness of between substantially 2mm and substantially 5mm, or between substantially 1mm and substantially 10mm. That may ensure there is a sufficient amount of ductile material 104b to prevent the plates of ductile material 104b from simply wearing through under the action of the cutting tool, without introducing excessive weight to the composite material 100. In the embodiment shown, the plates of ductile material 104b are spaced apart from one another by substantially 1mm. Alternatively, the plates of ductile material 104b may be spaced apart from one another by between substantially 0.5mm and substantially 3mm. That may ensure the plates of ductile material 104b are close enough to any cutting location so as to be easily forced against the cutting tool when the intumescent material 104a expands, without introducing excessive weight to the composite material 100. Alternatively, the mixture 104 may comprise one or more regions or portions of ductile material 104b of any suitable shape, size or configuration distributed within a matrix of intumescent material 104a. The ductile material 104b may have a substantially regular or periodic distribution within the matrix of intumescent material 104a, or may have a substantially homogeneous and/or random distribution within the intumescent material 104a.

In the embodiment shown, the intumescent material 104a comprises expanded graphite. The expanded graphite is mixed with silicone, although that is not essential. The expanded graphite may be used alone as the intumescent material 104a or may be mixed with a matrix material such as silicone. It will be appreciated any suitable intumescent material may alternatively be used. The ductile material 104b comprises Al-3003 aluminium alloy, although any suitable ductile material may alternatively be used such as aluminium, aluminium alloy (for example, Al-6063), copper, copper alloy (for example, 90/10 copper-nickel, aluminium bronze, nickel aluminium bronze 632).

The casing 102 comprises stainless steel (316 stainless steel), although any suitable material may be used, for example any suitable metal or alloy such as a steel. The casing 102 may be or comprise a case-hardened metal or alloy, for example a case-hardened steel such as case-hardened stainless steel.

In the embodiment shown, the casing 102 comprises a 19mm stainless steel tube of circular cross- section comprising a wall thickness of 2mm, although that is not essential. Together with the plates of ductile material 104b (discs having a diameter of approximately 15mm and a thickness of substantially 3mm) formed from Al-3003 alloy and the intumescent material 104a formed from expanded graphite mixed with silicone, the composite material provides a weight saving of approximately 60% compared to a construction of equivalent dimensions manufactured entirely from stainless steel. That reduction in weight is in direct contrast to conventional approaches for PTW security devices and/or resisting abrasive cutting, which typically look to increase one or more of weight, thickness or general size to resist abrasive cutting and deter theft. However, as noted above, any suitable material for each of the casing 102, intumescent material 104a and ductile material 104b may be used for the composite material. The intumescent material 104a will typically have a much lower density than a metal or alloy which would likely be used in conventional approaches. The replacement of that volume of material with the intumescent material 104a in the composite material 100 will therefore almost certainly result in a weight reduction of some degree (compared to conventional approaches), in addition to providing the operational advantages described above. It will also be appreciated the casing 102 need not have a circular cross-section, and may have any suitable shape or configuration.

Figure 4 shows another embodiment of a composite material 200 for resisting a cutting tool in accordance with the invention. The composite material 200 is substantially similar to the composite material 100 described above, with like reference numerals indicating like elements. The composite material 200 comprises plates of ductile material 204b comprising a chevron or V-shaped configuration, periodically arranged within a matrix of intumescent material 204a, although that is not essential. As described above with respect to the composite material 100, the opposing male and female faces of the chevron or V-shaped plates of ductile material 104b overlap spatially (along a longitudinal axis of the housing 202 in the embodiment shown) to provide additional resistance to cutting by tools such as bolt croppers.

Figure 5 shows an embodiment of a chain link 300 comprising the composite material 100 described above. The chain link 300 comprises a stainless steel tube 306 forming the casing 102, the stainless steel tube 306 comprising a first end or female end 306a and a second end or male end 306b which are joined together to form the chain link 300, as described in more detail below. In the embodiment shown, the stainless steel tube 306 comprises a substantially circular cross- section, although that is not essential and it will be appreciated the tube 306 may have any suitable cross-section such as triangular, square, rectangular, pentagonal, hexagonal and so on. A chain may be formed comprising one or more chain links 300, which may be used as a security device capable of resisting abrasive cutting as described above.

Figure 6 shows a method 400 of manufacturing a chain link 300 comprising the composite material 100, 200.

At step 405, the method 400 comprises internally swaging a first end 306a of a stainless steel tube 306 to form a female end. At step 410, the method 400 comprises externally swaging a second end 306b of the stainless steel tube 306 to form a male end. Swaging the two ends 306a, 306b of the stainless steel tube may allow the ends 306a, 306b to be connected to one another by forcing the first end or female end 306a over the second end or male end 306b and relying on a strong friction fit. That may enabling the two ends 306a, 306b to be joined together without using a process such as welding which is likely to heat the intumescent material 104a and cause difficulty in joining the two ends 306a, 306b together. Additionally or alternatively, the method 400 may comprise flaring the first end 306a to improve ease of bringing the first end 306a and the second end 306b together for joining.

At step 415, the method 400 comprises forming plates or discs of intumescent material 104a. At step 420, the method 400 comprises forming plates or discs of ductile material 104b. The plates or discs of intumescent material 104a and ductile material 104b may be formed by stamping plates or discs from a flat sheet of material. At step 425, the method 400 comprises disposing the plates or discs of intumescent material 104a and ductile material 104b into the stainless steel tube 306 in an alternating pattern. That may form a mixture 104 of the intumescent material 104a and the ductile material 104b, with alternating layers of intumescent material 104a and ductile material 104b. Alternatively, a mixture 104 of intumescent material 104a and ductile material 104b may be formed prior to disposing the mixture 104 in the stainless steel tube 306. For example, the alternating layers of intumescent material 104a and ductile material 104b may be layered or stacked together prior to disposing the stacked layers in the stainless steel tube 306, or a substantially homogeneous mixture of an intumescent material 104a and a ductile material 104b may be formed (e.g., without using plates or discs of the intumescent material 104a and the ductile material 104b) and subsequently disposed in the stainless steel tube 306.

At step 430, the method 400 comprises forming a first bend in the stainless steel tube 306. At step 435, the method 400 comprises forming a second bend in the stainless steel tube 306 and joining the first end 306a and the second end 306b together to complete the chain link 300. In the embodiment shown in Figure 5, the plate or disc nearest the first end 306a is a plate or disc of ductile material 104b. That plate or disc of ductile material 104b comprises an annular shoulder (shown in cross-section in Figure 5) configured to receive and seat the second end 306b of the stainless steel tube 306. That may provide additional support to the join between the first and second ends 306a, 306b, although that is not essential.

Figure 7 shows an alternative embodiment of a chain link 300 (for example, manufactured using the method 400 described above). In the embodiment shown, an olive or compression ring 308 is placed around the second end or male end 306b prior to joining the first end 306a and the second end 306b together. The first end 306a may then be compressed over the second end 306b. The presence of the olive or compression ring 308 may reinforce or strengthen the joint between the first end 306a and the second end 306b. The casing 102 may comprise a case-hardened material such as case-hardened stainless steel. However, the temperatures required for case-hardening may be significantly higher than a temperature at which the intumescent material 104a may be activated and dilate or expand. The casing 102 may therefore need to be case-hardened prior to manufacturing the chain link 300 in order to avoid activating the intumescent material 104a prematurely (e.g., before its intended purpose in contributing to cutting resistance of the composite material). However, a case- hardened material may be difficult to bend to bring the first end 306a and the second end 306b together for joining.

Figure 8 shows an alternative embodiment of a chain link 500. The chain link 500 comprises a casing 502 comprising a first hollow, substantially U-shaped tube 512a and a second hollow, substantially U-shaped tube 512b joined together to form the chain link 500. A mixture of an intumescent material 104a and a ductile material 104b is disposed within the casing 502 substantially as described above with respect to the composite materials 100, 200.

Each of the U-shaped tubes 512a, 512b comprises a first end 514a, 514b and a second end 516a, 516b. The respective ends of the U-shaped tubes 512a, 512b are each configured to be joined to a corresponding end of the other U-shaped tube 512a, 512b. In the embodiment shown, both the first end 514a and the second end 516a of the first U-shaped tube 512a comprises a female end (which may be formed by internal swaging and/or flaring, substantially as described above), whilst the first end 514b and the second end 516b of the second U-shaped tube 512b each comprise a male end (which may be formed by external swaging, substantially as described above). Alternatively, both the first end 514a and the second end 516a of the first U-shape tube 512a may comprise a male end, and both the first end 514b and the second end 516b of the second U-shaped tube 512b may comprise a female end. Alternatively, the first end 514a of the first U- shaped tube 512a may comprise a male end, whilst the second end 516a of the first U-shaped tube 512a may comprise a female end (or vice versa), and the corresponding first end 514b and second end 516b of the second U-shaped tube 512b may comprise a female end and a male end respectively (or vice versa). Optionally, an olive or compression fitting may be placed around or over one or both of the male ends prior to joining the ends of the two U-shaped tubes 512a, 512b together, substantially as described above.

The arrangement of the chain link 500 may be particularly suitable for a casing 102 comprising a case-hardened material. The hollow U-shaped tubes 512a, 512b may each comprise a material that has been case-hardened prior to disposing the mixture of intumescent material 504a and ductile material 504b in the tubes and joining the two U-shaped tubes 512a, 512b together. That may avoid the need to case-harden the casing 102 of the chain link 500 after manufacture of the chain link 500 (which is likely to prematurely activate the intumescent material 504a), and may also avoid the need to bend a case-hardened material into shape to form the chain link 500.

It will be appreciated the composite material 100, 200 may be manufactured to form products other than a chain link 300. For example, the composite material 100, 200 may be used to form a wide variety of security products, both for vehicles and more general applications. The composite material 100, 200 may be used to form a shield or cover for a catalytic converter of a vehicle (a high-value vehicle component which is frequently the target of theft).

Figure 9A shows an embodiment of a security device 600 comprising the composite material 100, 200. The security device 600 comprises a plurality of interlinking or interconnected sections of the composite material 100, 200 forming a web, net or brace. In the embodiment shown, the security device 600 comprises a pair of interlinking sections or lengths 670a, 670b of the composite material 100, 200. Each section 670a, 670b comprises a bend 672a, 672b allowing the sections 670a, 670b to overlap and interlink with one another at the bends 672a, 672b (for example, similar to a chain link fence construction. In the embodiment shown, each of the bends 672a, 672b forms a substantially 90° angle, although the bends may be or form any suitable angle (for example an acute angle less than 90° or an obtuse angle greater than 90°). In the embodiment shown, the pair of interlinking sections 670a, 670b form a substantially X-shaped configuration, although it will be appreciated that other shapes may be formed depending on the form, shape or configuration of the lengths or sections 670a, 670b. It will also be appreciated that each length or section 670a, 670b may comprise a plurality of bends 672a, 672b and any number of lengths or sections may be interlinked or interconnected as described above,

Each of the sections 670a, 670b may be manufactured in a substantially similar manner as described above, although the respective ends of each section 670a, 670b may not be joined to each other or to the ends of the other section 670a, 670b. In the embodiment shown, the respective ends of each of the sections or lengths 670a, 670b are capped. That may provide additional constraint of the intumescent material of the composite material 100, 200 during dilation or expansion to ensure effective operation of the composite material 100, 200.

In the embodiment shown, the security device 600 further comprises a plurality of fixtures 675. The fixtures 675 each comprise a U-shaped fixture formed from or comprising the composite material 100, 200, shown in Figure 9B. The U-shaped fixture 675 may be formed substantially as described above with respect to the chain link 300. The U-shaped fixture 675 includes a threaded insert 678 in each end of the U-shape. The threaded inserts 678 are configured to receive a threaded fastener such as a bolt. The bolt may be a tamper proof bolt, for example a Tamper- Resistant Torx® bolt. That may enable the U-shaped fixture 675 to be fixed to one or more mounting points, in turn enabling the web or brace of interlinking sections 670a, 670b to be fixed to one or more mounting points. That may also protect the threaded fastener from attack by a cutting tool, by locating the threaded fastener within the composite material 100, 200.

The U-shaped fixtures 675 are each configured to receive a length or section 670a, 670b in the bend of the U-shape in order to connect to and support the sections 670a, 670b. In the embodiment shown, the U-shaped fixtures 675 are located near the ends of the sections 670a, 670b, although that is not essential. The configuration of the U-shaped fixtures 675 receiving the sections 670a, 670b in the bend of the U-shape may enable the U-shaped fixtures 675 to be positioned at any location along the lengths or sections 670a, 670b. The U-shaped fixtures 675 may therefore be moveable relative to (e.g., slide along) the sections 670a, 670b in order to provide flexibility in securing the security device 600 to one or more mounting points. It will also be appreciated the sections 670a, 670b may interlink with one another indirectly via a chain link, for example a chain link 300, 500 as described above. Each section 670a, 670b may be passed through the chain link before being secured to a mounting point via the U-shaped fixtures 675.

The security device 600 described above may be used to form a shield or cover for a catalytic converter of a vehicle. The one or more U-shaped fixtures 675 may be fixed to structural mounting points on the vehicle using one or more threaded fasteners. The security device 600 over the catalytic converter may resist cutting by cutting tools, substantially as described above, and may therefore prevent the catalytic converter from being removed from the vehicle.

A method of manufacturing the composite material 100, 200 may comprise disposing a mixture of an intumescent material 104a and a ductile material 104b into a hollow casing 102 of any suitable shape or configuration. The method may comprise disposing alternating layers of intumescent material 104a and ductile material 104b into the hollow casing 102.

From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art of composite materials, cutting resistant materials and/or security devices, and which may be used instead of, or in addition to, features already described herein.

Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

For the sake of completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude a plurality, and any reference signs in the claims shall not be construed as limiting the scope of the claims.