Non-pneumatic tire

Abstract

A composite material comprises a plurality of springs forming a structure embedded within a polymer. Each spring is interwoven with at least one other spring thereby forming an entirely polymer-coated structure.

Claims

1. A composite material comprising a plurality of springs forming a structure embedded within polyurethane, each spring being interwoven with at least one other spring thereby forming an entirely polyurethane-coated structure, the composite material forming a toroidal carcass structure extending about an entire circumference of a non-pneumatic tire, each spring including a first end portion, a second end portion, and an arching middle portion interconnecting the first end portion and the second end portion, each first end portion being secured to a first annular bead and each second portion being secured to a second annular bead, the first and second annular beads both being seated to a wheel rim such that the toroidal carcass structure is secured to the wheel rim wherein the springs are elliptical.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The structure, operation, and advantages of the present invention will become more apparent upon contemplation of the following description as viewed in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 schematically shows a first step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(3) FIG. 2 schematically shows a second step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(4) FIG. 3 schematically shows a third step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(5) FIG. 4 schematically shows a fourth step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(6) FIG. 5 schematically shows a fifth step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(7) FIG. 6 schematically shows a sixth step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(8) FIG. 7 schematically shows a seventh step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(9) FIG. 8 schematically shows an eighth step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(10) FIG. 9 schematically shows a ninth step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(11) FIG. 10 schematically shows a tenth step of constructing an example non-pneumatic tire comprised of a composite material in accordance with the present invention.

(12) FIG. 11 represents a schematic illustration of a conventional wire mesh sheet.

(13) FIG. 12 represents a sheet of interwoven helical springs for use with the composite material of the present invention.

(14) FIG. 13 represents an intermediate step in forming the sheet of FIG. 12.

(15) FIG. 14 represents another intermediate step in forming the sheet of FIG. 12.

(16) FIG. 15 represents a step in securing two sheets, such as the sheet of FIG. 12, together.

(17) FIG. 16 represents an example helical spring for use with the composite material of the present invention.

(18) FIG. 17 represents the helical spring of FIG. 16 in a deflected condition.

(19) FIG. 18 represents a schematic illustration of an example tire and wheel assembly comprised of the composite material of the present invention.

(20) FIG. 19 represents a section taken through line 19-19 in FIG. 18.

(21) FIG. 20 represents a section taken through line 20-20 in FIG. 19.

(22) FIG. 21 represents a schematic perspective view of an example tire of a composite material of the present invention.

(23) FIG. 22 represents a schematic orthogonal view of the tire of FIG. 21.

(24) FIG. 23 represents a schematic cross-sectional view of the tire of FIG. 21.

(25) FIG. 24 represents a schematic of an example load/deflection curve.

(26) FIG. 25 represents a schematic of another example load/deflection.

(27) FIG. 26 represents a schematic of still another example load/deflection curve.

(28) FIG. 27 represents a schematic of yet another example load/deflection curve.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE COMPOSITE MATERIAL OF THE PRESENT INVENTION

(29) A system may comprise a method 500 of constructing a tire for non-pneumatic support of a vehicle, a non-pneumatic tire 100 for supporting a vehicle, or both.

(30) The method 500 may include providing a segmented cylindrical open-ended mold 510, a circular mold cap 520 corresponding to the mold, and an inflatable/expandable bladder 530. In a first construction step 501, an open ended cylindrical carcass ply, for example the carcass ply defined by the springs 310 below, may be slid over, or lowered around, the bladder 530. In a second step 502, a first circular bead 541 is seated in a corresponding first circular groove (not shown) in the mold 510. In a third step 503, the bladder 530 is partially inflated to form a bulged ply. In a fourth step 504, an elastomer 550, such as polyurethane, is poured into the mold 510. In a fifth step 505, the mold cap 520 is lowered into closing engagement with the mold 510 thereby seating a second circular bead 542 in a corresponding second circular groove (not shown) in the mold cap and also axially compressing the beads 541, 542 of the carcass ply creating a toroidal carcass structure. In a sixth step 506, the bladder 530 is further inflated, thereby expanding the carcass ply further and facilitating flow of the elastomer 550 around the exposed surfaces of the carcass ply. Air and excess elastomer 550 may be expelled from the interior of the mold/mold cap 510, 520 through a one-way check valve (not shown) in the mold/mold cap during this sixth step 506.

(31) In a seventh step 507, the bladder 530 is fully inflated, thereby fully expelling air and excess elastomer 550 from the interior of the mold/mold cap 510, 520. Following this seventh step 507, the mold/mold cap assembly 510, 520 may be relocated to a convenient location since the assembly is self-contained at this point. In an eighth step 508, following a sufficient cure time, the bladder 530 is deflated, the mold cap 520 is raised out of engagement with the mold 510, and the mold segments 511 are disengaged from each other and the newly cured tire 600. In a ninth step 509, the tire 600 is fully removed from engagement with the bladder 530 and is ready for use.

(32) During the fifth, sixth, and seventh steps 505-507, the actual dimensions of the bladder 530, mold/mold cap 510, 520, and carcass ply will determine whether the carcass ply will be completely encased by the elastomer 550 (FIG. 23) or the inner surface of the carcass ply forms the inner toroidal surface of the tire 600. In other words, the fully inflated bladder 530 will either directly engage the inner surface of the carcass ply, expanded by the axial converging of the beads 541, 542, thereby forming a tire 600 having an inner toroidal surface which is the inner surface of the carcass ply; or the fully inflated bladder will not reach the inner surface of the carcass ply, thereby allowing the elastomer to flow into that gap and forming a completely encased carcass ply.

(33) An example tire 300, 600 may include an interwoven, or interlaced, plurality of helical springs (i.e., coiled wires which deform elastically under load with little energy loss). The tire 300, 600 may define a toroidal shaped structure for mounting to a wheel 200. The tire 300, 600 may contour to a surface on which the tire engages to facilitate traction while mitigating vibration transmission to a corresponding vehicle. The helical springs support and/or distribute a load of the vehicle. The tire 300, 600 may be pneumatic or non-pneumatic.

(34) Under the weight of a vehicle, the tire 300, 600 may be driven, towed, or provide steering to the vehicle. The helical springs of the tire 300, 600 may passively contour to any terrain by flexing and moving with respect to each other. The interwoven structure of the helical springs provides stability to the tire 300, 600 and prevents the structure from collapsing as the tire rotates and engages variable terrain.

(35) The helical springs of the tire 300, 600 may be resilient through a finite range of deformation, and thus a relatively rigid frame similar to a carcass ply may be used to prevent excessive deformation. Radially oriented portions of the springs may be used to connect the tire 300, 600 to the wheel 200. These springs may be interwoven, or interlaced. Other springs may be incorporated with the tire at any bias angle, from radial to circumferential, with the purpose of distributing load. These other springs may be helical springs. Further, as one example, these other springs may extend circumferentially around the tire at a radially outer portion of the tire 300, 600.

(36) External covering of some kind (i.e., a tread, an elastomer 550) may be added to partially or fully protect the helical springs from impact damage and/or to change the tire's ability to float and generate traction. As one example, four basic steps may be utilized to manufacture one example carcass ply structure for the tire 300, 600: i) twisting helical springs together to form a rectangular sheet with a length corresponding to the desired tire circumference; ii) interweaving ends of the rectangular sheet of springs to form a mesh cylinder (FIG. 2); iii) collapsing one end of the mesh cylinder and attaching it to a rim of a wheel 200; and iv) flipping the other end of the mesh cylinder inside out and attaching it to another axially opposite rim of the wheel 200.

(37) The example tire 300, 600 may be utilized on Earth, the Moon, Mars, and/or any other planetary body, since its elements operate reliably in atmospheric and terrain conditions of these planets. The tire 300, 600 may be utilized on its own, or incorporated as a partial or auxiliary load support/distribution system within another tire type. The tire 300, 600, however, requires no air, operates in difficult environments, and contours to all terrains.

(38) The tire 300, 600 provides an improvement over the conventional wire mesh, non-pneumatic tire of the Apollo LRV. The tire 300, 600 provides higher load capacity, since wire size of the helical springs may be increased with relatively little functional alteration. The tire 300, 600 provides a longer cycle life, since wire stresses of the helical springs are more uniformly distributed throughout the carcass ply-like structure. Further, the tire 300, 600 provides relatively low weight per unit of vehicle weight supported, since the interwoven helical spring network (like a carcass ply) is fundamentally stronger than the crimped wire mesh. Additionally, helical springs are able to compress and elongate to accommodate manufacturing variations. Finally, the tire 300, 600 provides improved design versatility, since load distribution springs may be added to vary the tire strength in different tire locations and directions.

(39) The example tire 300, 600 may further provide relatively low energy loss compared to tires that use frictional or hysteretic materials in a carcass, since the helical springs consume near zero energy during deformation. The example tire 300, 600 contains redundant load carrying elements and may operate normally even after significant damage. The example tire 300, 600 may thus be utilized for low vehicle energy consumption, for tire failure posing a critical threat, for traveling through rough terrain, for exposure to extreme temperatures or high levels of radiation, and/or for exposure to gun fire or bomb blasts.

(40) As shown in FIG. 11, a woven wire mesh has been used for a conventional lunar tire. However, as discussed above, greater strength and durability is desired. FIG. 12 shows a mesh sheet 50 of interwoven helical springs 55 that may provide greater strength and durability than the wire mesh. FIGS. 13, 14, and 15 show intermediate steps in forming a mesh sheet 50 as shown in FIG. 12. In FIG. 13, a first helical spring 55 is shown being rotated thereby interweaving that same first spring with a second helical spring 55. In FIG. 14, a third helical spring 55 is shown being rotated thereby interweaving that third spring with the already woven first and second springs 55. In FIG. 15, a helical spring 55 is shown being rotated for connecting two mesh sheets 50 (i.e., the sheet of FIG. 12) of helical springs 55. FIG. 6 shows a single helical spring 55 for use as described above in FIGS. 12-15. FIG. 17 shows a single helical spring 55 deflected for use in a tire such as the tires 300, 600, as described below.

(41) As shown in FIGS. 18-20, an example assembly 100 includes a wheel 200 and a tire 300. The wheel 200 has an annular rim 202 at each axial side for securing the tire 300 to the wheel. Each rim 202 is fixed relative to the other rim 202. Each rim 202 may include a plurality of socket holes 204 for aligning the tire 300 with the rim. Any other suitable means may be used for securing the tire 300 to the rim 200.

(42) The example tire 300 may include a plurality of helical springs 310 extending radially away from the wheel 200 in an arching configuration and radially back toward the wheel. Each end 315 of each spring 310 may be secured to wheel at a corresponding rim 202 of the wheel. Each spring 310 has a middle portion interconnecting the ends 315. Each end 315 may be secured at an axial orientation (FIG. 19) or at an angled orientation, with each spring 310 extending axially outward from one rim 202, then away from the wheel 300, then back over itself, then inward, and finally axially toward the other rim 202. Each end 315 of each spring may thereby be oriented coaxially (or at an angle) with the other end 315 of the same spring.

(43) Further, each spring 55 may be interwoven with adjacent springs 55 (FIG. 12) enabling load sharing between springs. As shown in FIG. 12, each spring 55 is interwoven, or interlaced, with an adjacent spring 55 on a first side of the spring and further being interwoven with an adjacent spring 55 on a second opposite side of the spring. Thus, the springs 310 extend radially and axially and form a woven toroidal structure, similar to the carcass ply of a pneumatic tire, extending about an entire circumference of the tire 300 (FIGS. 8-10).

(44) The helical springs 310 may be any suitable length, gauge, pitch, and shape (i.e., oval springs, elliptical springs, etc.). The helical springs 310 may vary in coil diameter (i.e., barrel springs may be used) to create continuity in the mesh through the range of radial positions in the tire 300 (i.e., narrower coil width at the beads). The helical springs 310 may be further structured as two or more plies, one or more radially inner plies being radially overlapped by one or more radially outer plies. Further, at least one helical spring of one ply may be interwoven with at least one helical spring of another ply for advantageously increasing strength of the overall structure. The helical springs 310 may be TiN alloy, steel, titanium, polymer, ceramic, or any other suitable material.

(45) The purely metallic, non-pneumatic spring tire 300 described above has been developed for space applications. The structure is a series of interwoven springs as seen in FIG. 20. This structure was well suited to space applications where rubber is not permitted due to temperature variations (40K to 400K). In addition, the spring tire 300 may achieve excellent traction where soil composition may be soft sand such as the Moon.

(46) On Earth, however, the variety of road surfaces causes the purely metallic contact interface of the above example tire 300 to have limited application. Based on this limited commercial application, the interwoven structure of the example tire 300 may be enhanced for terrestrial applications.

(47) In order to achieve traction on the wide variety of terrestrial road surfaces, a polymer may be added to the all-metal example tire 300 to serve as a tread. For step 504 of the method 500, one option is to use a two-part polyurethane that may be poured into the mold 510 containing the pre-assembled example spring tire 300. Once the two parts are mixed together, a chemical reaction occurs that cures the polymer at ambient temperature and pressure. Once the cure is complete, the resulting tire 300 is removed from the form and is ready for use.

(48) In laboratory samples, fatigue was tested per the dimensions from Table 1 below with cycling of over one million cycles with a deflection of 1.5 inches. Based on prospective load requirements and terrain specifications, a polymer coated tire was exemplarily targeted at an all-terrain vehicle (ATV). As shown in FIGS. 21-23, such an example tire 600 was determined to have load/deflection characteristics indicated by the load/deflection curve of the non-pneumatic tire 600 shown in FIG. 24. The structural stiffness of the tire 600 was significantly higher than was expected from the spring structure itself. The polymer used, urethane, itself not only carries some load in bending, but also constrains the spring motion in such a way (e.g. prevention of rotation) as to increase the bending stiffness of the springs.

(49) TABLE-US-00001 Outer Diameter (mm) 6.985 Inner Diameter (mm) 4.318 Wire Filament Diameter (mm) 1.397 Spring Pitch (mm) 6.620

(50) As shown in FIGS. 21-23, the rims 202 used for the example lunar spring tire 300 may not be utilized with the method 500. A rim similar to those used for standard pneumatic tires may be used with the method 500 to produce the example tire 600. By way of example only, three options are: 1) a custom rim designed specifically for the particular vehicle and service application; 2) a standard (commercially available) rim, for light duty applications; and 3) a standard (commercially available) rim modified to allow mechanical fasteners to fix the tire bead to the rim (since the beads 541, 542 need not have an air-tight engagement with the rim).

(51) The example polymer/spring tire 600 thus partially shares its load carrying mechanism with lunar spring tire 300 (i.e., the interwoven spring carcass-like structure). Additionally, the polymer encased interwoven spring ply becomes an anisotropic ply, with different properties along the axes and transverse to the spring axes. However, unlike typical fiber reinforced plies, the reinforcing springs 310 themselves have a bending stiffness, due to the width of the helixes of each spring, which may be greater than bending stiffness of the reinforcing filaments or yarns alone.

(52) This additional bending stiffness contributes significantly to the overall bending stiffness of the interwoven spring ply. Since bending stiffness carries the load placed on the example spring ply tires 300, 600, this is contrary to conventional pneumatic tires, which carry load in tension away from the footprint in the cords (filaments or yarns) of the upper segment of the pneumatic tire. Other conventional non-pneumatic tires also carry loads by tension in members in an upper section of such tires. Thus, an interwoven spring tire of a spring/polymer composite in accordance with the present invention may produce a bottom-loaded structure unlike conventional tires. As shown in FIGS. 21-23, the polymer coating of the interwoven spring ply may form a tread pattern 601 designed for traction with the spring ply structure carrying part of the load.

(53) The example polymer 550 may comprise an elastomeric material which may have a Young's modulus E from about 21 Kg/cm.sup.2 to about 21,000 Kg/cm.sup.2. The tensile modulus at 300% may be 161 Kg/cm.sup.2 or 915.9 MPa. As another alternative, a Young's modulus greater than 140 Kg/cm.sup.2 may require a mixture of polyurethane and chopped fibers of an aromatic polyamide. Also, boron may be mixed with polyurethane.

(54) As stated above, a carcass ply structure 300 of radial springs 310 produces excellent load bearing performance in the example non-pneumatic tire 300 or 600. This carcass ply structure 300 thus enhances the performance of the example non-pneumatic tire 300 or 600. Though non-pneumatic, the similarity of the carcass ply structure 300 to a traditional pneumatic tire carcass ply produces an instructive comparison.

(55) The complexities of the structure and behavior of the pneumatic tire are such that no complete and satisfactory theory has been propounded. Temple, Mechanics of Pneumatic Tires (2005). While the fundamentals of classical composite theory are easily seen in pneumatic tire mechanics, the additional complexity introduced by the many structural components of pneumatic tires (and the example non-pneumatic tire 300, 600) readily complicates the problem of predicting tire performance. Mayni, Composite Effects on Tire Mechanics (2005). Additionally, because of the non-linear time, frequency, and temperature behaviors of polymers and rubber (and elastomers), analytical design of pneumatic tires is one of the most challenging and underappreciated engineering challenges in today's industry. Mayni.

(56) A pneumatic tire (and the example non-pneumatic tire 300, 600) has certain essential structural elements. United States Department of Transportation, Mechanics of Pneumatic Tires, pages 207-208 (1981). An important structural element is the carcass ply, typically made up of many flexible, high modulus cords of natural textile, synthetic polymer, glass fiber, or fine hard drawn steel embedded in, and bonded to, a matrix of low modulus polymeric material, usually natural or synthetic rubber. Id. at 207 through 208. The example non-pneumatic tire 300, 600 in accordance with the present invention has a carcass ply structure 300 of radial springs 310.

(57) The flexible, high modulus cords are usually disposed as a single layer. Id. at 208. Tire manufacturers throughout the industry cannot agree or predict the effect of different twists of carcass ply cords on noise characteristics, handling, durability, comfort, etc. in pneumatic tires, Mechanics of Pneumatic Tires, pages 80 through 85. A prediction of the effect of interweaving helical springs on noise characteristics, handling, durability, comfort, etc. is even less likely.

(58) These complexities are demonstrated by the below table of the interrelationships between tire performance and tire components.

(59) TABLE-US-00002 LINER CARCASS PLY APEX BELT OV'LY TREAD MOLD TREADWEAR X X X NOISE X X X X X X HANDLING X X X X X X TRACTION X X DURABILITY X X X X X X X ROLL RESIST X X X X X RIDE COMFORT X X X X HIGH SPEED X X X X X X AIR RETENTION X MASS X X X X X X X

(60) As seen in the table, carcass ply cord characteristics affect the other components of a pneumatic tire (i.e., carcass ply affects apex, belt, overlay, etc.), leading to a number of components interrelating and interacting in such a way as to affect a group of functional properties (noise, handling, durability, comfort, high speed, and mass), resulting in a completely unpredictable and complex composite. Thus, changing even one component can lead to directly improving or degrading as many as the above ten functional characteristics, as well as altering the interaction between that one component and as many as six other structural components. Each of those six interactions may thereby indirectly improve or degrade those ten functional characteristics. Whether each of these functional characteristics is improved, degraded, or unaffected in the example non-pneumatic tire 300, 600, and by what amount, certainly would have been unpredictable without the experimentation and testing conducted by the inventors.

(61) Thus, for example, when the structure (i.e., spring stiffness, spring diameter, spring material, etc.) of the carcass ply structure 300 of the example non-pneumatic tire 300, 600 is modified with the intent to improve one functional property of the non-pneumatic tire, any number of other functional properties may be unacceptably degraded. Furthermore, the interaction between the carcass ply structure 300 and the cured elastomer 550 may also unacceptably affect the functional properties of the non-pneumatic tire. A modification of the carcass ply structure 300 may not even improve that one functional property because of these complex interrelationships.

(62) Thus, as stated above, the complexity of the interrelationships of the multiple components makes the actual result of modification of a carcass ply structure of a non-pneumatic tire, in accordance with the system of the present invention, impossible to predict or foresee from the infinite possible results. Only through extensive experimentation have the carcass ply structure 300 and elastomer 550 of the system of the present invention been revealed as an excellent, unexpected, and unpredictable option for a non-pneumatic tire.

(63) As partially described above, a composite material in accordance with the present invention may comprise a series of interwoven springs embedded in a polymer. The mechanical properties of such a composite material produce more than the mere superposition, or addition, of the strengths of the springs and the polymer (not a mere-collocation or aggregation).

(64) Further, properties of the composite material may be easily tunable. Bending stiffness may be tuned by changes to the material, pitch, filament diameter, and diameter of the springs. Weight may be tuned by changes to the spring and/or polymer material. Damping and viscous losses may also be tuned by changes to the spring and/or polymer material.

(65) The springs of the composite material may be in the shape of an ellipse or other helix to conform to spatial restraints. Further, the springs may be of diverse materials, such as metal, plastic, polyurethane, rubber, and carbon (as described above). The springs need not be coated or treated to create adhesion with the polymer matrix, as mechanical interlocking of the springs with the cured polymer provides an appropriate securement mechanism.

(66) The free-density of springs may be (a) tightly laterally compressed or (b) tightly laterally tensioned. Thus, for case (a), each spring is laterally compressed with an adjacent spring such that an outer part of each coil of each spring engages an inner part of each coil of the adjacent spring. For case (b), each spring is laterally tensioned with an adjacent spring such that an inner part of each coil of each spring engages an inner part of each coil of the adjacent spring.

(67) In case (a), the distance between one spring and its neighbor is approximately the spring filament diameter. In case (b), the distance is approximately the coil diameter minus the filament diameter. For example, the above example tires 300, 600 have laterally compressed springs (case (a)) in the bead area for a high stiffness transitioning to laterally tensioned springs (case (b)) in the crown to produce low stiffness needed for obstacle enveloping and for eliminating tire outer diameter growth with speed or load (FIG. 20).

(68) For example, the measured vertical stiffness of an example ATV tire 600 was 1590 lb/in. In contrast, an example lunar tire 300, having approximately 30% more springs configured in a beam spring arrangement, had a stiffness of 589 lb/in. The 270% higher vertical stiffness of the example tire 600 with the springs embedded in polymer cannot be attributed to the addition of the polymer alone, but to the combination of the springs and polymera mesh locking effect.

(69) Another example spring may be constructed of Normal Tensile (NT) steel, clean and uncoated with a 0.35 spring OD, 0.055 wire diameter, 0.28 pitch, and with the springs placed in lateral tension. The polymer may be high durometer (80-90) urethane, such as Repro 83 from Repro Urethanes, Poly PT Flex 20, Poly PT Flex 60, Poly PT Flex 70, Poly PT Flex 80, and/or Poly PT Flex 85 from Polytek Development Corporation of Easton, Pa., and/or a castable elastomer such as Fast-Cast Urethane from Freeman Manufacturing & Supply Company of Avon, Ohio. The composite material in accordance with the present invention may be exemplarily used as a non-pneumatic tire material or a runflat structure material such as an insert in a pneumatic tire. The composite material may also improve the puncture resistance and/or the structural stiffness of any structure.

(70) Conventional composite materials usually rely on the embedding of reinforcing fibers or cords in an elastomer matrix. The fibers/cords are typically cylindrical, with a length (l) and a diameter (d). Such fibers/cords may be long (l>>d) or short (l>d), but usually have a high tensile stiffness with respect to the polymer matrix. The bending stiffness of such fibers/cords, however, is typically low because of low area moment of inertia (I=Pi*d^4/64) and small diameter of the fiber/cord. Conventional materials, however, may achieve high bending stiffness as the fibers/cords are loaded in tension and compression as the material is bent by an amount dependent on the position of the fibers/cords relative to the neutral axis of bending.

(71) In comparison to the conventional material, the composite material of the present invention derives bending stiffness from the bending stiffness of the spring mesh itself, the bending stiffness of the polymer, and the mechanical restriction of relative motion between the springs and the other springs and the polymer (mesh locking effect). The mesh locking effect may thus cause the bending stiffness of the composite material to be greater than the bending stiffness of the spring mesh added to the bending stiffness of the polymer (i.e., 9% greater in the example graph of a spring/rubber composite in FIG. 25). Thus, the spring mesh and polymer are more than a mere collocation or aggregation of strengths.

(72) Also, adhesive bonding between a reinforcing material and an elastomer is critical, because there is little or no physical interlocking between the fibers/cords and elastomer. Thus, if standard fibers/cords de-bond from the elastomer, mechanisms like socketing may occur where the fiber/cord loses all contribution to the composite material's mechanical strength (i.e., bending stiffness). In a composite material in accordance with the present invention, mechanical interlocking is a significant mechanism securing the reinforcing springs in the polymer and contributing to the composite material's structural properties.

(73) The example graph of FIG. 26 illustrates an increase of 20.1% over the mere addition of stiffness of the springs and the polymer Poly PT Flex 60.

(74) The example graph of FIG. 27 illustrates an increase of 32.5% over the mere addition of stiffness of the springs and the polymer Poly PT Flex 70

(75) In the foregoing description, certain terms have been used for brevity, clearness, and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the present invention is by way of example, and the scope of the present invention is not limited to the exact details shown or described.

(76) Having now described the features, discoveries, and principles of the present invention, the manner in which the present invention is constructed and used, the characteristics of the construction, and the advantageous, new, and useful results obtained, the scope of the new and useful structures, devices, elements, arrangements, parts, and combinations are hereby set forth in the appended claims.