ENERGY ABSORBING DEVICES

The wi tìon relate to energy absorber or controlling devices. Açcordìng tO the invention, there is provided an energy controlling device comprising elastomeric material with a plurality of filaments of flexible material embedded therein and bonded or mechanically locked thereto so as to pìoduGe a composite beam structure, the composite beam structure being so s2ranged for motmtìng with respect be the positioning of the îilaments in the L elastomeric material õ id with respect to a predetermined impact direction that when the structuìe bends in response to an impact occurring in said direction ab least some of the filaments are placed in compression and at least some of the filsmlenbs are placed in tension the îilaments having such Cross-sectional area and modulus of: elasticity that the compressive forces gènerated in the structure by the impact are principally taken by the filaments snd the energy of the impaqb is at least partially contìolled by the consequential increased bending resistance of the composite beam structure. According to the invention, there is also provided an energy controlling device comprising elastomeric material with a plurality : of fìlaménts of flexible material embedded therein and •bonded or mechanically locked thereto so as tO produce a composite beam structure, and support means attached te the composite beam structure for supporting it at such a position or positions thereon that impacts received by the material along a range of directions which are predetermined with respect te the support meals and $he filaments tend to place at least some of said filaments in compression and at least some of said filaments in tension, the filaments having such cross-sectional area and modulus of elasticity, that the said impacts are principally absorbed by the resistance te ,bending imparted to the elastomeric material by the resistance to compression of those fi1 filaments placed• in compression. lO i '7 "• ,j.. !ii• • • .i I ZZ I l0 .00509â According ço the invention, there is further provided a energy controlling device comprising wall means embracin5 or surrounding a space and Outwardly presenting an impact receiving face d at least partly made of elastomericmaterial with a plurality of embedded filaments of flexible material which extend longitudinally towards said face the filaments being bonded or mechanically locked to the elastomeric material so as to produce a composite beam structure, and the filaments being so positioned in the eiastomeric material ha an impact on said face tending to deform the wall means.places ai least some 'of the fi1 aments in compressìon and at least some of the fi1 aments in tension» the filaments having such cross-sectìonal area'and modulus of elasticity that the. energy ofthe impacts is at least partially controlled by the resistance to bending imputed fo the composite beam structure by the resist ce1 to compressiòn of those filaments which take the compressive forces generated by said • imp acte. According to the ìnventlon there is yet further provided an energy controlling bumper or fender for protecting .a.vehicle against impacts occurring in anticipated directions which comprises an elastomaric material having filaments embedded therein and bohded .or mechanically locked thereto, and havìug such cross-sectional area and modulus o£ elasticity» so as to produce a composite beam structure which had a substantially higher resistance to bending in directions which place at least some of the filaments in compreseìon and at least some of the filaments in tension than bas the elastomeric material alone, and means mounting the composite beam structure on he vehìcle so as to present a face positioned to receive said ìmpacbssuch that they tend to bend the structure in said directions whereby the c0mpressive, forces generated by the impacts are maìnly taken by those filaments place in compression. Accordìng to the invention, there is yet further provìded am energy controlling devìce comprising wall means embracing or surrounding a.space and outwardly presenting an impact-receiving lacer [ ....... !" I I -- " I .... [ '1100,1D094 lO ii • the wall means being made of elasticity maÙerial .»«ith two parallel fabric layers embedded therein ud respectively positioned adjacent the inner and outer faces of the wall means, each fabrìc layer incorporating a plurality of filamen'bs of a plastic material .which over a portion of their lengths, at least, extend longitudinally towards said face éach filament ha.ring a modulus of elasticity in the range 400,000 to 600,000 lbs.per sq.inch, a breakS_uS stress between 50,000. and lO0,O00 Ibs.per sq.lnch, end a disJaeter or effectïve diameter .exceeding O.OO1 inches, the fila- .ments being bonded or.mechanically locked te the elastomeric material so as to produce therewith a composíte beam structure, whereby an impact on said• face tends to deform the wall means placing .at least some of the filaments in compression a d at least some of the filamënts in tension, such that the compressive forces geherated in the structure by the impacts are principally taken by those fìlaments placed in compression and the energy of the ìmpacts.is controlled by the consequential increased bending resistauce of the structure. Energy absorbing or controlling devices embodying the invention will now be described, by way of example only, with reference to the. accompanying drawings in which: Figure. 1 is a sectìon, on the line !-I of Fig.2, through a piece, of material :for use in the •devices ; Figure 2 is an elevation of the piece of material of Fig.1; F'ìBure 3 is a diagrammatic perspective view to a greatly enlarged scale of a piece, of woven fabric containing flexible plastics filaments for incorporation in the materia1 of Figs.1 and 2; Figure is a plan view of one of the energy absorbing devices; Figure 5 .is a cross-sectlon through the.device of Fig.$, on the liné V-V of Fig.4; Figure 6 is a cross-section corresponding to Figure 4 and through another of the devices; I - • I Figures 7 and 8 are diagrams explaJming.the operation of the devices of Figs.$ 5 and '6 and respectively sho%¢ the devices in the normal and deformed states; Figures 9 and I0 are diagrammatic cross-sectional views showìng another of the energy absorbing deviens respeo@ively in its normal a d deformed positions ; Figurës Il and 12 correspond respectively to Figures 9 and l0 but show a further one of the energy absorbing devices r - SalO 10059S4 Figure 15 is a cross-sectional view through a further one of the energy absorbing deviens Figure lZ is a perspective view of a cutaway end of the device of Figure 13; Figure 15 is a perspectìve view showing another one of the energy absorbing devices in position as a bumper or fender on a vehicle; and Figures 16, 17 ana 18 a e respectively diagrammatic perspective views of further ones of the energy absorbing devices. As will be desoribeå below there is provided an article which is made of flexible elastomeric or rubber material in which are embedded a plurality of flexible filaments. These filaments may be made of metal or plastics material of suitable modulus of elasticity and diameter and are found to increase the stiffness or resistance to bending of the artìcle with respect to forces acting about axes transverse to the directions of extension of the filaments. This increase in stiffness is caused by the filaments and the e!astomerio material acting together as a composite beam, that is, a beam where the tensile and compressive forces e mainly taken by the filaments and the shear forces mainly taken by the elastomeric material. For ease of manufacture, the filaments preferably comprise pieces of a woven fabric, and Figure 1 shows a crosssection through an element 20 made of rubber 22 in which t o layers 24 and 26 each made of such a fabric are embedded. In each fabric layer 24, 26, the filaments are arranged in parallel relation to each other and extend from the top 28 to the bottom 30 of the article; Fig°2 shows some of the • i .: .. • .ï ï lO 0"• filaments in'dotted outline, purely diagrammaticall7 for purposes of explanation. It is found that the filaments give the element a greatly increased resistance to bending forces acting about axes Axis 32, Fig.2, for example) transverse o the dircotlon o£ extension of the filaments. The resistance to bending fonces acting about axes (axis 3 ig.2, for example) parallel to the filaments is affected to a much lesser extent by the provision of the filaments. The increase in stiffness provided by Çhe filaments depends on the position of the filaments within the elastomeric material. Thus, the increase in stiffness is greater as the fabric layers 2Ç and 26 are moved apar'b and come respectively closer to the surfaces 36 and 38 of the article. In addition the stiffness may be altered by having a different number of filaments per lineal inch. Although two sets of filaments (that is, two fabric layers 24 and 26) have been shown in Figures 1 and 2, it will be appreciated that more or less numbers of filament sers may be provided, thouõh at least two sets of filaments are advantageously provided. Moreover, where two oz more rows of filaments are provided in the elastomericmaterial, the filaments of one row may extend• in a different direction from those in another row. In such a case, the element stiffness will be increased in more than one direction.' Thus, for example» if the filaments in the fabric layer 26 of Figures 1 and 2 extend perpendicula2 1y to those in the fabric layer 2z » t çn the resistance of the element to bending about axis 34 will be increased as well as its resistance about axis 32. ï. • • • ...,... ".. o'.,. í..... ; m [ - iç E I .............. 1 ..... r ï • i.i i. •ii l0 3o 10050 4 On the assumption that the filaments in at least one of the fabric layers 24 and 26 extend Irom the top 28 to the bottom 30 of the element 20 (so as to increase the resistance to bending about axis 32), the element of Figures 1 and 2 may be used as an energy absorbing or impact cushioning device if it is mounted so as to receive the impact in the direction of the arrow A. Such an impact will tend to bend the element about the axis 52 (and parallel axes) and •this will be resisted by the composite beam, and the energy of the impact will thus be absorbed by the resistance to bending imparted to the element by the composite beam effect of the filaments and the elastomeric material. Figure 3 shows part of one of the fabric la, ets 2 and 26 to a greatly enlarged scale. As shown, the filaments, referenced 40, axe arranged in bundles each containing seven filaments which are spun into respectivé yarns 42. The fabric contains two rows of yarns 42 and is woven so that the yarns of each row are separated by spacing strands 4 and held together by transverse lacing strands 46 which pass through the filament rows and around the yarns. As explained above, the stiffness imparted to the artic1e in which the fabric is embedded depends on the modulus of elasticity of the filaments and the number of filaments. In order to maximize the stiffness, the yarns 42 are spun with as little twist of the filaments as possible, since twisting reduces the modulus of elasticity of the yarn. By minimizing the amount of twist, the modulus of elasticity of each yarn is kept as close as possible to that of each filament. For the same reason, the yarns 42 are kept as straight as possible without inter-weaving and with little I ..... T" I .......... F I " I i • le 3o 10050B t or no crimping so that the Modulus of elasticity of the fabric in the direction of the yarns is as close as possible to hat of the yar and the filaments. The size and the modulus of elasticity of the filaments should be sufficiently high to give useful results. It is found that normally the modulus o£ elasticity should exceed lO,000 lbs.per sq. ineh (700 kilograms per sq.cm) and preferably be above 100,O00 lbs.per sq,inch C7000 kilograms per sq.cm); a value in the range 400000 to 600000 lbs.per sq.inch (28000 kilograms per sq°cm to 42000 kilograms per sq.cm.) is particularly suitable. The preferred size of the filaments depends on their modulus of elasticity; a lower modulus of élasticity requires a larger filament dìameter to give the same results as a higher modulus of elasticity with a smallerlfilament diameter. Normally, the filament diameter should exceed O.001 inches (0.025 millimetres). Preferably» the modulus of elasticity and the filament diameter are not suffìciently great te prevent or hinde weaving of the filaments into the fabric» using a standard weaving machine. In one particular example of the fabric each filament is made of polyethylene terephthalate polyethylene Trade Mark) and is of substantially circular cross-section with a diameter of O.OlO inches (0.25 millimètres) and a modulus of elasticity of about 600 000 lbs.per sq.inch (42000 kilograms pe sq.cm). Therein breaking stress is between 50,000 and lO0,O00 lbs.per sq.inch (3 500 to 7000 kilograms per sq. cm) and their extension at break is between 5% and 2 I this example, each ow in the fabric (Fig.3) has 22 yarns per inch (8.70 per centìmetre) so that there are a . I I l i, OEOGS094 lO ïl . i total of 4L yarns per inch (17.40 per centimetre). If has been found advantageous to stretch each yarn during manufacture and then to allow it partially te resile, before weaving it into the fabric. This is found to decrease the permanent set given to the yarn by any stretching which might take place subsequently in use for example. In addition it is found to increase the modulus of elasticity of the yarn. Although the ysmns 2 have been illustrated inFigure as all extending in the same direction they may be woven se as to extend in different directions, thus providing increased resistance to bending in various directions as explained above in connection with Figures 1 and 2. Although the filaments have been i1 illustrated as being of circular cross-section, they may instead be non-circular in cross-section, and for the purposes of thìs Specification, a filament of non-circula cross-section is considered to have a diameter equivalent to that of a filament of circula cross-section having a moment of inertia equal to the minimum moment of inertia of the filament of non-circular cross-section. Instead of polyethylene terephthalate, the filaments may be made of other material such as nylon Or other plastics materìa1 but te obtain similar results larger filament iameters•may be necessary than with polyethylene terephthalate. The filaments used should be resistant te fati ue able to bond to the elastomer and resistant to chemical moisture and radiation attack•and should have good ageing properties. The fabric may be incorporated into the elastomeric material by any suitable method which ensures adequate l [ • OEO }5OS bonding between the material and the £ab ic. The leave of bhe fabric may be sufficiently open so that rubber can readily penetrate tl e fabric during manu- '-" picture to provide a good bond. .. ..: -.. ' i..i'" "" .. '..5.. ... Fìguìes 4 and 5 show an' eneìgy absorbìng device in the .. • fo m of a bumper o fender such as for fitment to a vehicle. • :.. ::.. The device is hollow and of generally U-oh'ape in section, • The base 5'0 of the U-shape is poslbionòd fo receive the impact in the direction of the arrow B, and the device is support on the vehicle by strong clamps 52 anå 5 -which hold the distal ends of. the legs 56 and 58 of the U. The legs 56 and 58 are generally straight and parallel and the h0oEe device, especially the legs 56 and 58, is made of • máterial with Co0ã resistance tó bending about axes which lie in he planes of the legs and extend bet»Jeen the ends I 5o i. • 60 60 of the device. • . Figure 8 sho»Js how the device responds to an impact in the direction o£ the arrow B, By suitably constructive the legs 56 58, as by incorporating points of relatively lower bending'resistance in régions 62, 64 the legs 56 58 sme' caused to bend out,cards in response to the impact» and th resistance to bending, of the leõs 56 and 58 cushions the impact and absorbs i%s energy. Instead of incorporating points of loser bending resistance in the legs» it is found that the same effect may be achieved by adjusting the stiffness of the base 50 of the U relative to that of the legs 56 and 58. " .. . The aevlce of Figures and. 5 may be constructed of any suitable material, but advantageously the material is of the type disclosed above in connection.with Figs.1 and 2 in which ,.' - 9 ï . . .......... " F T ........... --7-- il q .!i ii L :i i fO d i .Æ00509 flexible filamenbs are embedded in elastomoric material such as rubber. °Figure 6 shows a cross-sectional, corresponding geneìally to Fig.5 and in plan appearing generally as in Fig.l trough such a dëvice in which the device is construct-- ed of rubber Édith t o fabric layers 66 and 68 (corresponding te fabric layers 24 and 2g of Figure i) embedded in it. The fi1filaments 'in each of thè layers 66 and 68 extend parallel to each other around the U. from the distal end of one leg 56 to the disçai end of the other leg 58, and the layers 66, 68 extend between the two ends 60. of the device. Additìonally» two further £abric layers ?0, 72» similar to the layers 24, 26 of Figure l, are embedded in the base 50 of the U. These layers also extend between the ç - o ends 60 of the device but the filaments in these layers extend perpendicular to the filaments in the layers 66 and 68. The device of Figure 6 has legions 62 and 64 of relatively lo» èr bending resistance ud it therefore resoonds to an impact in the manner shown in Fleure 8, These regions of'relktìvely lamper bendilng resistance may be obtained by, for exemple, crimping thë filaments in the fabìic layeìs 66 "68 at this point or forming a bend in the fabric itself. • Al ernàtively, the same effect may be obtained by adjusting the m elative stiffness of the base 50 and the legs 56, 58,. ' .. The use of the composite material of the type disclosed in •connection with Figure 1 in the device of Figure 6 has a number of important advantages. In particular, the material has 'great strength and its bending resistance can be made very hì'gh and easily adjusted during manufacture, and further- . P more the bending resistance of the material can easily be màde different in vá2 i0 us directions. It can easily Be :i -, -- " " lç i:i! • 1OO5094 gìçen a decorative finish or fitted with decorative attachments such as chromium-plated steel strips. When used as a bumper or fender for a vehicle» a number of the other points are worthy of note:- l. Complex shapes can be easily manufactured, such as holes or depressions for lights and other items. 2. Items such as over-rlders can be moulded within the main structure« 3, The structure can be moulded to fit refund a radíator grille, license plates» lamps and other fitments on the vehicle. 4. Items such as reflectors or decorative finishes can easily be incorporated in the rubber, either by compounding or by attachment. 5. By varying the rigidity at various points (in the manner described)» it is possible to make the structure more resistant to deformation at points near to lamps» hodywork and the llke. 6. By suitable predetermination of the rigidity of the various bending points in the structure, it is possible to arrange that the resisting forces per unit of total deformation linearly increase as in a spring or are linearly constant as in a hydraulic damper, or are of some other form such as decreasing or increasing in a no.-linear form. Such adjustment is simple and inexpensive. It will be noted that the energy absorbing devices descrlbed are distinguished from devices relying mainly or solely on rubber or an elastoraer, in which impact absorption is performed by the rubbèr er elastomer acting mainly in shear. As described in this Specification, on the other hand» the rubber is combined with another component to produce a composite v Il - l E I -- I ---- i 100509@ which acts in bending as a beam, but nevertheless retains the shear properties of the rubber which allow large deformations without failure. Figures 9 and I0 show a cross-sectlon through another form of bumper or fender which again is made of rubber material in which are embeded two" fabrlclayers 66 and 68 corres ponding to layers 66 and 68 of the device of Figure 6. Again, the filaments in the fabric extend around the whole of the U as in the Figure 6 device. Unlike the latter device» however, the device of Figures 9 and I0 does not have the additional fabric layers 70 and 72. Figure 10 shows the configuration which the device of Figure 9 assumes In response to an impact, and again it will ha seen that bending takes place which is resisted by the composite beam and absorbs the energy of the impact. The means by which the device of Figures 8 and 9 is clamped to the vehicle is not shown in these Figures. Figures Il and 12 correspond generally with Figures 9 and I0, respectively, and show another configuration. The energy absorbing device of Figures 13 and IA is again a bumper or fender for a vehicle and has embedded fabric layers 66, 68» 70 and 72 arranged generally similarly to the layers in Figure 6. Figure'f3 shows how a structure 90may be moulded into the rubber to hold a license plate. Figure 15 shows how the device of Figure 6 may be given a more complex shape so as to provide overall protection to the front of a vehicle, with openings and apertures for the lights, rad1 a{0 r grille, and license plates of the vehicle. One problem which may occur in designing the conflguration of an energy absorbing device such as, for example, a bumper or fender for a vehicle» is the difficulty of dealing - 12 100S09 ZO Z5 with different types of impact. Thus the impact may take place overonly a comparatívely small length of the devl¢e (for example, when the device is a bumper or fender on a vehicle and the vehicle strikes a post orpole) or over a greater part or whole of the length of the device. If the device is made sufficiently stiff te give the desired deçelerating forc€, over a predetermined deformation distance, in response to a point fmpa=t, the stiffness of the device will be such that in response to an impact over the full length or at least a considerable portoEon of the length of the device, only a small part of the distance available for deformtion will be utilised and the impact will be absorbed but will give considerably higher loads on the vehi¢ie .which may not be acceptable. Conversely if the device is designed to be of stiffness to give acceptable deceleration to a full width colllsiÇn, it will give Insufficient deceleration in response to a point impact and not absorb all the energy satisfactorily. Figures 16, 17 and 18 show perspective views of vehicle bumpers or fenders in which the impact receiving face is non-retili ear over a substantial part of its length. Therefore, a impact will be received by only a relatively small area of the impact receiv1 ns face, and those will be so whether the impact fs a point impact, such as by a collision of the vehicle w th a pole or post, or an impact with a larger area. This enables the Whole of the device to Se made suffiŒEíently stiff to give a desired deceleraoEing force over a predetermíned deformation distance in response to a point-type collision, since, effectively, the device will only be subjected to point-type impacts. - 13 - i005094 '!ii In the case of the device of Figure 16, the impact receiving face is convexly Curved for a substantial part of the length of the face« In a modified form, the face may be convexly curved over its whole length. In other constructions, the impäct receiving face may include straight portions or consist of straight portions 92,9 arranged in staggered relationship (as in the case of Figure 18). In the case of the device of Figure 17, the impact receiving face has projections 96. In modification there may be recesses instead or as well. The whole of the impact receiving face need not present the same stiffness. For example, when the projections are provided, the projections and/or adjoining portions may be of a different stiffness from the other parts of the structure, The devices of Figure 16 toi IB are made of suitable material whose design or configuration is such that it h s a high resistance to bending so as to absorb the energy of the impact« For example, the devices of Figures 16 to 18 may be ¢Eonstructed and may operate in the m armer described with reference to Figure 5 or 6. The energy absorglng devices described are not restricted to use on automobiles but may be used on ships and other moving objects and the word "vehicle" is to be construed aceordlngly. Furthermore the devices described may be used on fixed objects to provide =rash barriers and the like. The term "bumper" or "fender" for a vehicle as used herein in intended to include vehicle over-rlders and under-riders» and also to include an end or side vehicle body portion of the form shown in Figure i,i ï 1: -ï iOOS09 he embod menbs of the invention in which au exclusive property Or privilege is claimed are defined as follows:- I. An energy controlling device comprising elastomeric material wlth a plurality of filaments of flexible material embedded therein and bonded or mechanically locked thereto se as to produce a composite beam structure, the composite beam structure being so arranged for mounting with respect to the Rosibioning of the filaments in the elastomeric material and wìth respect to a predetermined impact direction that when the structure bends in response te an impact occurring in said directìon at least some of the filaments sme placed in compression and at least some of the filaments are placed in tension, the filaments having such crosssectional area and modulus of elasticity that the compressive forces generated in the structure by the impact are principally taken by the filaments and the energy of the impact is at least partially controlled by the consequential increased bendìn resistance of the c°mp°sìte beam structure. 2. A devíce accordinE to claim I» in which there are at least two sets of the filaments» each set including ab least one row of parallel filaments lying in a plane parallel to the plane of the row in each other set, the said sets being spaced apsmt in the elastomerìc material in a direction normal to the said planes, and the composite structure beìn so arranged for mountìng that impacts in the said direction tend to bend the structure about lines parallel to the said planes and transverse to the filaments. 3. A device according to claim 2» in which ail the filaments in said two sets extend in the same direction. 4. A device according to claim 2 or 3, in which the filaments of each of the two said sets are woven into a respective piece of a»rio. - i [ ..... :ï i [ 1 F .... t ........... ,