Abstract:
An energy absorbing system is provided. The system comprises a fitting having a crack inducing surface extending radially outward in relation to an axis. An energy absorbing structural element formed by a hollow body extends along the axis and has a first end adapted to interact with the crack inducing surface of the fitting so as to radially spread the hollow body. Cracks are formed in the hollow body in response to forces applied in a direction substantially parallel to the axis which forces push the crack inducing surface against the first end. The hollow body may have layers of reinforcing flat material embedded in a matrix material and may comprise a single winding of the flat material about the axis. A number of layers of the flat material in the hollow body may be different in different areas.

Description:
[0001]    This application is a continuation of co-pending, commonly assigned U.S. patent application Ser. No. 09/268,572 filed on Mar. 15, 1999. This application claims the benefit of German patent application no. 198 13 998.5 filed on Mar. 28, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a process for the production of structural elements absorbing energy with defined characteristics, these elements being produced as shaped members (also referred to herein as “hollow bodies”) from a matrix material and a reinforcing material embedded therein.  
           [0003]    Shaped members of this type are known, for example, from DE-B 37 44 349.  
           [0004]    The use of such shaped members as structural elements is likewise known, for example, in EP-A-0 130 009 or DE-A-196 27 061.  
           [0005]    Proceeding on the basis of the known solutions, the object underlying the invention is to provide a process for the production of an energy-absorbing structural element, with which an energy absorption with defined characteristics may be realized in a simple manner.  
         SUMMARY OF THE INVENTION  
         [0006]    This object is accomplished in accordance with the invention, in a process of the type described at the outset, in that in different areas of the shaped member layers of the reinforcing material are arranged so as to extend in relation thereto in a defined manner and be arranged with a number differing in a defined manner, and that the reinforcing material for the entire shaped member is wound in a single winding procedure to form the shaped member.  
           [0007]    The advantage of the inventive process is to be seen in the fact that, on the one hand, defined energy-absorbing characteristics of the structural element can be produced and that, on the other hand, such a complex structural element can be produced very easily, namely by means of a single winding procedure.  
           [0008]    A shaped member of this type may be produced in various ways, for example, by means of a winding procedure with multiple supply of pieces of flat material.  
           [0009]    However, the inventive process may be carried out particularly advantageously when the reinforcing material is supplied to the winding procedure in the form of a single piece of flat material which is contoured in such a manner that the required defined orientation of the layers and the number of layers differing in a defined manner are present in the shaped member after the winding procedure.  
           [0010]    This has the great advantage that the required orientation and, in particular, the different number of layers in different areas are defined by the contour of the piece of flat material such that no attention need be paid to the differences in the individual areas during the winding procedure.  
           [0011]    Furthermore, this process has the advantage that the number of layers present in the individual areas may also be altered in a simple manner, namely simply by altering the contour of the piece of flat material.  
           [0012]    With respect to the contouring of the individual pieces of flat material for achieving defined characteristics of the energy absorption, no further details have so far been given. This contouring may, in principle, be brought about in any optional manner.  
           [0013]    A basic pattern for such contoured pieces of flat material does, however, provide for the piece of flat material to have a section with a maximum width transverse to the winding direction and at least one section with a lesser width transverse to the winding direction. A contour of this type can, for example, be similar to a wedge or similar to a step and creates the possibility of generating with the section of a maximum width transverse to the winding direction layers which extend essentially over the entire length of the shaped member in the direction of the winding axis and then additional layers which serve, for example, as reinforcement layers so that areas with a greater number of layers and areas with a lesser number of layers result and when these break varying forces also occur and thus energy is absorbed to varying degrees.  
           [0014]    The contouring of the piece of flat material can take place at different points of time. For example, one embodiment of the inventive process advantageously provides for the piece of flat material to be contoured in the section influencing the areas having a number of layers differing in a defined manner during the course of the supply of a web of flat material to the winding procedure; this means that, for example, the piece of flat material results during cutting out of the contour from the web of flat material during supply thereof to the winding procedure.  
           [0015]    Another alternative solution provides for the piece of flat material to be contoured in the section influencing the areas having a number of layers differing in a defined manner prior to the supply to the winding procedure; this means that finished, contoured pieces of flat material are supplied individually one after the other to the various winding procedures.  
           [0016]    The contouring of the pieces of flat material, for example, proceeding from a web of flat material can be brought about in a simple manner in that the piece of flat material is contoured by means of a cutting procedure.  
           [0017]    This cutting procedure can be a cutting procedure of such a type that the contour to be cut out is followed with a cutting knife.  
           [0018]    It is, however, also possible to carry out the cutting procedure in such a manner that at least connected parts of the contour are cut out with a punch knife.  
           [0019]    The inventive process may be carried out particularly economically when the reinforcing material is wound such that a maximum extension of the contoured piece of flat material in the direction of a winding axis corresponds to the maximum extension of the shaped member in the direction of the winding axis; this means that the supply direction of the piece of flat material may essentially form a right angle with the winding axis and thus a particularly rapid supply of the piece of flat material to the winding procedure is possible.  
           [0020]    The winding of the shaped member may be designed to be particularly economic when several pieces of flat material are supplied to the winding procedure in parallel and thus several shaped members can be wound from the pieces of flat material at the same time. This is of considerable advantage, in particular, for a mass production or large-scale production.  
           [0021]    The supply of several pieces of flat material to the winding procedure may be of a particularly favorable design when the several pieces of flat material can be supplied to the winding procedure as a connected arrangement of pieces of flat material since, as a result, a parallel supply may be ensured in a simple manner due to the connection of the various pieces of flat material and thus the device for the supply of the several pieces of flat material can also be of as simple a design as possible.  
           [0022]    The several pieces of flat material could, in principle, be designed to be connected in all the sections. It is particularly favorable for the separation of the resulting shaped members when the several pieces of flat material are connected in the region of the sections which increase the number of layers in all the areas of the shaped member in an equal manner.  
           [0023]    In the case, in particular, of pieces of flat material which have a section of maximum width, it is provided for the pieces of flat material to be connected in the section of maximum width. In this respect, the pieces of flat material can, for example, be designed to be connected in the entire section of maximum width. It is, however, also possible for the pieces of flat material to be connected merely via webs so that the later shaped members are more easy to separate.  
           [0024]    The embedding of the reinforcing material in the matrix material can be brought about in the most varied of ways. It would, for example, be conceivable to wind the reinforcing material first of all and subsequently apply the matrix material after the winding. This would, however, impair the speed during the production of the inventive shaped members. For this reason, a particularly advantageous embodiment provides for the reinforcing material to be impregnated with the matrix material prior to the winding of the reinforcing material to form the shaped member and so during the winding not only is the reinforcing material shaped into the shaped member but the matrix material is supplied at the same time.  
           [0025]    During the supply of reinforcing material impregnated with matrix material it is particularly favorable when the winding is carried out with a flowable or saturatable matrix material so that the winding of the reinforcing material to form the shaped member can be used at the same time for the purpose of embedding the reinforcing material with the various layers completely in the entire matrix material since the flowing matrix material allows the desired embedding of the reinforcing material in it.  
           [0026]    For example, this would be possible in that the matrix material is supplied as a flowable or saturatable material with the reinforcing material; this does, however, have disadvantages for the handling of the reinforcing material during the supply to the winding.  
           [0027]    For this reason, it is preferably provided for the matrix material to become saturatable during the winding, i.e. either becomes more liquid in the case of a duroplast as a result of heating or in the case of a thermoplastic material is melted to the melting point as a result of heating.  
           [0028]    In the case of a thermoplastic material, it is provided for the matrix material to be kept at melting temperature during the entire winding.  
           [0029]    This would be possible, on the one hand, in that the matrix material is heated to melting temperature prior to the winding, for example, during the time, during which it is supplied to the reinforcing material.  
           [0030]    A particularly advantageous solution does, however, avoid the heating up of the matrix material to melting temperature prior to the winding and rather provides for the matrix material to be heated to melting temperature during the winding.  
           [0031]    One possibility is heating via an external supply of heat such as, for example, hot air, electromagnetic radiation or gas flame.  
           [0032]    As an alternative or in addition it is provided for the matrix material to be heated to melting temperature by means of a heated winding tube and kept at this temperature.  
           [0033]    The winding procedure may be carried out particularly quickly when the winding tubes are heated prior to the winding to the melting temperature of the matrix material or above this so that the matrix material is melted immediately upon contact of the reinforcing material with the impregnated matrix material.  
           [0034]    In this respect, it is favorably provided for the winding tubes to be heated prior to their insertion into the winding device so that the reinforcing material can be wound with matrix material immediately after insertion of a winding tube into the winding device without having to wait a heating-up time.  
           [0035]    Alternatively to providing a thermoplastic matrix material, another embodiment provides for the matrix material to be a duroplast.  
           [0036]    In this case, it is preferably provided for the matrix material to be heated during the winding only to such an extent that this is liquid to an adequate degree during the winding of the reinforcing material.  
           [0037]    In the case of a duroplast, it is preferably provided for the matrix material to be hardened in the shaped member after the winding and so an adequate hardening time for the matrix material must be provided after the winding.  
           [0038]    This may be carried out particularly favorably when the matrix material is hardened with a shaped member seated on the winding tube so that the winding tube determines the desired shape during the hardening of the matrix material.  
           [0039]    In order to achieve sufficiently high transit times, it is preferably provided for the winding tubes wound with the shaped members to be combined during the hardening of the matrix material to form groups of winding tubes which pass together through the hardening phase.  
           [0040]    With all the possible variations of the inventive process, it is preferably provided for the shaped members to be cooled when seated on the winding tubes and thus the shaped members are not removed from the winding tubes until after complete hardening or solidification of the matrix material.  
           [0041]    This removal of the shaped members from the winding tubes may be carried out, in particular, in that the shaped members are withdrawn from the winding tubes.  
           [0042]    When carrying out the embodiments of the inventive process described thus far, with which several pieces of flat material are designed to be connected, the separation of the shaped members produced therefrom by way of winding can be brought about in the most varied of ways. According to one variation it would be conceivable to separate the shaped members prior to the hardening, for example, on the winding tube.  
           [0043]    Alternatively thereto, it is provided for the shaped members to be separated after the hardening.  
           [0044]    This may be carried out particularly favorably when the connected shaped members are separated after the withdrawal from the winding tubes since, in this case, a simple separation, for example, by way of sawing may be realized.  
           [0045]    The present invention also provides an energy absorbing system, which employs an energy absorbing structural element produced in accordance with the processes described above.  
           [0046]    In an example embodiment of such an energy absorbing system, a fitting is provided having a crack inducing surface extending radially outward in relation to an axis. An energy absorbing element formed by a hollow body is also provided. The hollow body extends along the axis and has a first end adapted to interact with the crack inducing surface of the fitting so as to radially spread the hollow body, thereby forming cracks in the hollow body in response to forces applied in a direction substantially parallel to the axis which forces push the crack inducing surface against the first end. The hollow body may have layers of reinforcing flat material embedded in a matrix material and may comprise a single winding of the flat material about the axis. A number of layers of the reinforcing flat material in the hollow body may be different in different areas of the hollow body.  
           [0047]    The layers of reinforcing flat material may extend in the hollow body in a defined manner to cause: (i) the forces to be absorbed by the hollow body without folding; and (ii) the layers of reinforcing flat material to receive cracks which begin at the first end and expand through the different areas of the hollow body in the direction substantially parallel to the axis.  
           [0048]    The surface of the fitting may be toroidal in shape. A crack triggering element may be arranged on one of the fitting or the hollow body end. The crack triggering element may comprise a chamfer at the first end of the hollow body adapted to interact with the crack inducing surface. The crack triggering element may comprise slits in the first end of the hollow body.  
           [0049]    The reinforcing flat material may comprise a single piece of flat material. The single piece of flat material may have a section with a maximum width in a direction parallel to the axis and at least one section with a lesser width in the direction parallel to the axis.  
           [0050]    Sections of the flat material may be contoured to provide the different areas having the different number of layers during supplying the flat material to a mandrel to form the hollow body. The piece of flat material may be contoured by means of a cutting procedure.  
           [0051]    In an alternative example embodiment, sections of the piece of flat material may be contoured to provide the different areas having the different number of layers prior to supplying the flat material to a mandrel to form the hollow body. The piece of flat material may be contoured by means of a cutting procedure.  
           [0052]    A maximum extension of a contoured piece of flat material in a direction parallel to the axis may correspond to a maximum extension of the hollow body in the direction parallel to the axis.  
           [0053]    In one example embodiment, multiple pieces of flat material may be supplied to a winding procedure in parallel to form the hollow body. The multiple pieces of flat material may be supplied to the winding procedure as a connected arrangement of pieces of flat material in which the pieces of flat material are arranged in a sequence extending in a direction parallel to the axis. The multiple pieces of flat material may be connected in a section which increases the number of layers in all the areas of the hollow body in an equal manner. For example, the pieces of flat material may be connected in a section with maximum width.  
           [0054]    In a furether example embodiment of the present invention, the reinforcing flat material may be impregnated with the matrix material prior to a winding of the reinforcing flat material to form the hollow body. The winding of the reinforcing flat material may be carried out with one of a liquid or a liquifiable matrix material. The matrix material may be liquefied during the winding. The matrix material may be kept at a melting temperature during the entire winding of the reinforcing flat material. The matrix material may be heated to the melting temperature during the winding of the reinforcing flat material.  
           [0055]    The matrix material may be heated to the melting temperature by means of a mandrel which is heated and kept at the melting temperature. The mandrel may be heated to the melting temperature of the matrix material prior to the winding. The mandrel may be heated to the melting temperature of the matrix material prior to insertion into a winding device.  
           [0056]    The matrix material may be heated to such an extent that it is adequately liquefied during the winding of the reinforcing flat material.  
           [0057]    The matrix material may be hardened in the hollow body following the winding. The matrix material may be hardened with the hollow body seated on a winding tube.  
           [0058]    The matrix material may comprise one of a thermoplastic material or a duroplast material.  
           [0059]    The fitting may comprise a cylindrical guide section having a casing surface which abuts an inner surface of the hollow body at the first hollow body end and a channel section extending annularly around the axis and having a base surface bordering the casing surface and extending radially outward in relation to the axis. The channel section may be toroidal in shape.  
           [0060]    The energy absorbing system may further comprise a second fitting having a contact surface transverse to the axis and adapted to support the hollow body at a second end thereof.  
           [0061]    The energy absorbing system may further comprise securing means for securing the second end of the hollow body to the second fitting. The second end of the hollow body may be adapted to absorb the forces without folding and to transfer these forces to the second fitting so that the cracks are induced in the first end of the hollow body and extend along the axis toward the second end.  
           [0062]    Additional features and advantages of the inventive solution are the subject matter of the following illustrations of several embodiments of inventive shaped members and several embodiments of processes for the winding of such inventive shaped members.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0063]    The present invention will hereinafter be described in conjunction with the appended drawing figures, wherein like reference numerals denote like elements, and:  
         [0064]    [0064]FIG. 1 shows a longitudinal section through a first embodiment of an inventive shaped member, used in connection fittings which cause an energy-absorbing destruction of the shaped member when a force is applied thereto;  
         [0065]    [0065]FIG. 2 shows an illustration of the relationships between a piece of flat material for the production of the shaped member in accordance with the first embodiment, the shaped member and the energy absorption characteristics with the piece of flat material not yet wound for the production of the shaped member in FIG. 2 a    
         [0066]    the shaped member wound from a piece of flat material in FIG. 2 b  and  
         [0067]    the energy absorption characteristics in FIG. 2 c;    
         [0068]    [0068]FIG. 3 shows an illustration similar to FIG. 2 of a second embodiment of an inventive shaped member with:  
         [0069]    the piece of flat material not yet wound for the production of this shaped member in FIG. 3 a,    
         [0070]    the wound piece of flat material in FIG. 3 b  and  
         [0071]    the energy absorption characteristics in FIG. 3 c;    
         [0072]    [0072]FIG. 4 shows an illustration similar to FIG. 2 of a third embodiment of an inventive shaped member with  
         [0073]    the piece of flat material not yet wound in FIG. 4 a;    
         [0074]    the piece of flat material wound to form the shaped member in FIG. 4 b  and  
         [0075]    the energy absorption characteristics in FIG. 4 c;    
         [0076]    [0076]FIG. 5 shows a schematic illustration of the first embodiment of an inventive process for the winding of an inventive shaped member;  
         [0077]    [0077]FIG. 6 shows a view of a device for the impregnation of the reinforcing material with matrix material in the direction of the arrow A in FIG. 5;  
         [0078]    [0078]FIG. 7 shows a schematic illustration of a variation of the first embodiment of the inventive process in FIG. 5;  
         [0079]    [0079]FIG. 8 shows an illustration of a second embodiment of an inventive process;  
         [0080]    [0080]FIG. 9 shows an illustration of a third embodiment of the inventive process; and  
         [0081]    [0081]FIG. 10 shows an illustration of division of a web of flat material with several consecutive arrangements of pieces of flat material.  
     
    
     DETAILED DESCRIPTION  
       [0082]    The ensuing detailed description provides exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the ensuing detailed description of the exemplary embodiments will provide those skilled in the art with an enabling description for implementing an embodiment of the invention. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the invention as set forth in the appended claims.  
         [0083]    One embodiment of an inventive energy-absorbing structural element  10  illustrated in FIG. 1 is built up, for example, as a shaped member (hollow body) which is circular-cylindrical in relation to a central axis  12  and has several layers  16   a  to  16   h  of a flat material forming a reinforcing material, wherein, for example, only three layers  16   a  to  16   c  of flat material are provided in a first area  18   a  extending in the direction of the central axis  12  whereas five layers  16   a  to  16   e  of flat material are provided in a second area  18   b  and in a third area  18   c  of the shaped member  14  a total of eight layers  16   a  to  16   h  of the flat material are provided. In a final area  18   d , the individual layers of the flat material extend in the direction of the axis  12  over varying lengths, wherein the lowermost layer  16   a  extends in the direction of the central axis as far as an end edge  20  of the shaped member and the following layers are each set back in relation to the lowermost layer  16   a  such that, altogether, a chamfer  22  of the shaped member  14  is formed in the region of a first end  24  of the shaped member, wherein a surface  26  of the chamfer  22  represents a conical surface with respect to the central axis  12 .  
         [0084]    A second end  28  of the shaped member  14 , which is located opposite the first end  24  and from which the first area  18   a  proceeds, has an end face  30  which is located in a plane  32  extending at right angles to the axis  12 .  
         [0085]    Such an energy-absorbing structural element  10  may be arranged, for example, between two connection fittings  34  and  36 . The first connection fitting  34  triggering the energy absorption has a guide section  38  which has a cylindrical shape and a casing surface  40  circular-cylindrical in relation to the axis  12 . The guide section  38  engages in an interior  42  of the shaped member  14  and thereby abuts on an inner surface  44  of the shaped member  14  which limits the interior and is cylindrical in relation to the axis  12  so that the shaped member is guided in the direction of the axis  12 .  
         [0086]    The first connection fitting  34  has, in addition and following the guide section  38 , a channel  50  which extends annularly around the axis  12  and has, in particular, a base surface  52  which borders on the casing surface  40 , extends radially outwards in relation to the axis  12  and is, for example, toroidal in shape. If the shaped member  14  is pushed onto the guide section  38  with the first end  24 , namely to such an extent that an end edge  20  is located close to a beginning of the toroidal surface  52  of the channel  50  and the chamfer  22  adjoins this, the first end  24  of the shaped member  14  provided with the chamfer  22  is spread in a radial direction in relation to the axis  12  during a relative displacement of the first connection fitting  34  in the direction of the arrow  54  so that, in the region of the chamfer  22 , the layers  16   a  to  16   h  of the reinforcing material receive cracks extending in the direction of the axis  12  and thus the shaped member  14  is destroyed, for example, fractured in the region of the first end  24  and thus expands in a radial direction. This fracturing in a radial direction due to expansion or spreading of the first end  24  of the shaped member  14  then absorbs the desired energy, wherein the fracturing can continue beyond the area  18   d , the area  18   c  and the area  18   b  as far as the area  18   a.    
         [0087]    In order to support the shaped member  14  at the second end  28  when the connection fitting  34  is moved in the direction of the arrow  54 , the second connection fitting  36  is provided with a contact surface  60  which is parallel to the plane  32  and on which the end face  30  of the second end  28  is supported. The shaped member  14  is preferably also secured in the region of the second end  28  by means of a guide ring  62  abutting on the inner surface  44 .  
         [0088]    The stability of the shaped member  14  in the first area  18   a  must thereby be such that this area is in a position to absorb the forces acting in the direction of the axis  12  without folding and to transfer these to the connection fitting  36  with the end face  30 .  
         [0089]    Such a shaped member  14  illustrated in FIG. 1 may be produced in accordance with the invention, as illustrated in FIG. 2, from a reinforcing material which comprises a piece  72  of flat material consisting of reinforcing fibers and provided with a defined outer contour  70  by way of cutting and which has a maximum width B in the direction transverse to a main direction  73  of the orientation of the reinforcing fibers and approximately parallel to them longitudinal edges  74 ,  76 , which corresponds approximately to the extension of the shaped member  14  from the end edge  20  as far as the end face  30 .  
         [0090]    Furthermore, the second longitudinal edge  76  extends in the form of a continuous longitudinal edge from a later, interior transverse edge  78  of the winding, which extends essentially over the entire length of the shaped member  14  from the end edge  20  as far as the end face  30 , as far as a later, exterior transverse edge  88  of the winding.  
         [0091]    The first longitudinal edge  74  of the piece  72  of flat material extends from the later, interior transverse edge  78  of the winding as far as a step edge  80  which extends transversely to the main direction  73  to a longitudinal edge  82  which is set back and parallel to the longitudinal edge  74  and is offset in the direction of the longitudinal edge  76  in relation to the longitudinal edge  74  and, for its part, again extends as far as a step edge  84  extending transversely to the main direction  73  and proceeding from which an additional longitudinal edge  86  which is set back and parallel to the longitudinal edge  74  extends as far as the later, exterior transverse edge  88  of the winding which is located opposite the later, interior transverse edge  78  of the winding.  
         [0092]    In contrast to the longitudinal edges  74 ,  82  and  86 , the longitudinal edge  76  extends without any step from the transverse edge  78  as far as the transverse edge  88 .  
         [0093]    The longitudinal edge  76  deviates slightly from a fictitious transverse edge  90  extending parallel to the longitudinal edges  74 ,  82  and  86  and, proceeding from the later, interior transverse edge  78  of the winding, is placed with increasing extension in the direction of the later, exterior transverse edge  88  of the winding such that it has an increasing distance from the fictitious longitudinal edge  90  (FIG. 2 a ).  
         [0094]    If the piece  72  of flat material is now aligned such that the transverse edge  78  extends parallel to the axis  12  and is wound onto a winding tube rotating about the axis  12  and not illustrated in the drawings, the section having the maximum width B between the transverse edge  78  and the step edge  80  results in the first three layers  16   a  to  16   c , which are illustrated in FIG. 1 and extend essentially over the entire length of the shaped member  14  in the direction of the axis  12 . The step edge  80  thereby defines as a result of its extension in the direction of the axis  12  the extension of the area  18   a  in the direction of the axis  12  which has, for example, three layers  16   a  to  16   c  of the reinforcing material  70 .  
         [0095]    A further section of the piece  72  of flat material between the step edge  80  and the step edge  84  forms on the first three layers  16   a  to c two additional layers  16   d  and  16   e  in the areas  18   b  and  18   c  which, with respect to their extension in the direction of the axis  12 , correspond to the extension of the step edge  84  and the transverse edge  88  in the direction of the axis  12 . The step edge  84  thereby defines as a result of its extension in the direction of the axis  12  the extension of the area  18   b  in this direction. Finally, a section of the piece  72  of flat material between the step edge  84  and the transverse edge  88  essentially forms the section  18   c , comprising altogether eight layers  16   a  to  16   h , wherein the extension of the section  18   c  in the direction of the axis  12  corresponds to the extension of the transverse edge  88  in this direction.  
         [0096]    In order to obtain, in addition, at the first end  24  the chamfer illustrated in FIG. 1, the longitudinal edge  76  does not extend parallel to the fictitious longitudinal edge  90  but has an increasing distance from this fictitious longitudinal edge  90  with increasing distance from the transverse edge  78  of the piece  72  of flat material and so with increasing winding of the layers  16   a  to  16   h  in the region of the first end  24  the chamfer  22  illustrated in FIG. 1 is formed.  
         [0097]    When the longitudinal edge  76  forms the chamfer  22  and the longitudinal edge  74  the end face  30 , such a shaped member  14  illustrated again schematically in FIG. 2 b  increasingly absorbs energy over a first path section W 1  in accordance with the characteristics illustrated in FIG. 2 c  during the movement of the connection fitting  34  in the direction of the arrow  54 , wherein this corresponds to the breaking of the reinforcing fibers of the shaped member  14 , which extend in the piece  72  of flat material in the main direction  73  and in the shaped member  14  in azimuthal direction in relation to the axis  12 , close to the first end  24  in the region of the chamfer  22 .  
         [0098]    Subsequently, the greatest absorption of energy takes place over a path section W 2 , which corresponds approximately to the extension of the transverse edge  88  in the direction of the axis  12  and thus to the third area  18   c , as a result of further fracturing of the shaped member  14  over the section  18   c  since the reinforcing fibers extending in azimuthal direction in the area  18   c , which has the most layers  16   a  to h, break. Thereafter, a further fracturing in the area  18   b  follows over the path section W 3 , for which purpose less energy is required due to the smaller number of layers  16  and, finally, over the path section W 4  a breaking possibly in the region of the first section  18   a  which absorbs the least energy on account of the smallest number of layers  16 . A degressive characteristic of the absorbed energy can thus be achieved altogether, wherein the characteristics can be predetermined in a defined manner by the dimensioning of the edges of the outer contour  70  of the piece  72  of flat material to be wound.  
         [0099]    The characteristics of the absorbed energy may be varied, as illustrated, for example, in FIG. 3 on the basis of a second embodiment of an inventive shaped member  14 ′, due to alteration of the outer contour  70  into the outer contour  70 ′ of the piece  72  of flat material.  
         [0100]    If the outer contour  70 ′ is, for example, determined by the longitudinal edge  76  and the additional longitudinal edges  74  and  82 ′, wherein the longitudinal edge  74  merges into the longitudinal edge  82  via a step edge  80 ′ extending at an angle, the arrangement of the individual layers  16  may be altered by altering the measurements of the transverse edge  88  and the step edges  80  and the number of layers  16  by altering the longitudinal measurements of the individual longitudinal edges  74 ,  76 ,  82 ′, (FIG. 3 a ) in the shaped member  14 ′, (FIG. 3 b ) and thus the course of the absorbed energy according to FIG. 3 c , as well.  
         [0101]    Similarly, as illustrated in FIG. 4, a degressive course of the absorbed energy may be reversed in that the same piece  72  of flat material with the outer contour  70  is used as in the first embodiment but in a reverse arrangement so that, in this case, the first end  24  is formed by the longitudinal edge  74  while the second end  28  is formed by the longitudinal edge  76 .  
         [0102]    The production of inventive shaped members  14  may be brought about in the most varied of ways. A first embodiment illustrated in FIG. 5 provides for a web  100  of flat material, comprising the reinforcing material and an impregnation thereof with, for example, a thermoplastic matrix material, to be supplied from a supply device  104  in a supply direction  106  to a winding device  108  with a winding tube  110  driven for rotation about the axis  12  in order to produce the pieces  72  of flat material, wherein the web  100  of flat material has transversely to the supply direction  106  a width B which corresponds exactly to the width B of the piece  72  of flat material.  
         [0103]    During the supply of the web  100  of flat material to the winding tube  110 , the contour  70  of the piece of flat material is cut with a cutting device  112 , illustrated merely by way of a cutting knife, and so, in the end, the piece  72  of flat material is wound on the winding tube  110  with the desired contour. In order to thereby obtain an intimate bonding between the reinforcing material and the matrix material, the winding tubes  110  are preheated in a preheating device  114  arranged next to the winding device  108  prior to the winding of the piece  72  of flat material impregnated with matrix material and so during the winding of the piece  72  of flat material provided with matrix material onto the winding tube  110  the matrix material is liquefied and melted, as a result of which a secure embedding of the piece  74  of flat material serving as reinforcing material in the molten matrix is brought about.  
         [0104]    Following the winding of the shaped member  14 , this is cooled together with the winding tube  110  in a cooling device  116  with, for example, a cooling path so that the molten matrix material again has the possibility of hardening.  
         [0105]    Subsequently, the finished shaped member  15  is withdrawn from the winding tube  110  in a withdrawal device  118 , and this winding tube  110  is conveyed via a transport path  120  again to the heating device  114  for the purpose of heating up.  
         [0106]    The winding tubes  110  are preferably arranged not only in the winding device  108 , the heating device  114 , the cooling device  116  but also in the withdrawal device  118  so as to each be coaxial to the axis  12  and are merely displaced along the axis in order to move them from one device to the other.  
         [0107]    The provision of the web  100  of flat material with matrix material has not so far been described in detail. For example, as illustrated in FIGS. 5 and 6, an impregnating device  130  is provided which supplies thermoplastic films to the web  100  of flat material consisting of reinforcing material from both sides likewise in the form of a respective web  132  of material, these films being rolled onto respectively opposite sides of the web  100  of flat material in a rolling device  134  by means of two rollers  136  and  138  in order to obtain the web  100  of flat material provided with matrix material for supplying to the winding device  108 .  
         [0108]    In a variation of the inventive process according to FIGS. 5 and 6, illustrated in FIG. 7, the production of the pieces  72  of flat material impregnated with matrix material takes place separately and also the cutting thereof so that the pieces  72  of flat material which are already cut and impregnated with matrix material are placed on a transport device  150  for them and transported by the transport device  150  to the winding device  108  in order to likewise be wound onto the winding tubes  110  preheated in the heating device  114 .  
         [0109]    In a further embodiment of the inventive process, illustrated in FIG. 8, pieces  72 ′ of flat material are wound onto the winding tubes  110 , wherein, in this case, the pieces  72 ′ of flat material are impregnated with a duroplastic matrix material which hardens automatically.  
         [0110]    In this case, the heating device  114  serves merely for the preliminary heating of the winding tubes  110  in order to accelerate the duroplastic hardening process.  
         [0111]    In a hardening device  160  following the winding device  108 , the duroplastic material of the shaped members  14  already wound is hardened, wherein for reasons of saving on time several winding tubes  110  wound with shaped members  14  are preferably combined to form a group  162  of winding tubes which passes through the hardening device  160  and is subsequently cooled altogether in a cooling device  164 . This means that the relatively long periods of time for the hardening and cooling of the shaped members  14  provided with duroplastic matrix material is utilized in an optimum manner and so a high rate of production of shaped members  14  is nevertheless possible.  
         [0112]    The cooling device  164  is followed by the withdrawal device  118 , in which the finished shaped members  14  are withdrawn from the winding tubes  110  and the winding tubes  110  are again supplied to the heating device  114  via the transport path  120 .  
         [0113]    In addition, a machining device may be provided after the withdrawal device and this makes possible, for example, a machining of the chamfer  22  or instead of the chamfer  22  in the area  18   d  the introduction of so-called triggering slits extending in the direction of the axis  12 .  
         [0114]    In a third embodiment of the inventive process, illustrated in FIG. 9, several pieces  72   a  to f of flat material are arranged next to one another such that they are connected in the region of their longitudinal edges  74 ,  76  extending approximately parallel to one another, wherein the longitudinal edge  76   a  of the preceding piece  72   a  of flat material is connected, for example, to the longitudinal edge  74   b  of the subsequent piece  72   b  of flat material.  
         [0115]    The pieces  72  of flat material are connected, in particular, in their sections  180 , in which the longitudinal edges  74 ,  76  extend parallel to one another and with which no alteration in individual areas of the shaped member with respect to the number of the layers is possible. On the other hand, no connection of the pieces of flat material is preferably provided in the region of the sections  182  which, when wound to form the shaped member, result in a different number of layers in different areas of the shaped member.  
         [0116]    Such an arrangement  184  of pieces of flat material formed from connected pieces  72   a  to  72   f  of flat material may be supplied as a whole to the winding tube  110 ′ in the winding direction  106 , this tube having an extension in the direction of the axis  12  which allows all the pieces  72   a  to  72   f  of flat material to be wound at the same time.  
         [0117]    Thus, a plurality of shaped members  10 , which are all connected to one another, results on the winding tube  110 ′.  
         [0118]    The wound shaped members may then be hardened together on this winding tube  110 ′ and also be withdrawn together from the winding tube  110 ′ so that after the withdrawal of the entirety of shaped members, formed from the pieces  72   a  to  72   f  of flat material, a separation thereof, for example, by sawing can be carried out in the region of abutting longitudinal edges  74 ,  76 .  
         [0119]    In a particularly advantageous solution, illustrated in FIG. 10, it is illustrated in addition how several arrangements  184   a  to c of pieces of flat material may be produced from a single web  186  of material, the width of which corresponds to the width of the pieces  72   a  to  72   f  of flat material located next to one another, without a single cut, wherein the sections  182  of the individual pieces of flat material, which contribute to areas with different numbers of layers of the shaped member when they follow one another, must, however, have a complementary shape.  
         [0120]    Furthermore, different types of shaped members result during such a performance of the inventive process, namely those, in which the sections  182  are located radially inwards, and those, in which the sections  182  are located outwards.  
         [0121]    It should now be appreciated that the present invention provides advantageous processes for producing energy absorbing structural elements, as well as advantageous energy absorbing systems.  
         [0122]    Although the invention has been described in connection with various illustrated embodiments, numerous modifications and adaptations may be made thereto without departing from the spirit and scope of the invention as set forth in the claims.