Variable material stretch-forming apparatus and methods

Apparatus and methods of stretch-forming pre-preg material are provided. In one example embodiment, a variable material stretch-forming apparatus comprises a stretch-forming assembly configured to stretch-form at least one section of a sheet of pre-preg material to a longer length than at least one other section of the sheet of pre-preg material before the sheet of pre-preg material is applied to a tool.

BACKGROUND

Pre-impregnated (pre-preg) material is used in the formation of high-strength low weight structures, such as, but not limited to, parts used to build aircraft and spacecraft. Pre-preg material is typically made-up of a composite of reinforcing fibers (such as carbon, glass, aramid, and the like) that are bonded together with a resin system. Pre-preg material is typically manufactured in flat sheets that are applied in multiple fiber orientation layers onto surfaces of a tool to form the shape of a desired part. The laminate is subsequently compacted and heat set (cured or fused) into a composite structure. Other methods of hardening or curing the laminate can also be used with some resins including, but not limited to, electron beam cure, microwave cure and ultraviolet light cure. There are various pre-preg materials fiber architectures that include, but are not limited to, woven fabric, unidirectional tape (uni-tape), non-crimp stitched broadgoods, braid, multi-dimensional weave, stretch broken fibers, and strategically stitched materials. A wide variety of resins can be used including, but not limited to, room temperature set resins, thermoset resins, and thermoplastic resins. The application of pre-preg material on tools, which have forming surfaces with at least two different radii of curvature, can be difficult to accomplish without wrinkling the material, folding the material, or requiring the fibers to be cut (darting the material to conform without creating folds or wrinkles); all of which generally reduces structural properties and functionality of the structure.

For the reasons stated above and for other reasons stated below that will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a method of conditioning or stretch-forming pre-preg material for effective and efficient application to forming surfaces of a tool having at least two different radii of curvature.

SUMMARY

The above-mentioned problems of current systems are addressed by embodiments of the present invention and will be understood by reading and studying the following specification. The following summary is made by way of example and not by way of limitation. It is merely provided to aid the reader in understanding some of the aspects of the invention. Although, only a structure is described in the summary, methods are also claimed and described in the application.

In one embodiment, a variable material stretch-forming apparatus is provided. The variable material stretching apparatus comprises a stretch-forming assembly configured to stretch-form at least one section along a width of a sheet of pre-preg material to a longer length than at least one other section along the width of the sheet of pre-preg material before the sheet of pre-preg material is applied to a tool.

DETAILED DESCRIPTION

When flat sheets of pre-preg material are formed into a radial pattern they must be stretched in length as they conform to an increasing radius. This is typically done by hand on a tool surface as material is pressed into place and stretched manually from a smaller radius to a larger radius. Embodiments of the present invention create a method of doing this stretching automatically, prior to touching the tool surface. In embodiments, pre-preg material is stretch-formed before laying the material onto the tool surface. This increases the speed at which the material can be formed onto the tool thereby reducing labor content in the lay-up process and improving consistency of the forming by running the material through a machine operation instead of stretching it manually. In an embodiment, specific sections along a width of a sheet of pre-preg material are pre-formed by stretching the specific sections so they will travel a longer path distance on a forming surface of a tool. For a section of material to travel a longer path distance relative to another section of material, it must increase its lengthwise dimension or stretch. There is typically little or no elastic behavior in the longitudinal direction of continuous fibers of the pre-preg material. Generally stretch of the material comes from stretching the resin matrix that holds the fibers together and spreading the fiber bundles transverse to their longitudinal direction. With off-axis materials, the angle orientation of the fibers can change and the material can reduce in fiber area density to achieve the lengthwise dimensional increase. There may be a corresponding narrowing of width dimension in the stretch section in some embodiments. Examples of pre-preg material that can have sections stretched include, but are not limited to, woven fabrics, off-axis unidirectional tapes, non-crimp stitched broadgoods, braids, multi-dimensional weaves, stretch broken fiber products (off-axis and uni-directional) and strategically stitched materials.

FIG. 1illustrates a sheet of off-axis pre-preg material100. In particular, in this example the pre-preg material100is uni-tape having spaced fibers102that are at a select orientation angle106in relation to an edge108of the sheet100(i.e., the orientation of the fibers102are off-axis in relation to the edge108). The fibers102are pre-impregnated with, and held together by, resin104.FIG. 2illustrates a portion of a tool200that has tool surfaces having at least two different radii of curvature. In particular, tool200includes a forming surface202, which can generally be referred to herein as a “web” or “cylinder” of the tool. In the example inFIG. 2, the tool200has a constant radius from its center of revolution. Extending from web202are forming surfaces204and206, which both can be generally referred to as “flanges,” “tool flanges,” or “turned up flanges”. Flanges204and206can have the same or different outer radii of curvature necessitating the same or different amounts of linear stretch of pre-preg material to conform to the surfaces. Referring to flange206, flange206has a first radius of curvature R1and a second different radius of curvature R2. R2has a greater radius of curvature than R1. In applying a sheet of pre-preg material (such as the off-axis pre-preg material100) on the forming surfaces202,204,206of the tool200, the pre-preg material100must be pressed to extend about flanges204,206of the forming tool. However, even initially applying the pre-preg material100to the tool200can be a challenge since the shape of the forming surfaces202,204,206in relation to each other does not lend to the application of a flat sheet of pre-preg material100in a conformal manner. Further, it is difficult to get the sheet of pre-preg material100to lie on the forming surfaces202,204,206of the tool200in a desired fashion because of the differences of curvature of the radiuses of R1and R2of the tool200illustrated inFIG. 2. Moreover, pre-preg material100that conforms to surface202will not conform to surfaces204or206without stretching or darting to meet the increased radius R2.

Referring toFIG. 3, a side perspective view of a stretch-forming assembly300of one embodiment is illustrated. The stretching assembly300takes the pre-preg material100and stretches select sections along a width of the pre-preg material308and306so that an increase in curvature of radius on a forming surface, such as R2in relation to R1can be accommodated. In particular,FIG. 3illustrates a pre-formed pre-preg material302that includes a first section304that has not been stretched and sections306and308that have been stretched to accommodate different radius of curvature, such as the different radius of curvatures present in the forming surfaces204and206of tool200illustrated inFIG. 2. AlthoughFIG. 3illustrates an embodiment where two sections306and308of a preformed pre-preg material302have been stretched, any number of sections of a pre-formed pre-preg material302could be stretched depending on a particular shape of the forming surfaces of a tool. Moreover, the stretching may also occur for a select distance along the length of the material.

FIG. 4illustrates a block diagram of a stretch-forming assembly400. In particular,FIG. 4illustrates a stretch-forming device402(embodiments of which are further described below), a motor or motors404and a stretch-forming controller406. The controller406controls the motor or motors404to activate the shaping device402. In one embodiment, the stretch-forming controller406is in communication with an assembly controller408that allows synchronization between the stretch-forming device402and an assembly410. Examples of assemblies410that could be synchronized with the stretch-forming device402are the forming assembly1000ofFIG. 10and the storage core1120ofFIG. 11, each of which is described in further detail below. InFIG. 5, an example stretch-forming device500of one embodiment is illustrated. In particular,FIG. 5is a side perspective view of a roller stretch-forming device500. The roller stretch-forming device500includes a first roller502and a second roller504. The first roller502is positioned adjacent the second roller502such that a surface of the first roller502engages a surface of the second roller504. In particular, the first roller502and the second roller504are positioned so that a sheet of pre-preg material can pass between the first roller502and the second roller504, as the first and second roller502and504rotate. In the embodiment ofFIG. 5, the first roller502includes a first cylindrical shaped roller section502aand a second conical roller section502b. The second roller504similarly includes a first cylindrical roller section504aand a second conical roller section504b. The first cylindrical roller section504aof the second roller504engages the first cylindrical roller section502aof the first roller502. The second conical shaped section504bof the second roller504engages the second conical shaped section502bof the first roller502.

In the embodiment ofFIG. 5, the second conical section502bof the first roller502includes a first end501band a second end501c. The first end501bof the second conical section502babuts a first end501aof the first cylindrical section502a. The diameter of the first cylindrical section502aof the first roller502is approximately equal to the diameter at the first end501bof the second conical section502bof the first roller502. The second end501cof the second conical section502bof the first roller502has a greater diameter than the first end501bof the second conical section502bof the first roller502. The second conical section504bof the second roller504includes a first end503band second end503c. The first end503bof the second conical section504bof the second roller504is positioned adjacent a first end503aof the first cylindrical section504aof the second roller504. The first end503bof the second conical section504bof the second roller504has a diameter approximately equal to the diameter of the first cylindrical section504aof the second roller504. The second end503cof the second conical section504bof the second roller504has a smaller diameter than the first end503bof the conical section504bof the second roller504. Hence, the shape of the second conical section504bof the second roller504conforms to the shape of the second conical section502bof the first roller502. In the embodiment ofFIG. 5, a section of pre-preg material that passes between the second conical sections502bof the first roller502and the second conical section504bof the second roller504is stretched in relation to a remaining section of pre-preg material passing between the first cylindrical section502aof the first roller502and the first cylindrical section504aof the second roller504. Hence, in this embodiment only one section of pre-preg material is stretched. In one embodiment, the second conical section504bof the second roller504is segmented into segments506-1through506-n, as illustrated inFIG. 5. Further, in one embodiment each of the segments506-1through506-nis designed to move independently of each other such that different rotational speeds in different segments506-1through506-ncan be achieved. This further enhances stretching of the material between the second conical sections502band504b. An embodiment, further illustrating independent moving segments of a roller is provided below in regard toFIG. 8. Roller502is driven by a motor, such as motor404illustrated inFIG. 4. Rollers504, in one embodiment, are not driven and are free to rotate at speeds related to geometry of rollers502. Further, some embodiments apply a back tension on the pre-preg material as the stretch-forming device500selectively stretches sections of the pre-preg material to help prevent steering issues that can occur when the pre-preg material passes through the stretch-forming device500. Examples of assemblies that can apply the back tension are the supply roll-off1130ofFIGS. 11A and 11Band the nip rollers1220and1222ofFIG. 12, which are further described in detail below.

Referring toFIG. 6, another embodiment of a stretch-forming device600is illustrated. In particular,FIG. 6illustrates a gear stretch-forming device600. The gear stretch-forming device600includes a cylindrically shaped first roller602and cylindrically shaped second roller604(i.e., a pair of mating rollers602and604). The first roller602includes a first gearing end602aand a second gearing end602b. The second roller604also includes a first gearing end604aand a second gearing end604b. Each gearing end602aand602bof the first roller602and each gearing end604aand604bof the second roller604, respectively, includes a plurality of rounded teeth220(or shaped gear teeth) separated by a plurality of grooves222. In one embodiment, the teeth220are shaped irregularities similar to shaped gear teeth. As illustrated inFIG. 6, the gearing of the first roller602is mated with the gearing of the second roller604. In particular, teeth220of gear end602aof the first roller602are received in grooves222of gear end604aof the second roller604and teeth220of the first gear end604aof the second roller604are received in grooves222of the first gear end602aof the first roller602. Likewise, teeth220of the second gear end602bof the first roller602are received in grooves222of the second roller604and teeth220of the second gear end604bof the second roller604are received in grooves222of the second gear end602bof the first roller602. In this embodiment, as a sheet of pre-preg material passes between the first and second rollers602and604the respective gear ends602aand604aof the first and the second rollers602and604stretch a first end section of the pre-preg material. The second roller ends602band604bof the first and second rollers602and604stretch a second section of the pre-preg material. Hence, in this embodiment two different sections of pre-preg material are stretched with the gear stretching device600. Both gears602and604are motor driven to maintain synchronized mating of teeth220and valleys222in one embodiment. In one embodiment, teeth220and valleys222do not physically contact so as to allow the pre-preg material to move freely widthwise as it is stretched in the lengthwise direction moving through the convoluted path created by teeth220and valleys222. In another embodiment, the pre-preg material is gripped along the entire length of the constant cross-section, and along a contact line in the geared sections. Moreover, in another embodiment, the distance between the teeth220and valleys222of opposed rollers602and604are adjustable.

FIGS. 7A-7Cillustrate yet another embodiment of a stretch-forming device700. In particular,FIGS. 7A and 7Cillustrate a belt stretch-forming device700.FIG. 7Aillustrates an assembled belt stretch-forming device700andFIG. 7Cillustrates the belt stretch-forming device700partially unassembled. The belt stretch-forming device700includes a first belt member701and second belt member703. The first belt member701and the second belt member703are positioned to pass a sheet of pre-preg material720between themselves, as illustrated inFIG. 7A. The first belt member701includes an endlessly looped belt702and an endlessly looped stretching belt704. Belt702and stretching belt704are engaged with rotating support drums710and712. The second belt member703includes an endless looped belt706and an endlessly looped stretching belt708. Belt706and stretching belt708are engaged with rotating support drums714and716, respectively. The close-up view750ofFIG. 7Aillustrates that in one embodiment, the belts702and706include spikes752. The spikes752are designed to firmly grab the pre-preg material702, while not harming the pre-preg material702. Referring toFIG. 7C, the rotating support drums710and712, engaged to the first belt member701, are segmented into rotating support drum sections710aand710band rotating support drum sections712aand712b. Belt702engages rotating support drum sections710aand712a,respectively. Stretching belt704is engaged to rotating support drums710band712b,respectively. Stretching belts704and708each include a plurality of fins711(or ribs). The fins711are used to stretch a section of the sheet of pre-preg material720. Referring back toFIG. 7A, the fins711on the stretching belt704and708are positioned so they stagger each other as the sheet of pre-preg material720is pulled between the first belt member701and the second belt member703as the first and second belt members701and703are rotated. AsFIG. 7Billustrates, the fins711of the stretching belts704and708, stretch a section720aof the sheet of pre-preg material720. Hence, as the sheet of pre-preg material720is moved between the first belt member701and the second belt member703of the belt stretching device700, section720aof the sheet of pre-preg material720is stretched by the fins711. Further illustrated inFIGS. 7A and 7C, a first pressure platen730is positioned within stretching belt704and a second pressure platen732is positioned in stretching belt708. The pressure platens730and732apply pressure on the respective stretching belts704and708to stretch the pre-preg material720. In embodiments, the pressure platens730and732are adjustable so that the amount of pressure can be selected. Also illustrated inFIG. 7C, is a third pressure platen734designed to apply pressure to belt702. A similar pressure platen is designed to apply pressure to belt706. Pressure platen734is also adjustable, in one embodiment. In another embodiment, belts702and704of the first belt member701are integral as one unit with rollers710a,710band712a,712bof the first belt member701also being integral as one unit. Similarly, the second belt member703, in one embodiment, is integral as one unit. In yet other embodiments, more than two belt and roller assemblies per set are used with more complex forming work.

Yet still another embodiment of a stretch-forming device800is illustrated inFIG. 8. In particular,FIG. 8illustrates a segmented roller stretch-forming device800. This embodiment includes a first drive system810that is attached to a shaft system802. The drive system810is shown as using gears, but could be driven by other means. The drive system810includes gears810athrough810gthat are coupled, respectively, to shafts802athrough802gof the shaft system802. Shafts802athough802gare, in turn, attached to segmented driven rollers812athrough812g. The segmented driven rollers812athrough802gare in contact with segmented non-driven rollers814athrough814g. The non-driven rollers814athrough814gare rotationally mounted on shaft818. A sheet of pre-preg material816is passed between the driven rollers812athrough812gand the respective non-driven rollers814athrough814g. In the embodiment ofFIG. 8, gears810athrough810gare driven by individual motors via gear teeth811that drive each respective roller812athrough812gat individual speeds to control an amount of pre-preg stretch in those corresponding regions. For example, roller812acould be driven at a rotational speed that is different than the rotational speed at which roller812bis driven, which, in turn, could be different than the rotational speed at which roller812cis driven, and so-forth. This allows a sheet of pre-preg material816passing between the driven rollers812athrough812gand non-driven rollers814athrough814gto be selectively stretched in select sections. This embodiment allows the amount of stretch-forming in the material to vary along the width and to vary along the length of the material simultaneously, and to be programmed for complex geometry parts requiring different degrees of stretch-forming in different areas of the product. Driving individual segmented rollers is accomplished with a number of different drive means. For example, separate individual motors could be used. In another example, separate gear ratios connected to a common motor drive are used.

Referring toFIG. 9, a forming assembly900using pre-preg material906that has a stretch-formed section906ais illustrated. In this embodiment, the sheet of pre-preg material906will have another stretch-formed section (not shown) along an opposite edge (not shown) to accommodate the forming surfaces912,914and916of the tool902. A roll908of stretch-formed pre-preg material can be stored on a roll-off907, prior to use. The roll-off907is rotationally coupled to roll holder910. An operator904aligns the material with the tool902to place the pre-preg material906on the tool902. Tool902rotates about a central hub930that is rotationally coupled to a base922. A placement device920, places the pre-preg material906on forming surfaces912,914,916of the tool902. A forming head918presses the pre-preg material906onto forming surfaces912,914,916, of the tool902, as the tool902rotates about the central hub930. One benefit of the stretched sections906aof the pre-preg material906is when the operator904aligns the material and starts placement of the pre-preg material906on the forming surfaces912,914and916of the tool902, as the stretched edge sections906aallow the pre-preg material906to be easily laid up on the forming surfaces912,914,916. In particular, a mid-portion of the pre-preg material906will lay up on forming surface912, while sections near the edge of the pre-preg material906, such as edge section906a, that are stretched will lay up on the respective flange forming surfaces914and916and will remain on the forming surfaces914and916until the forming head918presses the pre-preg material906onto the forming surfaces912,914,916of the tool902. Without the stretching proximate the edge of the pre-preg material906, the pre-preg material906will tend to flip over on itself proximate the edges of the pre-preg material906. That is, without stretching the edges of the pre-preg material906, the edges of the pre-preg material906will not initially conform to forming surfaces914and916of the tool902and fold over onto itself on forming surface912. Also, the stretching of the edges, such as edge906a, of the pre-preg material906stretches the pre-preg material906to accommodate the differences in radii on the flange forming surfaces914and916.

FIG. 10illustrates an implementation of a stretch-forming assembly1000with the forming assembly900, of an embodiment (e.g.,FIG. 9). A roll of pre-preg material1002is stored on roll-off1004, which is rotationally coupled to supply base1008. The pre-preg material1002, in this embodiment, is passed through stretch-forming assembly1000. The stretch-formed pre-preg material1006then passes around guide roller1012, which directs the stretch-formed pre-preg material1006on the tool902. The stretch-formed pre-preg material1006is then formed on the tool902, as described above in regard toFIG. 9. In the embodiment ofFIG. 10, the guide roller1012includes conical ends1011that help retain the form of the stretch-formed pre-preg material1006before it is applied to the tool902.

FIG. 11Aillustrates an embodiment of a stretch-forming assembly1100, a supply roll-off1130and a storage core1120. In this embodiment, the supply roll-off1130includes a tension motor1132that supplies a select amount of back tension to the supply pre-preg material1102to assist in the stretch-forming process and to keep the pre-preg material1102aligned with the stretch-forming assembly1100. Stretch-formed pre-preg material1104includes a non-stretched section1104band stretched sections1104aand1104c. Although this example includes the non-stretched section1104bpositioned between the stretched sections1104aand1104c, any desired arrangement and any number of stretched and non-stretched sections can be used. In this embodiment, the stretch-formed pre-preg material1104is stored on the storage core1120. The storage core1120in this embodiment includes tapered end sections1120aand1120cand a mid-section1120bthat correspond to the respective sections1104a,1104band1104cof the stretch-formed pre-preg material1104. In particular, the tapered end sections1120aand1120care used to retain the stretching in the stretch-formed pre-preg material1104when stored for a period of time. For example, roll-off907ofFIG. 9in one embodiment is the storage core1120ofFIG. 11Ato retain the stretch-formed pre-preg material1104in the desired stretch-formed shape.FIG. 11Billustrates a stretch-forming device of the stretch-forming assembly1100ofFIG. 11A. The stretch-forming device of this embodiment includes a pair of first nip rollers1140and1142and a pair of secondary nip rollers1148and1150that pass the pre-preg material1102and1104. A pair of stretch-forming rollers1144and1146is positioned between the pair of first nip rollers1140and1142and the pair of secondary nip rollers1148and1150. The pair of stretch-forming rollers1144and1146(mating rollers) each have end forming sections1144a,1146a,1144cand1146c(not visible inFIG. 11B) that stretch-form select sections1104aand1104cof the pre-preg material1102into stretch-formed pre-preg material1104as the pre-preg material1102passes between the stretch-forming rollers1144and1146. The secondary nip rollers1148and1150are of a select length so that they engage only the non stretch-formed section1104bof the stretch-formed pre-preg material1104as they pass the stretch-formed pre-preg material1104. This prevents the secondary nip rollers1148and1150from deteriorating the stretch-formed sections1104aand1104c. In one embodiment, the pair of first nip rollers1140and1142, the constant diameter portion of the pair of second rollers1144and1146, and the pair of third nip rollers1148and1150are driven at a synchronized speed. The stretch-formed re-preg material1104is wound up on the shaped storage core1120.

Referring toFIG. 12A, another embodiment of a stretch-forming device is illustrated. In this embodiment, the stretch-forming device is a shaped core1200that can also be used to store the stretch-formed pre-preg material. The embodiment ofFIG. 12Aillustrates a pair of nip rollers1220and1222that provide back tension when applying the pre-preg material to the shaped core1200. As discussed above, the back tension assists in the stretching and forming process and keeping the material aligned with the stretch-forming device1200. As illustrated inFIG. 12A, the shaped core1200includes outer stretch-form sections1200aand1200cand a mid non-stretching section1200b. In an embodiment, the greatest diameter of the outer stretch-form sections1200aand1200cis equal to the diameter the mid-non-stretching section1200b. This allows the flat pre-preg material to be aligned when it is rolled onto the shaped core1200.FIG. 12Billustrates another embodiment of a stretch-forming device1250that uses a shaped core1258to form stretch-formed pre-preg material. In this embodiment, a tension motor1254controls the distribution of pre-preg material1252to the shaped core1258. The shaped core1258, in this embodiment, includes outer conical shaped stretch-forming sections1258aand1258cand a mid non-stretching section1258b. A nip roller1260is used to press a mid-portion of the pre-preg material1252onto the mid non-stretching section1258bof the shaped core1258. In operation, the shaped core1258is rotated to draw the pre-preg material1252onto the shaped core1258. Tension motor1254keeps tension in the pre-preg material1252to help form the pre-preg material1252and maintain an alignment of the pre-preg material1252onto the surface sections of the shaped core1258. The nip roller1260keeps the mid-portion of the pre-preg material1252in place while the outer portions of the pre-preg material1252are stretch-formed by the respective outer conical shaped stretch-forming sections1258aand1258bof the shaped core1258.FIG. 13illustrates, at least one layer of stretch-formed pre-preg material1300on the shaped core1200. Hence, any number of layers of the pre-preg material can be placed on the shaped core1200. The stretch-formed pre-preg material1300includes outer shaped sections1300aand1300cand a non-stretched mid-section1300b. Various methods can be used to stretch-form the pre-preg material1202into outer stretch-form sections1200aand1200cof the shaped core1200. For example, the shaped core1200with material1202could be subject to a vacuum bag, a vacuum bag and heat, or a vacuum bag with added external pressure. Other methods include physical pressing devices (motion compaction mechanisms), such as the transverse rollers1400aand1400bofFIG. 14. In this embodiment, the transverse roller1400aand1400bpress respective sections of the pre-preg material1202in the valleys of the outer stretch-form sections1200aand1200c. The transverse rollers1400aand1400bmove in a transverse direction in regard to the direction the pre-preg material1202is rolled onto the shaped core1200.

Another example of a stretch-forming device using a physical pressing device is illustrated inFIG. 15. In this embodiment, a belt1500is used as a physical pressing device to stretch-form pre-preg material1520on a shaped core1200. The belt1500has outer press-forming sections1500aand1500cand a mid-section1500bthat are complementary in shape to respective outer stretch-form sections1200aand1200cand the mid non-stretching section1200bof the shaped core1200. The outer press-forming sections1500aand1500cof the belt1500press respective sections of the pre-preg material1202in the valleys of the outer stretch-form sections1200aand1200cof the shaped core1200to form the stretch-formed pre-preg material1300, which in this embodiment is wrapped around the shaped core1200. The belt1150, in this embodiment, is an endlessly looped belt that moves about rotational idler rollers1504a,1504band1504c. Idler roller1504bcontrols a desired belt tension to keep the belt1150engaged intimately with the shaped core1200(or roller) and the applied pre-preg material1520. As discussed above, the stretch-formed pre-preg material1300can then be stored on the shaped core1200until use. Here again, as with all embodiments, the placement and number of the stretch-form sections1200aand1200cof the shaped core1200and the corresponding stretching sections1500aand1500ccan be selected in any manner to achieve a desired outcome. Still another example of a physical pressing device (motion compaction mechanism) is illustrated inFIG. 16. In this embodiment, a roller1600physical pressing device is used. The roller1600has outer press-forming sections1600aand1600cthat are complementary in shape to the outer stretch-forming sections1200aand1200cof the shaped core1200. In one embodiment, the outer stretch-forming sections1200aand1200care a plurality of rounded teeth220(or shaped gear teeth) separated by a plurality of grooves. The outer press-forming sections1600aand1600cof the roller1600press respective sections1300aand1300bof the pre-preg material1202in the valleys of the outer stretch-form sections1200aand1200cto form the stretch-formed pre-preg material1300. The roller1600further has a center section1600bthat is complementary in shape to center section1200bof the shaped core1200. As a result, the stretch-formed pre-preg material1300is formed to have outer shaped sections1300aand1300cand a non-stretched mid-section1300b.

FIG. 17illustrates a process flow diagram1700that can be used with the shaped core1200, as described above. As this process starts, one or more layers of pre-preg material are initially rolled on the shaped core (1702). To stretch select sections of the pre-preg material about the sheet of pre-preg material's width, several methods can be use either alone, or in combination. The methods include physically pressing the select sections of pre-preg material into stretching sections of the shaped core (1704), applying a vacuum (1706), applying heat (1708) and applying atmospheric pressure (1710). As stated above, any single method or any combination in any sequence can be used to form the pre-formed (or stretch-formed) pre-preg material (1712). For example, in one embodiment only the physical pressing (1704) is used. In another embodiment, the pre-preg material is physically pressed (1704) and then placed in an autoclave that applies a vacuum (1706), heat (1708) and pressure (1710). Further, in another example embodiment physical pressure (1704) and heat (1708) are applied to the one or more layers of pre-preg material on the shaped core (1702) separately. The shaped core is then vacuumed bagged and pressure (1710) and vacuum (1706) are applied to form the pre-formed pre-preg material (1712). In still another example embodiment, physical pressure (1704) and a vacuum (1706) are first applied. Then, heat (1708) and pressure (1710) are applied to form the pre-formed pre-preg material (1712). Hence, as stated above, any single method or any combination of methods in any sequence discussed above can be used to form the pre-formed pre-preg material on the shaped core.