JP4701439B2 - Sutured braid FRP pipe with impact energy absorption performance - Google Patents

Description

The present invention is made of fiber reinforced plastics (hereinafter referred to as FRP) obtained by braiding a fiber material for FRP such as carbon fiber using a braider device, more preferably carbon fiber reinforced plastic (carbon fiber). Reinforced plastics (hereinafter referred to as “CFRP”) relates to a cylindrical suture assembly FRP pipe.

As is well known, FRP is a composite material formed by bending a fiber material such as carbon fiber or glass fiber with a matrix of various plastics, and is a lightweight and high strength FRP composition structural material. It has been developed and used in many industrial fields. This FRP composition is composed as a cylindrical multi-layered structure around a mandrel by setting a fiber material such as carbon fiber or glass fiber in a braider device and performing a braiding process. When a preform is formed by the FRP structure formed in the cylindrical multiple layers, a resin material is impregnated or adhered to the FRP structure, and then cured and formed by heat and pressure treatment. Thereafter, the mandrel is extracted to obtain a cylindrical molded product.

In recent years, it has been proposed to apply a crash element to alleviate the impact on a passenger when a vehicle or other vehicle collision accident occurs. For example, when the crash element is applied to a car or the like, the crash element is interposed between the bumper and the vehicle body, and is used as a structural member that absorbs impact energy by being deformed and destroyed by itself. In general, this crush element is made of a metal material such as aluminum or iron, but it is clear that the crush element made of FRP has superior energy absorption performance compared to these metal materials such as aluminum and iron. Therefore, it is desired to develop a crash element made of FRP, more preferably CFRP.

On the other hand, in the FRP using a braid, the performance is improved by increasing the orientation angle of the braid and increasing the toughness of the resin material. However, the improvement of the energy absorption performance of the FRP is limited only by adjusting the orientation angle of the braid and improving the resin material. The development of higher performance crash elements can be expected to reduce weight and expand applications.

Conventionally, a preform molding method as described in Patent Document 1 is known as a method for molding an FRP preform. The preform molding method described in Patent Document 1 is for the purpose of preventing separation or displacement between layers when a cylindrical preform made of a plurality of layers is braided by a blader and then extracted from a mandrel. This is to temporarily fix the preform. This technique is merely a category of a preform molding method including a step of temporarily fixing each layer of the preform after brazing molding and before extracting from the mandrel when molding the preform.

JP 2001-30361 A (summary, FIGS. 5 to 8)

Therefore, the present invention is intended to provide a specific structure called a suture assembly FRP pipe having a high impact energy absorption performance while being a low-cost and simple structure.

As a result of repeated trial and error in order to solve this problem, the present inventors have observed the occurrence of a crack (central crack) at the center of the cross section from the detailed cross section observation after energy absorption destruction of the conventional braided cylindrical FRP. It was analyzed that suppression is effective in improving energy absorption performance. A braided cylindrical preform is sutured with aramid fibers, impregnated and cured with epoxy resin to produce a stitched braid FRP pipe, subjected to a static compression test, and compared to a braid FRP without stitching. An energy absorption performance improvement of 15% to 20% was obtained.

In order to achieve the above-described object, the present invention specifically uses a braider device to selectively combine a braid having an angle of ± θ ° with respect to the axis and a center yarn having an angle of 0 ° with respect to the axis. A braided cylindrical preform comprising a plurality of braid layers on a mandrel that is the core of the composition, and the braids in the inner and outer braid layers of the plural braid layers The assembly angle is large and the assembly angle of the assembly yarn in the intermediate assembly layer among the plurality of assembly layers is small, and the assembly cylindrical preform is sutured with sutures in the layer thickness direction. , Ri Na to form a suture braided FRP resin material impregnated cured to the stitching process, the braid along the generatrix direction of the cylindrical preform adapted to form a suture column, the adjacent suture If the stitching points are aligned in a row It constitutes a suture braided FRP pipe having an impact energy absorbing performance, characterized in that is unusually arranged.

Further, in this invention, the invention according to claim 2 is the suture braid FRP pipe according to claim 1, wherein the braided yarns in the inner and outer braid layers of the plural braid layers are arranged. The braid angle is large, and the braid angle of the braid in the middle braid layer among the plural braid layers is small.

Further, in the present invention, the invention described in claim 3 is the suture braid FRP pipe according to claim 1 or 2, wherein the stitching process is performed in the layer thickness direction of a plurality of cylindrical braids. It consists of what was sewn.

Furthermore, in the present invention, the invention according to claim 4 is the suture assembly FRP pipe according to any one of claims 1 to 3, wherein the suture is an aramid fiber. To do.

Furthermore, in this invention, the invention according to claim 5 is the suture assembly FRP pipe according to any one of claims 1 to 4, wherein the resin material is a thermosetting resin. It is a feature.

Furthermore, in this invention, the invention according to claim 6 is the suture assembly FRP pipe according to any one of claims 1 to 5, wherein the suture assembly FRP pipe is a crash element for a vehicle body, or helicopter crash element is also characterized by the fact that constitutes the crash element for the drive shaft.

The stitched braid FRP pipe having impact energy absorption performance according to the present invention is constituted by a plurality of braid layers, and the braid angles of the braids in the inner and outer braid layers of the plural braid layers. Is formed by reducing the braid angle of the braid in the middle braid layer of the plurality of braid layers, sewing with a suture in the layer thickness direction, and impregnating and hardening the resin material. In addition, when this is applied to various crash elements, it is possible to suppress the occurrence of cracks at the center of the cross section after energy absorption destruction of the braided cylindrical FRP, and it can be said that it acts extremely effectively on improving energy absorption performance. It can be used for various purposes as a crash element for vehicle bodies, a crash element for helicopters, a crash element for drive shafts, etc.

Hereinafter, the stitched braid FRP pipe having impact energy absorption performance according to the present invention will be described in detail based on specific embodiments shown in the drawings. FIG. 1 is a schematic perspective view showing the form of a multi-layered (seven-layered) FRP tissue body obtained by a braiding process in the manufacturing process of a stitched braid FRP pipe according to the present invention. On the other hand, FIG. 6 is a schematic side sectional view showing an example of a basic configuration of a multiple braider device for manufacturing a suture assembly FRP pipe according to the present invention.

In the present invention, for example, using carbon fiber, a pair angle of the mandrel with respect to the axis line is ± θ ° (where the set angle θ is 0 ° <θ ° <90 °), Y (4, 4) and the center yarn y (5) whose angle with respect to the axis is 0 °, each is set in a braider device, and a tubular FRP structure is woven around the mandrel by braiding.

A configuration example of a multiple braider device used for manufacturing the FRP tissue body according to the present invention will be described. In FIG. 6, the multiple braider device includes a mandrel automatic supply device (not shown), a plurality of vertical braider units BR, a shake prevention device Os, and an automatic preform take-out device Pu. Are arranged in series. As shown in FIG. 6, the braider unit BR feeds a pair of braided yarns Y, Y (4, 4) and a central yarn y (5) for forming a braid braid layer 2 around the mandrel M. It is.

The braider unit BR includes a vertical raceway surface 21 having a center hole 21a through which a mandrel M passes and two ridges of a corrugated annular raceway (not shown) formed outside the center hole 21a, and these annular raceways. Two groups of bobbin carriers 22 guided in the opposite directions and traveling in opposite directions, a bobbin stand erected from the raceway surface 21, and a plurality of erections standing from the center of the raceway surface 21 surrounded by the annular raceway. And a cylindrical body 23 for supplying a central yarn.

The bobbin carrier 22 feeds the yarns Y and Y (4, 4) obliquely intersecting on the surface of the mandrel M at a yarn angle ± θ °, and a yarn bobbin B around which the yarn Y is wound is set. The The bobbin stand is for feeding the central yarn y (5) along the longitudinal direction of the mandrel M on the surface of the mandrel M, and the central yarn bobbin b around which the central yarn y is wound is set.

While the mandrel M is placed at a constant speed by a chuck (not shown) on the right side in FIG. 6, the mandrel M is wound around the surface so that a plurality of braided yarns Y and Y intersect, and the central yarn y is combined with this. A braided braid layer 2 is formed.

The anti-vibration tool Os includes two sets of anti-vibration rollers 27 and 27 that are pressed toward each other. This shake prevention tool Os prevents the mandrel M from meandering with the rollers 27 and 27 of each set. The preform automatic take-out device Pu is provided with a chuck 28 for pulling the mandrel M forward while holding the tip of the mandrel M that has come out of the shake prevention tool Os.

Next, the basic structure of the braided tissue body according to the present invention will be described in detail based on the basic configuration example shown in FIG. In order to characterize the basic structure of the present invention, the basic braided cylindrical preform 1 shown in FIG. 1 is composed of a cylindrical (pipe-shaped) braided layer 2 in multiple layers (seven layers in the embodiment shown in the figure). FIG. 1 is a schematic perspective view showing each layer partially broken.

In the basic configuration example shown in FIG. 1, the braid layer 2 is composed of braids 4 and 4 having a braid angle of ± θ ° with respect to the axis and a central yarn 5 having an angle of 0 ° with respect to the axis. is there. As shown in FIG. 6, these braided yarns 4, 4 and the central yarn 5 are selectively combined around the mandrel M and woven as a braided cylindrical preform 1 along the mandrel M. In the present invention, according to a preferred embodiment, it is effective that the material of the braided yarns 4, 4 and the central yarn 5 is a CFRP fiber material mainly composed of carbon fiber or the like.

As shown in FIG. 1, the braided cylindrical preform 1 is composed of, for example, seven braided layers 2, which are the first braided layer 2-1 from the inside, 2nd layer assembly layer 2-2, 3rd layer assembly layer 2-3, 4th layer assembly layer 2-4, 5th layer assembly layer 2-5, 6th layer assembly It consists of a layer 2-6 and a seventh layer assembly layer 2-7. In FIG. 1, with respect to the first braided layer 2-1 and the seventh braided layer 2-7, a central yarn is organized with respect to the braided yarn. Therefore, the first layer, that is, the inner layer, and the seventh layer, that is, the outer layer are composed only of the braids 4 and 4.

Furthermore, an important element in the present invention is the layer structure of each layer in the braided cylindrical preform 1. That is, in the present invention, among the plurality of braid layers 2, the braids 4, 4 in the braid layer 2-1 on the inner side (first layer) and the braid layer 2-7 on the outer side (seventh layer) The angle ± θ ° (where the set angle θ ° is 0 ° <θ ° <90 °) is relatively large, for example, the yarn is organized by the braids 4 and 4 with θ = ± 60 °, The central yarn 5 having an angle of 0 ° is formed by only the braids 4 and 4 with relatively little or no use. According to the inner braid layer 2-1 and the outer braid layer 2-7 having the above-described configuration, when the test piece as shown in FIG. A physical layer is formed. Such a braided layer is composed of only the braided yarns 4 and 4 and does not have a central yarn whose angle with respect to the axis is 0 °, and has a low axial elastic modulus and a large breaking strain. Form a structure. On the other hand, the intermediate (second to sixth) assembled layers 2-2 to 2-6 have a relatively small assembly angle ± θ ° with respect to the axis, for example, θ = ± 15 °. The braids 4 and 4 and the central yarn 5 having an angle with respect to the axis of 0 ° are organized, and under the test conditions as described above, the braid responsible for improving the axial strength when subjected to the axial impact pressure. A material layer is formed. Such a braided layer is formed by the braided yarns 4 and 4 and the central yarn 5 having an angle of 0 ° with respect to the axis, and forms a layer structure having a high elastic modulus in the axial direction.

Generally, in the laminated structure 1 of the FRP composition, the factors that define the elastic modulus in the axial direction are the braid angle ± θ ° of the braid, the presence / absence of the central yarn, and the ratio of the central yarn to the braid Is obtained by a selective combination of For example, the axial elastic modulus of each braid layer in the laminated structure 1 of the FRP composition is adjusted by setting the braid angle ± θ °, and the braid angle ± θ ° Is small, and low when the braid angle ± θ ° is large. Further, the axial elastic modulus of each braid layer in the laminated structure 1 of the FRP composition is adjusted by whether or not the central yarn is incorporated into the braided yarn, in other words, by the presence or absence of the central yarn. It is high when a central yarn is incorporated into the braid, and low when it does not have the central yarn. Furthermore, the axial elastic modulus of each braid layer in the laminated structure 1 of the FRP composition is adjusted by the ratio of the central thread to the braid, and the ratio of the central thread to the braid is High when there are many, low when the ratio of the center yarn to the braid is small.

In this invention, the braids 4 and 4 with a braiding angle of ± θ ° with respect to the axis and the central yarn 5 with an angle of 0 ° with respect to the axis are selectively combined and placed on the mandrel which is the core of the composition by the braider device. A braided cylindrical preform 1 composed of a plurality of braided layers is composed, and the braided cylindrical preform 1 is sutured with sutures 6 in the layer thickness direction as shown in FIG. The suture material FRP is formed by impregnating and curing the resin material.

That is, the braided cylindrical preform 1 has a plurality of layers as shown in FIG. 1, so that the braided cylindrical preform 1 has a layer thickness as shown in FIG. A suturing process is performed by the suture thread 6 in the direction. This stitching process is configured by stitching in a layer thickness direction of a plurality of cylindrical assemblies. The suture 6 used for the stitching is, for example, an aramid fiber, and is sutured at a stitching pitch p of about 4 mm along the generatrix direction of the braided cylindrical preform 1. The braided cylindrical preform 1 is stitched with a stitching row interval d of about 4 mm in the circumferential direction. As shown in FIG. 2B, at the stitching point 7, fiber damage of the braid layer due to the stitching process and generation of a resin-rich portion due to the suture thread 6 cause deterioration of the inner surface characteristics of the FRP molded product. Therefore, by arranging the stitching points 7 so as not to be in a straight line in adjacent stitching rows, the stitching points are arranged so as to suppress the influence of the deterioration of the in-plane characteristics at the stitching points 7 on the energy absorption characteristics.

On the other hand, the assembled cylindrical preform 1 is subjected to a suturing treatment with the suture thread 6 and impregnated and cured with a resin material to form a suture assembly FRP. In this case, for example, a thermosetting resin such as an epoxy resin is used as the resin material, and a diluted resin solution obtained by diluting the epoxy resin with a solvent (acetone) is impregnated and applied to the assembled cylindrical preform 1. To do.

The suture assembly FRP formed in this way is cut into a desired length dimension in the axial direction, and formed as a suture assembly FRP pipe having impact energy absorption performance according to the present invention.

FIG. 2 shows an embodiment of the present invention, in which the braided yarn and the central yarn show a stitched CFRP pipe 11 made of carbon fiber, and FIG. 2A shows the appearance of a test piece N that has not been stitched. FIG. 2B relates to the present invention. FIG. 2B shows the appearance of the test piece ST in which the suture assembly CFRP pipe 11 having the above-described configuration is sutured with the suture thread 6 in the layer thickness direction. FIG. 2C is an enlarged view of a portion surrounded by a circle in FIG. 2B.

Results of a test in which the finished test piece ST shown in FIG. 2B and the test piece N shown in FIG. 2A not subjected to the sewing process were performed under the test conditions shown in FIG. Will be described. First, Table 1 shows the types (internal structural elements) of test pieces prepared for this test.

This is then shown in Table 2 for the respective dimensions for the specimen samples prepared for the test.

From these test piece samples, the test piece ST subjected to the suturing treatment and the test piece N not subjected to the suturing treatment were tested under the test conditions shown in FIG. As a result, a load-displacement curve N shown in FIG. 5A and a load-displacement curve ST shown in FIG. 5B were obtained. As is clear from this graph, according to the test piece ST subjected to the suturing process, compared to the test piece N not subjected to the suturing process, the load with respect to the displacement amount is large and the area under the curve is increased. This suggests that the impact energy absorption performance is excellent. Table 3 shows a comparison between the test piece ST subjected to the suturing process and the test piece N not subjected to the suturing process.

The stitched assembly FRP pipe having the impact energy absorbing performance as described above can be applied very effectively as, for example, a vehicle crash element, a helicopter crash element, or a drive shaft crash element. That is, as a crash element for a vehicle body, by installing the pipe between the bumper and the vehicle body, with its one axial end facing the bumper and the other axial end facing the vehicle. In the event of a collision accident, the crash element can absorb the shock and protect the vehicle body, which works effectively.

FIG. 1 shows a basic configuration of a braided cylindrical preform composed of a plurality of braided layers for the present invention, and is a schematic perspective view showing each layer partially broken. FIG. 2A is an external view of a test piece N that is not sutured, and FIG. 2B is an external view of a test piece ST that is sutured with a suture thread in the layer thickness direction of a braided FRP pipe. FIG. 2C is an enlarged view of a circled portion in FIG. 2B. FIG. 3 is a schematic perspective view showing a stitching form in which a stitching process is performed on the braided cylindrical preform 1 with the suture thread 6. FIG. 4 is an explanatory diagram for explaining test conditions for the test piece. FIG. 5A is a graph showing a load-displacement curve of the test piece N, and FIG. 5B is a graph showing a load-displacement curve of the test piece ST. FIG. 6 is a schematic cross-sectional side view of a multiple braider apparatus for composing a braided cylindrical preform comprising a plurality of braid layers.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Braided cylindrical preform 2 Braided layers 4, 4 Braided yarn with a braid angle of ± θ ° with respect to the axis 5 Center yarn 6 with an angle with respect to the axis of 6 ° Braided CFRP pipe BR Braider unit Y Braid y Center yarn B Bobbin for braid b Bobbin M for central yarn Mandrel

Claims (6)

The braid device is composed of a plurality of braided layers on a mandrel that is the core of the composition by selectively combining a braid having an angle of ± θ ° with respect to the axis and a center yarn having an angle of 0 ° with respect to the axis becomes compositionally the braided cylindrical preform, the braided cylindrical preform sutured treated with sutures in the layer thickness direction, Ri na a resin material impregnated cured to form a suture braided FRP, the The stitching process is performed so as to form a stitching row along the generatrix direction of the braided cylindrical preform, and the stitching points are arranged so that the stitching points do not line up in the adjacent stitching rows. A suture composition FRP pipe having impact energy absorption performance. The braid angle of the braid is large in the inner and outer braid layers of the plural braid layers, and the braid angle of the braid in the middle braid layer is small in the plural braid layers The stitched braid FRP pipe having impact energy absorption performance according to claim 1, wherein 3. The suture braid FRP pipe having an impact energy absorption performance according to claim 1, wherein the stitching process includes stitching in a layer thickness direction of a plurality of cylindrical braids. The said suture thread is an aramid fiber, The suture braid FRP pipe which has the impact energy absorption performance in any one of Claims 1-3 characterized by the above-mentioned. The stitched braid FRP pipe having impact energy absorption performance according to any one of claims 1 to 4, wherein the resin material is a thermosetting resin. The impact energy absorption performance according to any one of claims 1 to 5, wherein the suture braid FRP pipe constitutes a crash element for a vehicle body, a crash element for a helicopter, or a crash element for a drive shaft. A suture braid FRP pipe having.

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