CN205209886U - One -way fibre reinforced composite perpendicular to fiber direction's tensile testing loading device - Google Patents

Abstract

The utility model discloses a tensile test loading device and a testing method for a unidirectional fiber-reinforced composite material perpendicular to the fiber direction. Clamping rod; the force transmission piece is divided into an upper force piece and a lower force transmission piece, the upper force piece is pasted on the upper end of the unidirectional fiber reinforced composite material specimen, and the lower force transmission piece is pasted on the lower end of the unidirectional fiber reinforced composite material specimen , the fibers in the unidirectional fiber reinforced composite material specimen are perpendicular to the tensile test direction, the loading frame includes the upper loading frame and the lower loading frame, the upper force plate is fixedly installed in the upper loading frame, and the lower force plate is fixedly installed in the lower loading frame Among them, the upper clamping rod is fixedly connected with the upper loading frame, and the lower clamping rod is fixedly matched with the lower loading frame through the threaded connecting rod and the clearance eliminating nut. The utility model has the advantages of being able to avoid the damage to the sample caused by the clamping force of the testing machine, eliminating the connection gap between the fixture parts, improving the test precision and accurately centering the test piece.

Description

Tensile Test Loading Apparatus Perpendicular to Fiber Direction for Unidirectional Fiber Reinforced Composites

technical field

The utility model relates to the field of mechanical testing of composite materials, in particular to a tensile test loading device for unidirectional fiber-reinforced composite materials perpendicular to the fiber direction.

Background technique

Fiber-reinforced composites have the advantages of high specific strength, high specific modulus, and good chemical stability, and are widely used in energy, military, and transportation fields. With the extensive application of fiber-reinforced composites, the testing methods of their mechanical properties have also received extensive attention. The mechanical performance parameters such as tensile strength, elastic modulus and Poisson's ratio of the material can be obtained through the tensile test of the fiber reinforced composite material, which has important guiding significance for the safe and reliable application of the composite material.

Most of the tensile test methods of fiber reinforced composite materials in the prior art are carried out according to standards such as GB/T1040.4-2006, GB/T1040.5-2008, ASTMC1359 and ASTMD3039. Most of the prior art uses wedge-shaped fixtures, pin-shaped fixtures or dovetail-shaped fixtures to load tensile samples of fiber-reinforced composite materials. These methods can better realize the tensile test and weaving of unidirectional fiber-reinforced composite materials along the fiber direction. Tensile testing of structural composites. However, the mechanical properties of unidirectional fiber-reinforced composites have significant directionality, that is, they have high tensile strength along the fiber direction, while the tensile strength perpendicular to the fiber direction is low and the bonding force between fiber bundles is weak. When the existing technology is used to perform tensile tests on unidirectional fiber reinforced composite materials perpendicular to the fiber direction, the failure site is likely to appear in the clamping section of the tensile sample, resulting in invalid test data. Among them, the wedge-shaped fixture is clamped along the thickness direction of the sample by the wedge-shaped block of the fixture. The stress gradient between the clamping section and the test section is relatively large, and the clamping section will produce greater damage under the clamping force of the wedge-shaped block. , when the clamping force is large, the clamping section of the sample will be directly flattened, causing the sample to crack between the fiber bundles at the boundary of the clamping section, resulting in end failure of the tensile sample during the test. The pin-shaped fixture test method needs to open holes in the clamping section of the sample. For unidirectional fiber-reinforced composite materials with low transverse strength, it is very easy to fail prematurely at the stress concentration of the circular hole, resulting in test failure. The dovetail loading method transmits tensile load to the sample through the slope of the fixture, and for unidirectional fiber-reinforced composites with low transverse strength, the probability of failure at the contact surface is high.

The tensile fixture disclosed in Chinese patent CN103018101A "A Fixture for High Temperature Tensile Testing of Ceramic Matrix Composite Materials" can be used for most structures of composite materials, but it is used for tensile strength of unidirectional fiber-reinforced composite materials perpendicular to the fiber direction. During the tensile test, the specimen will fail at the contact surface of the grips. Chinese patent CN104634656A "Composite Material Uniaxial Tensile Test Fixture" discloses a non-clamping composite material tensile fixture. This type of clamp is similar to a dovetail clamp and is prone to failure at the interface. The fixture is designed with a circular arc surface that matches the test piece, but the machining error will cause a fit gap between the two, resulting in uneven force on the sample and affecting the test accuracy. For test pieces with different arc sizes, the fixture cannot be used universally, and the fixture needs to be reprocessed according to the arc size of the sample, which increases the test cost. Chinese patent CN203941063U "Ultra-thin Metal Strip High Temperature Tensile Test Fixture" discloses a kind of tension fixture for plate-like samples. The fixture adopts bolt connection to clamp the sample, so the uneven force on the clamping section is prone to slipping. In addition, none of the technical solutions disclosed in the prior art involves a solution to the problem of eliminating the fit gap between the components of the combined fixture.

Utility model content

The technical problem to be solved by the utility model is to provide a method that can avoid damage to the sample caused by the clamping force of the testing machine, ensure that the tensile test of the unidirectional fiber reinforced composite material perpendicular to the fiber direction can be carried out smoothly, and eliminate the gap between the clamp parts. A tensile test loading device and a test method for unidirectional fiber-reinforced composite materials perpendicular to the fiber direction, which improve the test accuracy and precisely center the test pieces, are provided by connecting gaps.

In order to solve the problems of the technologies described above, the technical solution adopted in the utility model is:

A tensile test loading device for unidirectional fiber-reinforced composite materials perpendicular to the fiber direction, including: an upper clamping rod, a loading frame, a force transmission piece and a lower clamping rod; the force transmission piece is divided into an upper force transmission piece and a lower force transmission piece , the upper force sheet is pasted on the upper end of the unidirectional fiber reinforced composite material specimen, the lower force transfer sheet is pasted on the lower end of the unidirectional fiber reinforced composite material specimen, and the fibers in the unidirectional fiber reinforced composite material specimen are perpendicular to the tensile test direction, the loading frame includes an upper loading frame and a lower loading frame, the upper force plate is fixedly installed in the upper loading frame, the lower force plate is fixedly installed in the lower loading frame, the upper clamping rod is fixedly connected with the upper loading frame, and the lower clamping rod Fixed connection with the download box.

In order to optimize the above technical solutions, the specific measures taken also include:

The above-mentioned upper loading frame and the lower loading frame are both frame structures with openings, and the inner frame opening surfaces of the upper loading frame and the lower loading frame are provided with long positioning slots, and positioning slots are provided on the force transmission plate corresponding to the positions of the long positioning slots. Protrusion, the positioning protrusion can be snapped into the long positioning groove so that the force transmission piece is fixedly matched with the corresponding loading frame.

The center of the upper end surface of the above-mentioned upper loading frame and the lower end surface of the lower loading frame are all provided with threaded holes, one end of the upper clamping rod and the lower clamping rod are provided with threads, the other end is a polished rod, and the thread of the upper clamping rod One end is screwed into the threaded hole of the upper loading frame; the tensile test loading device also includes a threaded connecting rod and a gap eliminating nut, one end of the threaded connecting rod is screwed into the threaded hole of the lower loading frame, and the other end is screwed into one side of the gap eliminating nut, The threaded end of the lower clamping rod is screwed into the other side of the clearance eliminating nut; the screw threads on both sides of the clearance eliminating nut are in opposite directions, and when the clearance eliminating nut is rotated, the threaded connecting rod and the lower clamping rod can be moved closer or farther away from each other.

The above-mentioned upper force sheet is two pieces, one positive and one reverse pasted on the upper end of the unidirectional fiber reinforced composite material specimen, and the lower force transmission piece is two pieces, one positive and one reverse pasted on the unidirectional fiber reinforced composite material specimen The lower end of each force transmission sheet is provided with a groove, the depth of the groove is half of the thickness of the unidirectional fiber reinforced composite material specimen, and the shape of the groove is the same as that of the end of the unidirectional fiber reinforced composite material specimen. The shape is matched, and the end of the unidirectional fiber reinforced composite material is inserted into the groove and bonded with the force transmission sheet.

The above-mentioned groove is a groove structure with a wide outside and a narrow inside.

The above long positioning groove is a V-shaped groove, and correspondingly, the positioning protrusion is a V-shaped protrusion.

One end of the clearance elimination nut has rounded corners for marking the orientation. The rounded end of the clearance elimination nut is connected to the threaded connecting rod, and the unrounded end of the clearance elimination nut is connected to the lower clamping rod. The clearance elimination nut has a convenient Wrench bit for wrench rotation operation.

The glue used when pasting the force transmission sheet and the unidirectional fiber-reinforced composite material specimen is epoxy resin glue or acrylic glue, and the glue is evenly applied in the groove.

A tensile test method for unidirectional fiber reinforced composite materials perpendicular to the fiber direction, including the following steps:

Step 1. Take two pairs of force transmission sheets and apply glue evenly on the force transmission sheets, and then paste the force transmission sheets to the clamping sections at both ends of the unidirectional fiber reinforced composite material specimen;

Step 2. Start the tensile testing machine and loosen the upper and lower jaws of the testing machine;

Step 3. Connect the upper clamping rod to the upper loading frame, then put the polished part of the upper clamping rod into the jaw of the upper chuck of the testing machine, and operate the testing machine to clamp the jaw of the upper chuck;

Step 4: Put the uploading force sheet on the upper end of the unidirectional fiber reinforced composite material specimen into the upper loading frame, so that the uploading force sheet is fixed with the upper loading frame;

Step five, set the load sensor of the tensile testing machine, and set the reading of the load sensor to zero;

Step 6. Connect the lower loading frame with the threaded connecting rod, connect the threaded connecting rod with the gap eliminating nut, and screw the lower clamping rod into the gap eliminating nut;

Step 7. Put the lower force transmission sheet at the lower end of the unidirectional fiber reinforced composite material specimen into the lower loading frame, so that the lower force transmission sheet and the lower loading frame are fixed;

Step 8. Set the tensile testing machine to the displacement control mode, adjust the position of the beam of the testing machine through the displacement controller so that the polished part of the lower clamping rod penetrates into the jaw of the lower chuck, and then clamp the jaw of the lower chuck;

Step 9. Reset the indication of the displacement sensor of the testing machine to zero;

Step 10. Rotate the gap elimination nut to eliminate the connection gap between the sample loading components;

Step 11. Set the tensile testing machine to the force control mode, and start the tensile test on the unidirectional fiber reinforced composite material specimen until the specimen breaks;

Step 12, read the data of the force sensor and the displacement sensor of the tensile test machine, and obtain the tensile load-displacement curve and the maximum tensile load of the sample.

The loading speed of the tensile test in step eleven is 0.02kN/s.

The utility model has the following positive effects:

(1) The loading frame of the utility model transmits the tensile load of the testing machine to the force transmission sheet, and the force transmission sheet transmits the load to the surface of the sample through the glue bonding the sample and the force transmission sheet to apply the load to the sample. Therefore, the sample has no compressive force in the thickness direction during loading, avoiding the damage caused by the clamping force of the testing machine to the sample during direct loading, and ensuring that the tensile test of the unidirectional fiber reinforced composite material perpendicular to the fiber direction can be It went smoothly.

(2) The force transmission plate and the loading frame of the utility model are respectively provided with a V-shaped positioning protrusion and a V-shaped positioning long groove. Through the cooperation of the two, the precise centering of the sample can be ensured, and the accuracy of the test result can be ensured. .

(3) The utility model can be applied to samples of different thicknesses and widths only by adjusting the groove depth and width of the force transmission plate. The test device has a wide application range and low test cost.

(4) The utility model is equipped with a gap elimination nut, and the two ends of the nut are designed with threads with opposite rotation directions. Rotating the gap elimination nut can make the clamp and the lower connecting rod move toward each other, so as to eliminate the connection gap between the clamp components. Improved test accuracy.

Description of drawings

Fig. 1 schematic diagram of the upper clamping rod of the utility model;

Fig. 2 schematic diagram of loading frame of the utility model;

Figure 3 is a schematic diagram of the utility model force transmission sheet;

Fig. 4 Schematic diagram of long strip tensile specimen of unidirectional fiber reinforced carbon/carbon composite;

Fig. 5 schematic diagram of threaded connecting rod of the utility model;

Fig. 6 is a schematic diagram of the clearance eliminating nut of the utility model;

Fig. 7 is a schematic diagram of the lower clamping rod of the utility model;

Fig. 8 is a schematic diagram of the cooperation relationship between the force transmission sheet of the utility model and the long tensile sample of the unidirectional fiber reinforced carbon/carbon composite material;

Figure 9 is a schematic diagram of the assembly of the loading and clamping device and the tensile sample of the utility model;

Fig. 10 schematic diagram of dog-bone tensile specimen of unidirectional fiber-reinforced resin-based composite material;

Fig. 11 is a schematic diagram of the cooperation relationship between the force transmission sheet of the utility model and the dog bone tensile sample of the unidirectional fiber-reinforced resin-based composite material;

Fig. 12 Schematic diagram of unidirectional fiber reinforced ceramic matrix composite dovetail tensile specimen;

Fig. 13 is a schematic diagram of the dovetail groove force transmission piece of the utility model;

Fig. 14 is a schematic diagram of the cooperation relationship between the dovetail groove force transmission piece of the utility model and the dovetail tensile sample of the unidirectional fiber reinforced ceramic matrix composite material.

The horizontal bars on the unidirectional fiber-reinforced composite material specimen 4 in the figure represent fibers.

The reference signs are: upper clamping rod 1, loading frame 2, upper loading frame 21, lower loading frame 22, positioning slot 23, force transmission piece 3, groove 3a, upper force piece 31, lower force transmission piece 32. Positioning protrusion 33. Unidirectional fiber reinforced composite material specimen 4. Threaded connecting rod 5. Gap eliminating nut 6. Lower clamping rod 7.

detailed description

Below in conjunction with accompanying drawing, the technical solution of the utility model is described in detail.

First embodiment:

A tensile test loading device for unidirectional fiber-reinforced composite materials perpendicular to the fiber direction, including an upper clamping rod 1, a loading frame 2, a force transmission piece 3, a threaded connecting rod 5, a gap elimination nut 6, and a lower clamping rod 7; One end of the clamping rod 1 is provided with a right-handed thread, and the other end is a polished rod; one end of the lower clamping rod 7 is provided with a left-handed thread, and the other end is a polished rod; the loading frame 2 is two identical upper loading frame 21 and lower loading frame 22 , wherein the upper loading frame 21 is connected with the upper clamping rod 1, and the lower loading frame 22 is connected with the threaded connecting rod 5; A V-shaped positioning long groove with the same thickness as the loading frame 2 is symmetrically provided on the opening surface of the frame; the force transmission sheet 3 is provided with four identical pieces, which are respectively pasted on a long strip of unidirectional fiber-reinforced carbon/carbon composite material. The two ends of the stretched sample; the force transmission piece 3 is a cuboid with a groove, and the depth of the groove is 1/2 of the thickness of the strip-shaped tensile sample of the unidirectional fiber reinforced carbon/carbon composite material. The cross-sectional size is the same as the cross-sectional size of the clamping section of the elongated tensile sample of unidirectional fiber reinforced carbon/carbon composite material. The force transmission piece 3 is symmetrically provided with V-shaped positioning protrusions on one side, and the force transmission piece 3 passes through the V The V-shaped positioning protrusion is connected with the V-shaped positioning long groove of the loading frame 2, and the thickness of the force transmission piece 3 is 1/2 of the thickness of the loading frame 2; the threaded connecting rod 5 is connected with the lower loading frame 22 and the gap elimination nut 6; the threaded connection The rod 5 is a right-handed threaded rod; one end of the gap elimination nut 6 has a rounded corner for marking the orientation, and the center of the end face of the gap elimination nut 6 with rounded corners has a right-handed threaded hole that can be connected with the threaded connecting rod 5, and the gap elimination nut 6 There is a left-handed threaded hole in the center of the end surface of the non-rounded end, which can be connected with the lower clamping rod 7, and the gap elimination nut 6 has a wrench position to facilitate the rotation operation.

A tensile test method for unidirectional fiber reinforced composite materials perpendicular to the fiber direction, including the following steps:

Step 1. Take two pairs of force transmission sheets 3 and apply epoxy resin or acrylic glue evenly in the grooves of the force transmission sheets 3, and then paste the force transmission sheets 3 on the long strip of unidirectional fiber reinforced carbon/carbon composite material. The clamping sections at both ends of the tensile sample (Fig. 8), apply the load on the groove surface of the force transmission plate 3 to the upper and lower clamping sections of the elongated tensile sample of unidirectional fiber-reinforced carbon/carbon composites through glue surface;

Step 2. Start the tensile testing machine and loosen the upper and lower jaws of the testing machine;

Step 3: Connect the upper clamping rod 1 to the upper loading frame 21, then put the polished part of the upper clamping rod 1 into the jaws of the upper chuck of the testing machine, and operate the testing machine to clamp the jaws of the upper chuck;

Step 4: Put the force-loading sheet 31 on the upper end of the unidirectional fiber-reinforced carbon/carbon composite strip tensile sample into the upper loading frame 21, so that the uploading force sheet 31 and the upper loading frame 21 are fixed; Ensure that the V-shaped positioning long groove of the loading frame 2 cooperates with the V-shaped positioning protrusion of the force transmission piece 3. After the two are fully matched, it can ensure that the center line of the long-strip tensile sample of the unidirectional fiber reinforced carbon/carbon composite material is in line with the Alignment of the centerline of the chuck of the testing machine.

Step five, set the load sensor of the tensile testing machine, and set the reading of the load sensor to zero;

Step 6. Connect the lower loading frame 22 with the threaded connecting rod 5, connect the threaded connecting rod 5 with the gap eliminating nut 6, and screw the lower clamping rod 7 into the gap eliminating nut 6; when assembling, pay attention that the gap eliminating nut 6 is inverted The threaded hole on that side of the fillet links to each other with the threaded connecting rod 5 .

Step 7. Put the lower force transmission piece 32 at the lower end of the unidirectional fiber-reinforced carbon/carbon composite strip tensile sample into the lower loading frame 22, so that the lower force transmission piece 32 and the lower loading frame 22 are fixed; the connection process It should be ensured that the V-shaped positioning slot 23 of the loading frame 2 cooperates with the V-shaped positioning protrusion 33 of the force transmission piece 3.

Step 8, set the tensile testing machine to the displacement control mode, adjust the position of the beam of the testing machine through the displacement controller so that the polished part of the lower clamping rod 7 penetrates into the jaw of the lower chuck, and then clamp the jaw of the lower chuck;

Step 9. Reset the indication of the displacement sensor of the testing machine to zero;

Step 10. Rotate the gap elimination nut 6 clockwise. Since the threads of the threaded connecting rod 5 and the lower clamping rod 7 have the opposite direction of rotation, the threaded connecting rod 5 and the lower clamping rod 7 will move toward each other when the gap eliminating nut 6 is rotated clockwise. Tensioning of each grip assembly eliminates gaps between specimen loading assemblies;

Step 11. Set the tensile testing machine to the force control mode, adjust the loading speed to 0.02kN/s and start the tensile test until the elongated tensile specimen of the unidirectional fiber reinforced carbon/carbon composite material breaks;

Step 12: Read the force sensor data and the displacement sensor data of the tensile testing machine, and obtain the tensile load-displacement curve and the maximum tensile load of the unidirectional fiber-reinforced carbon/carbon composite strip-shaped tensile sample.

Second embodiment:

The unidirectional fiber-reinforced carbon/carbon composite elongated tensile specimen in the first embodiment is replaced by the unidirectional fiber-reinforced resin matrix composite dog-bone tensile specimen, as shown in Fig. 10 and Fig. 11 . The parts not described are the same as the first embodiment.

Third embodiment:

The unidirectional fiber-reinforced carbon/carbon composite strip tensile specimen in the first embodiment is replaced by the unidirectional fiber-reinforced ceramic matrix composite dovetail tensile specimen. Correspondingly, the groove 3a is as wide as the outside, The inner narrow dovetail-shaped tank body, as shown in Figure 12 to Figure 14. The parts not described are the same as the first embodiment.

The third embodiment improves the shape of the clamping part of the sample and the shape of the force transmission piece 3, so that the contact area between the sample and the force transmission piece 3 is larger. Wide and narrow inside, the sample is more difficult to come out, and the connection is firm.

The above are only preferred implementations of the utility model, and the scope of protection of the utility model is not limited to the above-mentioned embodiments, and all technical solutions under the thinking of the utility model all belong to the scope of protection of the utility model. It should be pointed out that for those of ordinary skill in the art, some improvements and modifications without departing from the principle of the utility model should be regarded as the protection scope of the utility model.

Claims (8)

1. Unidirectional Fiber-reinforced Composite is perpendicular to the extension test charger of machine direction, it is characterized in that: comprise supporting rod (1), load frame (2), steel tape (3) and lower supporting rod (7), described steel tape (3) is divided into steel tape (31) and lower steel tape (32), described upper steel tape (31) is pasted on the upper end of Unidirectional Fiber-reinforced Composite test specimen (4), described lower steel tape (32) is pasted on the lower end of Unidirectional Fiber-reinforced Composite test specimen (4), fiber in described Unidirectional Fiber-reinforced Composite test specimen (4) is perpendicular to extension test direction, described loading frame (2) comprises loading frame (21) and lower loading frame (22), described upper steel tape (31) is fixedly mounted in loading frame (21), described lower steel tape (32) is fixedly mounted in lower loading frame (22), described upper supporting rod (1) is fixedly connected with upper loading frame (21), described lower supporting rod (7) is fixed with lower loading frame (22) coordinate.

2. Unidirectional Fiber-reinforced Composite according to claim 1 is perpendicular to the extension test charger of machine direction, it is characterized in that: described upper loading frame (21) and lower loading frame (22) are the framed structure of band opening, the inside casing opening surface of upper loading frame (21) and lower loading frame (22) is equipped with positioning trough (23), on described steel tape (3) and positioning trough (23) corresponding position, position is provided with positioning convex (33), described positioning convex (33) can snap in positioning trough (23) and make steel tape (3) and corresponding loading frame (2) secure fit.

3. Unidirectional Fiber-reinforced Composite according to claim 2 is perpendicular to the extension test charger of machine direction, it is characterized in that: the described upper surface of upper loading frame (21) and the center of the lower surface of lower loading frame (22) all have threaded hole, described upper supporting rod (1) and lower supporting rod (7) are all provided with screw thread in one end, the other end is polished rod, and the thread end of described upper supporting rod (1) screws in the threaded hole loading frame (21); Extension test charger also comprises whorl brace rod (5), nut (6) is eliminated in gap, the threaded hole of frame (22) is loaded under one end screw-in of described whorl brace rod (5), the other end screws in the side that nut (6) is eliminated in gap, and the thread end of described lower supporting rod (7) screws in the opposite side that nut (6) is eliminated in gap; The thread rotary orientation that nut (6) both sides are eliminated in described gap is contrary, when rotary gap eliminates nut (6), whorl brace rod (5) can be made and lower supporting rod (7) is close to each other or away from.

4. Unidirectional Fiber-reinforced Composite according to claim 3 is perpendicular to the extension test charger of machine direction, it is characterized in that: described upper steel tape (31) is two panels, be pasted on to a positive and a negative the upper end of Unidirectional Fiber-reinforced Composite test specimen (4), described lower steel tape (32) is two panels, is pasted on to a positive and a negative the lower end of Unidirectional Fiber-reinforced Composite test specimen (4); Groove (3a) is provided with in the middle part of every sheet steel tape, the degree of depth of described groove (3a) is 1/2nd of Unidirectional Fiber-reinforced Composite test specimen (4) thickness, shape and Unidirectional Fiber-reinforced Composite test specimen (4) end shape of groove (3a) match, and described Unidirectional Fiber-reinforced Composite test specimen (4) end is stretched in groove (3a) and bonded with steel tape.

5. Unidirectional Fiber-reinforced Composite according to claim 4 is perpendicular to the extension test charger of machine direction, it is characterized in that: described groove (3a) is the trough body structure that outside is wide, inner side is narrow.

6. Unidirectional Fiber-reinforced Composite according to claim 2 is perpendicular to the extension test charger of machine direction, it is characterized in that: described positioning trough (23) is V-shaped groove, correspondingly, described positioning convex (33) is V-arrangement projection.

7. Unidirectional Fiber-reinforced Composite according to claim 3 is perpendicular to the extension test charger of machine direction, it is characterized in that: described gap is eliminated nut (6) one end and is rounded down for marking orientation, one end that nut (6) rounding is eliminated in described gap is connected with described whorl brace rod (5), one end that nut (6) non-rounding is eliminated in gap is connected with lower supporting rod (7), and described gap is eliminated nut (6) and had the spanner position being convenient to spanner rotation process.

8. Unidirectional Fiber-reinforced Composite according to claim 4 is perpendicular to the extension test charger of machine direction, it is characterized in that: the glue used when described steel tape (3) and Unidirectional Fiber-reinforced Composite test specimen (4) are pasted is epoxy resin glue or acrylate glue, and glue spreads upon in groove (3a) uniformly.