CN114878315A - Dynamic tensile test method for fiber bundle SHTB - Google Patents

Abstract

The invention discloses a dynamic tensile test method for a fiber bundle SHTB, which adopts a fiber bundle test piece manufacturing device and a fiber bundle test piece clamping device. According to the invention, a fiber bundle test piece prefabricating process is adopted, so that the situation that the fiber bundle is temporarily clamped on site directly to reduce the test efficiency is avoided, through a sandwich structure formed among the first reinforcing sheet, the fiber bundle and the second reinforcing sheet, on one hand, the reinforcing sheet is utilized to bear fastening force from the outside to clamp the fiber bundle, on the other hand, the fiber bundle can be prevented from being damaged in the fastening process, and the contact area and the roughness of the interface between the fiber bundle and the reinforcing sheet are increased in a mode that the reinforcing sheet is coated with fiber impregnating glue, so that the bonding performance between the fiber bundle and the reinforcing sheet is further improved.

Description

A kind of fiber bundle SHTB dynamic tensile test method

technical field

The invention relates to the technical field of dynamic mechanics of dry fiber materials, in particular to a SHTB dynamic tensile test method of fiber bundles.

Background technique

Fiber materials have the advantages of light weight, high strength, corrosion resistance, etc. With the excellent characteristics of fiber materials, fiber reinforced composite materials (Fiber Reinforced Polymer, referred to as FRP) and fibers are made of organic cementitious materials or inorganic cement-based cementitious materials. Fiber Reinforced Cementitious Matrix (FRCM for short) can be applied to new full FRP/FRCM structures or FRP/FRCM composite structures, or used as reinforcing materials to repair and reinforce existing structures. Existing research points out that when the building structure faces the risk of extreme effects such as explosion and impact, the use of FRP/FRCM composite materials can effectively improve the impact resistance of the structure. The dynamic mechanical properties of FRP/FRCM composites under impact load are closely related to the dynamic mechanical properties of fiber bundles in FRP/FRCM. Therefore, to carry out research on the dynamic mechanical properties, evolution law and failure morphology of fiber bundle materials under impact load will help to further promote the research and application of FRP/FRCM composite materials in construction engineering, especially under extreme loads.

At present, the dynamic mechanical properties of materials are tested mainly using high-speed hydraulic servo testing machines, drop-weight testing machines and separate Hopkinson rods. Among them, Split Hopkinson Torsion Bar (SHTB) is the most important and reliable experimental method to study the dynamic tensile mechanical properties of materials under medium and high strain rates. SHTB technology is based on the assumption of one-dimensional stress wave and the assumption of stress uniformity of the specimen. It consists of gun barrel, impact rod (commonly known as bullet), incident rod, transmission rod, energy absorber and corresponding air pressure device. The strain gauges on the rod and the transmission rod collect the stress wave signal through the ultra-dynamic strain gauge and the high-speed acquisition system. Based on the one-dimensional stress wave propagation theory, the stress-strain relationship of the specimen is finally obtained.

In general, specimens for SHTB tests are usually cylindrical and thin. Cylindrical specimens are usually threaded or glued to the SHTB. The thread method is to process the specimen into a dumbbell-shaped revolving body, and process the external threads at both ends that fit the internal threads of the incident rod and the transmission rod, and connect with the SHTB through the threads. However, for rock, concrete and other materials, the two ends of the specimen are not easy to be processed into external threads, so it is necessary to use an adapter fixture, glue the specimen on the adapter fixture, and then connect the adapter fixture to the SHTB through threads. Some test materials cannot be processed into cylindrical specimens with the required diameter due to insufficient thickness, and can only be processed into thin specimens, which are usually connected to SHTB by means of adapter fixtures.

For fiber materials, due to the small diameter and soft material of the specimen, it cannot be connected with SHTB according to the traditional connection method of cylindrical and thin specimens, and the lack of relevant technical standards and specifications makes the dynamic tensile mechanical properties of fiber materials difficult. test is difficult to carry out. Currently, fiber materials are usually tested with the aid of a separately designed adapter fixture. Patent CN202011366933.4 discloses a real-time tightening fiber bundle dynamic tensile test fixture and its clamping method. The fiber bundle test piece is formed into a whole through the mutual engagement of two tooth-shaped surface fastening blocks, and the conical limit is The shell is sleeved into the meshed whole, and then the limiting block is inserted into the conical limiting shell until it abuts with the meshed whole to complete the clamping of the fiber bundle test piece. Patent CN202011354348.2 discloses a fiber bundle dynamic tensile test fixture and its experimental use method. The fiber bundle test piece is placed in the long groove of the fan-shaped structure in the main body of the cylindrical fixture, and the long groove of the fan-shaped structure is filled into it. The two are engaged with each other to form a whole, and then the cylindrical fastening shell is sleeved into the meshed whole, so that the fastening block compresses the fiber bundle test piece. Patent CN 202110917308.2 discloses a detachable Hopkinson tie rod test fixture. The wire test piece is put into two pieces of guards to form a sandwich structure. The sleeve of the groove is inserted into the ejector rod, so that the ejector rod is abutted with the wedge-shaped clamping block, so as to realize the stable clamping of the wire specimen.

The above three patents all use transfer fixtures to realize the connection between the fiber material and the SHTB. The transfer fixtures contain a variety of different components, and the shapes are relatively complex, making the fixtures difficult to process and expensive. At the same time, due to the large number of components in the transfer fixture, the clamping steps of the fiber bundle specimen during the test are cumbersome, which will inevitably affect the clamping effect and accuracy. In addition, each test needs to unscrew the adapter fixture from the SHTB, and then install it after the fiber bundle specimen is clamped. On the one hand, the efficiency of the test is reduced. The twisting effect is produced, which changes the shape of the fiber bundle and cannot reflect the true dynamic tensile mechanical properties of the fiber material.

SUMMARY OF THE INVENTION

The invention provides a fiber bundle SHTB dynamic tensile test method. On the one hand, it can meet the tightening requirements of the fiber bundle test piece in the SHTB test through the fixture main body and the fixture pressing block, so as to ensure the reliability and accuracy of the test results, and on the other hand In addition, it has the advantages of simple structure, quick assembly, reusability, and batch production of test pieces.

A fiber bundle SHTB dynamic tensile test method adopts a fiber bundle test piece making device and a fiber bundle test piece clamping device;

The fiber bundle test piece manufacturing device comprises a lower mold for the fiber bundle test piece and an upper mold for the fiber bundle test piece that can be clamped with each other; the lower mold for the fiber bundle test piece is provided with a plurality of grooves for placing the first reinforcing sheet 1. There are several grooves for placing the second reinforcing sheet on the mold on the fiber bundle test piece; 2;

The fiber bundle test piece clamping device comprises a clamp main body and a clamp pressing block that can cooperate with each other for clamping; the clamp main body and the clamp pressing block are both provided with grooves for placing reinforcing sheets;

Described fiber bundle SHTB dynamic tensile test method comprises steps:

S1. According to the gauge length required for the SHTB test of the fiber bundle, place the lower mold of the fiber bundle test piece at both ends, and place the first reinforcing sheet in the groove one;

S2. Evenly apply fiber impregnating glue on the surface of the first reinforcing sheet that is used for contacting the fiber bundles, tension the fiber bundles and place them on the center line of the first reinforcing sheet on both sides, and place the first reinforcing sheet on the fiber bundle. Apply fiber impregnating glue evenly on the contact surface of the bundle again, so that the fiber impregnating glue is fully infiltrated in the fiber bundle;

S3. Align the second reinforcing sheet on the first reinforcing sheet according to the side in contact with the fiber bundle, then align the groove 2 with the second reinforcing sheet, and place the upper mold of the fiber bundle test piece on the lower mold of the fiber bundle test piece , clamp the upper mold of the fiber bundle specimen and the lower mold of the fiber bundle specimen together;

S4. After curing until the fiber impregnating glue is cured, demould, and cut the exposed end of the fiber bundle to obtain a fiber bundle specimen for SHTB test that is cured and clamped together with the first reinforcing sheet and the second reinforcing sheet on both sides to form a whole;

S5. Fix the incident rod and the projection rod of the SHTB with one end of the fixture body respectively;

S6. Adjust the incident rod and the projection rod of the SHTB on which the fixture body is installed, so that the surface of the side of the fixture body with groove three is kept on the same level;

S7, put the reinforcing sheet of the fiber bundle test piece for the SHTB test into the groove three, and then align the groove four of the clamp pressing block with the reinforcing sheet of the fiber bundle test piece for the SHTB test. Place the clamp pressing block, so that the clamping block, the fiber bundle test piece for SHTB test, and the main body of the fixture form a tight clamping;

S8. Carry out SHTB dynamic tensile test of fiber bundles.

The invention adopts the prefabrication process of the fiber bundle test piece, which avoids the temporary clamping of the fiber bundle directly on site and reduces the efficiency of the test. The reinforcing sheet is used to bear the external tightening force to clamp the fiber bundle, and on the other hand, it can avoid damage to the fiber bundle during the tightening process. The contact area and roughness of the sheet interface further improve the bonding performance between the fiber bundle and the reinforcing sheet.

In a preferred example, the surfaces of the first reinforcing sheet and the second reinforcing sheet for contacting the groove, and the bottom surfaces of the first groove, the second groove, the third groove and the fourth groove are serrated surfaces that engage with each other.

In a preferred example, the tooth profile angle of the sawtooth surface is 42° to 46°, and the tooth height is 0.2 mm to 0.5 mm.

In a preferred embodiment, a platform 1 higher than the bottom surface of the groove 1 is provided at both ends of the groove 1 near the edge of the lower mold of the fiber bundle test piece, and the surface of the platform 1 is lower than the lower mold surface of the fiber bundle test piece.

In a preferred example, the two ends of groove two are provided with platform two corresponding to platform one and higher than the bottom surface of groove two near the edge of the upper mold of the fiber bundle test piece, and the surface of platform two is lower than the upper mold surface of the fiber bundle test piece. ; The space formed by the platform 1 and the platform 2 can provide the activity space for the fiber bundle to pass through.

In a preferred example, the clamp body includes a threaded connection piece and a connection block that is fixedly connected to the threaded connection piece through a receiving block and used to place the clamp pressure block; the threaded connection piece is located at the end of the clamp body and is used for connecting with the incident rod or The projection rod is fixedly connected; the groove 3 is arranged on the connecting block, and the end of the groove 3 away from the receiving block is close to the edge of the connecting block with a platform 3 higher than the bottom surface of the groove 3, and the surface of the platform 3 is lower than the surface of the connecting block.

In a preferred example, the four ends of the groove are provided with a platform four corresponding to the platform three and higher than the bottom surface of the four grooves, and the surface of the platform four is lower than the surface of the clamp pressing block; the platform three and the platform four The space formed can provide a living space for the fiber bundle to exit.

In a preferred example, the connecting block has a surface center axis of one side of the groove 3, the center axis of the receiving block, and the center axis of the threaded connection member aligned with the center axis of the SHTB.

In a preferred example, a positioning rod is provided on the lower mold of the fiber bundle test piece, and a positioning hole that can be matched with the positioning rod is provided on the upper mold of the fiber bundle test piece.

In a preferred example, between the upper mold of the fiber bundle test piece and the lower mold of the fiber bundle test piece, the clamping block, the fiber bundle test piece for SHTB test and the main body of the fixture are all clamped by fastening bolts.

Compared with the prior art, the main advantages of the present invention include:

1. The present invention realizes the prefabrication of the fiber bundle test piece for SHTB test, avoids the temporary clamping of the fiber bundle directly on site, reduces the test efficiency, and saves time and cost in the test process.

2. The present invention adopts the prefabrication process of the fiber bundle test piece, and uses the lower mold of the fiber bundle test piece, the upper mold of the fiber bundle test piece, the first reinforcing sheet, and the second reinforcing sheet, which has the advantages of simple process, convenient disassembly, pipeline work, and batch processing. The advantages of uniformity of the overall shape and size of the production and specimen.

3. The present invention uses the sandwich structure formed between the first reinforcing sheet, the fiber bundle and the second reinforcing sheet. On the one hand, the reinforcing sheet is used to bear the tightening force from the outside to clamp the fiber bundle. Avoid damage to fiber bundles during tightening.

4. The present invention increases the contact area and roughness of the interface between the fiber bundle and the reinforcing sheet by coating the fiber impregnating glue on the reinforcing sheet, and further improves the bonding performance between the fiber bundle and the reinforcing sheet.

5. The clamping device of the present invention adopts an assembly design, and each part of the clamping device is an independent device. When any part of the clamping device is damaged, the damaged parts can be replaced without discarding and fixing the damaged parts. Connecting other devices saves economical costs during the test.

6. The clamping device of the present invention has fewer parts, simple shape, convenient processing, low cost, and convenient installation. At the same time, the clamping steps of the fiber bundle test piece during the test are relatively simple. The tightening requirements of the fiber bundle specimens in the test realize the first clamping and tightening to ensure the reliability and accuracy of the test results.

7. The contact surface between the reinforcing sheet and the groove of the present invention is provided with a toothed surface, which increases the contact area and roughness between the reinforcing sheet and the groove of the clamping device, and ensures that the interior of the clamping device is reinforced after clamping. The fiber bundle specimen formed by the sheet and the fiber bundle is solidified and clamped to form a whole without sliding, realizing double tightening effect. At the same time, the specifications of the reinforcing sheet and the groove are unified, and the tightening force is applied to further ensure the fiber bundle specimen and the clamping device. The coaxiality with the SHTB ensures the precision and accuracy of the test.

8. The present invention satisfies the transient nature of the clamping device, and the test can be carried out after clamping and tightening the fiber bundle test piece, which improves the test efficiency.

9. The present invention can realize the dynamic tensile mechanical property test on the fiber bundle specimen under the condition of strain rate of 100s ^-1 -1000s ^-1 on SHTB.

Description of drawings

Fig. 1 is the structural diagram after the assembly of the fiber bundle test piece making device;

Fig. 2 is the structural representation of each component in the fiber bundle test piece making device;

Fig. 3 is the axial side view of the mold under the fiber bundle test piece;

Fig. 4 is the axial side view of the mold on the fiber bundle test piece;

Figure 5 is a side view of the first reinforcing sheet shaft;

Figure 6 is a side view of the second reinforcing sheet shaft;

Fig. 7 is the axial side view of the fiber bundle specimen;

Figure 8 is a structural diagram of the fiber bundle specimen clamping device after assembly;

Figure 9 is a schematic diagram of the structure of each component in the fiber bundle specimen clamping device;

Figure 10 is an axial side view of the main body of the fixture;

Figure 11 is an axial side view of the clamp pressing block;

Reference number:

1. Lower mold for fiber bundle specimen; 1-1, groove one; 1-1-1, serrated surface one; 1-2, platform one; 1-3, positioning rod; 1-4, bolt hole one;

2. Upper mold of fiber bundle specimen; 2-1, groove 2; 2-1-1, sawtooth surface 2; 2-2, platform 2; 2-3, positioning hole; 2-4, bolt hole 2;

3. The first reinforcing sheet; 3-1, the sawtooth surface three;

4. The second reinforcing sheet; 4-1, the serrated surface four;

5. Fiber bundles;

6. Fixture main body; 6-1, threaded connection; 6-2, receiving block; 6-3, connecting block; 6-3-1, groove three; 6-3-1-1, serrated surface five; 6 -3-2, platform three; 6-3-3, bolt hole three;

7. Fixture pressing block; 7-1, groove four; 7-1-1, serrated surface six; 7-2, platform four; 7-3, bolt hole four;

8. Fasten the bolts.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. The operation method without specifying the specific conditions in the following examples is usually in accordance with the conventional conditions, or in accordance with the conditions suggested by the manufacturer.

As shown in FIGS. 1 to 7 , the fiber bundle test piece preparation device includes a fiber bundle test piece lower mold 1 , a fiber bundle test piece upper mold 2 , a first reinforcing sheet 3 , a second reinforcing sheet 4 , and a fiber bundle 5 .

The lower mold 1 of the fiber bundle test piece includes a plurality of grooves-1-1, platform-1-2, positioning rods 1-3 and bolt holes-1-4 with the same shape and size and arranged in parallel. The bottom surface of groove one 1-1 is provided with sawtooth surface one 1-1-1, the length of the long side of groove one 1-1 is less than the width of the mold 1 under the fiber bundle test piece, and the short side side of groove one 1-1 The outer surface of the mold 1 with the fiber bundle test piece has a platform 1-2. The surface of the platform one 1-2 is 0.5mm lower than the surface of the mold 1 under the fiber bundle test piece. The positioning rods 1-3 are symmetrically arranged at both ends of the mold 1 under the fiber bundle test piece. Bolt holes 1-4 are arranged symmetrically at the four corners of the mold 1 under the fiber bundle specimen. When there are many grooves 1-1 in the mold 1 under the fiber bundle specimen, in order to prevent the length of the mold 1 under the fiber bundle specimen from being too long If deformation occurs, a pair of bolt holes 1-4 can be added in the middle of the lower mold 1 of the fiber bundle specimen.

The upper mold 2 of the fiber bundle test piece includes a plurality of grooves 2-1, platform 2-2, positioning holes 2-3 and bolt holes 2-4 with the same shape and size and arranged in parallel. The bottom surface of the groove two 2-1 is provided with a sawtooth surface two 2-1-1, the length of the long side of the groove two 2-1 is less than the width of the mold 2 on the fiber bundle test piece, and the short side of the groove two 2-1 The outer surface of the mold 2 with the fiber bundle test piece has a platform II 2-2. The surface of the platform 2-2 is 0.5 mm lower than the surface of the mold 2 on the fiber bundle test piece. The positioning holes 2-3 are symmetrically arranged on both ends of the mold 2 on the fiber bundle specimen. Bolt holes 2 2-4 are symmetrically arranged at the four corners of the mold 2 on the fiber bundle specimen. When there are many grooves 2 2-1 on the fiber bundle specimen, in order to prevent the length of the mold 2 on the fiber bundle specimen from being too long If deformation occurs, a pair of bolt holes 2-4 can be added in the middle of the mold 2 on the fiber bundle specimen.

The structural dimensions of the upper mold 2 on the fiber bundle test piece are the same as the structure size of the mold 1 under the fiber bundle test piece. The structural dimensions of the groove one 1-1 of the mold 1 and the platform one 1-2 under the test piece are the same, and the groove two 2-1 of the mold 2 on the fiber bundle test piece, the platform two 2-2, the positioning hole 2- 3. The positions of bolt hole two 2-4 and the groove one 1-1, platform one 1-2, positioning rod 1-3 and bolt hole one 1-4 of the lower mold 1 of the fiber bundle test piece match each other.

The space formed by the platform one 1-2 and the platform two 2-2 can provide the active space for the fiber bundle 5 to pass through, preventing the lower mold 1 of the fiber bundle specimen and the upper mold 2 of the fiber bundle specimen from being clamped by the fastening bolts 8 After being together, the fiber bundles 5 are squeezed to produce shear damage.

The number of grooves 1-1 in the lower mold 1 of the fiber bundle specimen and the grooves 2-1 in the upper mold 2 of the fiber bundle specimen is 3 to 6, and the spacing is 15 to 20 mm, which can realize multiple fiber bundles. At the same time, it is produced to meet the needs of mass production, and at the same time, it provides a suitable operating space for production, and also ensures that the length of the mold 1 under the fiber bundle test piece and the mold 2 on the fiber bundle test piece will not be too long to cause deformation.

The side of the first reinforcing sheet 3 in contact with the groove one 1-1 is provided with a sawtooth surface three 3-1, the sawtooth surface three 3-1 of the first reinforcing sheet 3 and the sawtooth surface one of the groove one 1-1-1- 1-1 mesh with each other. The side of the second reinforcing sheet 4 in contact with the second groove 2-1 is provided with a serrated surface 4-1. 1-1 mesh with each other.

The structural dimensions of the first reinforcing sheet 3 and the second reinforcing sheet 4 are the same as those of groove one 1-1 of the lower mold 1 of the fiber bundle test piece, and groove two 2-1 of the mold 2 on the fiber bundle test piece. In order to match the positions of the first reinforcing sheet 3 and the second reinforcing sheet 4 during mold support, laying and assembly, the overall shape and size formed by the solidifying and clamping of the reinforcing sheet and the fiber bundle are uniform.

A sandwich structure is formed among the first reinforcing sheet 3 , the fiber bundle 5 , and the second reinforcing sheet 4 . The reinforcing sheet can not only bear the tightening force from the external mold to clamp the fiber bundle, but also avoid damage to the fiber bundle during the tightening process.

The first reinforcing sheet 3 and the second reinforcing sheet 4 can be made of metal materials such as aluminum or non-metallic materials such as acrylic.

The contact surfaces of the first reinforcing sheet 3 and the second reinforcing sheet 4 and the fiber bundle 5 are coated with fiber impregnating glue (eg, epoxy impregnating glue, etc.). By coating the fiber impregnating glue on the contact surface of the reinforcing sheet and the fiber bundle, the contact area and roughness of the interface between the fiber bundle and the reinforcing sheet are increased, and the bonding performance between the fiber bundle and the reinforcing sheet is further improved.

The tooth angle of the serrated surface 1-1-1, the serrated surface 2-1-1, the serrated surface 3-1 and the serrated surface 4-1 are 42° to 46°, and the tooth height is 0.2mm to 0.5mm . By setting a sawtooth surface at the contact surface between the reinforcing sheet and the mold groove, the contact area and roughness of the reinforcing sheet and the mold groove are increased to ensure that the internal reinforcing sheet will not slide after the upper and lower molds are clamped, so that the reinforcing sheet It can be closely bonded with the fiber bundle, which further ensures that the overall shape, regular size and uniformity formed by the solidification and clamping of the reinforcing sheet and the fiber bundle.

The material of the fiber bundle material includes, but is not limited to, alkali-resistant glass fiber, carbon fiber, aramid fiber, basalt fiber, polyphenylene benzobisoxazole fiber, and natural fibers such as sisal and ramie.

The specific fabrication process of fiber bundles for SHTB test is as follows:

1) Formwork:

According to the gauge length required for the SHTB test of the fiber bundle, the lower mold 1 of the fiber bundle specimen is placed symmetrically at both ends, and the first reinforcing sheet 3 and the first reinforcing sheet 3 are placed in the groove 1-1 of the lower mold for the fiber bundle specimen. The serrated surface 3-1 of the groove 1-1 and the serrated surface 1-1-1 of the groove 1-1 mesh with each other;

2) Laying:

Apply fiber impregnating glue evenly on the contact surface of the first reinforcing sheet 3 and the fiber bundle 5, tension the fiber bundle 5 and place it on the center line of the first reinforcing sheet 3 on both sides. The contact surface of the fiber bundles 5 is evenly coated with the fiber impregnating glue again, so that the fiber impregnating glue is fully infiltrated in the fiber bundles 5 . Since the contact surface between the reinforcing sheet and the fiber bundle is coated with fiber impregnated glue, the contact area and roughness of the interface between the fiber bundle and the reinforcing sheet are increased, and the bonding performance between the fiber bundle and the reinforcing sheet is further improved. In order to ensure that the fiber bundles will not be slack due to retraction during the production of fiber bundle specimens, so that the actual gauge length does not meet the required gauge length for the test, the exposed ends of the fiber bundles can be suspended by means of weights, etc., to ensure that the fibers The straightness of the beam and the coaxiality with the reinforcing sheet;

3) Assembly:

The side of the second reinforcing sheet 4 in contact with the fiber bundle 5 is aligned and placed on the first reinforcing sheet 3, so that a sandwich structure is formed between the first reinforcing sheet 3, the fiber bundle 5 and the second reinforcing sheet 4. The reinforcing sheet not only It can take the tightening force from the external mold to clamp the fiber bundle, while avoiding damage to the fiber bundle during the tightening process. Then align the groove two 2-1 of the upper mold 2 of the fiber bundle test piece with the second reinforcing sheet 4, and move the fiber bundle test piece upper mold 2 along the positioning rod of the fiber bundle test piece lower mold 1 through the positioning hole 2-3 1-3 is placed on the lower mold 1 of the fiber bundle test piece, the serrated surface 4-1 of the second reinforcing sheet 4 and the serrated surface 2-1-1 of the groove 2-1 are meshed with each other, and then tightened. The bolts 8 pass through the upper mold 2 of the fiber bundle test piece and the bolt hole two 2-4 and the bolt hole one 1-4 of the lower mold 1 of the fiber bundle test piece. Mold 1 is clamped together under the test piece. Since the contact surface between the reinforcing sheet and the mold groove is provided with a sawtooth surface, the contact area and roughness between the reinforcing sheet and the mold groove are increased, so that the internal reinforcing sheet after the upper and lower molds is clamped will not slide. The fiber bundles can be tightly bonded, which further ensures that the overall shape, regular size, and uniformity formed by the curing and clamping of the reinforcing sheets and the fiber bundles, and further ensures the coaxiality of the fiber bundles and the reinforcing sheets after applying the tightening force;

4) Maintenance and mold removal:

After curing at a certain temperature and humidity until the fiber impregnating glue is cured, remove the fastening bolts 8, remove the upper mold 2 of the fiber bundle test piece, and take out the fiber bundle test piece from the lower mold 1 on both sides with the first reinforcing sheet 3 and The second reinforcing sheets 4 are co-cured and clamped to form an integral fiber bundle 5, and after cutting the exposed ends on both sides of the fiber bundle 5, a fiber bundle test piece for SHTB test can be obtained.

As shown in FIGS. 8 to 11 , the fiber bundle specimen clamping device includes a fixture body 6 , a fixture pressing block 7 , and a fastening bolt 8 , and the fixture body 6 includes a threaded connector 6 - 1 (in this embodiment, the external thread is specifically) , the receiving block 6-2 and the connecting block 6-3, and the clamp pressing block 7 corresponds to the connecting block 6-3 of the clamp main body 6.

The external thread 6-1 of the fixture body 6 is used to connect with the internal thread of the incident rod or the projection rod of the SHTB, and the central axis of the external thread 6-1 of the fixture body 6 is aligned with the central axis of the SHTB. One end of the receiving block 6 - 2 of the fixture main body 6 receives the external thread 6 - 1 of the fixture main body 6 , and the other end receives the connecting block 6 - 3 of the fixture main body 6 . The height of the receiving block 6-2 of the fixture body 6 is the same as the diameter of the external thread 6-1 of the fixture body 6, and the central axis of the receiving block 6-2 of the fixture body 6 is the same as the central axis of the external thread 6-1 of the fixture body 6 Align. The connecting block 6-3 of the fixture main body 6 includes a groove three 6-3-1, a platform three 6-3-2 and a bolt hole three 6-3-3, and the height of the connecting block 6-3 of the fixture main body 6 is the fixture main body. Half the height of the receiving block 6-2 of the fixture body 6, the central axis of the surface of the side of the connecting block 6-3 of the fixture body 6 with the groove is aligned with the central axis of the external thread 6-1 of the fixture body 6. The bottom surface of the third groove 6-3-1 is provided with a sawtooth surface five 6-3-1-1, the sawtooth surface five 6-3-1-1 of the third groove 6-3-1 and the sawtooth surface of the first reinforcing sheet 3 The three 3-1 teeth are meshed with each other, the length of the long side of the groove three 6-3-1 is smaller than the width of the connecting block 6-3 of the fixture body 6, and one of the short sides of the groove three 6-3-1 is the same as The surface of the receiving block 6-2 of the fixture main body 6 is flush, and the other side and the outer surface of the connecting block 6-3 of the fixture main body 6 have a platform three 6-3-2. The surface of the third platform 6-3-2 is lower than the surface of the connecting block 6-3 of the fixture main body 6 by 0.5 mm. The bolt holes 3 6-3-3 are symmetrically arranged at both ends of the connecting block 6-3 of the clamp main body 6 parallel to the central axis.

The clamp pressing block 7 includes a groove four 7-1, a platform four 7-2 and a bolt hole four 7-3. The bottom surface of the groove 4 7-1 is provided with a serrated surface 67-1-1, and the serrated surface 67-1-1 of the groove 4 7-1 and the serrated surface 4-1 of the second reinforcing sheet 4 are meshed with each other, The length of the long side of the groove four 7-1 is less than the width of the clamp pressing block 7, one of the short sides of the groove four 7-1 is flush with the surface of the clamping pressing block 7, and the other side is flush with the surface of the clamping pressing block 7. The outer surface has platform four 7-2. The surface of the platform 4 7-2 is lower than the surface of the clamp pressing block 7 by 0.5 mm. The four bolt holes 7-3 are symmetrically arranged at both ends of the clamp pressing block 7 parallel to the central axis.

The structural dimensions of the clamp pressing block 7 are the same as the structural dimensions of the connecting block 6-3 of the clamp main body 6, and the structural dimensions of the groove four 7-1 and the platform four 7-2 of the clamp pressing block 7 are the same as those of the connecting block 6 of the clamp main body 6. -3 groove 3 6-3-1 and platform 3 6-3-2 have the same structural dimensions, groove 4 7-1 of clamp pressure block 7, platform 4 7-2 and bolt hole 4 7-3 are the same as the clamp The positions of the groove 3 6-3-1, the platform 3 6-3-2 and the bolt hole 3 6-3-3 of the connecting block 6-3 of the main body 6 match each other. The structural dimensions of the groove three 6-3-1 and the groove four 7-1 of the clamp pressing block 7 are the same as those of the first reinforcing sheet 3 and the second reinforcing sheet 4, which ensures that the reinforcing sheet and the fiber bundle are separated during the test. The position of the fiber bundle test piece that has been solidified and clamped to form a whole is matched with the position of the fixture main body 6 and the fixture pressing block 7, which ensures that the fiber bundle test piece can be fastened through the connecting block 6-3 of the fixture main body 6 and the fixture pressing block 7. The bolts 8 form a tight clamping, realize the first clamping and tightening, and at the same time ensure the coaxiality of the fiber bundle specimen, the clamping device and the SHTB, and ensure the precision and accuracy of the test.

The space formed by the platform 3 6-3-2 and the platform 4 7-2 can provide an active space for the fiber bundle to pass through, preventing the connecting block 6-3 of the fixture main body 6 and the fixture pressing block 7 from being clamped by the tightening bolt 8 After being together, the fiber bundles are squeezed to produce shear damage.

The tooth angle of the serrated surface 3-1, the serrated surface 4-1, the serrated surface 5 6-3-1-1 and the serrated surface 6 7-1-1 is 42° to 46°, and the tooth height is 0.2mm to 0.5mm. By arranging a sawtooth surface at the contact surface between the reinforcing sheet and the groove of the clamping device, the contact area and roughness of the reinforcing sheet and the groove of the clamping device are increased, so as to ensure that the interior of the clamping device is clamped by the reinforcing sheet and the fiber. The bundle is solidified and clamped to form an integral fiber bundle specimen without slippage, achieving a double tightening effect.

The experimental use method of the above-mentioned fiber bundle specimen clamping device includes the following steps:

Step 1: Connect the incident rod and the projection rod of the SHTB to the external thread 6-1 of the fixture main body 6 through threads;

Step 2: Adjust the incident rod and the projection rod of the SHTB on which the fixture body 6 is installed, so that the surface of the grooved side of the connecting block 6-3 of the fixture body 6 is kept on the same level to ensure that the fiber bundle specimen is placed. The straightness of the rear fiber bundle will not cause the twisting effect due to the change of the shape of the fiber bundle due to the rotation of both ends, which ensures that the real dynamic tensile mechanical properties of the fiber material can be reflected;

Step 3: Put the first reinforcing sheet 3, the fiber bundle 5, and the second reinforcing sheet 4 into the groove three 6-3-1 of the connecting block 6-3 of the fixture main body 6 to be cured and clamped together to form a whole SHTB test. The fiber bundle test piece, the serrated surface 3-1 of the first reinforcing sheet 3 and the serrated surface 5 6-3-1-1 of the groove 3 6-3-1 are meshed with each other, and then the groove of the fixture pressing block 7 is Four 7-1 is aligned with the reinforcing sheet of the fiber bundle test piece, and then the clamp pressing block 7 is placed on the main body 6 of the fixture. -1 meshing with each other;

Step 4: Pass the fastening bolts 8 through the bolt holes 4 7-3 and 3 6-3-3 of the clamp pressing block 7 and the main body 6 of the clamp, and apply a tightening force to make the pressing block 7, the main body 6 of the clamp and the bolt hole three 6-3-3. A tight clamping is formed between the fiber bundle specimens, and the first heavy clamping is realized. Since the serrated surface is arranged at the contact surface between the reinforcing sheet and the groove of the clamping device, the contact area and roughness of the reinforcing sheet and the groove of the clamping device are increased, and it is ensured that after the clamping device is clamped, the inner part of the reinforcing sheet and the fiber bundle is clamped. The fiber bundle specimen formed by curing and clamping will not slide, realizing double tightening effect. At the same time, after the tightening force is applied, the coaxiality of the fiber bundle specimen, the clamping device and the SHTB is further ensured. The precision and accuracy of the test.

Step 5: Carry out the SHTB dynamic tensile test of fiber bundles.

In the present invention, through the steps of mold support, laying, assembly, maintenance and mold removal, the lower mold 1 of the fiber bundle test piece, the upper mold 2 of the fiber bundle test piece, the first reinforcing sheet 3, the second reinforcing sheet 4 and the fastening bolts are used. 8. The prefabrication of fiber bundle specimens for SHTB test is realized, which has the advantages of simple process, convenient disassembly, assembly line work, batch production, and uniform overall shape and size of the specimen.

In the present invention, the sandwich structure formed between the first reinforcing sheet 3, the fiber bundle 5, and the second reinforcing sheet 4 can avoid damage to the fiber bundle during the fastening process, and at the same time, the reinforcing sheet is coated with fiber impregnating glue. In this way, the bonding performance between the fiber bundle and the reinforcing sheet is further improved.

The clamping device using the assembly design in the present invention has the advantages of fewer parts, simple shape, convenient processing, low cost, convenient installation, easy replacement, and simple clamping steps. The tightening bolt 8 meets the tightening requirements of the fiber bundle specimen in the SHTB test, realizes the first clamping and tightening, and ensures the reliability and accuracy of the test results.

In the present invention, by arranging mutually toothed serrated surfaces at the contact surface of the reinforcing sheet and the groove of the clamping device, it is ensured that the fiber bundle test piece formed as a whole by the reinforcing sheet and the fiber bundle solidified and clamped inside after the clamping device is clamped will not be There will be sliding to achieve double tightening effect. At the same time, the specifications of the reinforcement sheet and the groove of the clamping device are unified. After the tightening force is applied, the coaxiality of the fiber bundle specimen, the clamping device and the SHTB is further ensured, and the test is ensured. precision and accuracy.

The invention satisfies the transient nature of the clamping device, and the test can be carried out after clamping and tightening the fiber bundle test piece, which improves the test efficiency, and at the same time can realize the strain rate of the fiber bundle test piece on the SHTB at a strain rate of 100s ^-1 -1000s ^- Dynamic tensile mechanical properties test under ¹ condition.

In addition, it should be understood that after reading the above description of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims (8)

1. A dynamic tensile test method of a fiber bundle SHTB is characterized in that a fiber bundle test piece manufacturing device and a fiber bundle test piece clamping device are adopted;

the fiber bundle test piece manufacturing device comprises a fiber bundle test piece lower die (1) and a fiber bundle test piece upper die (2) which can be matched and clamped with each other; a plurality of first grooves (1-1) for placing first reinforcing sheets (3) are formed in the lower fiber bundle test piece die (1); a plurality of grooves II (2-1) for placing second reinforcing sheets (4) are formed in the upper die (2) of the fiber bundle test piece;

the fiber bundle test piece clamping device comprises a clamp main body (6) and a clamp pressing block (7) which can be matched and clamped with each other; grooves for placing the reinforcing sheets are formed in the clamp main body (6) and the clamp pressing block (7);

the method for testing the SHTB dynamic tensile test of the fiber bundle comprises the following steps:

s1, placing lower molds (1) of the fiber bundle test pieces at two ends according to the gauge length required by the SHTB test of the fiber bundles, and placing first reinforcing sheets (3) in the first grooves (1-1);

s2, uniformly coating fiber impregnating adhesive on the surface, used for being in contact with the fiber bundle (5), of the first reinforcing sheet (3), tensioning, centering and horizontally placing the fiber bundle (5) on the central line of the first reinforcing sheets (3) on two sides, uniformly coating the fiber impregnating adhesive on the contact surface of the first reinforcing sheet (3) and the fiber bundle (5) again, and fully soaking the fiber impregnating adhesive in the fiber bundle (5);

s3, placing a second reinforcing sheet (4) on a first reinforcing sheet (3) in an aligned mode according to the face, in contact with the fiber bundle (5), of the second reinforcing sheet, then aligning a second groove (2-1) with the second reinforcing sheet (4), placing an upper fiber bundle test piece die (2) on a lower fiber bundle test piece die (1), and clamping the upper fiber bundle test piece die (2) and the lower fiber bundle test piece die (1) together;

s4, curing until the fiber impregnating adhesive is cured, demolding, and cutting the exposed end of the fiber bundle to obtain a fiber bundle test piece for the SHTB test, wherein both sides of the fiber bundle test piece are cured and clamped together with the first reinforcing sheet (3) and the second reinforcing sheet (4) to form a whole;

s5, fixedly connecting an incident rod and a projection rod of the SHTB with one end of the clamp main body (6) respectively;

s6, adjusting an incident rod and a projection rod of the SHTB provided with the clamp main body (6) to ensure that the surface of one side of the clamp main body (6) provided with the groove III (6-3-1) is kept on the same horizontal plane;

s7, placing the reinforcing sheet of the fiber bundle test piece for the SHTB test into a groove III (6-3-1), aligning a groove IV (7-1) of a clamp pressing block (7) with the reinforcing sheet of the fiber bundle test piece for the SHTB test, and placing the clamp pressing block (7) on a clamp main body (6) to form firm clamping among the clamp pressing block (7), the fiber bundle test piece for the SHTB test and the clamp main body (6);

and S8, carrying out a dynamic tensile test of the fiber bundle SHTB.

2. The dynamic tensile test method of the fiber bundle SHTB according to claim 1, wherein the surfaces of the first reinforcing sheet (3) and the second reinforcing sheet (4) which are in contact with the grooves, and the bottom surfaces of the first groove (1-1), the second groove (2-1), the third groove (6-3-1) and the fourth groove (7-1) are serrated surfaces which are engaged with each other.

3. The method of claim 2 wherein the serrated face has a profile angle of 42 ° to 46 ° and a tooth height of 0.2mm to 0.5 mm.

4. The dynamic tensile test method for the fiber bundle SHTB according to claim 1, wherein a first platform (1-2) higher than the bottom surface of the first groove (1-1) is arranged at the two ends of the first groove (1-1) close to the edge of the lower die (1) of the fiber bundle test piece, and the surface of the first platform (1-2) is lower than the surface of the lower die (1) of the fiber bundle test piece;

a second platform (2-2) which corresponds to the first platform (1-2) and is higher than the bottom surface of the second groove (2-1) is arranged at the two ends of the second groove (2-1) and close to the edge of the upper mold (2) of the fiber bundle test piece, and the surface of the second platform (2-2) is lower than the surface of the upper mold (2) of the fiber bundle test piece; the space formed by the first platform (1-2) and the second platform (2-2) can provide a penetrating movable space for the fiber bundle (5).

5. The dynamic tensile test method of the fiber bundle SHTB according to claim 1, wherein the clamp body (6) comprises a threaded connector (6-1) and a connecting block (6-3) fixedly connected with the threaded connector (6-1) through a receiving block (6-2) and used for placing a clamp pressing block (7); the threaded connector (6-1) is positioned at the end part of the clamp body (6) and is used for being fixedly connected with an incident rod or a projection rod of the SHTB; the groove III (6-3-1) is arranged on the connecting block (6-3), a platform III (6-3-2) higher than the bottom surface of the groove III (6-3-1) is arranged at one end, far away from the bearing block (6-2), of the groove III (6-3-1) and close to the edge of the connecting block (6-3), and the surface of the platform III (6-3-2) is lower than that of the connecting block (6-3);

one end of the groove IV (7-1), which is close to the edge of the clamp pressing block (7), is provided with a platform IV (7-2) which corresponds to the platform III (6-3-2) and is higher than the bottom surface of the groove IV (7-1), and the surface of the platform IV (7-2) is lower than the surface of the clamp pressing block (7); the space formed by the third platform (6-3-2) and the fourth platform (7-2) can provide a penetrating movable space for the fiber bundle (5).

6. The dynamic tensile test method of the fiber bundle SHTB of claim 5, wherein the connecting block (6-3) has a surface central axis of one side of the groove three (6-3-1), a central axis of the receiving block (6-2), and a central axis of the threaded connection member (6-1) aligned with a central axis of the SHTB.

7. The dynamic tensile test method of the fiber bundle SHTB according to claim 1, wherein the lower die (1) of the fiber bundle test piece is provided with a positioning rod (1-3), and the upper die (2) of the fiber bundle test piece is provided with a positioning hole (2-3) which can be matched with the positioning rod (1-3).

8. The dynamic tensile test method of the fiber bundle SHTB according to claim 1, wherein the clamping pressure block (7) between the upper die (2) and the lower die (1) of the fiber bundle test piece, the fiber bundle test piece for the SHTB test and the clamp body (6) are clamped by the fastening bolt (8).

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