A test fixture for the whole process of impact and post-impact compression

Abstract

The present invention discloses a test fixture for the whole process of impact and post-impact compression, which includes a fixed base, a clamping tool, an impact fixture sleeve, a double-threaded bolt, a double-threaded rod, a specimen pressing cover, and a clamping base. Four clamping tools are placed in the limiting groove of the fixed base and connected to the bolts in the limiting groove on the side, so as to clamp specimens with different thicknesses, ensuring the front and rear horizontal displacement of the clamping tools; the clamping base is connected to the double-threaded rod, and the top of the double-threaded rod is connected to the base, achieving the effect of tightening the threaded rod unidirectionally and keeping the center line unchanged when clamping the specimen front and back; the clamping tool is connected to the double-threaded bolt, achieving the effect of tightening the threaded rod unidirectionally and clamping the specimen front and back to keep the center line; the specimen pressing cover clamps the specimen to ensure uniform force on the specimen during compression; the fixture sleeve clamps the specimen and is fixed above the fixed base through bolts to ensure the displacement of the specimen in other directions during the impact test.

Description

Technical Field

[0001] The present invention belongs to the field of impact and post-impact compression test devices, and particularly relates to a full-process test fixture for impact and post-impact compression based on ASTM standards. Background Art

[0002] During these decades of rapid development, composite materials have found many industrial applications, such as in aerospace, automotive manufacturing, and the military. Composite materials are renowned for their distinct characteristics, such as their high strength and stiffness-to-weight ratio, excellent fatigue performance, vibration damping, and outstanding corrosion resistance. Therefore, the aerospace industry has begun to extensively use composite materials instead of metal materials to save resources. However, many complex situations still arise during the damage prediction process, so it is necessary to understand more properties of composite materials. But during the manufacturing or use process, due to the complexity of their structure, compared with metal materials, composite materials may experience various damage and failure modes during this process. In addition, if damage occurs inside the structure of composite materials, their performance will be significantly reduced. Internal damage caused by low-velocity impact is one of the most critical damages in laminated composite structures, accounting for approximately 80% of the usage damage. It will significantly reduce the strength and stiffness of laminated composite materials without causing any visible damage to the surface. Since low-velocity impact can greatly weaken the bearing capacity of general composite laminated structures, the compression performance of laminated plates after low-velocity impact is one of the serious situations that must be considered in the damage tolerance design of composite structures, and is even used to comprehensively characterize the toughness of fiber-reinforced resin-based composite materials.

[0003] Currently, most of the test fixtures for impact and post-impact compression cannot achieve fixture integration, and most of the individual fixtures during use also cannot achieve the effect of completely centering the specimen during compression. When conducting tests, the fixture position needs to be adjusted multiple times, reducing the test efficiency and not necessarily ensuring the accuracy of the test results. Therefore, it is necessary to design a full-process test fixture for impact and post-impact compression based on ASTM standards and capable of centering the clamped specimen. Summary of the Invention

[0004] The purpose of the present invention is to provide a full-process test fixture for impact and post-impact compression to solve the technical problems of inconsistent impact and post-impact compression impact fixtures, inability to meet the requirements of specimens with different thicknesses, and inability to ensure the horizontal and vertical alignment of the specimen after clamping.

[0005] To solve the above technical problems, the specific technical solution of the present invention is as follows:

[0006] A full-process test fixture for impact and post-impact compression, comprising a fixed base, a clamping tool, an impact fixture sleeve, a bidirectional threaded bolt, a bidirectional threaded rod, a specimen pressing cover, and a clamping base;

[0007] A specimen is placed in the groove of the impact fixture sleeve, and the specimen is fixed around with rubber stoppers. The impact fixture sleeve is fixed on the fixed base; four of the clamping cutters are placed in the limit grooves of the fixed base, and the clamping cutters are connected to the bidirectional threaded bolts in the side limit grooves of the fixed base, ensuring that the clamping cutters can move back and forth in the limit grooves to achieve clamping of different thicknesses of the compressed specimen; the clamping base is connected to the fixed base through a bidirectional threaded rod;

[0008] Both the bidirectional threaded bolts and the bidirectional threaded rods have threads with different helix directions at both ends. Two bidirectional threaded bolts are symmetrically arranged and connected to the threaded holes in the middle of the clamping cutters through the threaded parts at the tops of the bidirectional threaded bolts and installed on the fixed base. The bidirectional threaded rod and the clamping base are connected through threads, ensuring that by turning the threads on one side, the front and rear ends can move simultaneously towards the middle to achieve the effect of clamping the specimen tightly.

[0009] During the compression test, the specimen cap clamps the top of the specimen, and the other parts of the specimen are embedded in the groove of the fixed base, achieving the effect of uniform stress on the compression surface of the specimen during compression.

[0010] Preferably, four of the clamping cutters are connected to two of the bidirectional threaded bolts. The left-handed internal threaded hole in the middle of the clamping cutter is connected to the left-handed external threaded end at the top of the bidirectional threaded bolt, and the right-handed internal threaded hole in the middle of the clamping cutter is connected to the right-handed external threaded end at the top of the bidirectional threaded bolt; a threaded hole is opened in the middle of the side of the clamping cutter and connected to the fixed bolt on the outside of the fixed base. By turning the bidirectional threaded bolt on one side, not only can the specimen be clamped tightly in the front and rear directions, but also the center line of the specimen can be aligned with the center line of the bottom clamping seat, achieving the effect of uniform stress on the specimen.

[0011] Preferably, the clamping base is connected to the bidirectional threaded rod. The left-handed internal threaded hole in the middle of the clamping base is connected to the left-handed external threaded end at the top of the bidirectional threaded rod, and the right-handed internal threaded hole in the middle of the clamping base is connected to the right-handed external threaded end at the top of the bidirectional threaded rod, and the small cylinder at the top of the bidirectional threaded rod is aligned with the round hole at the lower end of the bottom of the fixed base. In the case where the bilateral clamping cutters are centered and tightened, by tightening the threaded rod on one side, the effect of keeping the center line unchanged during the front and rear tightening of the specimen can also be achieved.

[0012] Preferably, the impact fixture sleeve is a structure designed according to ASTM standards, which clamps the specimen and is then connected to the fixed base through the threaded holes above.

[0013] Preferably, the cross-section of the fixed base presents the shape of an I-beam, with a stable structure, enabling impact testing to be carried out at the upper end of the fixed base of the fixture, and multi-size specimen impact and subsequent compression test testing to be carried out at the middle groove of the fixed base of the fixture.

[0014] Preferably, the limiting groove of the fixed base is rectangular, and four are symmetrically located in the middle groove of the base for clamping the front and rear movement of the cutting tool; two round-headed rectangular grooves are opened on the side for the movement and fixation of the bolt and the clamping cutting tool.

[0015] Preferably, the front end of the bidirectional threaded rod has a small cylinder so that there will be no vertical displacement when placing the clamping base.

[0016] Advantages of the present invention:

[0017] 1. The fixture of the present invention integrates the impact and post-impact compression fixtures on the basis of the ASTM standard, realizing the use of the same fixture for both the impact and post-impact compression processes.

[0018] 2. The clamping cutting tool and the middle part of the bottom clamping seat of the fixture of the present invention are provided with threaded holes and are connected by a bidirectional threaded bolt, realizing the effect of being perpendicular and located on the center line of the fixture when clamping the specimen.

[0019] 3. The four clamping cutting tools of the fixture of the present invention are located in the groove of the fixed base, realizing the centered clamping of laminate specimens with different thicknesses.

[0020] 4. The fixed base of the fixture of the present invention is provided with four rectangular limiting grooves and movable bolts on the side of the fixed base to fix the clamping cutting tool, realizing the horizontal displacement of the clamping cutting tool. Description of the drawings

[0021] Figure 1 It is a schematic diagram of the overall structure of the laminate specimen of the present invention during the impact test;

[0022] Figure 2 It is a schematic diagram of the overall structure of the laminate specimen of the present invention during the compression test;

[0023] Figure 3 It is the front view of the laminate specimen of the present invention during the compression test;

[0024] Figure 4 It is the left view of the laminate specimen of the present invention during the compression test;

[0025] Figure 5 It is a schematic diagram of clamping the specimen of the laminate specimen of the present invention during the compression test;

[0026] Figure 6 It is a schematic diagram of the structure of the impact fixture sleeve of the present invention;

[0027] Figure 7 It is a detailed diagram of the structure of the bidirectional threaded bolt of the present invention;

[0028] Figure 8 It is a schematic diagram of the structure of the clamping cutting tool of the present invention;

[0029] Figure 9 Structural view of the fixed base of the present invention

[0030] Figure 10 Schematic diagram of the clamping base structure of the present invention

[0031] Figure 11 Schematic diagram of the specimen pressing cover structure of the present invention

[0032] Explanation of the markings in the figure: 1. Impact fixture sleeve; 2. Rubber stopper; 3. Fixed base; 4. Clamping tool; 5. Clamping tool fastening bolt; 6. Clamping base; 7. Bidirectional threaded rod; 8. Bidirectional threaded bolt; 9. Fastening bolt moving groove; 10. Clamping tool rectangular keyway; 11. Clamping tool threaded hole; 12. Clamping tool limit key; 13. Clamping base boss; 14. Specimen pressing cover Detailed implementation manners

[0033] The present invention will be further described below in conjunction with the accompanying drawings and detailed implementation manners:

[0034] As Figures 1-11 shown, an impact and post-impact compression full-process test fixture includes an impact fixture sleeve 1, a fixed base 3, a clamping tool 4, a clamping base 6, a bidirectional threaded rod 7, a bidirectional threaded bolt 8, and a specimen pressing cover 14;

[0035] Impact part: A laminated board specimen is placed in the groove of the impact fixture sleeve 1, and the laminated board specimen is fixed around with a rubber stopper 2. The impact fixture sleeve 1 is fixed on the fixed base 3 with a jacket fastening bolt. There is a compression specimen moving groove in the middle of the fixed base 3, and after completion, the impact test can be carried out.

[0036] In this embodiment, there are 6 threaded holes on the fixed base 3. The impact fixture sleeve 1 is installed directly above the fixed base 3, and there is a groove below for placing the impact fixture sleeve 1. When the impact fixture sleeve 1 is tightened with the jacket fastening bolt, the size of the impact fixture sleeve 1 is the same as the upper end size of the fixed base 3. There is a compression specimen moving groove in the middle of the fixed base 3 for the deformation allowance caused by the punch during the impact test.

[0037] Compression part: The clamping tool 4 is connected by a bidirectional threaded bolt 8 and placed in the rectangular groove of the fixed base 3. At the same time, two clamping tool fastening bolts 5 are arranged in the fastening bolt moving groove of the fixed base 3 on the side and connected to the clamping tool threaded hole of the clamping tool 4, so as to limit the lateral displacement of the clamping tool 4. The clamping base 6 is connected to the fixed base 3 through a bidirectional threaded rod 7 and is placed through the specimen observation port on the front. The clamping base 6 is adjusted with bolts to achieve the effect of centering and clamping the specimen. The specimen is placed in the groove of the specimen pressing cover 14 at the upper end and clamped, so that the specimen can only be compressed during compression.

[0038] In this embodiment, the middle clamping tool thread hole of the clamping tool 4 is connected by a two-way threaded bolt 8; the clamping tool thread hole on the side of the clamping tool 4 is combined with the moving groove of the clamping tool fastening bolt of the fixed base 3 and the clamping tool rectangular key groove 10 and the clamping tool limit key 12 at the bottom of the fixed base 3, restricting the displacement of the clamping tool 4 in other directions, that is, it can only move in the horizontal direction. By installing the clamping tools 4 at both ends on the two-way threaded bolts 8 with equal distance, equal length and different helix directions at the same time, the effect that the tools on both sides can be tightened by turning one side is achieved. Tightening the two-way threaded bolt 8 passes through the circular opening of the fixed base 3 and is at the same vertical distance as the two-way threaded bolt 8 and has a suitable size. The clamping tool 4 clamps the laminate specimen, and the clamping distance at both ends is the standard distance referred to in ASTM_D7137-07. The distance for clamping the laminate specimen of the clamping base 6 is the same. The clamping base achieves the effect of simultaneously clamping and centering the specimen based on the principle of equal distance, equal length and different helix directions at both ends of the two-way threaded screw. The upper end is placed in the specimen pressing cover 14, and the laminate specimen in the specimen pressing cover 14 is clamped by bolts, achieving the effect of compressing the specimen by the specimen pressing cover 14.

[0039] For the two-way threaded bolt 8 and the clamping tool 4, according to this embodiment, the left and right sides have threads with equal distance, equal length and different helix directions. An internal hexagonal groove is opened at one end, which is smaller than the bolt diameter, for adjusting the clamping thickness of the clamping tool 4 through the circular opening of the fixed base 3. And the clamping tool thread holes 22 are all opened in the middle of the clamping tool 4, facilitating the movement in the lower part and the first fastening bolt moving groove 17 on the side under force, and a 10-mm rectangular limiter is left in the middle of the fixed base 3 to limit the excessive fit of the clamping tool. The cutting edge of the clamping tool 4 is a pentagonal structure with a 5-mm long bottom in the shape of a rectangle. When the clamping tool 4 is completely clamped, the top of the cutting edge is completely fitted.

[0040] In this embodiment, there are 6 threaded holes at the upper end of the fixed base 3 for clamping the impact fixture sleeve 1 during the impact test. There are 2 holes in the middle of the fixed base 3 for adjusting the horizontal displacement of the clamping tool. There are 4 fastening bolt moving grooves in the middle of the side for fixing the clamping tool 4. There are 4 clamping tool rectangular key grooves 10 at the lower end of the fixed base 3, with a distance of 10 mm between them. When the clamping tool limit key 12 of the clamping tool 4 moves to the top, it just makes the cutting edge of the clamping tool 4 completely fitted.

[0041] In this embodiment, a two-way threaded rod 8 is used for connection. There is a 3-mm clamping base boss 13 at one end for placing the laminate specimen to prevent the two-way threaded rod 8 from contacting the laminate specimen.

[0042] In this embodiment, mainly there are two rectangular cutting edge strips at the lower end of the specimen pressing cover 14, and bolts are used for clamping at the upper end, which are used for clamping and compressing the upper end of the laminate specimen and play a fixing role in the compression test.

[0043] The present invention is described by way of some embodiments. Those skilled in the art will appreciate that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the present invention. Additionally, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A test fixture for the whole process of impact and post-impact compression, characterized in that: It includes a fixed base, a clamping tool, an impact fixture sleeve, a double-threaded bolt, a double-threaded rod, a specimen gland, and a clamping base; A specimen is placed in the groove of the impact fixture sleeve, and the specimen is fixed around with rubber stoppers. The impact fixture sleeve is fixed on the fixed base. Four of the clamping tools are placed in the limit grooves of the fixed base, and the clamping tools are connected to the double-threaded bolts in the side limit grooves of the fixed base. The clamping base is connected to the fixed base through a double-threaded rod; Both the double-threaded bolt and the double-threaded rod have threads with different helix directions at both ends. Two double-threaded bolts are symmetrically arranged and connected through the threaded holes in the middle of the clamping tool and installed on the fixed base. The double-threaded rod and the clamping base are connected by threads; During the compression test, the specimen gland clamps the top of the specimen, and the other parts of the specimen are embedded in the groove of the fixed base; Four of the clamping tools are connected to two of the double-threaded bolts. The left-handed internal threaded hole in the middle of the clamping tool is connected to the left-handed external threaded end at the top of the double-threaded bolt, and the right-handed internal threaded hole in the middle of the clamping tool is connected to the right-handed external threaded end at the top of the double-threaded bolt. A threaded hole is opened in the middle of the side of the clamping tool and is connected to the fixing bolt on the outside of the fixed base; The clamping base and the double-threaded rod are connected. The left-handed internal threaded hole in the middle of the clamping base is connected to the left-handed external threaded end at the top of the double-threaded rod, and the right-handed internal threaded hole in the middle of the clamping base is connected to the right-handed external threaded end at the top of the double-threaded rod, and the small cylinder at the top of the double-threaded rod is fitted into the round hole at the lower end of the bottom of the fixed base.

2. The full-process test fixture for impact and post-impact compression according to claim 1, characterized in that: The impact fixture sleeve is a structure designed according to ASTM standards, clamps the specimen, and is then connected to the fixed base through the threaded hole above.

3. The full-process test fixture for impact and post-impact compression according to claim 1, characterized in that: The cross-section of the fixed base presents the shape of an I-beam, and a groove is provided in the middle of the fixed base for compression test.

4. A test fixture for the entire process of impact and post-impact compression according to claim 1, characterized in that: The limit grooves of the fixed base are rectangular, and four are symmetrically located in the middle groove of the fixed base for the forward and backward movement of the clamping tools. Two round-headed rectangular grooves are opened on the side for the movement and fixation of the bolts and the clamping tools.

5. The full-process test fixture for impact and post-impact compression according to claim 1, characterized in that: The front end of the double-threaded rod has a small cylinder, so that the clamping base will not move up and down when placed.

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