Test tool and method for testing material interface shear strength

Abstract

The invention relates to a test tool and method for testing the shear strength of a material interface. The tool comprises a chuck, a fixing block, a base and a sliding block, a guide rail groove is formed in the base, one side of the guide rail groove is connected with the sliding block, and the other side of the guide rail groove is connected with the fixing block; the fixing block is provided with a fixing hole and a fixing block threaded hole, a pin penetrates through the fixing hole, the sample hole and the sliding block hole to fix the sample, and a bolt is fixed to the base through the fixing block threaded hole. The sliding block is provided with a sliding block sliding rail, a sliding block threaded hole and a sliding block hole, and the sliding block sliding rail is arranged in the guide rail groove of the base and fixed through a bolt; the chuck is located on the lower side of the base and serves as a device for connecting the base and the stretcher. According to the invention, the interface shear strength performance test can be carried out on the sample with any thickness, the bonding surface of the sample is always kept parallel to the axial force line in the initial sample mounting process and the tensile test process, and the bonding surface of the sample base material and the lap joint material in the initial test state is prevented from being abnormally damaged.

Description

Technical Field

[0001] The present invention relates to the technical field of material performance testing, and in particular to a test tool and method for testing the shear strength of a material interface. Background Art

[0002] The interface shear specimen consists of a lap material and a substrate, with the lap material sandwiched between two parallel substrate lap structures. The substrate is generally two metal sheets or two composite sheets, with a circular hole at one end as the direct contact point with the interface shear tooling, and the other end bonded to the lap material. The lap material varies depending on the test object, such as QJ2038.2-91 "Test Method for Interface Bonding Strength of Solid Rocket Motor Combustion Chamber - Shear Method", the lap material is insulation layer-liner-propellant-liner-insulation layer, HG 4-853-84 "Determination of Shear Strength of Vulcanized Rubber to Metal", the lap material is rubber, GJB 1709-93 "Test Method for Low-Temperature Tensile Shear Strength of Adhesives", there is no lap material, and only the two substrates are bonded together with an adhesive.

[0003] Although the base material and the overlapping material composition of the test specimens for interface shear strength testing are different, the required test fixtures are basically the same and are briefly described in some test standards. The interface shear fixture structure is relatively simple, consisting of a holding end and a specimen receiving end. The specimen receiving end is mainly a rectangular slot with holes on the left and right sides of the slot. The two holes are parallel and in the same space. The holding end is connected to the material tensile machine. In the entire testing system, a total of two sets of fixtures are required. One set of fixture holding ends is installed in the upper fixture of the tensile machine, and the other set is installed in the lower fixture. The two sets of fixtures are axially symmetrical. It should be noted that although the two sets of fixtures are axially symmetrical, there are two main types of positional relationships between the two fixture rectangular slots. One is that the upper and lower fixture rectangular slots are axially symmetrical (as described in QJ2038.2-91), and the other is that one fixture rectangular slot is located to the left or right of the symmetrical structure of the other fixture rectangular slot (as described in GJB 1709-93). Both positional relationships are intended to ensure that the force line of the specimen is consistent with the center line of the specimen during the tensile process.

[0004] Although the existing tooling can complete most interface shear specimen mechanical property testing tests, it has certain limitations when used for specimens with thicker overlapping materials. The main reasons are as follows:

[0005] (1) During the test operation, the maximum horizontal distance between the right side of the upper tooling rectangular groove and the left side of the lower tooling rectangular groove (or the maximum horizontal distance between the left side of the upper tooling rectangular groove and the right side of the lower tooling rectangular groove) must be greater than the sum of the thickness of the lap material and the two base materials. Otherwise, when the specimen is placed in the rectangular groove and the tensile test is not formally carried out, the tooling will destroy the interface formed by the base material and the lap material, causing the two to debond. The final data obtained cannot reflect the true shear strength of each interface, and the data is seriously inconsistent with the actual value. For specimens with thinner lap materials, the above problem does not exist. However, for specimens with thicker lap materials, such as the lap material in standard QJ2038.2-91, which consists of five layers: insulation layer, lining layer, propellant, lining layer, and insulation layer, the above-mentioned adverse situation is likely to occur. In addition, for some non-standard specimens with thicker lap materials, the above problem will also be encountered.

[0006] (2) Each test standard specifies the material shear strength test method. The test operation process is roughly the same, that is, first connect the upper and lower tooling support ends with the upper and lower clamps of the material stretching machine, then place the end of the sample substrate with a hole into the rectangular slot of the upper and lower tooling, then insert the pins into the slots on both sides and the sample hole, and finally use the clamp on the stretching machine to drive the sample to stretch upward to shear the material interface. However, in actual operation, after the operator uses the pins to fix the upper substrate and the tooling, the entire sample is in a deflected hanging state. If the subsequent operation does not adjust the sample to a vertical position and directly inserts the lower end pin into the lower end substrate sample hole and the tooling slot hole, the interface shear test will cause the tensile force line and the bonding surface to be non-parallel from the initial state. In addition, since the pins and the circular holes of the substrate are both circular, as the applied load increases, the contact surface formed by the two is prone to sliding, causing the sample to deflect slightly to the left or right as a whole. The above two situations will eventually result in large discreteness of the test data and data distortion. The greater the thickness of the sample overlap material, the more obvious the above adverse effects.

[0007] (3) When exploring and studying the bonding quality between different materials, the interface shear strength is generally used as a conventional mechanical property test item. Different fields are used, and the base materials and overlapping materials are different, so there are many non-standard specimens. Among various types of interface shear specimens, since the thickness of the base materials used is generally not much different, the accuracy of the test results is basically not affected during the test process. However, the thickness of the overlapping materials varies in different fields, and the difference is large. Therefore, in order to accurately detect the interface shear strength and avoid the influence of inconsistent force lines and bonding surfaces during operation, especially for specimens with thick overlapping materials, the operators generally adjust the width of the rectangular groove according to the thickness of the overlapping materials and then make different shearing tools, which will ultimately cause unnecessary waste of resources. Summary of the Invention

[0008] Based on the aforementioned drawbacks of existing test fixtures for testing thicker overlapping material specimens, the present invention proposes a test fixture and method for testing the interfacial shear strength of materials. This solves the problems of existing test fixtures for testing thicker overlapping material specimens, such as abnormal debonding between the substrate and the overlapping material, misalignment of the axial force line with the specimen's centerline, and specimen positional shifting during the test, which ultimately lead to poor test result accuracy. This ensures accurate and reliable test data for interfacial shear strength.

[0009] In order to solve the above technical problems, one of the purposes of the present invention is to provide a test fixture for testing the shear strength of material interfaces, which includes a chuck 1, a fixed block 2, a base 3, a movable slider 4, a slider bolt 8 and a guide rail slot slider 9.

[0010] The base 3 is provided with a guide rail groove 32, one side of the guide rail groove is connected to the movable slider 4, and the other side is connected to the fixed block 2;

[0011] The fixing block 2 is provided with a fixing block optical hole 23 and a fixing block threaded hole 21. The pin passes through the fixing block optical hole 23, the sample hole and the slider optical hole 41 to fix the sample. The fixing block bolt is fixed to the base through the fixing block threaded hole 21.

[0012] The movable slider 4 is provided with a slider rail 43, a slider threaded hole 42 and a slider light hole 41. The slider rail 43 is placed on the upper part of the guide rail groove 32 of the base and is connected to the guide rail groove slider placed on the lower part of the guide rail groove 32 through a slider bolt 8. After the movable slider is adjusted to the optimal position, the slider bolt is tightened to tighten the movable slider to ensure that the movable slider does not slip during the test;

[0013] The chuck 1 is located at the lower side of the base and serves as a device for connecting the base and the stretching machine.

[0014] Furthermore, the base 3 is provided with a fixing block threaded hole 31 , which cooperates with the fixing block threaded hole 21 to fix the fixing block.

[0015] Furthermore, the fixing block is also provided with a movable bolt threaded hole 22. After the movable bolt passes through the movable bolt threaded hole, the tail of the movable bolt contacts the substrate and applies a small pre-tightening force, so that it can apply a certain horizontal pressure to the sample substrate to ensure that the sample does not deviate during the test.

[0016] Furthermore, the movable bolt threaded hole 22 is above the fixed hole 23 , so that the movable bolt and the sample substrate not only have sufficient contact area but also improve the overall pressing effect.

[0017] Based on the same concept, the present invention also proposes a test method for testing the shear strength of a material interface, the specific steps of which are as follows:

[0018] S1: Install the fixed block 2 on the left side of the base 3 and tighten it with the fixing bolt. At the same time, screw part of the moving bolt into the threaded hole of the moving bolt.

[0019] S2: Place the movable slider 4 into the guide rail groove 32 along the right guide rail of the base, insert the slider bolt into the slider threaded hole 42, and connect it to the guide rail groove slider 9;

[0020] S3: Install the fixture chuck 1 to the lower side of the base 3. After installation, place the chuck into the lower fixture of the stretching machine, and at the same time, place the original shear fixture chuck into the upper fixture of the stretching machine;

[0021] S4: After all the components of the tooling are installed, place the substrate with the circular hole on one side of the specimen into the rectangular slot of the upper tooling, and insert pins into the slots and circular holes on both sides. At this point, the specimen is in a deflected hanging state.

[0022] S5: Adjust the upper and lower clamp positions of the tensile machine, and adjust the position of the movable slider according to the overall thickness of the sample so that the other side of the substrate can be close to the inner side of the movable slider, tighten the slider bolt, and then insert the pin into the circular holes of the three;

[0023] S6: Rotate the movable bolt of the fixed block until the tail of the bolt contacts the substrate on the other side and apply a small pre-tightening force so that it can apply a certain horizontal pressure to the specimen to ensure that the specimen does not deflect during the stretching process;

[0024] S7: After the installation of the above specimens is completed, start the tensile machine to start the test switch, continuously load at a constant rate until the specimen is broken, and record the test data.

[0025] Furthermore, the test fixture chuck in S3 must be parallel to the original fixture chuck and in the same plane.

[0026] Furthermore, the sample S4 is suspended on the pin, and the substrate is pressed against the left or right side of the rectangular groove with the fingers to make the sample in a vertical state, and the substrate is pressed with the fingers to maintain this state.

[0027] Furthermore, the S5 is performed until the circular hole of the substrate on the other side of the sample and the light hole of the slider and the light hole of the fixed block are at the same horizontal position.

[0028] Furthermore, the tail of the bolt contacts the other side of the substrate and applies a pre-tightening force of about 0.2N to 0.5N.

[0029] The above one or more technical solutions of the present invention have at least one or more of the following technical effects:

[0030] The present invention uses a movable bolt to further fix the sample substrate. It only needs to rotate the fixing bolt until its tail gives a certain pre-tightening force to the sample substrate. It is not only easy to operate, but also has the same effect as adding a spacer.

[0031] The test fixture of the present invention can freely adjust the position of the slider according to the overall thickness of the sample. Using this patented fixture will avoid the above-mentioned adverse conditions and achieve better results.

[0032] The test fixture of the present invention can test standard specimens and non-standard specimens of any thickness in any industry. It is a "universal fixture" for testing interface shear strength and has better use value.

[0033] When using the test fixture of the present invention, the sample is further fixed by having the substrate plates on both sides of the sample tightly adhere to the inner side of the rectangular groove and the inner side of the fixture slider, and by moving the bolts to press the substrate, so as to prevent it from moving during the test, and the operation is more scientific. The interface shear data obtained by using the test fixture of the present invention is reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 : Side view of the test tooling of the present invention;

[0035] Figure 2 : Schematic diagram of the fixed block of the test fixture of the present invention;

[0036] Figure 3 : Schematic diagram of the test fixture base of the present invention;

[0037] Figure 4 : Schematic diagram of the mobile slider of the test fixture of the present invention;

[0038] Figure 5 : Schematic diagram of the guide rail slot slider of the test fixture of the present invention;

[0039] Figure 6 : Schematic diagram of the movable slider of the test fixture of the present invention being installed in the guide rail groove;

[0040] Figure 7 : Schematic diagram of the test fixture chuck of the present invention;

[0041] Figure 8 : Schematic diagram of the interface shear specimen being installed in the test fixture of the present invention;

[0042] Among them: 1-chuck, 2-fixed block, 3-base, 4-movable slider, 5-pin, 6-movable bolt, 7-fixed block bolt, 8-slider bolt, 9-guide rail slot slider, 10-substrate on one side of the specimen, 11-overlap material, 12-substrate on the other side of the specimen, 13-original tooling rectangular slot, 14-original tooling chuck, 21-fixed block threaded hole, 22-movable bolt threaded hole, 23-fixed block light hole, 31-connecting fixed block threaded hole, 32-guide rail slot, 41-slider light hole; 42-slider threaded hole; 43-slider rail. Specific implementation plan

[0043] The present invention relates to a test fixture for testing the interfacial shear strength of materials. In addition to a clear hole, the fixed block also includes a threaded hole and a movable bolt. A slider rail moves on a base rail to facilitate interfacial shear strength testing of specimens with varying overlapping material thicknesses. The fixed block is equipped with a movable bolt to prevent micro-movement of the specimen during tensile testing. Preload is applied to the substrate to prevent micro-deflection of the specimen to the left or right during testing. This fixture allows interfacial shear strength testing of specimens of any thickness, particularly those with thicker overlapping materials. The fixed block clear hole and the slider clear hole are positioned horizontally to secure the specimen in the fixture. Because the distance from the specimen's circular hole to the rear end of the substrate is relatively short, the present invention employs a design with the fixed block clear hole at the bottom and the threaded hole at the top, ensuring sufficient contact area between the movable bolt and the specimen substrate and enhancing the overall compression effect. The specimen can be secured in three ways: by having the substrate plates on both sides of the specimen cling tightly to the inside of a rectangular slot and the inside of the fixture's movable slider; by having the movable bolt compress the substrate; or by having a pin pass through the specimen's circular hole. The design mode of adding a slide rail to the bottom of the movable slider and opening a guide rail groove inside the base enables the two to move relative to each other.

[0044] The tooling of the present invention is installed in the lower fixture of the stretching machine (recorded as the lower tooling), and the tooling connected to the upper fixture is still the original shearing tooling (recorded as the upper tooling). The sample installation process is as follows: first, the substrate portion containing the circular hole on one side of the sample is placed in the rectangular groove of the upper tooling, and pins are inserted into the slots and circular holes on both sides. Then, the sample is adjusted to a vertical state, and the position of the movable slider is adjusted according to the overall thickness of the sample so that the substrate can be close to the slider. After the sample and the movable slider are adjusted, a pin is inserted into the fixed hole, the slider hole, and the circular hole of the sample. Finally, the movable bolt of the fixed block is rotated until the tail of the bolt contacts the substrate and a small pre-tightening force is applied, so that it can give a certain horizontal pressure to the sample substrate to ensure that the sample does not shift during the test. After the sample is installed, the stretching machine applies tension to the sample at a constant speed until the sample breaks.

[0045] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments obtained. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0046] The present invention provides a test fixture for testing the shear strength of a material interface, such as Figure 1-7 As shown. The test fixture includes a base, a fixed block, a movable slider, a guide rail slot slider and a chuck. The base contains a guide rail slot, one side of which is connected to the movable slider and the other side is connected to the fixed block. The fixed block mainly contains a light hole (referred to as a fixed hole), a threaded hole, and a movable bolt. At the initial stage of the test, a pin is inserted into the fixed hole, the specimen hole and the slider hole to fix the specimen. The movable bolt further fixes the specimen through the threaded hole to ensure that it does not move during the test. The slider is adjusted in position in the guide rail slot according to the thickness of the overlapping material. In addition, the slider contains a light hole (referred to as a slider hole) that is parallel to the fixed hole. The chuck is located on the lower side of the base and serves as a device for connecting the base and the tensile machine. The guide rail slot slider is clamped in the guide rail slot, and the slider bolt passes through the movable slider to connect it. Its main function is to tighten the slider bolt after the movable slider is adjusted to the optimal position to ensure that the movable slider does not slide during the test.

[0047] The present invention provides an auxiliary tool and a method for using the same for testing the strength of a thick interface shear specimen of a lap joint material. Figure 8 The specific usage is as follows:

[0048] (1) Install the fixed block on the left side of the base and tighten it with the fixing bolts. At the same time, screw part of the movable bolt into the threaded hole.

[0049] (2) Place the slider into the guide rail groove along the right side of the base, insert the slider bolt into the slider threaded hole, and connect it to the slider in the guide rail groove. At this time, there is no need to fix the slider.

[0050] (3) Install the tooling chuck to the lower side of the base. After installation, place the chuck in the lower fixture of the stretching machine. At the same time, place the original shear tooling chuck in the upper fixture of the stretching machine. At this time, the tooling chuck of the present invention must be parallel to the original tooling chuck and in the same plane.

[0051] (4) After all the components of the tooling are installed, place the substrate part with the circular hole on one side of the specimen into the rectangular slot of the upper tooling, and insert the pins into the slot holes and the circular holes on both sides. At this time, the specimen is in a deflected hanging state.

[0052] (5) For the sample hanging on the pin, use the fingers of your left hand to hold the substrate close to the left or right side of the rectangular groove so that the sample is in a vertical state, and press the substrate with your fingers to maintain this state.

[0053] (6) Use your right hand to adjust the position of the upper and lower clamps of the tensile machine until the circular hole of the substrate on the other side of the specimen and the light hole of the slider and the light hole of the fixed block are at the same horizontal position.

[0054] (7) Adjust the position of the movable slider so that the other side of the substrate can be close to the inner side of the slider, tighten the slider bolt, and then insert the pin into the three circular holes.

[0055] (8) At this time, release the left hand that is pressing the substrate and rotate the movable bolt of the fixed block until the tail of the bolt contacts the substrate on the other side and applies a preload of about 0.2N to 0.5N, so that it can give a certain horizontal pressure to the specimen, further ensuring that the specimen does not deflect during the stretching process.

[0056] (9) After the above specimens are installed, start the tensile machine to start the test switch, and continuously load at a constant rate until the specimen is broken, and record the test data.

[0057] (10) After the test, loosen the moving bolts, remove the upper and lower pins and the stretched sample. When stretching the next sample, do not adjust the upper and lower clamp positions and the slider position of the equipment. Directly insert the pins into the three circular holes corresponding to the upper and lower substrates, apply pre-tightening force with the moving bolts, and then directly conduct the interface shear strength test.

[0058] The tooling of the present invention can perform interface shear strength performance tests on samples of any thickness of materials in any field; the tooling of the present invention can ensure that the sample bonding surface always remains parallel to the axial force line during the initial sample installation process and the tensile test process; the tooling of the present invention can prevent abnormal damage to the sample substrate and the bonding surface of the overlapping material in the initial state of the test.

[0059] The present invention proposes a novel interface shearing tool. This tool can be used to test the interface shear strength performance of specimens of any material and thickness in any field. It ensures that the specimen bonding surface remains parallel to the axial force line during initial specimen installation and tensile testing, preventing abnormal damage to the bonding surface between the specimen substrate and the overlapping material during the initial test. Furthermore, it avoids the need for multiple tooling sets, saving testing costs and ultimately eliminating test data distortion caused by inappropriate tooling, thereby ensuring accurate and reliable interface shear strength data for the tested materials.

[0060] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if such changes and modifications of the embodiments of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A test fixture for testing the shear strength of a material interface, characterized by: The tooling comprises a chuck (1), a fixed block (2), a base (3), a movable slider (4), a slider bolt (8) and a guide rail slot slider (9). The fixing block (2) is provided with a fixing block light hole (23) and a fixing block threaded hole (21); a pin passes through the fixing block light hole (23), the sample hole and the slider light hole (41) to fix the sample; and a fixing block bolt is fixed to the base (3) through the fixing block threaded hole (21); A guide rail groove (32) is provided in the base (3), one side of the guide rail groove is connected to the movable slider (4), and the other side is connected to the fixed block (2); The movable slider (4) is provided with a slider rail (43), a slider threaded hole (42) and a slider light hole (41). The slider rail (43) is placed on the upper part of the guide rail groove (32) of the base and is connected to the guide rail groove slider (9) installed on the lower part of the guide rail groove (32) through a slider bolt (8). After the movable slider is adjusted to the optimal position, the slider bolt is tightened to tighten the movable slider, thereby ensuring that the movable slider does not slide during the test; The clamp (1) is located on the lower side of the base and serves as a device for connecting the base and the stretching machine.

2. The test fixture for testing the interfacial shear strength of materials according to claim 1, characterized in that: The base (3) is further provided with a fixing block threaded hole (31) which cooperates with the fixing block threaded hole (21) to fix the fixing block.

3. The test fixture for testing the interfacial shear strength of materials according to claim 1, characterized in that: The fixing block is also provided with a movable bolt threaded hole (22). After the movable bolt passes through the movable bolt threaded hole, the tail of the movable bolt contacts the substrate and applies a small pre-tightening force, so that it can apply a certain horizontal pressure to the sample substrate to ensure that the sample does not deviate during the test.

4. The test fixture for testing the interfacial shear strength of materials according to claim 3, characterized in that: The threaded hole (22) of the movable bolt is above the light hole (23) of the fixed block, so that the movable bolt and the sample substrate not only have sufficient contact area but also improve the overall pressing effect.

5. The test method of the test fixture for testing the interface shear strength of materials according to any one of claims 1 to 4, characterized in that: The specific steps are as follows: S1: Install the fixed block (2) on the left side of the base (3) and tighten it with the fixing bolt, while screwing part of the moving bolt into the threaded hole of the moving bolt; S2: Place the movable slider (4) into the guide rail groove (32) along the right guide rail of the base, insert the slider bolt into the slider threaded hole (42), and connect it to the guide rail groove slider (9); S3: Install the fixture chuck (1) to the lower side of the base (3). After installation, place the chuck into the lower fixture of the stretching machine, and at the same time, place the original shear fixture chuck into the upper fixture of the stretching machine; S4: After all the components of the tooling are installed, place the substrate with the circular hole on one side of the specimen into the rectangular slot of the upper tooling, and insert pins into the slots and circular holes on both sides. At this point, the specimen is in a deflected hanging state. S5: Adjust the upper and lower clamp positions of the tensile machine, and adjust the position of the movable slider according to the overall thickness of the sample so that the other side of the substrate can be close to the inner side of the movable slider, tighten the slider bolt, and then insert the pin into the circular holes of the three; S6: Rotate the movable bolt of the fixed block until the tail of the bolt contacts the substrate on the other side and apply a small pre-tightening force so that it can apply a certain horizontal pressure to the specimen to ensure that the specimen does not deflect during the stretching process; S7: After the installation of the above specimens is completed, start the tensile machine to start the test switch, continuously load at a constant rate until the specimen is broken, and record the test data.

6. The test method for testing the interfacial shear strength of materials according to claim 5, characterized in that: The test fixture chuck in S3 must be parallel to the original fixture chuck and in the same plane.

7. The test method for testing the interfacial shear strength of materials according to claim 5, characterized in that: The sample S4 is suspended on the pin. The base material is pressed against the left or right side of the rectangular groove with the fingers to make the sample in a vertical state, and the base material is pressed with the fingers to maintain this state.

8. The test method for testing the interfacial shear strength of materials according to claim 5, characterized in that: The step S5 is performed until the circular hole of the substrate on the other side of the sample is at the same horizontal position as the light hole of the slider and the light hole of the fixed block.

9. The test method for testing the interfacial shear strength of materials according to claim 5, characterized in that: The tail of the bolt contacts the other side of the substrate and applies a pre-tightening force of about 0.2N to 0.5N.

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