Device and method for testing mechanical property of composite material based on angle sensing

Abstract

The invention belongs to the technical field of composite material mechanical property testing, and particularly relates to a composite material mechanical property testing device and method.The composite material mechanical property testing device is characterized in that an upper clamp comprises an upper pulling plate and an upper fixing plate fixedly arranged at the lower end of the upper pulling plate, and a lower clamp comprises a lower pulling plate and a lower fixing plate; the lower pulling plate is hinged to the lower end face of the lower fixing plate, one end of a to-be-detected test sample sheet can be detachably arranged on the lower end face of the upper fixing plate, the to-be-detected test sample sheet is fixed to the side, away from the upper pulling plate, of the upper fixing plate, and the other end of the to-be-detected test sample sheet is fixedly arranged on the upper end face of the lower fixing plate. The upper pulling plate and the lower pulling plate are arranged on the upper clamping jaw and the lower clamping jaw of the universal testing machine, so that the bending and stretching test of the to-be-detected test sample can be realized. Meanwhile, the angle sensing module is used for detecting the bending angle, located on one side of the lower pulling plate, of the to-be-detected test sample piece in the stretching process, and the mechanical properties of the to-be-detected test sample piece at different bending angles can be detected.

Description

Technical Field

[0001] This invention belongs to the field of composite material mechanical property testing technology, specifically relating to a composite material mechanical property testing device and method based on angle sensing. Background Technology

[0002] Carbon fiber composites, due to their superior specific strength and specific modulus, have become key materials for high-end equipment such as aerospace and new energy vehicles. Their structural components are often subjected to complex stress states in practical applications, such as out-of-plane bending under axial tension. Currently, standard electronic universal testing machines mainly acquire the macroscopic tensile properties of materials (such as ultimate strength and elastic modulus), making it difficult to directly and automatically measure the instantaneous mechanical response of materials at specific bending angles.

[0003] Existing solutions, such as high-speed photography and digital image correlation, can measure the entire field, but these systems are expensive, data processing is cumbersome, and they are difficult to integrate into routine quality control processes to achieve rapid, automated point-to-point measurements. Therefore, the industry urgently needs a dedicated device that is simple in structure, has a fast response, and is cost-effective to achieve automated and accurate testing of the mechanical properties of composite materials under multi-angle bending conditions. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a composite material mechanical property testing device and method based on angle sensing. In particular, it relates to a device and method that can automatically detect and record the tensile force values ​​of composite laminates at different bending angles under tensile-bending combined loads, thereby solving the problem that existing technologies cannot automatically and accurately capture tensile force values ​​at specific bending angles in tensile tests.

[0005] The technical problem to be solved by the present invention is achieved by the following technical solution: a composite material mechanical property testing device based on angle sensing, comprising a universal testing machine, a clamping system and an angle sensing module; The clamping system includes an upper clamp and a lower clamp. The upper clamp includes an upper pull plate and an upper fixing plate fixedly disposed at the lower end of the upper pull plate. The lower clamp includes a lower pull plate and a lower fixing plate. The lower pull plate is hinged to the lower end face of the lower fixing plate. The test sample to be tested is a flat plate structure. One end of the test sample to be tested is detachably set on the lower end face of the upper fixed plate. The test sample to be tested is fixed on the side of the upper fixed plate away from the upper pull plate. The other end of the test sample to be tested is fixed on the upper end face of the lower fixed plate. The upper pull plate and the lower pull plate are respectively mounted on the upper and lower jaws of the universal testing machine; The angle sensing module is used to detect the bending angle of the test sample on one side of the pull plate during the stretching process.

[0006] Preferably, the angle sensing module of this invention includes a scale plate mounted on the upper fixed plate. The scale plate is used to detect the bending angle of the test sample.

[0007] Preferably, the angle sensing module of the present invention includes a plurality of normally open proximity switches disposed on a universal testing machine and a control unit connected to the normally open proximity switches; Each normally open proximity switch corresponds to a preset angle; The control unit is used to stop the universal testing machine and record the corresponding tensile force value based on the detection signal from the normally open proximity switch. The normally open proximity switch is used to detect whether the test specimen has reached a preset angle, achieving automatic control and improving detection accuracy.

[0008] Preferably, the angle sensing module of the present invention further includes an intermediate relay disposed between the normally open proximity switch and the control unit. The intermediate relay automatically transmits the corresponding detection signal of the normally open proximity switch, which can automatically control the universal testing machine to stop at a specific angle, thus ensuring the accuracy of the testing process.

[0009] Preferably, the present invention also includes an alarm connected to the control unit, which is used to remind the test personnel to record and confirm the bending angle and tensile force.

[0010] Preferably, the upper pull plate and the upper fixing plate are vertically connected to ensure that the test sample to be inspected is in a horizontal state after installation, that is, the bending angle is zero, which facilitates the arrangement of normally open proximity switches.

[0011] Preferably, a reinforcing rib is provided between the upper pull plate and the upper fixed plate in this invention. The reinforcing rib enhances the connection strength between the upper pull plate and the upper fixed plate, and prevents the upper clamp from deforming during the stretching process, which would affect the test results.

[0012] Preferably, the present invention also includes a clamping plate, wherein the test sample to be tested is located between the clamping plate and the upper fixing plate. The clamping plate is fixedly mounted on the upper fixing plate by bolts. The clamping plate and the upper fixing plate are used to clamp and fix one end of the test sample to be tested, thereby ensuring the stability of the test sample to be tested during the testing process.

[0013] Preferably, the test sample to be tested is pasted on the lower fixing plate, which avoids damage to the free bending end of the test sample and enables more accurate testing of the performance of the test sample.

[0014] This invention also discloses a method for testing the mechanical properties of composite materials based on angle sensing. The method uses the aforementioned device to perform multi-angle mechanical property testing of composite materials, and includes the following steps: S1. Fix both ends of the test sample to be tested onto the upper and lower clamps respectively, and install the upper and lower clamps onto the upper and lower tensile jaws of the universal testing machine respectively; S2. According to the test requirements, adjust the angle position of one or more normally open proximity switches and fix them on the universal testing machine. Set the normally open proximity switch on the free bending end of the test sample to be tested. Connect the normally open proximity switch to the control unit through the intermediate relay and connect the control unit to the alarm. S3. Start the universal testing machine to cause the test sample to be bent and deformed; S4. When the test sample is bent to a preset angle, triggering the corresponding normally open proximity switch, the normally open proximity switch drives the intermediate relay to engage, and the change in the contact state of the intermediate relay is detected by the control unit. S5. After the change in the contact state of the intermediate relay is detected by the control unit, the control unit drives the alarm to sound an alarm and simultaneously records the tensile force value output by the universal testing machine at the corresponding moment, and the angle value is recorded manually at the same time. S6. Stop the test when the test specimen is damaged or the predetermined displacement is completed, and export the report.

[0015] Compared with the prior art, the beneficial effects of the present invention are: The upper clamp of this invention includes an upper pull plate and an upper fixed plate fixedly disposed at the lower end of the upper pull plate. The lower clamp includes a lower pull plate and a lower fixed plate. By hinged the lower pull plate to the lower end face of the lower fixed plate, one end of the test specimen to be tested can be detachably disposed on the lower end face of the upper fixed plate, fixing the test specimen to the side of the upper fixed plate away from the upper pull plate. The other end of the test specimen to be tested is fixedly disposed on the upper end face of the lower fixed plate. By placing the upper pull plate and the lower pull plate on the upper and lower jaws of the universal testing machine, bending and tensile testing of the test specimen to be tested can be realized. At the same time, the bending angle of the test specimen to be tested on the side of the lower pull plate during the tensile process is detected by the angle sensing module, which can detect the mechanical properties of the test specimen to be tested at different bending angles.

[0016] Because the pull-down plate is hinged to the lower end face of the lower fixed plate, the lower clamp is suitable for bending and stretching the test sample at different angles, thus avoiding damage to the lower clamp. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a composite material mechanical property testing device based on angle sensing. Figure 2 This is a schematic diagram of the clamping system. In the figure, there are upper clamp 1, lower clamp 2, upper pull plate 11, upper fixing plate 12, reinforcing rib 13, lower pull plate 21, and lower fixing plate 22; 100 test samples to be inspected; 3. Normally open proximity switch; 4. Control unit; 5. Intermediate relay; 6. Alarm; 7. Dial; 8. Clamping plate. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will now be clearly and completely described in conjunction with the accompanying drawings.

[0019] like Figure 1 and Figure 2 As shown, a composite material mechanical property testing device based on angle sensing includes a universal testing machine, a clamping system, and an angle sensing module.

[0020] The clamping system includes an upper clamp 1 and a lower clamp 2. The upper clamp 1 includes an upper pull plate 11 and an upper fixing plate 12 fixedly disposed at the lower end of the upper pull plate 11. The lower clamp 2 includes a lower pull plate 21 and a lower fixing plate 22. The lower pull plate 21 is hinged to the lower end face of the lower fixing plate 22.

[0021] The test specimen 100 is a flat plate structure. One end of the test specimen 100 is detachably set on the lower end face of the upper fixing plate 12. The test specimen 100 is fixed on the side of the upper fixing plate 12 away from the upper pull plate 11. The other end of the test specimen 100 is fixed on the upper end face of the lower fixing plate 22.

[0022] The upper pull plate 11 and the lower pull plate 21 are respectively mounted on the upper and lower jaws of the universal testing machine. In the initial state, i.e. before the tensioning begins, the upper pull plate 11 and the lower pull plate 21 are vertically arranged and located in the same plane.

[0023] The angle sensing module is used to detect the bending angle of the test specimen 100 on the side of the pull-down plate 21, i.e., the free end of the test specimen 100, during the stretching process.

[0024] The angle sensing module includes a dial 7 mounted on the upper fixed plate 12. The dial 7 is made of transparent material and is vertically mounted on the side of the test sample 100. Based on the angle value on the dial 7 when the test sample 100 is not bent, the tester can read the bending angle of the freely bending end of the test sample 100 during the test in real time.

[0025] The angle sensing module includes multiple normally open proximity switches 3 installed on the universal testing machine and a control unit 4 connected to the normally open proximity switches 3. The control unit 4 is connected to a computer.

[0026] Each normally open proximity switch 3 corresponds to a preset angle.

[0027] The control unit 4 is used to control the universal testing machine to stop and record the corresponding tensile force value according to the detection signal of the normally open proximity switch 3.

[0028] The angle sensing module also includes an intermediate relay 5 disposed between the normally open proximity switch 3 and the control unit 4.

[0029] The aforementioned angle-sensing-based composite material mechanical property testing device also includes an alarm 6 connected to the control unit 4.

[0030] The upper pull plate 11 and the upper fixing plate 12 are vertically connected.

[0031] A reinforcing rib 13 is provided between the upper pull plate 11 and the upper fixing plate 12.

[0032] The composite material mechanical property testing device based on angle sensing also includes a clamping plate 8. The test sample 100 to be tested is located between the clamping plate 8 and the upper fixing plate 12. The clamping plate 8 is fixed on the upper fixing plate 12 by bolts.

[0033] The test sample 100 to be tested is attached to the lower fixing plate 22.

[0034] A method for testing the multi-angle mechanical properties of composite materials using the above-mentioned apparatus includes the following steps: S1. Fix both ends of the test specimen 100 to be tested onto the upper clamp 1 and the lower clamp 2 respectively, and install the upper clamp 1 and the lower clamp 2 onto the upper and lower tensile jaws of the universal testing machine respectively.

[0035] Place the upper end of the test specimen 100 corresponding to the tensile test in the upper clamp 1, and tighten it with clamp plate 8 and bolts to make the test specimen 100 fit against the lower end face of the upper fixed plate 12. Clean the bonding surface between the lower end of the test specimen 100 corresponding to the tensile test and the lower clamp 2, and use high-strength epoxy resin adhesive with a shear strength of not less than 15MPa and a temperature resistance range of -40℃ to 80℃ to bond and fix it. After curing, install the upper clamp 1 and the lower clamp 2 into the upper and lower chucks of the universal testing machine, respectively.

[0036] S2. According to the test requirements, adjust the angle position of one or more normally open proximity switches 3 and fix them on the universal testing machine. Set the normally open proximity switch 3 on the free bending end of the test sample 100 to be tested. Connect the normally open proximity switch 3 to the control unit 4 through the intermediate relay 5, and connect the control unit 4 to the alarm 6.

[0037] Connect the power lines of each normally open proximity switch 3 to a DC power supply, and connect their signal output lines to the coil terminals of the intermediate relay 5; connect the normally open contacts of the intermediate relay 5 to the digital input port of the control unit 4; connect the alarm 6 to the digital output port of the control unit 4.

[0038] S3. Start the universal testing machine to cause the test sample 100 to be bent and deformed.

[0039] Set parameters such as tensile rate in the corresponding control software of the universal testing machine.

[0040] S4. When the test sample 100 is bent to a preset angle, triggering the corresponding normally open proximity switch 3, the normally open proximity switch 3 drives the intermediate relay 5 to engage, and the change in the contact state of the intermediate relay 5 is detected by the control unit 4.

[0041] Specifically, when the test specimen 100 bends to the first preset angle (e.g., 10°), the corresponding normally open proximity switch 4 (sensing distance range 2mm-10mm, angle adjustment accuracy ±0.1°) senses the test specimen 100, and its output signal energizes the coil of the intermediate relay 5, causing its normally open contact to close. The control unit 4 detects that the input point becomes high level and immediately executes the interrupt program to stop the universal testing machine from stretching. The interrupt program facilitates step S5, which records the tensile force and angle values ​​of the universal testing machine.

[0042] S5. After the change in the contact state of the intermediate relay 5 is detected by the control unit 4, the control unit 4 drives the alarm 6 to issue an alarm and simultaneously records the tensile force value output by the universal testing machine at the corresponding moment, and simultaneously records the angle value.

[0043] Specifically, the intermediate relay 5 controls the output point to conduct, driving the audible and visual alarm 6 to work and issue a warning.

[0044] The tensile force value at the current moment can be read and recorded by the testing machine or from its data stream. The angle value can be recorded manually and synchronously by setting a dial, or it can be automatically read by setting a camera and using relevant software.

[0045] The experiment continues, and when the preset angle (e.g., 20°) is reached, steps S3-S5 are repeated.

[0046] S6. Stop the test when the test specimen 100 is damaged or the predetermined displacement is completed, and export the report.

[0047] Through the above-described apparatus and method, this invention enables reliable, automated, and precise testing of the mechanical properties of composite materials under multi-angle bending.

[0048] The present invention has the following advantages: 1. High reliability: The introduction of intermediate relays improves the anti-interference capability of signal transmission and the overall electrical safety of the system, making the device more suitable for industrial environments.

[0049] 2. Precise and automatic: Through electromechanical integration, it achieves zero-delay bending at specific angles (the tensile force value can be automatically displayed by the computer), while the angle value is recorded manually in sync, resulting in high precision.

[0050] 3. Flexible and efficient: Multi-angle normally open proximity switches can be set independently, and mechanical parameters at multiple key angles can be obtained in one test, which greatly improves the testing efficiency. Compared with the traditional method of testing a single parameter in one test, the testing efficiency is improved by more than 30%.

[0051] 4. Cost advantage: Compared with optical measurement systems, the cost of this device is significantly reduced by about 60%, making it easy to widely apply in laboratories and factories.

Claims

1. An angle-sensor-based composite material mechanical property testing device, characterized in that: The universal testing machine comprises a clamping system and an angle sensing module. The clamping system comprises an upper clamp (1) and a lower clamp (2), the upper clamp (1) comprises an upper pull plate (11) and an upper fixed plate (12) fixedly arranged at the lower end of the upper pull plate (11), and the lower clamp (2) comprises a lower pull plate (21) and a lower fixed plate (22), the lower pull plate (21) is hingedly connected to the lower end surface of the lower fixed plate (22). The test sample (100) is in a flat plate structure, one end of the test sample (100) is detachably arranged on the lower end surface of the upper fixed plate (12), the test sample (100) is fixed on the side of the upper fixed plate (12) away from the upper pull plate (11), and the other end of the test sample (100) is fixedly arranged on the upper end surface of the lower fixed plate (22). The upper pull plate (11) and the lower pull plate (21) are arranged on the upper and lower clamping jaws of the universal testing machine, respectively. The angle sensing module is used for detecting the bending angle of the test sample (100) on the side of the lower pull plate (21) during the stretching process.

2. The composite material mechanical property testing device based on angle sensing of claim 1, wherein: The angle sensing module comprises a plurality of normally open proximity switches (3) arranged on the universal testing machine and a control unit (4) connected with the normally open proximity switches (3). Each normally open proximity switch (3) corresponds to a preset angle. The control unit (4) is used for controlling the stop of the universal testing machine and recording the corresponding tensile force value according to the detection signal of the normally open proximity switch (3).

3. The composite material mechanical property testing device based on angle sensing of claim 2, wherein: The angle sensing module further comprises an intermediate relay (5) arranged between the normally open proximity switch (3) and the control unit (4).

4. The composite material mechanical property testing device based on angle sensing of claim 2, wherein: The angle sensing module further comprises an alarm (6) connected with the control unit (4).

5. The composite material mechanical property testing device based on angle sensing of claim 2, wherein: The angle sensing module comprises a scale disc (7) arranged on the upper fixed plate (12).

6. The angle-sensor-based composite material mechanical property testing device according to claim 1, wherein: The upper pull plate (11) and the upper fixed plate (12) are vertically connected.

7. The composite material mechanical property testing device based on angle sensing of claim 1 or 6, wherein: A reinforcing rib (13) is arranged between the upper pull plate (11) and the upper fixed plate (12).

8. The device for testing mechanical properties of composite materials based on angle sensing according to claim 1, characterized in that: The test sample (100) is located between the clamping plate (8) and the upper fixed plate (12), and the clamping plate (8) is fixedly arranged on the upper fixed plate (12) by bolts. 9.The angle-sensor-based composite material mechanical property testing device according to claim 1, wherein: The test sample (100) is pasted on the lower fixed plate (22).

10. A method for testing the mechanical properties of composite materials based on angle sensing, using the device according to claim 1 for testing the mechanical properties of composite materials at multiple angles, characterized in that, The method comprises the following steps: S1, fixing the test sample (100) at both ends on the upper clamp (1) and the lower clamp (2) respectively, and installing the upper clamp (1) and the lower clamp (2) on the upper and lower stretching clamping jaws of the universal testing machine; S2, adjusting the angle position of one or more normally open proximity switches (3) according to the test requirement and fixing the normally open proximity switch (3) on the universal testing machine, arranging the normally open proximity switch (3) on the side of the free bending end of the test sample (100), connecting the normally open proximity switch (3) with the control unit (4) through the intermediate relay (5), and connecting the control unit (4) with the alarm (6); S3, starting the universal testing machine to make the test sample (100) bend and deform; S4, when the test sample (100) is bent to a preset angle, the normally open proximity switch (3) is triggered, the normally open proximity switch (3) drives the intermediate relay (5) to be attracted, and the change of the contact state of the intermediate relay (5) is detected by the control unit (4); S5, after the change of the contact state of the intermediate relay (5) is detected by the control unit (4), the control unit (4) drives the alarm (6) to issue an alarm, and synchronously records the tensile force value output by the universal testing machine at the corresponding time, and manually records the angle value; S6, after the test is stopped when the test sample (100) is destroyed or the predetermined displacement is completed, the report is exported.

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