A high and low temperature vibration test device for flexible piezoelectric composite materials in a bending state and a method for using the same

Abstract

The present invention relates to a high and low temperature vibration test device for flexible piezoelectric composite materials in a bending state and a method for using the same. The device includes a fixed base, a high and low temperature test chamber, an excitation system, a displacement sensing system, and an arc sample holder; wherein the fixed base is fixed to the side of the high and low temperature test chamber and is connected to the excitation system and the displacement sensing system, the excitation system and the displacement sensing system are located in a studio inside the high and low temperature test chamber, the arc sample holder is fixedly connected to the excitation system, and the displacement sensing system faces the sample to be tested on the arc sample holder. The device can simultaneously perform vibration fatigue tests at a fixed temperature or high and low temperature alternating cycle temperature, a fixed frequency or a variable frequency on one or more identical or different bending samples, and has the advantages of high efficiency, good repeatability, high reliability, and low testing cost, and has made a positive contribution to exploring the generation of fatigue and failure causes of flexible piezoelectric composite materials in a space environment.

Description

Technical Field

[0001] The present invention relates to the technical field of inspection and testing equipment and composite materials, and in particular to a high and low temperature vibration test device for a flexible piezoelectric composite material in a bent state and a method for using the same. Background Art

[0002] Piezoelectric composite materials and devices are often used in the aerospace field. They are prone to vibration fatigue due to the complex space environment during their service. Therefore, simulating the space environment and conducting vibration fatigue strength tests on related products are very important for exploring the causes of fatigue and failure of piezoelectric composite materials in the space environment.

[0003] In the space environment, thermal cycles and vibrations will have serious damaging effects on aerospace materials and devices, which in turn affect the dimensional stability, physical and mechanical properties of the materials. During the operation of the spacecraft in low-Earth orbit, it repeatedly enters and exits the shadow of the Earth, and the ambient temperature alternates between 113K and 393K. At the same time, many piezoelectric composite materials and devices work in a bent state. Therefore, the vibration test equipment used for aerospace flexible piezoelectric composites must not only provide high and low temperature alternating cycle temperature conditions of -100℃ to 200℃, but also ensure that the sample is always in a bent state during the vibration test. At present, no readily available test equipment has been found.

[0004] The inventor team searched with keywords such as "high and low temperature", "vibration", and "fatigue", and found the following patents. Chinese patent CN207662586U discloses a high-vacuum high-temperature vibration test device, which uses the sealing of the bracket and the bellows to isolate the vacuum test box from the vibration table, effectively transmitting vibration while ensuring the sealing of the vacuum test box, and can complete the vacuum vibration test of straight sheet samples with regular shapes. Chinese patent CN209069545U discloses a blade high-temperature vibration fatigue test system, which can measure the fatigue life of turbine blades in a high-temperature environment of 1200°C. Chinese patent CN215492335U discloses a vibration test device suitable for aerospace, which solves the problem that the excitation frequency of the existing ordinary vibration table at room temperature is difficult to meet the test requirements through a vibrating mechanism. Chinese patent CN113804379A discloses a composite material ultra-high temperature vibration fatigue test method, which can provide an ultra-high temperature and vibration environment of more than 1000°C for composite materials in a non-bending state. Chinese patent CN212904213U discloses a bending vibration fatigue test device for composite material test pieces, which solves the problem that the existing test devices are inconvenient to fix the test pieces at room temperature and cannot test test pieces of different thicknesses. Chinese patent CN111024349A discloses a high-temperature multi-axis vibration fatigue test method, which can be used to measure the high-temperature multi-axis vibration fatigue performance of materials. Chinese patent CN214149741U discloses a high-temperature environment vibration fatigue test system, which can use sonar to monitor (non-contact) the fatigue state of the test piece in a high-temperature environment. Chinese patent CN108709797A discloses a loading device and method for bending-torsion vibration fatigue testing, which can complete the vibration fatigue performance test of rectangular and circular cross-section test pieces at room temperature.

[0005] Analysis shows that the existing related patent technologies are difficult to meet the vibration test requirements of flexible piezoelectric composite materials and devices for aerospace use. The reasons include: (1) The test system disclosed in the existing patents is difficult to perform vibration fatigue tests on piezoelectric sheets under high and low temperature cyclic alternating conditions, such as the last 8 patents mentioned above; (2) The test system disclosed in the existing patents is not suitable for vibration fatigue tests on piezoelectric sheets in a bent state, but can only perform vibration fatigue tests on samples with regular shapes and flat surfaces, such as all the above patents. Therefore, it is necessary to develop and design a test device that can perform vibration fatigue tests on flexible piezoelectric sheets in a bent state under high and low temperature cyclic alternating conditions of -100℃ to 200℃. Summary of the invention

[0006] The purpose of the present invention is to overcome the above problems existing in the prior art, and to provide a new high and low temperature vibration test device and a corresponding test method, which can provide an adjustable vibration test frequency under the conditions of -100℃~200℃ high and low temperature alternating cycle, and then complete the vibration fatigue test of flexible piezoelectric composite materials under different bending states, and the test results have good repeatability and high credibility. To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A high and low temperature vibration test device for a flexible piezoelectric composite material in a bending state, the device comprises a fixed base, a high and low temperature test chamber, an excitation system, a displacement sensing system, and an arc sample holder; wherein the fixed base is fixedly connected to the high and low temperature test chamber, one end of the excitation system and the displacement sensing system are both fixed to the fixed base, and the other ends are both sealed in a working room inside the high and low temperature test chamber; the arc sample holder is fixedly connected to the excitation system, and is used for receiving vibration transmitted by the excitation system; the displacement sensing system is directly facing the sample to be tested on the arc sample holder, and is used for detecting its vibration frequency and amplitude.

[0008] Furthermore, the fixed base is installed and fixed on the outside of the high and low temperature test box.

[0009] Furthermore, the high and low temperature test chamber is divided into two layers, the upper layer is the working room and the lower layer is the control room. The components inside the working room, the excitation system, and the displacement sensing system are connected to the control equipment (such as switches, relays, etc.) inside the control room through wires, so that the test temperature, vibration frequency and other parameters can be conveniently adjusted through the control room.

[0010] Furthermore, the excitation system includes a vibration rod, a vibration transmission rod, and an exciter, wherein the vibration rod horizontally passes through the high and low temperature test chamber and is fixedly connected to a fixed base, one end of the vibration transmission rod is connected to the vibration rod located in the working room of the high and low temperature test chamber, and the other end vertically passes through the middle partition of the high and low temperature test chamber and is connected to the exciter located in the control room of the high and low temperature test chamber.

[0011] Furthermore, the excitation system also includes a connecting ring, which is sleeved on the vibration rod near the fixed base and locked, and the vibration transmission rod is fixedly connected to the connecting ring.

[0012] Furthermore, the displacement sensing system includes a telescopic rod and a displacement sensor, wherein the displacement sensor is fixed on the telescopic rod located in the high and low temperature test chamber working room and faces the arc-shaped sample holder, and the telescopic rod horizontally passes through the high and low temperature test chamber and is fixedly connected to a fixed base.

[0013] Furthermore, the number of the vibration excitation systems and displacement sensing systems is the same, both being 1 to 5 groups.

[0014] Furthermore, the number of the excitation systems and displacement sensing systems is two, and the two excitation systems are arranged side by side on the same horizontal plane, and the two displacement sensing systems are also arranged side by side on the same horizontal plane, and the displacement sensors of the displacement sensing systems are respectively located above the arc-shaped sample holders of the excitation systems.

[0015] Another object of the present invention is to provide a method for using the above-mentioned high and low temperature vibration testing device, which includes the following steps: first, fix the flexible piezoelectric composite material to be tested on an arc-shaped sample holder to ensure that the sample is in a bent state; then start the high and low temperature test chamber, perform the test according to the set mode, collect and analyze the signal fed back by the displacement sensor, and finally obtain the vibration fatigue performance of the sample.

[0016] Furthermore, the flexible piezoelectric composite material to be tested is specifically a sheet, that is, a flexible piezoelectric sheet.

[0017] Furthermore, the test modes of the device include a fixed frequency-high and low temperature alternating cycle mode, a fixed temperature-variable frequency mode, and a fixed temperature-fixed frequency mode.

[0018] Furthermore, in the fixed frequency-high and low temperature alternating cycle mode, the frequency of the excitation system does not exceed 5000Hz, and the temperature in the working room is adjusted to high temperature or low temperature through the temperature control program of the high and low temperature test chamber and kept warm for no more than 24 hours, and then adjusted in the opposite direction to low temperature or high temperature and kept warm for no more than 24 hours, and finally repeated the above temperature adjustment several times. In this process, the heating rate is 1-10℃1111, the high temperature range is 100-200℃, the cooling rate is 1-10℃1111, and the low temperature range is -100 to 0℃.

[0019] Furthermore, in the constant temperature-variable frequency mode, the temperature in the working room of the high and low temperature test chamber is set to a certain constant value between -100°C and 200°C and remains unchanged, and then the frequency of the excitation system is first adjusted to a certain value (not exceeding 5000Hz), and then the frequency of the excitation system is adjusted to another constant value (not exceeding 5000Hz).

[0020] Furthermore, in the constant temperature-constant frequency mode, the temperature in the working room of the high and low temperature test chamber is set to a certain constant value between -100°C and 200°C and remains unchanged, and the frequency of the excitation system is set to a certain constant value (not exceeding 5000Hz) and remains unchanged.

[0021] Compared with the existing similar technologies, the improved effects of the present invention are embodied in the following aspects:

[0022] (1) It can provide a fixed temperature of -100℃ to 200℃ or a high and low temperature cycle test environment, which can realistically simulate the use scenarios of piezoelectric composite materials for aerospace, and the accuracy and repeatability of the test results are better;

[0023] (2) A series of arc-shaped sample holders of different sizes and shapes are specially designed. These holders better fit the contour of the flexible aerospace piezoelectric composite material to be tested in a bent state, and the test results can more accurately reflect the actual service state of the sample, so the test results obtained are more reliable;

[0024] (3) Multiple sets of excitation systems and displacement sensing systems are arranged side by side in the high and low temperature test chamber, which can complete vibration fatigue tests on multiple samples at one time and provide a variety of test modes for selection. It has the advantages of high efficiency, low cost, and rich functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the high and low temperature vibration test device of the present invention;

[0026] Figure 2 It is a schematic diagram of the right side structure of the high and low temperature vibration test device of the present invention;

[0027] Figure 3 It is a schematic diagram of the assembly structure of the vibration rod and the arc-shaped sample holder of the present invention;

[0028] Figure 4 It is a partial physical diagram of the vibration excitation system of the present invention;

[0029] Figure 5 Schematic diagram of the sample to be tested of the present invention.

[0030] Among them, 1-fixed base, 2-high and low temperature test chamber working room, 3-telescopic rod, 4-displacement sensor, 5-vibration rod, 6-arc sample holder, 7-connecting ring, 8-vibration transmission rod, 9-exciter, 10-high and low temperature test chamber control room. DETAILED DESCRIPTION

[0031] In order to enable ordinary technicians in the field to fully understand the technical solutions and beneficial effects of the present invention, further description is given below in conjunction with specific embodiments and drawings.

[0032] like Figure 1-4A high and low temperature vibration test device shown mainly includes a high and low temperature test chamber and a fixed base (1) fixed on the upper left side of the chamber, wherein the high and low temperature test chamber is divided into two layers, the upper layer is a working room, and the lower layer is a control room, and the upper and lower layers are physically separated by thermal insulation materials. A plurality of through holes are arranged on the left side of the working room (2) of the upper layer high and low temperature test chamber, and the telescopic rod (3) and the vibration rod (5) are fixed on the fixed base (1) after passing through the through holes. Strict sealing and heat insulation treatment is adopted at all the through holes to minimize the influence of vibration and internal and external temperature difference. At least one displacement sensor (4) is fixed downward on the telescopic rod (3), and when the telescopic rod is controlled to extend or shorten, the displacement sensor (4) also moves left and right accordingly, so as to better detect the vibration frequency and amplitude of the sample. The vibration rod (5) is located below the telescopic rod (3) and cannot extend or shorten. A connecting ring (7) and an arc-shaped sample holder (6) are fixed on the vibration rod (5). The connecting ring (7) is connected to one end of a vibration transmission rod (8). The other end of the vibration transmission rod (8) vertically passes through the middle partition of the high and low temperature test chamber and enters the control room. The exciter (9) is hung on the end of the vibration transmission rod (8). The vibration rod (5), the connecting ring (7), the vibration transmission rod (8) and the exciter (9) of the device form an excitation system. The exciter (9) transmits the vibration of a specific frequency through the vibration transmission rod (8), the connecting ring (7) and the vibration rod (5) and acts on the sample to be tested on the arc-shaped sample holder (6). The telescopic rod (3) and the displacement sensor (4) form a displacement sensing system. The displacement sensor (4) is used to monitor the vibration frequency and amplitude of the flexible bending piezoelectric sheet to be tested.

[0033] A preferred implementation example is Figure 2 As shown in the figure, two sets of excitation systems and two sets of displacement sensing systems are arranged side by side in the high and low temperature test chamber, and the displacement sensing system and the excitation system are arranged at a certain distance above and below. This design can test two identical or different samples at a time. Of course, according to the size of the equipment and the test needs, one set of excitation system and one set of displacement sensing system, or three sets of excitation systems and three sets of displacement sensing systems can also be set in the high and low temperature test chamber.

[0034] The high and low temperature vibration test device can test the flexible piezoelectric sheet in a bent state in different test modes according to different test requirements.

[0035] The structure of the flexible aerospace piezoelectric composite material to be tested in the present invention is as follows: Figure 4As shown, its length and width are 2.5*20cm, including at least 5 layers, the bottom layer and the surface layer are both polyimide film layers with interdigitated electrodes on the surface, the middle layer is a piezoelectric ceramic fiber-epoxy resin composite layer, and the remaining interlayers are epoxy resin layers. For details, please refer to the document (S1art Mater. Struct. 21 (2012) 105037). Of course, the device of the present invention is not only applicable to this kind of sample, but also to other compositions and structures of flexible piezoelectric composite materials in a bent state.

[0036] Example 1

[0037] The experimental process of vibration test under fixed frequency + high and low temperature alternating cycle conditions is as follows:

[0038] The material of the vibration rod is 6012 aluminum alloy with a diameter of 3511. The bending radius of the test sample is 5011, so an arc-shaped sample holder with a bending radius of 5011 is selected.

[0039] Fix the selected arc sample holder on the vibration rod, fix the sample to be tested on the sample holder, adjust the length of the telescopic rod so that the displacement sensor is located directly above the sample to be tested, set the vibration frequency of the exciter to 100Hz, and set the working temperature control program of the high and low temperature test chamber: first cool down from room temperature to -100℃ at a cooling rate of 5℃1111, and keep it at this temperature for 1h; then heat it to 200℃ at a heating rate of 5℃1111, and keep it at this temperature for 1h. After the program is set, start the entire device to start the test. If multiple high and low temperature alternating cycles are required, the temperature control program of the high and low temperature test chamber can be set in multiple stages, and the vibration frequency and amplitude signals fed back by the displacement sensor can be recorded and analyzed.

[0040] Example 2

[0041] Determine the experimental process of vibration test under temperature + different frequency conditions as follows:

[0042] The material of the vibration rod is carbon fiber T7001 epoxy resin-based composite material with a diameter of 3511. The bending radius of the test sample is 4011, so an arc-shaped sample holder with a bending radius of 4011 is selected.

[0043] Fix the selected arc sample holder on the vibration rod, fix the sample to be tested on the sample holder, adjust the length of the telescopic rod so that the displacement sensor is located directly above the sample to be tested, set the vibration frequency of the exciter to 100Hz, and set the working temperature control program of the high and low temperature test chamber: increase the temperature from room temperature to 200℃ at a heating rate of 5℃1111, and keep it at this temperature for 1h. After the program is set, start the entire device, adjust the vibration frequency of the exciter to 1000Hz after 1h to continue the test, record the vibration frequency and amplitude signal fed back by the displacement sensor, and analyze and process it.

[0044] Example 3

[0045] Determine the temperature + determine the frequency + vibration test process under different conditions of sample bending radius:

[0046] The material of the vibration rod is carbon fiber T7001 epoxy resin-based composite material with a diameter of 2011. The bending radius of the test sample is 4011 and 5011, so two arc-shaped sample holders with bending radius of 4011 and 5011 are selected.

[0047] Fix the two selected arc sample holders on two parallel vibration rods, fix the sample to be tested on the sample holder, adjust the length of the telescopic rod so that the displacement sensor is located directly above the sample to be tested, set the vibration frequency of the exciter to 500Hz, and set the working temperature control program of the high and low temperature test chamber: at a heating rate of 5℃1111, from room temperature to 100℃, and keep it at this temperature for 12h. After the program is set, start the entire device for testing, record the vibration frequency and amplitude signals fed back by the displacement sensor, and analyze and process them.

Claims

1. A high and low temperature vibration test device for flexible piezoelectric composite materials in a bending state, characterized by: The device includes a fixed base, a high and low temperature test chamber, a vibration excitation system, a displacement sensing system, and an arc sample holder; The fixed base is fixedly connected to the high and low temperature test chamber, one end of the excitation system and the displacement sensing system are fixed on the fixed base, and the other end is sealed in the working room inside the high and low temperature test chamber; the arc sample holder is fixedly connected to the excitation system, and the displacement sensing system is facing the sample to be tested on the arc sample holder.

2. The device according to claim 1, characterized in that: The high and low temperature test box is divided into two layers, the upper layer is a working room and the lower layer is a control room. The components inside the working room, the excitation system, and the displacement sensor system are connected to and controlled by the control equipment inside the control room through wires.

3. The device according to claim 1, characterized in that: The excitation system includes a vibration rod, a vibration transmission rod, and an exciter, wherein the vibration rod horizontally passes through the high and low temperature test chamber and is fixedly connected to a fixed base, one end of the vibration transmission rod is connected to the vibration rod located in the working room of the high and low temperature test chamber, and the other end vertically passes through the middle partition of the high and low temperature test chamber and is connected to the exciter located in the control room of the high and low temperature test chamber.

4. The device according to claim 3, characterized in that: The excitation system also includes a connecting ring, which is sleeved on a side of the vibration rod close to the fixed base and locked, and the vibration transmission rod is fixedly connected to the connecting ring.

5. The device according to claim 1, characterized in that: The displacement sensing system comprises a telescopic rod and a displacement sensor, wherein the displacement sensor is fixed on the telescopic rod located in the high and low temperature test chamber working room and faces the arc-shaped sample support, and the telescopic rod passes horizontally through the high and low temperature test chamber and is fixedly connected to a fixed base.

6. The device according to claim 1, characterized in that: The number of the excitation systems and displacement sensing systems is the same, and both are 1 to 5 groups.

7. The device according to claim 6, characterized in that: The number of the excitation systems and displacement sensing systems are both two, and the two excitation systems are arranged side by side on the same horizontal plane, and the two displacement sensing systems are also arranged side by side on the same horizontal plane, and the displacement sensors of the displacement sensing systems are respectively located above the arc-shaped sample holders of the excitation systems.

8. The method for using the high and low temperature vibration test device according to any one of claims 1 to 7, characterized in that: The method includes the following steps: first, fix the flexible piezoelectric composite material to be tested on an arc-shaped sample holder to ensure that the sample is in a bent state; then start the high and low temperature test chamber, perform the test according to the set mode, collect and analyze the signal fed back by the displacement sensor, and finally obtain the vibration fatigue performance of the sample.

9. The method according to claim 8, characterized in that: The flexible piezoelectric composite material to be tested is specifically a flexible piezoelectric sheet in a bent state.

10. The method according to claim 8, characterized in that: The test modes of the device include fixed frequency-high and low temperature alternating cycle mode, fixed temperature-variable frequency mode, and fixed temperature-fixed frequency mode. In the fixed frequency-high and low temperature alternating cycle mode, the frequency of the excitation system does not exceed 5000Hz. The temperature in the working room is adjusted to high temperature or low temperature through the temperature control program of the high and low temperature test chamber and kept warm for no more than 24 hours, and then adjusted in the opposite direction to low temperature or high temperature and kept warm for no more than 24 hours. Finally, the above temperature adjustment is repeated several times. The heating rate during this period is 1-10℃ / min, and the high temperature range is 100-2 00℃, the cooling rate is 1-10℃ / min, and the low temperature range is -100 to 0℃; in the constant temperature-variable frequency mode, the temperature in the working room of the high and low temperature test chamber is set at a fixed value between -100℃ and 200℃ and remains unchanged, and then the frequency of the excitation system is adjusted to a certain value, and then the frequency of the excitation system is adjusted to another fixed value; in the constant temperature-constant frequency mode, the temperature in the working room of the high and low temperature test chamber is set at a fixed value between -100℃ and 200℃ and remains unchanged, and the frequency of the excitation system is set to a certain value and remains unchanged.

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