Testing device and testing method for friction performance of bionic non-smooth surface based on piezoelectric drive

Abstract

The application relates to a piezoelectric driving-based bionic non-smooth surface friction performance testing device and testing method. According to the two-force balance principle, the normal pressure and friction force of a friction pair are measured, and the mass is measured by using an electronic balance. The testing device comprises a bottom plate, a flexible mechanism, a friction head, a bionic non-smooth surface, a guide rail support plate, an L-shaped plate, a light-reflecting plate, a push plate and a baffle, an output module, a pre-tightening module, a pressure measuring module and a displacement detection module. The application has the advantages that the friction coefficient and wear resistance between different normal pressures, different driving frequencies, different types of driving transmission pairs and different bionic non-smooth surfaces can be measured, the friction coefficient is calculated through the Coulomb friction law, the wear resistance is measured by the mass difference before and after the friction head and the bionic non-smooth surface are abraded, the device is also suitable for testing the friction performance of other surfaces, the structure is compact, the control is simple, the speed is high when high-frequency driving, the testing time is saved, and the practicability is high.

Description

Technical Field

[0001] This invention relates to the field of precision machinery, and particularly to a device and method for testing the frictional properties of biomimetic non-smooth surfaces based on piezoelectric actuation. It can measure the frictional properties of friction pairs used in piezoelectric actuation, biomimetic friction, precision transmission, and braking. It provides research methods for the application of biomimetic tribology in various fields, especially for the study of friction pairs driven by stick-slip piezoelectric actuators. Background Technology

[0002] Stick-slip piezoelectric actuators are simple in structure, easy to control, and can be miniaturized and achieve large-stroke outputs. However, because they rely solely on the frictional force of the friction pair to provide the driving force for the output module, their load capacity is relatively small, making it difficult to design high-thrust actuators. Therefore, improving the frictional performance of the friction pair surface in stick-slip piezoelectric actuators is of considerable research value.

[0003] In the long course of biological evolution, many organisms have developed excellent microstructures on their surfaces to adapt to their environment. Consequently, more and more scholars have begun to study biomimetic friction surfaces, researching the unique microstructures of biological surfaces and attempting to improve their frictional properties by fabricating similar structures. Currently, extensive research has been conducted on the surfaces of many typical animals, such as dung beetles, lizards, geckos, pangolins, sharks, and snakes, as well as the surfaces of some plant fruits, such as dewdrops and cockleburs. However, there is still a lack of comprehensive testing methods for the frictional properties of these fabricated biomimetic non-smooth surfaces.

[0004] This invention combines piezoelectric actuation technology and tribological testing technology to design a testing device for the tribological properties of biomimetic non-smooth surfaces based on piezoelectric actuation. This device is used to study the influence of the normal force of the friction pair on the tribological properties, provides a standard for adjusting the preload of the piezoelectric actuation device to improve performance, and allows for the study of the influence of various types of biomimetic microstructures on the performance of the piezoelectric device by changing different biomimetic non-smooth surfaces. The device and research method proposed in this paper are of great significance for promoting research on piezoelectric actuators and biomimetic friction. Summary of the Invention

[0005] The purpose of this invention is to provide a testing device and method for the frictional properties of biomimetic non-smooth surfaces based on piezoelectric actuation, solving the aforementioned problems existing in the prior art. Based on the principle of two-force equilibrium, this invention uses a pressure sensor to measure the normal force and frictional force of the friction pair, calculates the friction coefficient of the friction pair using Coulomb's law of friction, and employs a detachable installation method to measure the mass loss of the friction pair before and after wear using an electronic balance to assess the wear resistance of the friction pair. By changing different friction heads and biomimetic non-smooth surfaces, the influence of different microstructures on surface frictional properties can be measured, providing a technical means for the research of stick-slip piezoelectric actuators and biomimetic friction.

[0006] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0007] A testing device for the friction properties of a biomimetic non-smooth surface based on piezoelectric drive includes a base plate 3, a flexible mechanism 14, a friction head 11, a biomimetic non-smooth surface 10, a guide rail support plate 7, an L-shaped plate 15, a reflector 8, a push plate 2 and a baffle 12, an output module, a pre-tightening module, a pressure measurement module, and a displacement detection module.

[0008] The flexible mechanism 14 and the L-shaped plate 15 are mounted on the base plate 3. The flexible mechanism 14 has two mounting slots. One mounting slot is used to mount the friction head 11, which adopts a flexible structure design to compensate for assembly errors. The other mounting slot is used to mount the piezoelectric element 16. Each mounting slot also has a threaded hole at its fixed position. One hole is used to fix the friction head 11, and the other hole is used to pre-tighten the piezoelectric element 16. The L-shaped plate 15 is used to reinforce the fixation of the flexible mechanism. In addition, a positioning plane is provided at the position on the base plate where the flexible mechanism is fixed to ensure the horizontal positioning accuracy of the flexible mechanism.

[0009] The output module includes an output guide rail 9, a biomimetic non-smooth surface 10, and a reflector 8. The output guide rail 9 is mounted on a guide rail support plate 7. The pre-tightening force applied by the pre-tightening module cooperates with the friction head 11 to provide driving force for the output module. A positioning surface is provided on the guide rail support plate 7 at the position where the output guide rail 9 is mounted to ensure the lateral positioning accuracy of the output guide rail 9. The biomimetic non-smooth surface 10 adopts a U-shaped groove structure and is fixed to the output guide rail 9 with screws to ensure that the inner surface is completely in contact with the output guide rail 9. The reflector 8 is mounted on the output guide rail 9 to reflect the laser emitted by the laser micrometer 19 in the displacement detection module to realize the measurement of the output displacement of the output module.

[0010] The pre-tightening module is divided into a piezoelectric element pre-tightening mechanism and a pre-tightening mechanism that provides positive pressure to the friction pair. The piezoelectric element pre-tightening mechanism includes a flexible mechanism 14 and a pre-tightening screw 17 to pre-tighten the piezoelectric element 16. The pre-tightening mechanism that provides positive pressure to the friction pair includes a manual displacement stage 1 and a push plate 2. The manual displacement stage 1 is mounted on the base plate 3. A positioning surface is provided at the position where the manual displacement stage 1 is mounted on the base plate 3 to ensure the lateral positioning accuracy of the manual displacement stage 1. The push plate 2 adopts a U-shaped groove structure and is fixed to the manual displacement stage 1 with screws to ensure that the inner surface is completely in contact with the manual displacement stage 1.

[0011] The pressure measurement module includes pressure sensor A4, pressure sensor B6, pressure sensor controller A20, and pressure sensor controller B21. Pressure sensor A4 is placed on the base plate 3 and is used to measure the normal pressure of the friction pair. Pressure sensor controller A20 is connected to pressure sensor A4 and is used to display the pressure magnitude. Pressure sensor B6 is placed on the guide rail support plate 7 and is used to measure the friction force on the output module. Pressure sensor controller B21 is connected to pressure sensor B6 and is used to display the magnitude of the friction force. Finally, the friction coefficient of the friction pair is calculated using Coulomb's law of friction. The specific formula is as follows:

[0012]

[0013] Where N represents the normal force of the friction pair; F represents the frictional force on the output module.

[0014] The formula for calculating the basic error δ caused by the influence of sensor performance during the testing process is as follows:

[0015]

[0016] Wherein, NL represents pressure nonlinearity, HY represents pressure hysteresis, and PR represents pressure repeatability.

[0017] The displacement detection module includes a laser micrometer 19, a controller 22, and a computer 23. The laser micrometer 19 is used to measure the output displacement of the output module, and the computer is used to display the magnitude of the displacement in real time and plot the displacement-time curve.

[0018] Another objective of this invention is to provide a method for testing the frictional properties of a biomimetic non-smooth surface based on piezoelectric actuation, comprising the following steps:

[0019] Step (1): Select the friction head (11) and the bionic non-smooth surface (10) to be tested, perform strict cleaning of residual stains on the surface, measure the overall mass with an electronic balance and record it as M1, and then install them in the mounting slot of the flexible mechanism (14) and the output guide rail (9) respectively.

[0020] Step (2): Apply appropriate preload to the piezoelectric element (16) by rotating the preload screw (17), adjust the positive pressure of the friction pair to the target value by manually adjusting the displacement table (1), and measure it in real time by the pressure sensor A (4) and display it on the pressure sensor controller A (20).

[0021] In step (3), the baffle (12) is installed on the output guide rail (9). The sliding baffle (12) contacts the pressure sensor B (6) to measure the friction force between the friction head and the non-smooth surface, which is displayed by the pressure sensor controller B (21). The laser micrometer (19) is aligned with the reflector (8) and adjusted to a suitable working distance to measure the output displacement of the output module in real time, and the result is uploaded to the computer (23) to display the measurement result.

[0022] Step (4): Apply a driving signal of a certain frequency to the piezoelectric element (16) to make the test device work and measure the corresponding friction coefficient. During the operation of the device, collect displacement-time data and plot the curve. When the change in the slope of the curve is greater than the preset value (set according to the initial slope), stop the test, record the test time and measure the friction coefficient after wear.

[0023] Step (5): Remove the friction head (11) and the biomimetic non-smooth surface (10), perform rigorous cleaning of residual surface stains, measure its overall mass and record it as M2, and then calculate the mass difference before and after the test as an indicator of wear resistance performance. The specific formula is as follows:

[0024] ΔM=M1-M2

[0025] Where ΔM represents the quality difference before and after the test, M1 represents the overall quality before the test, and M2 represents the overall quality after the test.

[0026] Finally, the wear amount per unit time is calculated using the following formula:

[0027]

[0028] Where W represents the wear rate and T represents the test time.

[0029] The above testing method can not only obtain the wear rate between the friction head and the non-smooth surface, but also measure the change of the friction coefficient during the wear resistance test. Subsequently, the relationship between the friction coefficient change rate and the wear rate can be analyzed.

[0030] The beneficial effects of this invention are: it can measure the friction coefficient and wear resistance between different types of drive transmission pairs and different biomimetic non-smooth surfaces under different normal pressures and driving frequencies, and study the influence of different types of drive transmission pairs and different biomimetic non-smooth surfaces on the load-bearing capacity of piezoelectric actuators. This device is also suitable for testing the friction properties of other surfaces. It has a wide range of applications and potential applications in piezoelectric precision drives, tribology, biomimetic engineering, and other fields, demonstrating strong practicality. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the testing principle of the device of the present invention;

[0033] Figure 2 This is a schematic diagram of the device structure of the present invention;

[0034] Figure 3 This is a schematic diagram of the flexible mechanism of the present invention;

[0035] Figure 4 This is a schematic diagram of the working friction pair of the present invention;

[0036] Figure 5 This is a drawing of a biomimetic non-smooth surface part according to the present invention;

[0037] Figure 6 This is a drawing of the friction head component of the present invention;

[0038] Figure 7 This is a flowchart of the testing method of the present invention.

[0039] Explanation of reference numerals in the attached diagram: 1. Manual displacement stage; 2. Push plate; 3. Base plate; 4. Pressure sensor A; 5. Load-bearing guide rail (left); 6. Pressure sensor B; 7. Guide rail support plate; 8. Reflector; 9. Output guide rail; 10. Bionic non-smooth surface; 11. Friction head; 12. Baffle; 13. Preload screw; 14. Flexible mechanism; 15. L-shaped plate; 16. Piezoelectric element; 17. Preload screw; 18. Load-bearing guide rail (right); 19. Laser micrometer; 20. Controller; 21. Computer; 22. Piezoelectric sensor controller A; 23. Piezoelectric sensor controller B. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Reference Figure 1 and Figure 2 A piezoelectric-driven biomimetic non-smooth surface friction performance testing device is proposed. Based on the principle of two-force equilibrium, the device uses a pressure sensor to measure the normal pressure and frictional force of the friction pair, calculates the friction coefficient of the pair using Coulomb's law of friction, and employs a detachable installation method. An electronic balance is used to measure the mass loss of the friction pair before and after wear to assess its wear resistance. Changes in wear resistance are observed by plotting a mass-time curve. By changing different friction heads and biomimetic non-smooth surfaces, the influence of different microstructures on surface friction performance can be measured. The device includes a base plate 3, a flexible mechanism 14, a friction head 11, a biomimetic non-smooth surface 10, a guide rail support plate 7, an L-shaped plate 15, a reflector 8, a push plate 2 and a baffle 12, an output module, a pre-tightening module, a pressure measurement module, and a displacement detection module.

[0042] like Figures 3 to 7 As shown, the flexible mechanism 14 and the L-shaped plate 15 are mounted on the base plate 3. The flexible mechanism 14 has two mounting slots. One mounting slot is used to mount the friction head 11, which adopts a flexible structure design to compensate for assembly errors. The other mounting slot is used to mount the piezoelectric element 16. Each mounting slot also has a threaded hole at its fixed position. One hole is used to fix the friction head 11, and the other hole is used to pre-tighten the piezoelectric element 16. The L-shaped plate 15 is used to reinforce the fixation of the flexible mechanism. In addition, a positioning plane is provided at the position on the base plate where the flexible mechanism is fixed to ensure the horizontal positioning accuracy of the flexible mechanism.

[0043] The output module includes an output guide rail 9, a biomimetic non-smooth surface 10, and a reflector 8. The output guide rail 9 is mounted on a guide rail support plate 7. The pre-tightening force applied by the pre-tightening module cooperates with the friction head 11 to provide driving force for the output module. A positioning surface is provided on the guide rail support plate 7 at the position where the output guide rail 9 is mounted to ensure the lateral positioning accuracy of the output guide rail 9. The biomimetic non-smooth surface 10 adopts a U-shaped groove structure and is fixed to the output guide rail 9 with screws to ensure that the inner surface is completely in contact with the output guide rail 9. The reflector 8 is mounted on the output guide rail 9 to reflect the laser emitted by the laser micrometer 19 in the displacement detection module to realize the measurement of the output displacement of the output module.

[0044] The pre-tightening module is divided into a piezoelectric element pre-tightening mechanism and a pre-tightening mechanism that provides positive pressure to the friction pair. The piezoelectric element pre-tightening mechanism includes a flexible mechanism 14 and a pre-tightening screw 17 to pre-tighten the piezoelectric element 16. The pre-tightening mechanism that provides positive pressure to the friction pair includes a manual displacement stage 1 and a push plate 2. The manual displacement stage 1 is mounted on the base plate 3. A positioning surface is provided at the position where the manual displacement stage 1 is mounted on the base plate 3 to ensure the lateral positioning accuracy of the manual displacement stage 1. The push plate 2 adopts a U-shaped groove structure and is fixed to the manual displacement stage 1 with screws to ensure that the inner surface is completely in contact with the manual displacement stage 1.

[0045] The pressure measurement module includes pressure sensor A4, pressure sensor B6, pressure sensor controller A20, and pressure sensor controller B21. Pressure sensor A4 is placed on the base plate 3 and is used to measure the normal pressure of the friction pair. Pressure sensor controller A20 is connected to pressure sensor A4 and is used to display the pressure magnitude. Pressure sensor B6 is placed on the guide rail support plate 7 and is used to measure the friction force on the output module. Pressure sensor controller B21 is connected to pressure sensor B6 and is used to display the magnitude of the friction force. Finally, the friction coefficient of the friction pair is calculated using Coulomb's law of friction. The specific formula is as follows:

[0046]

[0047] Where N represents the normal force of the friction pair; F represents the frictional force on the output module.

[0048] The formula for calculating the basic error δ caused by the influence of sensor performance during the testing process is as follows:

[0049]

[0050] Wherein, NL represents pressure nonlinearity, HY represents pressure hysteresis, and PR represents pressure repeatability.

[0051] The displacement detection module includes a laser micrometer 19, a controller 22, and a computer 23. The laser micrometer 19 is used to measure the output displacement of the output module, and the computer is used to display the magnitude of the displacement in real time and plot the displacement-time curve.

[0052] like Figure 1 and Figure 7 As shown, the present invention provides a method for testing the frictional properties of biomimetic non-smooth surfaces based on piezoelectric actuation. By changing the normal force and actuator frequency, and replacing the friction head and the biomimetic non-smooth surface, the frictional properties between different surfaces under different conditions are analyzed. Specifically, the method includes the following steps:

[0053] Step (1): Select the friction head (11) and the bionic non-smooth surface (10) to be tested, perform strict cleaning of residual stains on the surface, measure the overall mass with an electronic balance and record it as M1, and then install them in the mounting slot of the flexible mechanism (14) and the output guide rail (9) respectively.

[0054] Step (2): Apply appropriate preload to the piezoelectric element (16) by rotating the preload screw (17), adjust the positive pressure of the friction pair to the target value by manually adjusting the displacement table (1), and measure it in real time by the pressure sensor A (4) and display it on the pressure sensor controller A (20).

[0055] In step (3), the baffle (12) is installed on the output guide rail (9). The sliding baffle (12) contacts the pressure sensor B (6) to measure the friction force between the friction head and the non-smooth surface, which is displayed by the pressure sensor controller B (21). The laser micrometer (19) is aligned with the reflector (8) and adjusted to a suitable working distance to measure the output displacement of the output module in real time, and the result is uploaded to the computer (23) to display the measurement result.

[0056] Step (4): Apply a driving signal of a certain frequency to the piezoelectric element (16) to make the test device work and measure the corresponding friction coefficient. During the operation of the device, collect displacement-time data and plot the curve. When the change in the slope of the curve is greater than the preset value (set according to the initial slope), stop the test, record the test time and measure the friction coefficient after wear.

[0057] Step (5): Remove the friction head (11) and the biomimetic non-smooth surface (10), perform rigorous cleaning of residual surface stains, measure its overall mass and record it as M2, and then calculate the mass difference before and after the test as an indicator of wear resistance performance. The specific formula is as follows:

[0058] ΔM=M1-M2

[0059] Where ΔM represents the quality difference before and after the test, M1 represents the overall quality before the test, and M2 represents the overall quality after the test.

[0060] Finally, the wear amount per unit time is calculated using the following formula:

[0061]

[0062] Where W represents the wear rate and T represents the test time.

[0063] The above testing method can not only obtain the wear rate between the friction head and the non-smooth surface, but also measure the change of the friction coefficient during the wear resistance test. Subsequently, the relationship between the friction coefficient change rate and the wear rate can be analyzed.

[0064] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A testing device for the frictional properties of a biomimetic non-smooth surface based on piezoelectric drive, comprising a base plate (3), a flexible mechanism (14), a friction head (11), a guide rail support plate (7), an L-shaped plate (15), a push plate (2), a baffle (12), an output module, a pre-tightening module, a pressure measurement module, and a displacement detection module, characterized in that: The flexible mechanism (14) and L-shaped plate (15) are mounted on the base plate (3). The flexible mechanism (14) has two mounting slots. One mounting slot is used to mount the friction head (11), which adopts a flexible structure design to compensate for assembly errors. The other mounting slot is used to mount the piezoelectric element (16). Each mounting slot has a threaded hole at its fixed position. One hole is used to fix the friction head (11), and the other is used to pre-tighten the piezoelectric element (16). The L-shaped plate (15) is used to strengthen the fixation of the flexible mechanism. A positioning plane is provided at the position where the flexible mechanism is fixed on the base plate to ensure the horizontal positioning accuracy of the flexible mechanism. Output module The system includes an output guide rail (9), a biomimetic non-smooth surface (10), and a reflector (8). The output guide rail (9) is mounted on a guide rail support plate (7). The pre-tightening force applied by the pre-tightening module cooperates with the friction head (11) to provide driving force for the output module. A positioning surface is provided on the guide rail support plate (7) at the position where the output guide rail (9) is mounted to ensure the lateral positioning accuracy of the output guide rail (9). The biomimetic non-smooth surface (10) adopts a U-shaped groove structure and is fixed to the output guide rail (9) with screws to ensure that the inner surface is completely in contact with the output guide rail (9). The reflector (8) is mounted on the output guide rail (9) to reflect the laser micrometer (19) emitted by the displacement detection module. The light is used to measure the output displacement of the output module; the pre-tightening module is divided into a piezoelectric element pre-tightening mechanism and a pre-tightening mechanism that provides positive pressure to the friction pair. The piezoelectric element pre-tightening mechanism includes a flexible mechanism (14) and a pre-tightening screw (17) to pre-tighten the piezoelectric element (16); the pre-tightening mechanism that provides positive pressure to the friction pair includes a manual displacement stage (1) and a push plate (2). The manual displacement stage (1) is installed on the base plate (3). A positioning surface is provided at the position where the manual displacement stage (1) is installed on the base plate (3) to ensure the lateral positioning accuracy of the manual displacement stage (1). The push plate (2) adopts a U-shaped groove structure and is fixed to the manual displacement stage (1) with screws to ensure that the inner surface is flush with the manual displacement stage (1). The pressure measurement module includes pressure sensor A (4), pressure sensor B (6), pressure sensor controller A (20), and pressure sensor controller B (21). Pressure sensor A (4) is placed on the base plate (3) to measure the normal pressure of the friction pair. Pressure sensor controller A (20) is connected to pressure sensor A (4) to display the pressure magnitude. Pressure sensor B (6) is placed on the guide rail support plate (7) to measure the friction force on the output module. Pressure sensor controller B (21) is connected to pressure sensor B (6) to display the magnitude of the friction force. Finally, the friction coefficient of the friction pair is calculated using Coulomb's law of friction. The specific formula is as follows: ； Where N represents the normal force of the friction pair, and F represents the frictional force on the output module; The formula for calculating the basic error δ caused by the influence of sensor performance during the testing process is as follows: ； Wherein, NL represents pressure nonlinearity, HY represents pressure hysteresis, and PR represents pressure repeatability; The displacement detection module includes a laser micrometer (19), a controller (22), and a computer (23). The laser micrometer (19) is used to measure the output displacement of the output module, and the computer is used to display the magnitude of the displacement in real time and draw the displacement-time curve.

2. The testing method for a piezoelectric-driven biomimetic non-smooth surface friction performance testing device according to claim 1, characterized in that: Includes the following steps: Step (1): Select the friction head (11) and bionic non-smooth surface (10) to be tested, perform strict cleaning of residual stains on the surface, measure its overall mass with an electronic balance and record it as M1, and then install it in the mounting slot of the flexible mechanism (14) and on the output guide rail (9) respectively. Step (2): Apply appropriate preload to the piezoelectric element (16) by rotating the preload screw (17), adjust the positive pressure of the friction pair to the target value by manually adjusting the displacement table (1), and measure it in real time by the pressure sensor A (4) and display it by the pressure sensor controller A (20). Step (3): Install the baffle (12) onto the output guide rail (9), slide the baffle (12) into contact with the pressure sensor B (6), and use it to measure the friction force between the friction head and the non-smooth surface of the output. The force is displayed by the pressure sensor controller B (21). Align the laser micrometer (19) with the reflector (8) and adjust it to a suitable working distance. Measure the output displacement of the output module in real time and upload it to the computer (23) to display the measurement results. Step (4): Apply a certain frequency driving signal to the piezoelectric element (16) to make the test device work and measure the corresponding friction coefficient. During the operation of the device, collect displacement-time data and plot the curve. When the change in the slope of the curve is greater than the preset value, stop the test, record the test time and measure the friction coefficient after wear. Step (5): Remove the friction head (11) and the biomimetic non-smooth surface (10), perform rigorous cleaning of residual surface stains, measure its overall mass and record it as M2, and then calculate the mass difference before and after the test as an indicator of wear resistance performance. The specific formula is as follows: ； Where ΔM represents the quality difference before and after the test, M1 represents the overall quality before the test, and M2 represents the overall quality after the test. Finally, the wear amount per unit time is calculated using the following formula: ； Where W represents the wear rate and T represents the test time.

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