CN117073539A - Piezoelectric ceramic bit output characteristic testing device and method - Google Patents

Abstract

The invention belongs to the field of piezoelectric ceramic characteristic measurement, and provides a piezoelectric ceramic power position output characteristic testing device and method. The method has the advantages that the pressure sensor is arranged in the testing device, the external force applied to the piezoelectric ceramic can be obtained in real time, the spring at the front end can provide allowance for the expansion and contraction of the piezoelectric ceramic while applying pressure, the damage of the piezoelectric ceramic is avoided, and the displacement of the piezoelectric ceramic can be measured by the laser displacement sensor. The laser displacement sensor adopts a floating design, avoids the deformation influence of structural members, and ensures that the measuring head end and the measuring tail end are consistent with the ceramic elongation displacement. In order to ensure the neutrality of the ceramic, the device adopts a spherical matching structure for pretightening. The output displacement measurement of the piezoelectric ceramics under different driving voltages and different stress states is realized. The mode of bolt pretension and spring force can guarantee that ceramic receives the directional load that the size is stable in extension action. The whole test method can ensure the synchronous and accurate measurement of force and position and has the characteristics of compact structure, simple and convenient control and the like.

Description

A piezoelectric ceramic force position output characteristic testing device and method

Technical field

The invention relates to the field of piezoelectric ceramic characteristic measurement, and in particular to a piezoelectric ceramic force position output characteristic testing device and method.

Background technique

The dynamic stability derivative is a key parameter in the analysis and design of aircraft stability and controllability, and has an important impact on the design of the aircraft's control system and flight quality. As aircraft systems continue to develop in the direction of high speed and precision, the performance requirements for aircraft design are also constantly increasing. Among them, the damping derivatives, cross derivatives, and cross coupling derivatives generated by the aircraft under ultra-high speed and large-scale maneuvers include Dynamic derivatives play a vital guiding role in aircraft shape analysis and design. For example, the cross-coupling derivatives generated by the longitudinal motion of the aircraft under large angles of attack significantly affect the stability of the aircraft. Since the effects of pure rotational rate and translational acceleration cannot be separated in traditional forced vibration tests, the combined dynamic derivative is given. Usually, some mathematical models use combined dynamic derivatives to give predicted flight characteristics that are reasonably consistent with the actual situation. However, this approximation is not applicable in all cases. For example, using rotationally forced oscillation data to represent the derivatives produced by pure rotational angular rates can produce non-negligible deviations at large angles of attack. Therefore, it is necessary to determine the dynamic derivatives and their coupling effects in each direction of pitch, yaw and roll to improve the prediction of aircraft flight characteristics.

The multi-degree-of-freedom dynamic derivative experiment of an aircraft in a high-speed wind tunnel faces the following difficulties: first, the driving element needs to drive the model to complete multi-dimensional composite excitation motion in a limited space; second, the driving element needs to resist instantaneous vibration in a complex flow field environment. Variable multi-dimensional loads and output precision motion; finally, the measurement tasks of various dynamic derivatives are different. In order to enhance the adaptability of the test mechanism, the driving components need to have high load-bearing, high stiffness, wide-band response and other capabilities. Conventional dynamic derivative testing mechanisms No longer applicable. The stacked piezoelectric ceramic actuator arranges piezoelectric ceramic sheets in series in structure, and the piezoelectric ceramic sheets are connected in parallel on the circuit. It has the characteristics of fast response speed, compact structure, etc., and the piezoelectric ceramics are small in size and have high driving force. It has a large ratio to energy consumption and can efficiently convert electrical energy into mechanical energy. As an actuator for dynamic derivative test equipment, it can achieve better driving effects. However, the physical properties of the piezoelectric material itself cause it to have nonlinear characteristics such as hysteresis and creep, and its load limits are different in all directions. The axial load capacity is much greater than the tangential direction. It is necessary to ensure that the piezoelectric ceramics are stressed in the axial direction to strengthen the Device reliability. The output displacement of piezoelectric ceramics will relatively decrease when force is applied, showing a time-varying nonlinear stiffness characteristic, which seriously affects the control accuracy of piezoelectric ceramic actuators in practical applications. This requires testing and research on the stress limit and output displacement characteristics of piezoelectric ceramics under different driving voltages and load conditions. Currently commonly used piezoelectric ceramic displacement measurement devices and measurement methods do not consider the coupling relationship between the load characteristics of piezoelectric ceramics and the output displacement characteristics.

The patent "Piezoelectric Ceramic Actuator Displacement Measuring Device" by Chen Shenghua and others, with patent number CN202121375877.0, discloses a piezoelectric ceramic actuator displacement measuring device. This device uses a piezoelectric ceramic actuator to push the weak part to deform. High-precision strain gauges are pasted on the weak part of the outer frame to measure the displacement, which can greatly improve the torsional strength of the piezoelectric ceramic actuator itself. The patent "An Experimental Instrument for Measuring Voltage-Displacement Characteristics of Piezoelectric Materials" by Pei Shixin and others, with patent number CN201820915686.0, discloses a piezoelectric ceramic actuator displacement measurement device based on the Michelson interference principle. It controls the movement of the plane mirror by changing the operating voltage of the piezoelectric material, and then measures the movement number of the interference fringes to obtain the relationship between the displacement of the piezoelectric material and the loading voltage. However, the above device does not consider the impact of external force on the ceramic output, and can only characterize the output of the piezoelectric ceramic when it is no-load.

The patent "An Active Piezoelectric Ceramic Maximum Output Force Measuring Device" by Rong Weibin et al., patent number CN201610891447.1 discloses an active piezoelectric ceramic maximum output force measuring device. The device has high stiffness, can achieve zero displacement output when the piezoelectric ceramic force is output, and can accurately measure and calibrate the force output values at different displacement outputs. However, this device uses a large stiffness structure to fix the displacement of the piezoelectric ceramics and ignores the influence of external forces on the piezoelectric ceramics. It can only measure the maximum output force of the ceramics at a certain displacement and cannot obtain the force displacement of the piezoelectric ceramics under the action of different external forces. Correspondence.

Contents of the invention

The main technical problem solved by the present invention is to overcome the shortcomings of the existing technology and invent a piezoelectric ceramic force position output characteristic testing device and method to realize the output displacement measurement of piezoelectric ceramics under different driving voltages and different stress states.

The technical solution of the present invention is as follows: a piezoelectric ceramic force position output characteristic testing device, including a parallel block 1, a main body 2, a spring 4, a front pressure plate 5, a laser displacement sensor 7, a sensor positioning plate 8, a cantilever 9, a rear End pressure plate 11, pressure sensor 13, piezoelectric ceramics 14, movable base 15, main base 18, cylindrical cover 19, adjustable support block 20 and force conduction stud 22; the main base 18 is L-shaped, with One side is fixedly connected to one end of the main body 2, and the other side is fixed to one side of the main body 2 through an adjustable support block 20; a trapezoidal groove is opened at the bottom of the main body 2, and one end of the adjustable support block 20 is in the trapezoidal groove to support the main body 2; inside the main body 2 There are 3 cylindrical grooves of different sizes. The spring 4 and the front pressure-bearing plate 5 are installed in the first cylindrical groove. There is a transverse groove at the bottom of the first cylindrical groove; one end of the front-end pressure plate 5 is connected to the parallel block 1, and the parallel block 1 is at Move in the transverse groove; one side of the front end pressure-bearing plate 5 is a protrusion, the spring 4 is set on the protrusion, and both ends are in contact with the inner wall of the first cylindrical groove and the front end pressure-bearing plate 5 respectively; installed in the second cylindrical groove Piezoelectric ceramics 14; the rear pressure-bearing plate 11 is installed in the third cylindrical groove; both ends of the piezoelectric ceramics 14 contact the front pressure-bearing plate 5 and the rear pressure-bearing plate 11 respectively through the moving base; one end of the rear pressure-bearing plate 11 The pressure sensor 13 is connected to the pressure sensor 13 through the force transmission stud 22; the pressure sensor 13 is fixed on one side of the main body base 18; the other end of the rear end pressure plate 11 is connected to one end of the cantilever 9; the other end of the cantilever 9 is connected to the sensor positioning plate 8; the sensor is positioned The laser displacement sensor 7 is installed on the plate 8; the cylindrical cover 19 is installed on the main body 2.

A piezoelectric ceramic force position output characteristic testing method, based on the piezoelectric ceramic force position output characteristic testing device, measuring the output displacement of the piezoelectric ceramic under different driving voltages and different force states; the specific steps are as follows:

The first step: Assemble the piezoelectric ceramic force position output characteristic testing device; the laser displacement sensor 7 and the pressure sensor 13 are connected to the data acquisition module; the data acquisition module is connected to the host computer, real-time controller and power amplifier in turn; install the piezoelectric ceramic 14 to On the piezoelectric ceramic force position output characteristic testing device, a preload force is applied to the piezoelectric ceramic 14; the power amplifier is connected to the piezoelectric ceramic 14;

Step 2: Apply input signals of different sizes, frequencies and waveforms to the piezoelectric ceramic 14 to complete the piezoelectric ceramic preset experiment;

Step 3: Collect the output data of the laser displacement sensor 7 and the pressure sensor 13 through the host computer. After processing the data, the displacement values of the piezoelectric ceramic 14 under different voltages and the corresponding pressure values are obtained.

The displacement value of the piezoelectric ceramic 14 and its corresponding pressure value are as follows:

The laser displacement sensor 7 includes a laser, a CCD camera and a photosensitive element; the laser emitted by the laser is incident on the surface of the object being measured at a certain angle with the normal line of the object surface, and the reflected light and scattered light are condensed and imaged by the lens at O, and are finally captured by the photosensitive element collection;

The angle between the incident light AB and the baseline AC is α, AO is the distance between the center of the laser and the center of the CCD camera, OE is the focal length f of the lens, and D is the limit of the reflected light imaging on the photosensitive element when the measured object is infinitely far away from the baseline. position; DF is the displacement of the light spot from the limit position on the photosensitive unit, recorded as x; △ABO∽△DOF, then there is a side length relationship:

When the measured surface is relatively displaced from the baseline AO, x changes to x’. From the above conditions, the displacement value y of the piezoelectric ceramic 14 is:

In the pressure sensor 13, the strain gauges are arranged as a Wheatstone bridge and deflect when pressure is applied;

The force at both ends of the piezoelectric ceramic 14 is given by formula (5):

Among them, ΔL represents the displacement value of the piezoelectric ceramic 14 , E represents the elastic modulus of the piezoelectric ceramic 14 , S represents the cross-sectional area of the piezoelectric ceramic 14 , and L is the length of the piezoelectric ceramic 14 .

Beneficial effects of the present invention: a piezoelectric ceramic force position output characteristic testing device and method are proposed to realize the output displacement measurement of piezoelectric ceramics under different driving voltages and different stress states. The piezoelectric ceramic force position output characteristic testing device has a built-in pressure sensor that can obtain the pressure on the piezoelectric ceramic in real time. The high-stiffness spring at the front end can provide margin for the expansion and contraction of the piezoelectric ceramic while applying pressure, ensuring that the ceramic can expand and contract freely under a stable load. , the displacement of piezoelectric ceramics can be measured by a laser displacement sensor, which can provide high-precision data for piezoelectric ceramic dynamic modeling and so on.

Description of the drawings

Figure 1 is a schematic connection diagram of the piezoelectric ceramic force position output characteristic testing device of the present invention;

Figure 2 is a flow chart of the piezoelectric ceramic force position output characteristic testing method of the present invention;

Figure 3 is a structural diagram of the piezoelectric ceramic force position output characteristic testing device of the present invention;

Figure 4 is a cross-sectional view of the center of the piezoelectric ceramics and pressure sensor;

Figure 5 is a structural diagram of the bottom of the main body;

Figure 6 shows the working principle diagram of the laser displacement sensor;

Figure 7 shows the working principle diagram of the pressure sensor.

In the picture: 1-parallel block, 2-main body, 3-cylindrical cover set screw, 4-spring, 5-front pressure plate, 6-laser displacement sensor set screw, 7-laser displacement sensor, 8-sensor positioning Plate, 9-cantilever, 10-positioning plate set screw, 11-rear end pressure plate, 12-cantilever set screw, 13-pressure sensor, 14-piezoelectric ceramics, 15-moving base, 16-positioning pin , 17-main body set screw, 18-main base, 19-cylindrical cover, 20-adjustable support block, 21-force sensor set screw, 22-force conduction stud.

Detailed ways

The implementation process of the present invention will be described in detail below with reference to the technical solutions and drawings.

The piezoelectric ceramic force position output characteristic testing device has a built-in pressure sensor 13, which can obtain the external force exerted by the piezoelectric ceramic 14 in real time. The front spring 4 can provide margin for the expansion and contraction of the piezoelectric ceramic while applying pressure to avoid damage to the piezoelectric ceramic 14. , the displacement of the piezoelectric ceramic 14 can be measured by the laser displacement sensor 7 . The laser displacement sensor 7 adopts a floating design to avoid the influence of deformation of structural parts and ensure that the measurement head and end are consistent with the elongation displacement of the piezoelectric ceramic. In order to ensure the force neutrality of piezoelectric ceramics, the piezoelectric ceramic force position output characteristic testing device adopts a spherical matching structure to preload. The bolt pre-tightening and spring force application can ensure that the ceramic is subjected to a stable directional load during the elongation action. The overall testing method can ensure synchronous and accurate measurement of force and position, and has the characteristics of compact structure and simple control.

The technical solutions adopted in this method are as follows:

The first step: Assemble the piezoelectric ceramic force position output characteristic testing device; install the piezoelectric ceramic 14 on the piezoelectric ceramic force position output characteristic testing device, and apply a preload force to the piezoelectric ceramic 14;

As shown in Figure 1, the piezoelectric ceramic force position output characteristic testing device, power amplifier, real-time controller, data acquisition device, host computer, etc. form a piezoelectric ceramic data acquisition hardware system. The structure of the test device is shown in Figures 3, 4, and 5. The parallel block 1 fixes the front pressure plate 5 to the front end of the main body 2 through a threaded connection to ensure the verticality of the front pressure plate 5 and the main body 2; the rear pressure plate 11 Cooperate with the groove of the main body 2 to determine the verticality; the movable bases 15 at both ends of the piezoelectric ceramic 14 cooperate with the grooves in the middle of the front pressure-bearing plate 5 and the rear pressure-bearing plate 11 to ensure that the ceramic pressure measured by the pressure sensor 13 The output is axial output; a trapezoidal groove is opened at the bottom of the main body 2, and the positioning pin 16 and the adjustable support block 20 cooperate with the main body base 18 to position and support the main body to maintain a horizontal state; the main body 2 is connected to the main body through the main body tightening screw 17 The base 18 is connected, and different initial pre-tightening forces can be applied to the piezoelectric ceramics 14 through the main body set screw 17; the pressure sensor 13 is connected to the main body base 18 through the pressure sensor set screw 21; the rear end pressure plate 11 is connected through The force transmission stud 22 is connected to the pressure sensor 13, which can transmit the force of the piezoelectric ceramic 14 to the pressure sensor in real time, and at the same time determine the position of the rear end pressure plate 11; the cantilever 9 is connected to the rear end pressure through the cantilever set screw 12 The plate 11 is connected; the sensor positioning plate 8 is connected to the cantilever 9 through the positioning plate set screw 10; the laser displacement sensor 7 is connected to the sensor positioning plate 8 through the laser displacement sensor set screw 6, the laser displacement sensor 7 is fixed, and it is connected to the front end by measuring The relative distance of the pressure-bearing plate 5 obtains the output displacement of the piezoelectric ceramic 14; the cylindrical cover 19 is connected to the main body 2 through the cylindrical cover set screw 3, which can prevent the internal components of the main body from coming out.

Step 2: Apply input signals of different sizes, frequencies and waveforms to the piezoelectric ceramic 14 to complete the piezoelectric ceramic preset experiment;

Step 3: Collect the output data of the laser displacement sensor 7 and the pressure sensor 13 through the host computer. After processing the data, the displacement values of the piezoelectric ceramic 14 under different voltages and the corresponding pressure values are obtained.

In summary, the force position output characteristic data of the piezoelectric ceramic 14 is obtained through the piezoelectric ceramic testing system.

In the laser displacement sensor 7, the laser, CCD camera and photosensitive element are the main components of the laser displacement sensor. As shown in the optical path diagram in Figure 6, the laser emitted by the laser is incident on the surface of the measured object at a certain angle with the normal line of the object surface. The reflected light and scattered light are condensed and imaged through the lens at O, and finally collected by the photosensitive element;

The angle between the incident light AB and the baseline AC is α, AO is the distance between the center of the laser and the center of the CCD camera, OE is the focal length f of the lens, and D is the limit of the reflected light imaging on the photosensitive element when the measured object is infinitely far away from the baseline. position; DF is the displacement of the light spot from the limit position on the photosensitive unit, recorded as x; △ABO∽△DOF, then there is a side length relationship:

When the measured surface is relatively displaced from the baseline AO, x changes to x’. From the above conditions, the displacement value y of the piezoelectric ceramic 14 is:

In the pressure sensor 13, the strain gauges are arranged as a Wheatstone bridge and deflect when pressure is applied;

The force at both ends of the piezoelectric ceramic 14 is given by formula (5):

Among them, ΔL represents the displacement value of the piezoelectric ceramic, E represents the elastic modulus of the piezoelectric ceramic, S represents the cross-sectional area of the piezoelectric ceramic, and L is the length of the piezoelectric ceramic.

The piezoelectric ceramic force position output characteristic testing device of the present invention can measure the output displacement of the piezoelectric ceramic under different driving voltages and different stress states. The device has a compact structure and easy control, and can provide high-precision data for piezoelectric ceramic dynamics modeling, etc., filling the gaps in the existing technical field and having great application potential.

Claims (3)

1. The piezoelectric ceramic force position output characteristic testing device is characterized by comprising a parallel block (1), a main body (2), a spring (4), a front end bearing plate (5), a laser displacement sensor (7), a sensor positioning plate (8), a cantilever (9), a rear end bearing plate (11), a pressure sensor (13), piezoelectric ceramic (14), a movable base (15), a main body base (18), a cylindrical cover (19), an adjustable supporting block (20) and a force transmission stud (22); the main body base (18) is L-shaped, one side of the main body base is fixedly connected with one end of the main body (2), and the other side of the main body base is fixed on one side of the main body (2) through the adjustable supporting block (20); the bottom of the main body (2) is provided with a trapezoid groove, one end of an adjustable supporting block (20) is arranged in the trapezoid groove, and the main body (2) is supported; the main body (2) is internally provided with 3 cylindrical grooves with different sizes, a spring (4) and a front end bearing plate (5) are arranged in the first cylindrical groove, and the bottom of the first cylindrical groove is provided with a transverse groove; one end of the front end bearing plate (5) is connected with the parallel block (1), and the parallel block (1) moves in the transverse groove; one side of the front end bearing plate (5) is a bulge, the spring (4) is sleeved on the bulge, and the two ends of the spring are respectively contacted with the inner wall of the first cylindrical groove and the front end bearing plate (5); a piezoelectric ceramic (14) is arranged in the second cylindrical groove; a rear end bearing plate (11) is arranged in the third cylindrical groove; two ends of the piezoelectric ceramic (14) are respectively contacted with the front end bearing plate (5) and the rear end bearing plate (11) through the movable base; one end of the rear end bearing plate (11) is connected with the pressure sensor (13) through a force transmission stud (22); the pressure sensor (13) is fixed on one side of the main body base (18); the other end of the rear end bearing plate (11) is connected with one end of the cantilever (9); the other end of the cantilever (9) is connected with a sensor positioning plate (8); a laser displacement sensor (7) is arranged on the sensor positioning plate (8); a cylindrical cover (19) is arranged on the main body (2).

2. The method for testing the output characteristics of the piezoelectric ceramic power position is characterized by measuring the output displacement of the piezoelectric ceramic under different driving voltages and different stress states based on the device for testing the output characteristics of the piezoelectric ceramic power position according to claim 1; the method comprises the following specific steps:

the first step: assembling a piezoelectric ceramic bit output characteristic testing device; the laser displacement sensor (7) and the pressure sensor (13) are connected with the data acquisition module; the data acquisition module is sequentially connected with the upper computer, the real-time controller and the power amplifier; mounting the piezoelectric ceramic (14) on a piezoelectric ceramic power position output characteristic testing device, and applying a pretightening force to the piezoelectric ceramic (14); the power amplifier is connected with the piezoelectric ceramics (14);

and a second step of: applying input signals with different sizes, different frequencies and different waveforms to the piezoelectric ceramic (14) to finish a piezoelectric ceramic preset experiment;

and a third step of: the upper computer is used for collecting output data of the laser displacement sensor (7) and the pressure sensor (13), and the piezoelectric ceramic (14) displacement values and the corresponding pressure values under different voltages are obtained after the data are processed.

3. The method for testing the output characteristics of the piezoelectric ceramic power bit according to claim 2, wherein the displacement value of the piezoelectric ceramic (14) and the corresponding pressure value thereof are specifically as follows:

the laser displacement sensor (7) comprises a laser, a CCD camera and a photosensitive element; the laser emitted by the laser device and the normal line of the object surface form a certain angle to be incident on the surface of the object to be measured, the reflected light and the scattered light are converged and imaged by the lens at the O position, and finally collected by the photosensitive element;

the included angle between the incident light AB and the base line AC is alpha, AO is the distance between the center of the laser and the center of the CCD camera, OE is the focal length f of the lens, and D is the limit position of the reflected light on the photosensitive element when the measured object is far from the base line infinity; DF is the displacement of the light spot deviating from the limit position on the photosensitive unit and is marked as x; delta ABO-Delta DOF, there is a side length relationship:

when the measured surface and the base line AO generate relative displacement, x is changed into x', and the displacement value y of the piezoelectric ceramic (14) is obtained by the conditions:

in the pressure sensor (13), the strain gauge is arranged as a wheatstone bridge, the strain gauge being deflected when pressure is applied;

the magnitude of the stress at the two ends of the piezoelectric ceramic (14) is given by the formula (5):

wherein DeltaL represents a displacement value of the piezoelectric ceramic (14), E represents an elastic modulus of the piezoelectric ceramic (14), S represents a cross-sectional area of the piezoelectric ceramic (14), and L is a length of the piezoelectric ceramic (14).