WO2020191704A1 - Composite material dynamic fatigue testing device and method based on reverse resonance - Google Patents

Abstract

Provided are a composite material dynamic fatigue testing device and a method based on reverse resonance, wherein the testing device comprises a double-cantilever-beam vibration testing system, an electronic acquisition system, and a measurement and control system; the device uses an eccentric motor (3) to drive a beam to be tested (12) to vibrate, compared with a vibration exciter, the device has a small size and less energy consumption, and is convenient to carry, the device uses a double-cantilever vibration beam (2) to drive the beam to be tested (12) to vibrate through inverse resonance, the test efficiency is improved and energy is saved, compared with the prior testing device, the device broadens an amplitude range of the beam to be tested (12). The method precisely controls the eccentric motor (3), uses a variety of precision instruments to measure and analyze the fatigue features of the material to be tested from optics, acoustics, time domain waveform, etc., and has extremely high test accuracy. The device is simple, most of components are detachable, dismounting is convenient, portability is good and the device is easy to operate.

Description

Composite material dynamic fatigue test device and method based on inverse resonance Technical field

The invention belongs to the technical field of composite material structural fatigue testing, and specifically relates to a composite material dynamic fatigue testing device and method based on inverse resonance.

Background technique

With the deepening of research, fiber-reinforced composite materials have high specific strength, high specific modulus, good thermal stability, and certain damping and vibration reduction capabilities, and many superior properties are known to people. They are not only widely used in aviation Aerospace and other high-tech fields can also be used in cultural and sports supplies, textile machinery, medical equipment, biological engineering, building materials, chemical machinery, transportation vehicles, etc. However, in the process of using composite material components, it is often damaged or even destroyed due to stress and environmental factors, among which fatigue damage is one of the main failure forms. The generation, expansion and accumulation of fatigue damage will aggravate the environment and stress corrosion of the material, accelerate the aging of the material, cause a serious decline in the environmental resistance of the material and a sharp loss of strength and rigidity, greatly reduce the service life of the material, and even cause catastrophic consequences . Therefore, it is extremely important to study the fatigue properties of composite materials and their parts, which is of great significance to the future research and manufacturing of composite materials.

At present, people have conducted in-depth research in the field of composite material fatigue testing, and some fatigue testing machines have been designed. Patent CN 108801823 A uses a vibration exciter to measure aircraft structures and provides a multi-scale composite material structure local fatigue assessment method and system. However, the vibration exciter is not suitable for the measurement of large structures. You will encounter difficulties when making parts. Patent CN 105004618 A uses an eccentric wheel for testing and provides a test method for fatigue analysis of rubber composite materials, but it only studies rubber composite materials with a narrow research scope and insufficient control of the eccentric wheel during the measurement process. It is not considered to achieve the effect of improving efficiency by controlling the eccentric to make the material resonate. Patent CN 107966354 A uses laminated unidirectional plates to measure the fatigue of composite materials, and provides a method, device and electronic equipment for predicting fatigue life of composite materials, but it relies too much on the support of existing databases to improve the fatigue performance of new composite materials Insufficient research capabilities. The electro-hydraulic servo method can realize large load loading, but the work efficiency is low. The electromagnetic resonance method uses electronic control technology to achieve the purpose of energy saving, but the amplitude is small and it is not easy to control.

With the widespread use of fiber-reinforced composite materials, although the traditional universal material testing machine can evaluate materials to a certain extent, for example, the materials can be subjected to separate static load loading such as tension, compression, and torsion. The effect of force on fatigue characteristics, the test frequency is very low (about 3 ~ 10Hz) can not carry out dynamic fatigue testing. The universal material testing machine has great limitations and is not suitable for the measurement and evaluation of the fatigue characteristics of fiber reinforced composite materials at this stage.

Summary of the invention

In order to solve the problems in the prior art, the present invention provides a composite material dynamic fatigue test device and method based on inverse resonance. The technical solution is as follows:

A composite material dynamic fatigue test device based on inverse resonance, including a double cantilever beam vibration test system, an electronic acquisition system, and a measurement and control system;

The double-cantilever beam vibration test system includes two cantilever vibration beams, an eccentric motor and a bottom plate. The left side of the top of the bottom plate is fixedly equipped with a left fixed plate, and the right side of the top of the bottom plate is slidably equipped with a right fixed plate, and a left fixed plate and The right fixed plate is arranged in parallel, two cantilever vibration beams are arranged between the left fixed plate and the right fixed plate, the left end of the left cantilever vibration beam is fixedly connected with the left fixed plate, and the right end of the right cantilever vibration beam is connected to the right The side fixed plate is fixedly connected, the right end of the left cantilever vibrating beam and the left end of the right cantilever vibrating beam are both suspended and equipped with eccentric motors. The two ends of the beam to be measured are connected to the right and right cantilever of the left cantilever vibrating beam. The left end of the vibrating beam is fixedly connected, the left cantilever vibrating beam, the right cantilever vibrating beam and the beam to be measured are arranged collinearly, the two eccentric motors are arranged symmetrically around the beam to be measured, and there is a half cycle between the two eccentric motors的phase difference;

The electronic acquisition system includes a displacement sensor, a test recorder 16 and a data acquisition card. There are three displacement sensors, which are respectively arranged below the right end of the left cantilever vibrating beam, below the left end of the right cantilever vibrating beam, and the beam to be tested. The upper part is used to measure the vibration deformation of the cantilever vibrating beam and the beam to be tested. The test recorder 16 is set behind the beam to be tested for recording test records. The data acquisition card is electrically connected to the displacement sensors and the test recorder 16 respectively. , Used to store the data collected by the displacement sensor and the test recorder 16;

The measurement and control system includes a numerical control panel 21, the numerical control panel 21 is fixedly connected to the base plate, the numerical control panel 21 is electrically connected with a data acquisition card and two eccentric motors, and the numerical control panel 21 has a built-in measurement and control software based on LabVIEW for Receive and record the test records of the test recorder 16, and integrate the data in the data acquisition card for comprehensive analysis.

The electronic acquisition system further includes a sound sensor and an electron microscope, the sound sensor is arranged below the beam to be measured, the electron microscope is arranged above the beam to be measured, and both the sound sensor and the electron microscope are electrically connected to the data acquisition card;

The displacement sensors located below the right end of the left cantilever vibrating beam and the left end of the right cantilever vibrating beam are specifically eddy current displacement sensors, and the displacement sensor located above the beam to be measured is specifically a laser displacement sensor.

The top of the bottom plate is provided with a first guide rail, the first guide rail is arranged in parallel with the cantilever vibration beam, the first guide rail is slidably fitted with a first guide rail slider, and the right side fixing plate is fixedly assembled on the top of the first guide rail slider, so A mechanical locking mechanism is arranged between the first rail slider and the first rail.

The left end of the left cantilever vibrating beam and the left fixed plate, and the right end of the right cantilever vibrating beam and the right fixed plate are all fixedly connected by a cantilever beam clamping device, and the cantilever beam clamping device includes a lower A fastening support device, an upper fastening device and a lower fastening support pad, the lower fastening support device is fixedly connected to the left side fixing plate or the right side fixing plate, and the upper fastening device is connected to the lower fastening support device by bolts , The cantilever vibration beam is clamped between the upper fastening device and the lower fastening support device. There are gaps between the left cantilever vibration beam and the left fixed plate, and the right cantilever vibration beam and the right fixed plate. The fastening support pad is assembled in the gap, and the thickness of the lower fastening support pad is smaller than the thickness of the cantilever vibration beam.

The fracture toughness of the cantilever vibration beam is at least

The bottom plate is also provided with a second guide rail, the second guide rail is arranged parallel to the cantilever vibration beam, the second guide rail is slidably fitted with three lower guide rail brackets, and the tops of the three lower guide rail brackets are respectively arranged from left to right Eddy current displacement sensor, sound sensor and eddy current displacement sensor.

An upper support beam is provided on the top of the left and right fixed plates, the top of the upper support beam is equipped with a third guide rail, the third guide rail is arranged in parallel with the cantilever vibration beam, and the third guide rail is slidably fitted with two On the upper rail bracket, the bottom of the two upper rail brackets are respectively provided with a laser displacement sensor and an electron microscope from left to right.

The two ends of the beam to be measured are respectively detachably connected to the left cantilever vibration beam and the right cantilever vibration beam. The right end surface of the left cantilever vibration beam and the left end surface of the right cantilever vibration beam are provided with connection holes. The two ends of the measuring beam are respectively inserted into the connecting holes on both sides. The right top of the left cantilever vibration beam and the left top of the right cantilever vibration beam are equipped with locking screws, and the two locking screws respectively vibrate with the left cantilever. The beam and the right cantilever vibration beam are screwed together, and the screw rods of the two locking screws respectively extend into the connecting holes on both sides to contact the tops of the left and right sides of the beam to be measured.

A right arch is provided on the right side of the test device, the right arch is fixedly connected to the top of the bottom plate, the outer side of the right arch is fixedly equipped with a right protective cover, the front side of the test device is provided with a front protective cover, and the front protective cover is fixedly connected to the top of the bottom plate, The top, back and left sides of the test device are provided with protective plates;

A supporting device is arranged below the bottom plate, the supporting device includes a supporting leg and a supporting angle iron, the supporting leg is provided with a plurality of sets of fixing holes from top to bottom, and the bottom plate is bolted to the supporting leg through a set of fixing holes to support The angle iron is fixedly assembled on the bottom of the supporting leg.

A composite material dynamic fatigue test method based on inverse resonance. The aforementioned composite material dynamic fatigue test device based on inverse resonance is characterized in that it comprises the following steps:

Step 1. Use the cantilever beam clamping devices on the left fixed plate and the right fixed plate to clamp the two cantilever vibration beams respectively, and assemble the two eccentric motors on the suspended ends of the two cantilever vibration beams;

Step 2. Make the composite material to be tested into a beam to be tested of appropriate size, and fix it between the cantilever vibrating beams on both sides by locking screws, adjust the positions of the eccentric motors on both sides, and measure the center distance of the left eccentric motor respectively. The distance between the right end of the side cantilever vibrating beam, the distance between the center of the right eccentric motor and the left end of the right cantilever vibrating beam, the size of the beam to be measured and the size of the cantilever vibrating beam, power on each system, and input the measured distance and size to the CNC panel 21 Built-in measurement and control software;

Step 3. Close the right shield and the front shield, start the two eccentric motors, the laser displacement sensor and the eddy current displacement sensor transmit the vibration data of the two cantilever vibration beams and the beam to be measured to the measurement and control software built into the numerical control panel 21. Form the time-domain waveform diagrams of the vibration of the cantilever vibrating beam and the beam to be measured. By observing the time-domain waveform diagrams of the two cantilever vibrating beams, control the vibration frequency and phase of the two eccentric motors, so that the two cantilever vibrating beams reach resonance respectively, and both There is a half-period phase difference to realize the reverse resonance of the two eccentric motors;

Step 4. The measurement and control software built into the numerical control panel 21 automatically judges whether fatigue damage has occurred:

When fatigue failure occurs, the time-domain waveform graph changes abruptly, and the system automatically judges whether the test stop requirement is met according to the change range. When the material meets the required test stop requirement, the control panel controls the eccentric motor to stop vibrating, and at the same time emits a test end prompt sound. The measurement and control software processes and analyzes the test data and evaluates the fatigue characteristics of materials;

Step 5. Use an electron microscope to observe the fatigue damage of the beam to be tested, take photos and record, combine the test data of the displacement sensor, the test recorder 16 and the sound sensor, and analyze the fatigue damage of the composite material under test by integrating the time domain waveform diagram, acoustics and optics .

Compared with the prior art, the beneficial effects of the present invention are:

The dual-cantilever vibrating beam type dynamic fatigue test device of the present invention is suitable for fatigue damage testing of a variety of composite materials, highlights the influence of dynamic load on composite material fatigue damage, and can study various situations including material high-cycle fatigue, low-cycle fatigue, etc. Under the fatigue damage characteristics and fatigue life. The invention uses an eccentric motor to drive the beam to be tested to vibrate. Compared with the exciter, it has the characteristics of small size, less energy consumption and convenient carrying. The invention uses the double cantilever vibrating beam to drive the beam to be tested to vibrate by using the reverse resonance of the double cantilever vibration beam to improve the test efficiency. , It saves energy, and compared with the existing test equipment, it widens the amplitude range of the beam to be tested. The present invention accurately controls the eccentric motor, and uses a variety of precision instruments to test the fatigue characteristics of the material to be measured from optics, acoustics, Time-domain waveforms and other aspects have been measured and analyzed, and have extremely high test accuracy. The equipment of the present invention is simple, and most of the components adopt a detachable design, which is convenient to disassemble, has good portability, and is easy to operate.

Description of the drawings

Figure 1 is a schematic diagram of the three-dimensional structure of the present invention;

2 is a schematic diagram of the three-dimensional structure of the double cantilever beam vibration test system of the present invention;

Figure 3 is a schematic diagram of the front structure of the double cantilever beam vibration test system of the present invention;

Figure 4 is a schematic diagram of the appearance of the present invention;

5 is a schematic diagram of the connection structure between the cantilever vibrating beam and the beam to be tested according to the present invention;

Fig. 6 is a schematic diagram of the connection structure of the cantilever beam clamping device of the present invention.

Among them: left fixed plate 1; cantilever vibrating beam 2; eccentric motor 3; upper rail bracket 4; laser displacement sensor 5; electron microscope 6; lower fastening support device 7; upper fastening device 8; right fixing plate 9; Right arch 10; eddy current displacement sensor 11; beam to be measured 12; sound sensor 13; lower rail bracket 14; third rail 15; test recorder 16; first rail 17; front protective cover 18; right protective cover 19; Two guide rails 20; numerical control panel 21; support legs 22; support angle iron 23; bottom plate 24; lower fastening support pad 25; first guide rail slider 26; upper support beam 27; connecting hole 28; locking screw 29; protection Board 30.

detailed description

It should be noted that all directional indicators (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relationship between components in a particular posture (as shown in the accompanying drawings). If the relative position relationship, movement situation, etc. change, the directional indication will change accordingly.

As shown in Figure 1 to Figure 6, the present invention provides a composite material dynamic fatigue test device based on inverse resonance, including a double cantilever beam vibration test system, an electronic acquisition system, and a measurement and control system;

The double cantilever beam vibration test system includes two cantilever vibration beams 2, an eccentric motor 3, and a bottom plate 24. The top left side of the bottom plate 24 is fixedly equipped with a left fixed plate 1, and the top right side of the bottom plate 24 is slidably equipped with a right fixed plate. 9. The distance between the left fixed plate 1 and the right fixed plate 9 can be adjusted to adapt to the cantilever vibrating beam 2 and the beam to be measured 12 of different lengths. The left fixed plate 1 and the right fixed plate 9 are arranged in parallel. A cantilever vibration beam 2 is arranged between the left fixed plate 1 and the right fixed plate 9, the left end of the left cantilever vibration beam 2 is fixedly connected to the left fixed plate 1, and the right end of the right cantilever vibration beam 2 is fixed to the right The plate 9 is fixedly connected, the right end of the left cantilever vibrating beam 2 and the left end of the right cantilever vibrating beam 2 are both suspended and equipped with eccentric motors 3 respectively. The two ends of the beam 12 to be measured are respectively connected to the right end of the left cantilever vibrating beam 2 It is fixedly connected to the left end of the right cantilever vibrating beam 2, the left cantilever vibrating beam 2, the right cantilever vibrating beam 2 and the beam under test 12 are arranged collinearly, and the two eccentric motors 3 are arranged symmetrically with the beam under test 12 as the center, and There is a half-cycle phase difference between the two eccentric motors 3, which improves test efficiency and saves energy.

Specifically, the eccentric motor 3 on the left and the eccentric motor 3 on the right respectively drive the left cantilever vibrating beam 2 and the right cantilever vibrating beam 2 to vibrate to achieve resonance effects respectively, and under the condition of applying accurate electrical signals ( The electrical signal comes from the numerical control panel 21), which accurately adjusts the rotation speed and phase of the eccentric motor 3, so that the cantilever vibration beams 2 on both sides can resonate and there is a half-period phase difference between the two. The eccentric motor 3 passes through the angle iron. And bolts are installed on the suspended end of the cantilever vibration beam 2, and the distance between the eccentric motor 3 and the suspended end of the cantilever vibration beam 2 can be adjusted.

The electronic acquisition system includes a displacement sensor, a test recorder 16 and a data acquisition card. There are three displacement sensors, which are respectively arranged below the right end of the left cantilever vibrating beam 2, and below the left end of the right cantilever vibrating beam 2, and to be tested. The upper part of the beam 12 is used to measure the vibration deformation of the cantilever vibrating beam 2 and the beam 12 to be tested. The test recorder 16 is set behind the beam 12 to be tested for recording test records. The data acquisition card is connected to each displacement sensor and The test recorder 16 is electrically connected to store the data collected by the displacement sensor and the test recorder 16;

The test recorder 16 is mainly composed of a camera and its analysis and processing system, which is used to photograph the test process and store the photographed video data in a data acquisition card.

The measurement and control system includes a numerical control panel 21, the numerical control panel 21 is fixedly connected to the base plate 24, the numerical control panel 21 is electrically connected to the data acquisition card and the two eccentric motors 3, and the numerical control panel 21 has built-in measurement and control software based on LabVIEW, It is used to receive and record the test records of the test recorder 16, integrate the data in the data acquisition card for comprehensive analysis, and control the work of the eccentric motor 3 through the numerical control panel 21 and the measurement and control software.

The electronic acquisition system also includes a sound sensor 13 and an electron microscope 6. The sound sensor 13 is arranged below the beam 12 to be measured, the electron microscope 6 is arranged above the beam 12 to be measured, and both the sound sensor 13 and the electron microscope 6 are connected to the data. Electrical connection of acquisition card;

The sound sensor 13 is composed of a sound-sensitive capacitive electret microphone and an analysis and processing system.

The electron microscope 6 is used to observe the internal structural changes of the beam 12 to be tested after fatigue failure to study the fatigue failure of the composite material.

The displacement sensor located below the right end of the left cantilever vibrating beam 2 and the left end of the right cantilever vibrating beam 2 is specifically an eddy current displacement sensor 11, and the displacement sensor located above the beam 12 to be measured is specifically a laser displacement sensor 5.

Specifically, the eddy current displacement sensor 11 is composed of a sensor coil, a sensor probe, and an oscillation circuit. Since the eddy current can penetrate the insulator, even if the surface is covered with the metal material of the insulator, it can also be used as the measured object of the eddy current sensor, so it is used for the measurement of the vibration of the cantilever vibrating beam 2.

The laser displacement sensor 5 is composed of a laser, a laser detector and a measuring circuit. The laser displacement sensor 5 is used to detect the vibration deformation of the composite material test beam, and comprehensively analyze the vibration characteristics of different composite materials under different conditions.

A first guide rail 17 is provided on the top of the bottom plate 24. The first guide rail 17 is arranged in parallel with the cantilever vibration beam 2. A first guide rail slider 26 is slidably mounted on the first guide rail 17, and the right side fixing plate 9 is fixedly mounted on the On the top of a guide rail slider 26, a mechanical locking mechanism is provided between the first guide rail slider 26 and the first guide rail 17. The structure and setting method of the mechanical locking mechanism for the guide rail belong to the prior art and will not be described here. More details.

The left end of the left cantilever vibrating beam 2 and the left fixed plate 1 and the right end of the right cantilever vibrating beam 2 and the right fixed plate 9 are all fixedly connected by a cantilever beam clamping device, and the cantilever beam clamp The tightening device includes a lower tightening support device 7, an upper tightening device 8 and a lower tightening support pad 25. The lower tightening support device 7 is fixedly connected to the left fixing plate 1 or the right fixing plate 9, and the upper tightening The device 8 is connected to the lower fastening support device 7 by bolts, the cantilever vibration beam 2 is clamped between the upper fastening device 8 and the lower fastening support device 7, between the left cantilever vibration beam 2 and the left fixed plate 1, right There is a gap between the side cantilever vibrating beam 2 and the right fixed plate 9, the lower fastening support pad 25 is assembled in the gap, and the thickness of the lower fastening support pad 25 is smaller than that of the cantilever vibration beam 2. Thickness, the purpose of providing a lower fastening support pad 25 between the cantilever vibration beam 2 and the fixed plate on the left or right side is to give the cantilever vibration beam 2 a certain vibration space to facilitate the vibration of the cantilever vibration beam 2.

在本实施例中,悬臂振动梁2可采用不锈钢或多层金属粘接复合材料制成。 The fracture toughness of the cantilever vibration beam 2 is at least

In this embodiment, the cantilever vibration beam 2 can be made of stainless steel or multilayer metal bonding composite materials.

The bottom plate 24 is also provided with a second guide rail 20, the second guide rail 20 is arranged in parallel with the cantilever vibrating beam 2, the second guide rail 20 is slidably assembled with three lower guide rail brackets 14, and three lower guide rail brackets 14 An eddy current displacement sensor 11, an acoustic sensor 13 and an eddy current displacement sensor 11 are respectively arranged on the top from left to right.

The top of the left side fixing plate 1 and the right side fixing plate 9 is provided with an upper support beam 27, and the top of the upper support beam 27 is equipped with a third guide rail 15 which is arranged parallel to the cantilever vibration beam 2. Two upper rail brackets 4 are slidably assembled on the rail 15, and the bottom of the two upper rail brackets 4 are respectively provided with a laser displacement sensor 5 and an electron microscope 6 from left to right.

The two ends of the beam 12 to be tested are detachably connected to the left cantilever vibrating beam 2, the right cantilever vibrating beam 2, and the right end face of the left cantilever vibrating beam 2 and the left end face of the right cantilever vibrating beam 2 are both opened There are connecting holes 28, and the two ends of the beam 12 to be tested are inserted into the connecting holes 28 on both sides respectively. The left top of the left cantilever vibrating beam 2 and the left top of the right cantilever vibrating beam 2 are both provided with locking screws 29. Two locking screws 29 are respectively screwed to the left cantilever vibrating beam 2 and the right cantilever vibrating beam 2, and the screws of the two locking screws 29 respectively extend into the connecting holes 28 on both sides of the beam 12 to be tested. When the side top is in contact, the pressure on the upper surface of the beam 12 to be measured is fixed by the locking screw 29 to realize the fixation between the beam to be measured 12 and the cantilever vibration beam 2.

A right arch 10 is provided on the right side of the test device, the right arch 10 is fixedly connected to the top of the bottom plate 24, the right arch 10 is fixedly equipped with a right protective cover 19, and a front protective cover 18 is provided on the front side of the test device. 18 is fixedly connected to the top of the bottom plate 24, and a protective plate 30 is provided on the top, rear and left sides of the test device;

A supporting device is provided under the bottom plate 24, the supporting device includes a supporting leg 22 and a supporting angle iron 23. The supporting leg 22 is provided with a plurality of sets of fixing holes from top to bottom, and the bottom plate 24 is supported by one set of fixing holes. The legs 22 are connected by bolts, and the supporting angle iron 23 is fixedly assembled on the bottom of the supporting legs 22.

Specifically, in this embodiment, the model of the eddy current displacement sensor 11 is ML33-50MM-V, the model of the laser displacement sensor 6 is HG-C1050, the model of the electron microscope 6 is X-603, and the model of the acoustic sensor 13 is ISD1820P, the model of the test recorder 16 is 3200_1080P, the model of the data acquisition card is NI4431, and the model of the motherboard of the CNC panel 21 is the Advantech P4 industrial motherboard PCA-6006LV.

A composite material dynamic fatigue test method based on inverse resonance. The aforementioned composite material dynamic fatigue test device based on inverse resonance is characterized in that it comprises the following steps:

Step 1. Use the cantilever beam clamping devices on the left fixed plate 1 and the right fixed plate 9 to clamp the two cantilever vibration beams 2 respectively, and assemble the two eccentric motors 3 on the two cantilever vibration beams 2 respectively The floating end

Step 2. Make the composite material to be tested into the beam 12 of appropriate size, and fix it between the cantilever vibrating beams 2 on both sides by locking screws 29, adjust the positions of the eccentric motors 3 on both sides, and measure the left eccentricity respectively The distance between the center of the motor 3 and the right end of the left cantilever vibrating beam 2, the distance between the center of the right eccentric motor 3 and the left end of the right cantilever vibrating beam 2, the size of the beam 12 to be measured, and the size of the cantilever vibrating beam 2. The measured distance and size are input into the measurement and control software built into the numerical control panel 21;

Step 3. Close the right shield 19 and the front shield 18, start the two eccentric motors 3, the laser displacement sensor 5 and the eddy current displacement sensor 11 to transmit the vibration data of the two cantilever vibration beams 2 and the beam to be measured 12 to the numerical control panel 21. In the built-in measurement and control software, the time-domain waveform diagrams of the vibration of the cantilever vibrating beam 2 and the beam under test 12 are formed. By observing the time-domain waveform diagrams of the two cantilever vibrating beams 2, the vibration frequency and phase of the two eccentric motors 3 are controlled to make The two cantilever vibrating beams 2 reach resonance respectively, and there is a half-period phase difference between the two cantilever vibration beams 2 to realize the reverse resonance of the two eccentric motors 3;

Step 4. The measurement and control software built into the numerical control panel 21 automatically judges whether fatigue damage has occurred:

When fatigue failure occurs, the time-domain waveform graph changes abruptly, and the system automatically judges whether the test stop requirement is met according to the change range. When the material meets the required test stop requirement, the control panel controls the eccentric motor 3 to stop vibrating, and the test end prompt sound , The measurement and control software processes and analyzes the test data and evaluates the fatigue characteristics of the material;

Step 5: Use the electron microscope 6 to observe the fatigue damage of the beam 12 to be tested, take photos and record, combine the test data of the displacement sensor, the test recorder 16 and the sound sensor 13, and integrate the time-domain waveform diagram, acoustics, and optics. The situation is analyzed.

Specifically, the operating principle of the LabVIEW-based measurement and control software is as follows:

Measurement and control software includes front panel, analog sine signal output module, data acquisition module, frequency sweep module and frequency tracking control module;

The front panel is a human-computer interaction interface for setting initial data and real-time display of collected data waveforms; the front panel of the measurement and control software mainly includes motor operating frequency, data acquisition channel (physical channel), and real-time waveform Display (real-time waveform display), power spectrum display (power spectrum), sampling rate (sampling rate).

The analog signal output module can generate a signal with adjustable amplitude and frequency, as an excitation source to drive the eccentric motor 3 to work. This module mainly consists of the While Loop loop structure and DAQmx Clear Task.VI, AO Configure.VI, DAQmx Write.VI, subGenerate WDT.VI, DAQmx Stop Task.VI, DAQmx Start Task.VI.

The data acquisition and processing module is mainly to realize the acquisition, processing, analysis and display of the measured signal. The function used is similar to the analog signal output module, except that the analysis sub-function is added. Data collection mainly uses Acquisition sub-templates to collect data. After the data is collected, data processing is performed. Data processing is mainly to perform windowing and filtering functions on the collected signals. Windowing is mainly to reduce the leakage of the spectrum, and filtering is mainly to extract the expected value from the signal, mainly through the bandpass filtering of Filter.VI Filter to filter out high-frequency and low-frequency interference signals. The data analysis and display process is achieved by connecting a branch to Extract Single Tone Information.VI and Power Spectrum.VI to obtain the real-time frequency, amplitude and energy value of the current waveform, and the other branch is sent to the control Waveform Chart for real-time display. Data analysis is mainly time domain analysis and frequency domain analysis of data. Time domain analysis includes autocorrelation analysis, peak detection, etc. Frequency domain analysis includes amplitude spectrum and phase analysis.

In order to realize the working principle of reverse resonance, the resonance frequency of the cantilever vibrating beam 2 must be found. In principle, the theoretical resonance frequency can be calculated according to the structural parameters of the system, but there is still a large error with the actual resonance frequency. Therefore, the design is automatic Sweep program. The specific design idea is: set the upper limit and lower limit of the sweep frequency according to the theoretical resonance frequency, divide the difference between the upper limit of the sweep frequency and the lower limit of the sweep frequency into ten equal parts, and a total of eleven frequencies are used as the frequency of the analog signal. This signal drives the eccentric motor 3 to work; at the same time, the data acquisition card obtains the feedback waveform amplitude corresponding to eleven frequencies, finds the corresponding frequency with the largest amplitude and the two frequencies before and after, and uses the two frequencies before and after as the upper frequency of the next sweep. The lower limit frequency repeats the previous round of the algorithm again, until the frequency difference between the front and rear frequencies is less than or equal to the preset value, the cycle ends, and the resonance frequency is obtained.

After the frequency sweep is over, the cantilever vibrating beams 2 on both sides resonate at the resonance frequency, and the composite material fatigue test is performed. When the beam 12 to be tested cracks, the system resonance frequency drops. At this time, the measurement and control software must automatically track to find a new resonance frequency. The idea involved in the program is: when the waveform amplitude meets certain conditions, the frequency sweep module is automatically triggered to rescan the new resonance frequency.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the specific embodiments of the present invention can still be modified or equivalent Replacement, any modification or equivalent replacement that does not depart from the spirit and scope of the present invention, shall be covered by the scope of the claims.

Claims (10)

A composite material dynamic fatigue test device based on inverse resonance, which is characterized by comprising a double cantilever beam vibration test system, an electronic acquisition system, and a measurement and control system; The double-cantilever beam vibration test system includes two cantilever vibration beams, an eccentric motor and a bottom plate. The left side of the top of the bottom plate is fixedly equipped with a left fixed plate, and the right side of the top of the bottom plate is slidably equipped with a right fixed plate, and a left fixed plate and The right fixed plate is arranged in parallel, two cantilever vibration beams are arranged between the left fixed plate and the right fixed plate, the left end of the left cantilever vibration beam is fixedly connected with the left fixed plate, and the right end of the right cantilever vibration beam is connected to the right The side fixed plate is fixedly connected, the right end of the left cantilever vibrating beam and the left end of the right cantilever vibrating beam are both suspended and equipped with eccentric motors. The two ends of the beam to be measured are connected to the right and right cantilever of the left cantilever vibrating beam. The left end of the vibrating beam is fixedly connected, the left cantilever vibrating beam, the right cantilever vibrating beam and the beam to be measured are arranged collinearly, the two eccentric motors are arranged symmetrically around the beam to be measured, and there is a half cycle between the two eccentric motors的phase difference; The electronic acquisition system includes a displacement sensor, a test recorder and a data acquisition card. There are three displacement sensors, which are respectively arranged below the right end of the left cantilever vibrating beam, below the left end of the right cantilever vibrating beam, and above the beam to be tested. , Used to measure the vibration deformation of the cantilever vibrating beam and the beam to be tested. The test recorder is set at the back of the beam to be tested for recording test records. The data acquisition card is electrically connected to the displacement sensors and the test recorder. Store the data collected by the displacement sensor and test recorder; The measurement and control system includes a numerical control panel, the numerical control panel is fixedly connected to the base plate, the numerical control panel is electrically connected with the data acquisition card and two eccentric motors, and the numerical control panel is built with LabVIEW-based measurement and control software for receiving and recording tests The experiment record of the recorder integrates the data in the data acquisition card for comprehensive analysis. The composite material dynamic fatigue test device based on inverse resonance according to claim 1, wherein the electronic acquisition system further comprises a sound sensor and an electron microscope, the sound sensor is arranged under the beam to be measured, and the electron microscope Set above the beam to be measured, and both the sound sensor and the electron microscope are electrically connected to the data acquisition card; The displacement sensors located below the right end of the left cantilever vibrating beam and the left end of the right cantilever vibrating beam are specifically eddy current displacement sensors, and the displacement sensor located above the beam to be measured is specifically a laser displacement sensor. The composite material dynamic fatigue test device based on anti-resonance according to claim 2, wherein a first guide rail is provided on the top of the bottom plate, and the first guide rail is arranged in parallel with the cantilever vibration beam. The upper slide is equipped with a first rail slider, the right side fixing plate is fixedly assembled on the top of the first rail slider, and a mechanical locking mechanism is arranged between the first rail slider and the first rail. The composite material dynamic fatigue test device based on inverse resonance according to claim 3, characterized in that, between the left end of the left cantilever vibration beam and the left fixed plate, the right end of the right cantilever vibration beam and The fixing plates on the right side are all fixedly connected by a cantilever beam clamping device. The cantilever beam clamping device includes a lower fastening support device, an upper fastening device and a lower fastening support pad. The lower fastening support device is connected to The left side fixed plate or the right side fixed plate is fixedly connected, the upper fastening device is connected with the lower fastening support device by bolts, the cantilever vibration beam is clamped between the upper fastening device and the lower fastening support device, and the left cantilever vibration beam is connected with There is a gap between the left fixed plate, the right cantilever vibration beam and the right fixed plate, the lower fastening support pad is assembled in the gap, and the thickness of the lower fastening support pad is smaller than the cantilever The thickness of the vibration beam. The composite material dynamic fatigue test device based on inverse resonance according to claim 4, wherein the fracture toughness of the cantilever vibration beam is at least

A composite material dynamic fatigue test device based on inverse resonance according to claim 5, wherein a second guide rail is further provided on the bottom plate, and the second guide rail is arranged parallel to the cantilever vibration beam, and Three lower rail brackets are slidably assembled on the second rail. The tops of the three lower rail brackets are respectively provided with an eddy current displacement sensor, a sound sensor and an eddy current displacement sensor from left to right. A composite material dynamic fatigue test device based on inverse resonance according to claim 6, wherein the top of the left side fixing plate and the right side fixing plate are provided with an upper support beam, and the top of the upper support beam is equipped with The third guide rail is arranged in parallel with the cantilever vibration beam, and two upper guide rail brackets are slidably assembled on the third guide rail. The bottom of the two upper guide rail brackets are respectively provided with a laser displacement sensor and an electron microscope from left to right. The composite material dynamic fatigue test device based on inverse resonance according to claim 7, wherein the two ends of the beam to be tested are respectively detachably connected to the left cantilever vibrating beam and the right cantilever vibrating beam , The right end face of the left cantilever vibrating beam and the left end face of the right cantilever vibrating beam are both provided with connecting holes, and the two ends of the beam to be tested are inserted into the connecting holes on both sides respectively, and the left cantilever vibrating beam The top left side of the cantilever vibrating beam is provided with locking screws. The two locking screws are respectively screwed to the left cantilever vibrating beam and the right cantilever vibrating beam, and the screws of the two locking screws are respectively extended to the connection on both sides The hole is in contact with the top of the left and right sides of the beam to be tested. A composite material dynamic fatigue test device based on inverse resonance according to claim 8, characterized in that: A right arch is provided on the right side of the test device, the right arch is fixedly connected to the top of the bottom plate, the outer side of the right arch is fixedly equipped with a right protective cover, the front side of the test device is provided with a front protective cover, and the front protective cover is fixedly connected to the top of the bottom plate, The top, back and left sides of the test device are provided with protective plates; A supporting device is arranged below the bottom plate, the supporting device includes a supporting leg and a supporting angle iron, the supporting leg is provided with a plurality of sets of fixing holes from top to bottom, and the bottom plate is bolted to the supporting leg through a set of fixing holes to support The angle iron is fixedly assembled on the bottom of the supporting leg. A composite material dynamic fatigue test method based on inverse resonance adopts the composite material dynamic fatigue test device based on inverse resonance as claimed in claim 9, characterized in that it comprises the following steps: Step 1. Use the cantilever beam clamping devices on the left fixed plate and the right fixed plate to clamp the two cantilever vibration beams respectively, and assemble the two eccentric motors on the suspended ends of the two cantilever vibration beams; Step 2. Make the composite material to be tested into a beam to be tested of appropriate size, and fix it between the cantilever vibrating beams on both sides by locking screws, adjust the positions of the eccentric motors on both sides, and measure the center distance of the left eccentric motor respectively. The distance between the right end of the side cantilever vibrating beam, the distance between the center of the right eccentric motor and the left end of the right cantilever vibrating beam, the size of the beam to be measured and the size of the cantilever vibrating beam, power on each system, and enter the measured distance and size into the built-in CNC panel In the measurement and control software; Step 3. Close the right shield and the front shield, start the two eccentric motors, the laser displacement sensor and the eddy current displacement sensor transmit the vibration data of the two cantilever vibration beams and the beam to be measured to the measurement and control software built in the numerical control panel to form The time-domain waveform diagrams of the vibration of the cantilever vibrating beam and the beam to be measured. By observing the time-domain waveform diagrams of the two cantilever vibrating beams, the vibration frequency and phase of the two eccentric motors are controlled so that the two cantilever vibrating beams reach resonance respectively, and both have The phase difference of half a period realizes the reverse resonance of two eccentric motors; Step 4. The measurement and control software built into the numerical control panel automatically determines whether fatigue damage has occurred: When fatigue failure occurs, the time-domain waveform graph changes abruptly, and the system automatically judges whether the test stop requirement is met according to the change range. When the material meets the required test stop requirement, the control panel controls the eccentric motor to stop vibrating, and at the same time emits a test end prompt sound. The measurement and control software processes and analyzes the test data and evaluates the fatigue characteristics of materials; Step 5: Use an electron microscope to observe the fatigue damage of the beam to be tested, take photos and record, combine the test data of the displacement sensor, the test recorder and the sound sensor, and analyze the fatigue damage of the composite material under test by integrating the time domain waveform diagram, acoustics and optics.

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