Loading control device and method for triaxial hopkinson bar impact test

Abstract

The application discloses a loading control device and method of a triaxial Hopkinson bar impact test, and belongs to the technical field of triaxial impact tests.The application comprises a linear motor, a limiting rod, an end cover, a bullet launching cylinder, an experimental bullet, an air compressor, an air storage tank, a control console, a triaxial Hopkinson bar, a buffer gasket and a gasket clamping plate.The device and method are used in cooperation with the triaxial Hopkinson bar, the limiting mechanism can accurately control and adjust the launching position and acceleration distance of the experimental bullet, so that the acceleration peak value is accurately controlled, and then the corresponding relationship between the driving air pressure, the acceleration distance and the acceleration peak value is obtained through the experiment;the loading control device of the application is matched with the rapid resetting of the experimental bullet, can realize continuous multiple impact loadings with different acceleration peak values, triaxial multiple impact synchronous loadings and automatic single-axis cyclic loadings, and significantly improves the automation degree, the experimental efficiency and the control precision of the triaxial impact loading experiment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of triaxial impact test, and particularly relates to a loading control device and method for triaxial Hopkinson bar impact test. BACKGROUND

[0002] The Hopkinson bar impact test technology is widely applied in the fields of aircraft, weapons, electronic devices, materials, mechanics, etc., and is an important technology for the structure, function reliability and test calibration of electronic devices, material mechanics characteristics, sensors, etc., and is widely applied in civil, scientific research and national defense fields.

[0003] The existing Hopkinson bar device generally includes a single-axis Hopkinson compression rod and a triaxial Hopkinson bar device. The triaxial Hopkinson bar is divided into true triaxial and ordinary triaxial, and the ordinary triaxial is also called false triaxial. The true triaxial test is a triaxial test in which the test sample is in a stress combination state in which the principal stresses in three directions are not equal. The ordinary triaxial test is a test in which the principal stresses in two directions are the same. At present, the driving modes of the triaxial Hopkinson bar device are generally three kinds. One is the most common pneumatic loading mode, in which a bullet or a collision rod is driven by the gas of a compressor in a high-pressure container to directly impact the incident rod, such as application number CN201720205631.6. The second driving mode is electromagnetic loading mode, such as application number CN201811602351.4, which uses a capacitor and a copper coil to generate a strong magnetic field, and then generates an eddy current magnetic field and repulsion. The repulsion pulse is propagated through an amplifier to directly generate an incident pulse in the incident rod. The third is a confining pressure loading mode, that is, the test sample is wrapped in a container, the container is filled with liquid, and the stress of the test sample is loaded by the confining pressure of the liquid, such as application numbers CN201720205631.6 and 202122075303.8.

[0004] However, the above modes have their own shortcomings. For the triaxial pneumatic loading mode, the installation position of the bullet or the collision rod in the air gun is not the same every time, and the corresponding relationship between the impact speed and the air pressure is difficult to determine, so the amplitude of the incident wave cannot be accurately controlled. Therefore, multiple experiments need to be tried to obtain the required strain rate, and the working load is doubled because each Hopkinson rod needs to be adjusted separately, and the experimental repeatability is poor. The triaxial electromagnetic loading mode is complex and expensive, and the size of the electromagnetic repulsion is affected by the circuit structure parameters. The stress wave generated by the electromagnetic riveting technology is mainly generated by the acceleration of the collision rod driven by the electromagnetic repulsion to collide with the incident rod. The collision rod needs to be reinstalled for the next experiment, and the operation is complicated. The confining pressure loading mode is generally suitable for in-situ stress loading test of rock, but the principal stresses in two directions formed by the confining pressure can only be the same, so it belongs to false triaxial test, and the sealing requirement of the container is very high. The above series of problems result in very low efficiency and complicated operation of the triaxial impact test. SUMMARY

[0005] In order to solve the above problems, the main purpose of the present application is to provide a loading control device and method for triaxial Hopkinson bar impact test, which is matched with the triaxial Hopkinson bar, and can accurately control and adjust the launch position and acceleration distance of the experimental bullet through the limiting mechanism, so as to accurately control the acceleration peak value, and then obtain the corresponding relationship between the driving air pressure, acceleration distance and acceleration peak value through experiments; the loading control device cooperates with the rapid reset of the experimental bullet, can realize continuous multiple impact loading of different acceleration peak values, triaxial multiple impact synchronous loading, and automatic single-axis cyclic loading, and significantly improves the automation degree, experimental efficiency and control precision of triaxial impact loading experiment.

[0006] The purpose of the present application is realized by the following technical solutions:

[0007] The loading control device for triaxial Hopkinson bar impact test disclosed by the present application comprises a linear motor, a limiting rod, an end cover, a bullet launching cylinder, an experimental bullet, an air compressor, an air tank, a control console, a triaxial Hopkinson bar, a buffer gasket and a gasket clamping plate.

[0008] The air outlet of the air compressor is divided into three air channels through a four-way joint, each air channel is connected with an air inlet valve and an air tank respectively, and the air outlet of each air tank is connected with the air holes in the end covers of three bullet launching cylinders through air outlet valves and gas pipelines. The compressed air in the air tanks can provide driving force for the experimental bullets. The control console controls the air inlet valves and air outlet valves of the three air tanks to realize the control of air charging and air discharging of the air tanks, and when the air is discharged, the experimental bullets driven by the bullet launching cylinders hit the three Hopkinson bars respectively, and the automatic reset design of the experimental bullets can realize continuous multiple impact tests. Preferably, each bullet launching cylinder is connected with multiple air tanks side by side, and the multiple air tanks work alternately, which can reduce the interval time of the next firing.

[0009] The end cover is located at the end of the bullet launching cylinder and connected with the bullet launching cylinder. A limiting hole for the limiting rod to pass through and move forward and backward is processed in the center position of each end cover, and the limiting hole is a through hole. Symmetrical air holes are processed on both sides of the limiting hole, the air holes are through holes, one end of the air hole is connected with the air tank, and the other end is connected with the inner cavity of the bullet launching cylinder. Preferably, the air holes are symmetrically distributed on both sides of the limiting hole. The symmetrically distributed air holes can uniformly act on the bottom of the experimental bullet with the compressed air provided by the air tank, drive the experimental bullet to move linearly along the axis of the bullet launching cylinder, and avoid eccentric motion.

[0010] The limiting rods are respectively inserted into the three bullet launching cylinders through the limiting holes on the three end covers, and the other ends of the three limiting rods are respectively connected to the three linear motors. The linear motors can drive the limiting rods to move in and out, control the length of the limiting rods inserted into the bullet launching cylinders, and thus determine and control the launching position of the experimental bullets. The linear motors are installed at the rear end of the limiting rod axis, directly push and pull the limiting rods to move forward and backward to adjust the launching position. Or the linear motors are located on the side of the limiting rod, parallel to the limiting rod, and drive the limiting rod to move forward and backward through the connecting rod. There is no need to use transparent material to make the bullet launching cylinder for observing the position of the experimental bullet, and the transparent material has small pressure bearing capacity and cannot bear high pressure impact. The limiting rods are mainly used to determine and control the launching position of the experimental bullets, and this purpose is achieved through the following process: the limiting rods are driven by the linear motors to move to the specified position in the bullet launching cylinder, and then the three-axis Hopkinson bar and the device support are arranged obliquely upward, and the experimental bullets in the bullet launching cylinder automatically fall to the end of the limiting rod under the action of gravity and contact with the limiting rod, thereby controlling the launching position of the experimental bullets. Further, the distance of the experimental bullets can be accurately controlled by the linear motor controlling the movement of the limiting rod, and the experimental precision of the three-axis Hopkinson bar impact test is improved.

[0011] The bullet launching cylinders are respectively located on the device support of the three Hopkinson bars, and are in the form of a cylindrical structure with a cylindrical through hole machined inside, one end is provided with an end cover, and the other end is open and faces the end face of the Hopkinson bar. The experimental bullets are respectively located in each bullet launching cylinder, and the experimental bullets are in the same axis with the bullet launching cylinder. After the experimental bullets are shot out, they will collide with the end face of the Hopkinson bar.

[0012] The experimental bullets are in the form of a cylinder as a whole and are respectively located in the three bullet launching cylinders. The front end of the experimental bullet is machined with a circular truncated cone, and the diameter of the front end of the circular truncated cone is the same as the diameter of the Hopkinson bar. The two ends of the experimental bullet are machined with closed gas ring grooves, and sealing rings are installed in the grooves. The sealing rings have two functions: one is to seal the gap between the experimental bullet and the inner cavity of the bullet launching cylinder, and the other is to reduce the friction between the experimental bullet and the bullet launching cylinder, so that the experimental bullet can accelerate faster. The experimental bullet has two closed gas ring grooves, which has better sealing performance than the traditional cylindrical bullet without grooves, and reduces the wear of the experimental bullet on the inner cavity of the bullet launching cylinder, which is beneficial to the repeatability and consistency requirements of the impact measurement test.

[0013] The triaxial Hopkinson bar and device support overall profile is a right rectangular tetrahedron structure, which is composed of three Hopkinson bars, two of which are perpendicular to each other and arranged at an angle of 90 degrees. The test piece is installed at the intersection of the three Hopkinson bars. The three Hopkinson bars can apply impact of different intensities to the test piece from the three principal stress directions of the test piece, and can realize true triaxial impact test loading. Since the direction of the triaxial Hopkinson bar is oblique, the experimental bullet in the bullet launching cylinder will automatically fall back to the initial launching position under the action of gravity after hitting the Hopkinson bar, realizing the automatic resetting function of the experimental bullet. The automatic resetting design of the experimental bullet cooperates with the release of compressed air in the gas tank to launch the experimental bullet, which can realize continuous impact loading test for multiple times.

[0014] The buffer gasket is a rectangular strip-shaped sheet, and the two ends of the buffer gasket are clamped by the gasket clamping plate fixed on the device support. The plane of each buffer gasket is perpendicular to the corresponding Hopkinson bar axis and tightly abuts the impact end face of the Hopkinson bar. When the experimental bullet collides with the Hopkinson bar, the pulse width is adjusted through the buffer gasket. The material of the rectangular strip-shaped buffer gasket is selected from flexible sheet-shaped long strip materials. The flexible sheet-shaped long strip material includes nylon, rubber and wool felt.

[0015] The application also discloses a loading control method of the triaxial Hopkinson bar impact test, which is realized based on the loading control device of the triaxial Hopkinson bar impact test and includes the following steps.

[0016] Step 1: Fix the bullet launching cylinder and the corresponding diameter Hopkinson bar on the device support respectively, and connect and install the data measurement device of the Hopkinson bar.

[0017] Step 2: Install the sealing ring of the experimental bullet, and install the experimental bullet in the bullet launching cylinder. The sealing ring can seal the gap between the experimental bullet and the bullet launching cylinder, form a closed cavity, sufficiently reduce the friction between the experimental bullet and the bullet launching cylinder, and make the experimental bullet accelerate faster. Install the end cover of all bullet launching cylinders.

[0018] Step 3: Insert the limiting rods connected with the linear motor into the limiting holes of the end cover respectively; the linear motor can drive the limiting rods to move forward and backward, control the length of the limiting rods inserted into the bullet launching cylinder, and thus determine and control the launching acceleration distance of the experimental bullet. Seal the connection between the gas pipeline interface and the air hole of the end cover. The air holes are symmetrically distributed around the limiting holes. The symmetrically distributed air holes can uniformly act on the bottom of the experimental bullet during launching and resetting of the experimental bullet, so that the bullet can move in a straight line and avoid eccentric motion.

[0019] Step 4: Connect and check the air compressor, air tank and corresponding gas pipeline in turn. Connect the control console with the valve of each air tank, and check whether each part can work normally. The experimental system is ready. Turn on the air compressor, adjust the pressure control knob, and the pressure display instrument displays the pressure at any time. The air tank is inflated to the specified pressure, and the experimental bullet is in the standby state.

[0020] Step 5: The present application can realize five kinds of impact experiment loading control methods. Control method one: manually adjust the position of the limiting rod to control the acceleration distance of the experimental bullet, change the loading pressure of the air tank, and realize single impact loading experiment. Control method two: set the impact times and interval time to realize automatic multiple same peak impact loading experiment. Control method three: set the automatic adjustment of the moving limiting rod distance, set the impact times and interval time, and realize automatic multiple different peak impact loading experiment. Control method four: set the impact times and interval time of three-axis simultaneous firing to realize continuous three-axis simultaneous loading. Control method five: set the sequence and interval time of three-directional sequential firing to realize sequential single-axis loading cycle impact. According to the three-axis Hopkinson bar impact test working condition, select the corresponding control method to execute, and choose one of the five control methods to execute steps 6, 7, 8, 9 and 10 respectively to perform Hopkinson bar impact test under corresponding working condition. The control method one corresponds to step 6, the control method two corresponds to step 7, the control method three corresponds to step 8, the control method four corresponds to step 9, and the control method five corresponds to step 10. The Hopkinson bar impact test working condition parameters include impact loading times, acceleration distance, loading pressure and interval time.

[0021] Step 6: Single impact loading experiment of arbitrary acceleration distance and arbitrary air pressure is carried out by the control method one in step 5. The axial direction is selected by the axial selection button, and the target position of the limiting rod is adjusted manually by rotating the position adjusting knob clockwise or counterclockwise, that is, as the position adjusting knob is rotated, the linear motor moves automatically forward and backward to move the limiting rod to the set target position, and the position display screen displays the distance from the front end of the limiting rod to the starting position of the original point in real time. The experimental bullet is automatically reset and falls to the end of the limiting rod under the action of gravity. The one-way valve is controlled by rotating the pressure loading knob clockwise, and the air tank is slowly inflated to the target air pressure, and the pressure display screen displays the pressure in the air tank in real time. If the pressure exceeds the expected target air pressure of the loading, the pressure unloading knob is rotated counterclockwise to slowly release the gas through the air valve. The pressure in the air tank is adjusted to the target air pressure by the cooperation of the pressure loading knob and the pressure unloading knob. Click the acquisition button of the data acquisition software on the computer, and the data acquisition device and the data acquisition software enter the acquisition preparation state, and when the trigger signal comes, the test data will be automatically stored and recorded. When the acquisition software is in the acquisition preparation state, press the launch button quickly to start the experimental bullet firing and realize the collision of the experimental bullet and the Hopkinson bar, that is, when the launch button is pressed, the compressed air in the air tank is quickly released through the valve, the compressed air is suddenly loaded to the launch cylinder through the pipeline, and the reset experimental bullet is driven to move forward along the axis and collide with the end face of the Hopkinson bar. The end face of the Hopkinson bar has a buffer pad in front of it, which can adjust the pulse width. At the moment of collision between the experimental bullet and the Hopkinson bar, a trigger signal is generated, the data acquisition device starts the acquisition function, the data acquisition software completes the automatic storage and recording of the test data function, and the data processing software automatically processes the data to display the experimental results and experimental curves on the computer screen.

[0022] Step 7: Automatic multiple same peak impact loading experiment is carried out by setting the position of the limiting rod and controlling the acceleration distance of the experimental bullet through the control method two in step 5. First, set the impact number and interval time, that is, adjust the experimental number to the expected value by increasing and decreasing the impact number keys, then click the confirmation button to complete the impact number setting. Adjust the interval time to the expected value by increasing and decreasing the interval time keys, then click the confirmation button to complete the interval time setting. Adjust the initial value of the loading pressure to the expected value by increasing and decreasing the loading pressure keys, set the step pressure increase value to zero, that is, the pressure is constant and does not increase, then click the confirmation button to complete the setting of the loading pressure in the gas tank. Set the acceleration distance of the launched experimental bullet, that is, adjust the initial value of the acceleration distance to the expected value by increasing and decreasing the acceleration distance keys, set the step acceleration distance increase value to zero, that is, the acceleration distance is constant and does not increase, and finally click the confirmation button to complete the adjustment setting of the limiting rod position. After the above four initial parameters are set, the experiment is ready. Click the acquisition button of the data acquisition software on the computer, and the data acquisition device and the data acquisition software enter the acquisition preparation state, and when the trigger signal comes, the test data will be automatically stored and recorded. When the acquisition software is in the acquisition preparation state, press the launch button quickly to start the experimental bullet firing and realize the collision of the experimental bullet and the Hopkinson bar, that is, when the launch button is pressed, the compressed air in the gas tank is quickly released through the outlet valve, and the compressed air is suddenly loaded into the bullet launching cylinder through the gas pipeline, driving the experimental bullet in the reset state to move forward along the axis and collide with the end face of the Hopkinson bar. The end face of the Hopkinson bar has a buffer pad in front of it, which can adjust the pulse width. The experimental bullet collides with the Hopkinson bar for the first time, and a trigger signal is generated, and the data acquisition device starts the acquisition function. After completing one firing, the experimental bullet is automatically reset to the initial launch position under the action of gravity. The next firing experiment is automatically carried out according to the set impact number, interval time, loading pressure and acceleration distance parameters until the set impact number is completed. Preferably, multiple gas tanks are connected side by side for each bullet launching cylinder, and the multiple gas tanks work alternately to reduce the interval time for the next firing. Click the manual stop data acquisition button, and the data acquisition software will automatically store and record the test data to the computer hard disk, and click the manual data processing software button to display the experimental results and experimental curves on the computer screen.

[0023] Step 8: Set the automatic adjustment of the mobile limit rod position, set the initial value and step pressure increase value of the loading pressure, set the impact number and interval time by the control method three in step 5, and carry out the automatic multiple different peak impact loading experiment. First, select the axial direction by the axial selection button, set the impact number and interval time, that is, adjust the experiment number to the expected value by the impact number increase and decrease buttons, then click the confirmation button to complete the impact number setting. Adjust the interval time to the expected value by the interval time increase and decrease buttons, then click the confirmation button to complete the interval time setting. Adjust the initial value of the loading pressure to the expected value by the loading pressure increase and decrease buttons, set the step pressure increase value to the expected value, that is, the pressure increases by one step pressure each time, and finally click the confirmation button to complete the loading pressure setting in the gas storage tank. Finally, set the acceleration distance of the launched bullet, that is, adjust the initial value of the acceleration distance to the expected value by the acceleration distance increase and decrease buttons, set the step acceleration distance increase value to the expected value, that is, the acceleration distance increases by one step distance each time, and finally click the confirmation button to complete the limit rod position adjustment setting. After the above four initial parameters are set, the experiment preparation state is entered. Click the acquisition button of the data acquisition software on the computer, and the data acquisition device and the data acquisition software enter the acquisition preparation state. When the trigger signal arrives, the test data will be automatically stored and recorded. When the acquisition software is in the acquisition preparation state, press the launch button quickly to start the experiment bullet firing and realize the collision between the experiment bullet and the Hopkinson bar, that is, when the launch button is pressed, the compressed air in the gas storage tank is rapidly released through the valve, the compressed air is suddenly loaded into the bullet launching cylinder through the gas pipeline, and the reset state of the launched bullet is driven to move forward along the axis and collide with the end face of the Hopkinson bar. The end face of the Hopkinson bar has a buffer pad in front of it, which can adjust the pulse width. The first collision between the experiment bullet and the Hopkinson bar produces a trigger signal, and the data acquisition device starts the acquisition function. After completing one firing, the experiment bullet is automatically reset to the initial launch position under the action of gravity. According to the set parameters such as impact number, interval time, loading pressure increase value, and acceleration distance increase value, the next firing experiment is automatically carried out until the set impact number is completed. Preferably, multiple gas storage tanks are connected side by side for each bullet launching cylinder, and the multiple gas storage tanks work alternately to reduce the interval time for the next firing. Click the manual stop data acquisition button, and the data acquisition software will automatically store and record the test data to the computer hard disk. Click the manual data processing software button to display the experimental results and experimental curves on the computer screen.

[0024] Step 9: The continuous three-axis simultaneous loading impact control is performed by the control method four in step 5. The positions of the three limit rods are set respectively to control the acceleration distance of the test bullet. First, the impact number and interval time are set. That is, the impact number is adjusted to the expected value by increasing and decreasing the impact number keys, and then the confirmation button is clicked to complete the impact number setting. The interval time is adjusted to the expected value by increasing and decreasing the interval time keys, and then the confirmation button is clicked to complete the interval time setting. The initial value of the loading pressure is adjusted to the expected value by increasing and decreasing the loading pressure keys, and the step pressure increase value is set to zero, i.e., the pressure is constant and does not increase, and then the confirmation button is clicked to complete the loading pressure setting in the gas tank. Finally, the acceleration distance of the test bullet is set. That is, the initial value of the acceleration distance is adjusted to the expected value by increasing and decreasing the acceleration distance keys, and the step acceleration distance increase value is set to zero, i.e., the acceleration distance is constant and does not increase, and then the confirmation button is clicked to complete the position adjustment setting of the three limit rods. After the above four initial parameters are set, the experiment preparation state is entered. The acquisition button of the three-axis impact test data acquisition software on the computer is clicked, and the three-channel data acquisition device and the data acquisition software enter the acquisition preparation state. When the trigger signal arrives, the test data will be automatically stored and recorded. When the acquisition software is in the acquisition preparation state, the three-axis synchronous firing button is pressed quickly, and the three-axis experiment bullet is fired, realizing the synchronous collision of the three experiment bullets with the three orthogonal Hopkinson bars, i.e., when the three-axis synchronous firing button is pressed, the compressed air in the three gas tanks is rapidly released through the respective valves, and the compressed air is suddenly loaded into the three bullet launch tubes through the pipeline, driving the reset experiment bullet to move forward along the axis, and the three experiment bullets collide with the end faces of the three Hopkinson bars. The end face of the Hopkinson bar has a buffer pad in front of it, which can adjust the pulse width. The first collision of the experiment bullet with the Hopkinson bar generates a trigger signal, and the three-channel data acquisition device starts the acquisition function. After one firing, the experiment bullet falls on the end of the limit rod due to gravity and returns to the initial firing position. The next firing experiment is automatically performed according to the set impact number, interval time, loading pressure, and acceleration distance parameters until the set impact number is completed. Preferably, multiple gas tanks are connected side by side to each bullet launch tube, and the multiple gas tanks work alternately to reduce the interval time of the next firing. The manual stop data acquisition button is clicked, and the three-axis impact test data acquisition software automatically stores and records the test data of multiple experiments to the computer hard disk. The manual data processing software button is clicked to display the experimental results and experimental curves on the computer screen.

[0025] Step 10: Three-direction single-axis sequential loading multi-cycle impact control is performed by the control method five in step 5. Set the positions of the three limit rods respectively to control the acceleration distance of the experimental bullet, and complete the automatic multiple three-axis impact loading experiment with different peak values. First, set the impact number and interval time, that is, adjust the experimental number to the expected value by increasing and decreasing the impact number keys, then click the confirmation button to complete the impact number setting. Adjust the interval time to the expected value by increasing and decreasing the interval time keys, then click the confirmation button to complete the interval time setting. Adjust the initial value of the loading pressure to the expected value by increasing and decreasing the loading pressure keys, set the step pressure increase value to zero, that is, the pressure is constant and does not increase, then click the confirmation button to complete the loading pressure setting in the gas tank. Set the acceleration distance of the experimental bullet, that is, adjust the initial value of the acceleration distance to the expected value by increasing and decreasing the acceleration distance keys, set the step acceleration distance increase value to zero, that is, the acceleration distance is constant and does not increase, and finally click the confirmation button to complete the adjustment and setting of the positions of the three limit rods. After the above four initial parameters are set, the experiment is ready. Click the acquisition button of the three-axis impact test data acquisition software on the computer, and the three-channel data acquisition device and the data acquisition software enter the acquisition preparation state, and when the trigger signal comes, the test data will be automatically stored and recorded. When the acquisition software is in the acquisition preparation state, press the multi-cycle single-axis sequential firing button quickly, the three gas tanks release compressed air in sequence, the single-axis sequentially starts the experimental bullet firing, and the three experimental bullets sequentially collide with the three orthogonal Hopkinson bars, that is, when the multi-cycle single-axis sequential firing button is pressed, the compressed air in the three gas tanks is released quickly in sequence through the respective air release valves, the compressed air is loaded into the three bullet launch tubes in sequence through the gas pipeline, and the experimental bullets in the reset state are driven to move forward along the axis, and the three experimental bullets sequentially collide with the end faces of the three Hopkinson bars. The end face of the Hopkinson bar has a buffer pad in front of it, which can adjust the pulse width. The first collision of the experimental bullet with the Hopkinson bar generates a trigger signal, and the three-channel data acquisition device starts the acquisition function. After one round of firing is completed, the experimental bullet falls on the end of the limit rod due to gravity and returns to the initial firing position. The next round of firing experiment is automatically performed according to the set impact number, interval time, loading pressure, and acceleration distance parameters until the set impact number is completed. Preferably, multiple gas tanks are connected side by side to each bullet launch tube, and the multiple gas tanks work alternately to reduce the interval time for the next firing. Click the manual stop data acquisition button, and the three-channel data acquisition software automatically stores and records the multi-cycle single-axis sequential experiment data to the computer hard disk, and clicks the manual data processing software button to display the experimental results and experimental curves on the computer screen.

[0026] Beneficial effects:

[0027] 1. The loading control device and method of the triaxial Hopkinson bar impact test disclosed in the application can install a movable limiting rod in a bullet launching cylinder. By controlling the length of the limiting rod extending into the bullet launching cylinder, the launching position of the experimental bullet can be adjusted and determined, so that the acceleration distance of the experimental bullet can be accurately controlled, and the experimental precision is significantly improved. The problems of the prior art that the impact speed of the experimental bullet cannot be accurately adjusted, the acceleration peak value is difficult to control, and the corresponding relationship between the driving gas pressure and the acceleration peak value is difficult to determine are solved, and the experimental precision and the repeatability of the experimental results of the impact test are significantly improved.

[0028] 2. The loading control device and method of the triaxial Hopkinson bar impact test disclosed in the application, by the ingenious design that the experimental bullet in the bullet launching cylinder automatically returns to the initial launching position by gravity, the demand for automatic resetting of the experimental bullet after launching is realized, the automation degree of the triaxial Hopkinson bar impact test is improved, and the experimental efficiency of the Hopkinson bar impact test is significantly improved. Since the gravity resetting of the experimental bullet can overcome the shortcomings of the additional use of a magnetic device to attract the experimental bullet in the current method, the resetting cost of the magnetic device is reduced, and the learning cost of the additional control software for magnetic resetting is realized; and the ventilation holes on the end cover are symmetrically distributed around the limiting hole, which can make the gas pressure uniformly act on the bottom of the experimental bullet, make the experimental bullet move in a straight line, avoid eccentric motion, and improve the precision of the triaxial Hopkinson bar impact test.

[0029] 3. The loading control device and method of the triaxial Hopkinson bar impact test disclosed in the application, by the buffer gasket clamped by the gasket clamping plate at both ends and tightly attached to the impact end face of the Hopkinson bar, the impact pulse width when the experimental bullet collides with the Hopkinson bar is increased, and the triaxial Hopkinson bar impact loading test with adjustable pulse width in three loading directions can be realized.

[0030] 4. The loading control device and method of the triaxial Hopkinson bar impact test disclosed in the application, by manually adjusting the position of the limiting rod, the initial launching position of the experimental bullet is controlled and determined, so that the acceleration movement distance of the experimental bullet is determined. By changing the launching pressure, single impact experiments of the experimental bullet at any launching position and any gas pressure can be realized. Through multiple experiments, the corresponding relationship between the acceleration distance of the experimental bullet, the launching gas pressure and the acceleration peak value can be determined, and the experimental precision of the impact test is significantly improved.

[0031] 5. The loading control method of the triaxial Hopkinson bar impact test disclosed in the application, by controlling the opening of the gas outlet valve of the gas storage tank and using the gravity falling design of the experimental bullet, automatic launching of the experimental bullet and automatic resetting of the experimental bullet can be realized. By inputting the impact times and interval time in the control console, automatic continuous impact with controllable impact times and interval time can be realized, the automation of the triaxial Hopkinson bar impact test is realized, and the experimental efficiency of the triaxial Hopkinson bar test is significantly improved.

[0032] 6. The loading control method of the triaxial Hopkinson bar impact test disclosed in the application can realize automatic adjustment of the initial launching position of the experimental bullet in each impact by presetting the moving distance of the limiting rod. The experimental bullet can be launched and reset automatically according to the preset functions, and the impact number, interval time, launching position and launching pressure of the experimental bullet can be input in the control console, so that continuous multiple impacts of the experimental bullet can be realized with automatic adjustment of the launching position and pressure, and the experimental efficiency and accuracy of the Hopkinson bar test are significantly improved.

[0033] 7. The loading control method of the triaxial Hopkinson bar impact test disclosed in the application can realize continuous triaxial simultaneous loading impact by controlling the simultaneous launching of the experimental bullets in three directions. The experimental bullets in three directions can be launched in sequence to realize multiple round impact of single-axis loading in sequence in three directions.

[0034] 8. The loading control device and method of the triaxial Hopkinson bar impact test disclosed in the application can determine and control the acceleration distance of the experimental bullet by using the limiting rod, and the bullet launching cylinder can be made of steel material, so that the transparent material is not needed to make the bullet launching cylinder for observing the acceleration of the experimental bullet. The transparent material has small pressure bearing capacity and cannot bear high pressure impact, and is prone to rupture. The automatic loading control of the Hopkinson bar impact test and the loading control device can improve the safety of the impact test. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The loading control device of the triaxial Hopkinson bar impact test disclosed in the application is shown in the schematic diagram.

[0036] Figure 2 The assembly relationship structure diagram of the loading control device and the triaxial Hopkinson bar disclosed in the application is shown.

[0037] Figure 3 The end cover of the launching tube is shown in the schematic diagram.

[0038] Figure 4 The experimental bullet is shown in the schematic diagram.

[0039] Figure 5 The general flowchart of the loading control method of the triaxial Hopkinson bar impact test disclosed in the application is shown.

[0040] Figure 6 The flowchart of the loading control method of the triaxial Hopkinson bar impact test disclosed in the application is shown.

[0041] Figure 7 The manual operation panel on the control console of the loading control device disclosed in the application is shown.

[0042] Figure 8 Flow chart of the loading control method three of the triaxial Hopkinson bar impact test proposed in the present application.

[0043] Figure 9 Automatic operation panel on the control console of the loading control device proposed in the present application.

[0044] Figure 10 Flow chart of the loading control method four of the triaxial Hopkinson bar impact test proposed in the present application.

[0045] Figure 11 Flow chart of the loading control method five of the triaxial Hopkinson bar impact test proposed in the present application.

[0046] In the figure: 1 - linear motor, 2 - limiting rod, 3 - end cover, 4 - bullet launching cylinder, 5 - experimental bullet, 6 - air compressor, 7 - air inlet valve, 8 - air storage tank, 9 - air outlet valve, 10 - gas pipeline, 11 - control console, 12 - Hopkinson bar, 13 - device support, 14 - air vent hole, 15 - limiting hole, 16 - air closing ring groove, 17 - gasket clamping plate, 18 - buffer gasket. DETAILED DESCRIPTION

[0047] In order to better illustrate the purpose and advantages of the present application, the content of the application will be further described below in combination with the drawings and examples.

[0048] Example 1:

[0049] With reference to Figure 1 and Figure 2 The loading control device of the triaxial Hopkinson bar impact test disclosed in this embodiment comprises three linear motors 1, three limiting rods 2, three end covers 3, three bullet launching cylinders 4, three experimental bullets 5, an air compressor 6, three air storage tanks 8, a control console 11, a Hopkinson bar 12, a gasket clamping plate 17, and a buffer gasket 18.

[0050] With reference to Figure 1, the air compressor 6 is divided into three air passages via a four-way joint, each air passage is connected with two air inlet valves 7 and air tanks 8 respectively, the air outlet of each air tank 8 is connected with the air holes 14 on the end cap 3 of three sub bullet launchers 4 via air outlet valves 9 and gas pipes 10 with an outer diameter of 8mm respectively. Each sub bullet launcher is connected with two air tanks 8 arranged side by side, and the two air tanks 8 work alternately, which can reduce the interval time of the next firing. The compressed air in the air tank 8 can provide driving force for the experimental bullet 5 when entering the air hole. Each air tank 8 is connected with two gas pipes 10, which are the same as the number of air holes 14 on the end cap 3. The control console 11 controls the air inlet valves 7 and air outlet valves 9 of the six air tanks 8, realizes the control of air charging and air discharging of the air tank 8, and drives the experimental bullet 5 to impact three Hopkinson bars 12 respectively when air discharging. Combined with the automatic reset design of the experimental bullet 5, continuous impact test can be realized.

[0051] With reference to Figure 3 Each end cap 3 is located at the end of the bullet launcher 4 and is connected with the bullet launcher 4 through threads with a thread depth of 10mm. The outer diameter of each end cap 3 is 54mm, and a limiting hole 15 for the limiting rod 2 to pass through and move forward and backward is processed at the center position. The limiting hole 15 is a through hole with a diameter of 2mm. Two symmetric air holes 14 are processed on both sides of the limiting hole 15, the air holes 14 are through holes with a diameter of 8mm, one end of the air hole 14 is connected with the gas pipe 10, and the other end is connected with the inner cavity of the bullet launcher 4. Preferably, the air holes 14 are symmetrically distributed on both sides of the limiting hole 15. The symmetrically distributed air holes 14 can uniformly act on the bottom of the experimental bullet 5 to drive the experimental bullet 5 to move linearly along the axis of the bullet launcher, avoiding eccentric motion

[0052] With reference to Figure 1Three limiting rods 2 are inserted into three bullet launching barrels 4 through limiting holes 15 in three end covers 3, each with a length of 200 mm and a diameter of 2 mm, and the other ends of the three limiting rods 2 are connected to three linear motors 1. The linear motors 1 can drive the limiting rods 2 to move in and out, control the length of the limiting rods 2 extending into the bullet launching barrels 4, and thus determine and control the launching position of the experimental bullets 5. The linear motors 1 are installed at the rear ends of the axes of the limiting rods 2, directly push and pull the limiting rods 2 to move forward and backward to adjust the launching position. Alternatively, the linear motors 1 are located on the side of the limiting rods 2, parallel to the limiting rods 2, and drive the limiting rods 2 to move forward and backward through connecting rods. The bullet launching barrels 4 are not made of transparent material for observing the position of the experimental bullets 5, because transparent material has small pressure bearing capacity and cannot withstand high pressure impact. The limiting rods 2 are mainly used to determine and control the launching position of the experimental bullets 5, and this purpose is achieved through the following process: first, the limiting rods 2 are moved to the specified position by the linear motors 1, and then the experimental bullets 5 in the bullet launching barrels 4 automatically fall to the end of the limiting rods 2 under the action of gravity, thus controlling the launching position of the experimental bullets 5. Furthermore, the distance of the experimental bullets 5 can be accurately controlled by the linear motors 1 controlling the movement distance of the limiting rods 2, which improves the experimental accuracy.

[0053] Referring to Figure 2 , the bullet launching barrels 4 are respectively located on the device support 13, which are cylindrical structures with a diameter of 22 mm and a length of 220 mm. One end is provided with an end cover 3, and the other end is open and faces the end face of the Hopkinson bar 12. The experimental bullets 5 are located on the same axis as the bullet launching barrels 4. Each bullet launching barrel 4 is provided with an experimental bullet 5, and the experimental bullet 5 collides with the end face of the Hopkinson bar 12 after being shot out.

[0054] Referring to Figure 4 , the experimental bullet 5 is in the shape of a cylinder with a length and an outer diameter of 20 mm. A circular table is machined at the front end, and the diameter of the table surface is 16 mm, which is the same as the diameter of the Hopkinson bar 12. The experimental bullet 5 is provided with two gas sealing ring grooves 16 at both ends, and the depth and width of the grooves are both 1 mm. A sealing ring is installed in the gas sealing ring groove 16, and the sealing ring is made of nylon. The sealing ring has two functions: one is to seal the gap between the experimental bullet 5 and the inner cavity of the bullet launching barrel 4, and the other is to reduce the friction between the experimental bullet 5 and the bullet launching barrel to the greatest extent, so that the experimental bullet 5 can accelerate faster. The experimental bullet 5 designed in the present application has two gas sealing ring grooves 16, which has better sealing performance than the traditional cylindrical bullet without grooves, and reduces the wear of the inner cavity of the bullet launching barrel 4, which is beneficial to the repeatability and consistency of the impact measurement test.

[0055] Referring to Figure 2, the three-axis Hopkinson bar and device support 13 is a whole profile of a right rectangular tetrahedron structure, the three Hopkinson bars 12 are perpendicular to each other, and are arranged at 90 degrees. The test piece is installed at the intersection of the three Hopkinson bars 12. The three Hopkinson bars 12 can respectively apply impact to the test piece from the three principal stress directions of the test piece, and can realize true triaxial impact test loading. Since the direction of the Hopkinson bar 12 is obliquely upward, the experimental bullet 5 in the bullet launching cylinder 4 will automatically fall back to the initial launching position under the action of gravity after being launched and impacting the Hopkinson bar 12, realizing the automatic resetting function of the experimental bullet 5. The automatic resetting design of the experimental bullet 5 cooperates with the automatic release of compressed air in the air tank 8 to launch the experimental bullet 5, and can realize continuous multiple impact loading tests.

[0056] Referring to Figure 2 , the buffer gasket 18 is an oblong strip-shaped sheet, and the two ends of the three buffer gaskets 18 are clamped by three gasket clamping plates 17 respectively fixed on the device support 13. The three buffer gaskets 18 are respectively perpendicular to the axis of the three Hopkinson bars 12 and are respectively in close contact with the impact end face of the Hopkinson bar 12. When the experimental bullet 5 collides with the Hopkinson bar 12, the pulse width is adjusted through the buffer gasket 18. The oblong strip-shaped buffer gasket 18 can be made of flexible sheet-shaped long strip materials of different thicknesses, densities and materials such as nylon, rubber and wool felt.

[0057] The loading control method of the three-axis Hopkinson bar impact test disclosed in the embodiment is realized based on the loading control device of the three-axis Hopkinson bar impact test, and the specific implementation steps are as follows:

[0058] Step 1: referring to Figure 5 , fix the three bullet launching cylinders 4 and the corresponding diameter Hopkinson bars 12 on the device support 13, and connect and debug the data measurement device of the Hopkinson bar 12.

[0059] Step 2: install the sealing ring of the three experimental bullets 5, and install the three experimental bullets 5 in the bullet launching cylinder 4 respectively. The sealing ring can seal the gap between the experimental bullet 5 and the bullet launching cylinder 4, form a closed cavity, sufficiently reduce the friction between the experimental bullet 5 and the bullet launching tube, and make the experimental bullet 5 accelerate faster. Install the end cover 3 of the bullet launching cylinder 4.

[0060] Step 3: Three limiting rods 2 connected with three linear motors 1 are respectively inserted into the limiting holes 15 of the three end covers 3; the linear motor 1 can drive the limiting rod 2 to move forward and backward, control the length of the limiting rod 2 inserted into the bullet launching barrel 4, and thus determine and control the launching acceleration distance of the experimental bullet 5. The interfaces of the gas pipeline 10 are respectively and sealingly connected with the air holes 14 of the end cover 3. The two air holes 14 are symmetrically distributed around the limiting hole 15. The symmetrically distributed air holes 14 can uniformly act on the bottom of the experimental bullet 5 when the experimental bullet 5 is launched, so that the experimental bullet 5 can move in a straight line and eccentric motion is avoided.

[0061] Step 4: The air compressor 6, the gas storage tank 8 and the corresponding gas pipeline 10 are connected and checked in sequence. The control console 11 is connected with the valve of each gas storage tank, and it is detected whether each part can work normally, and the experimental system is ready. The air compressor 6 is turned on, the gas storage tank 8 is inflated to the specified pressure, and the experimental bullet 5 is in a standby state.

[0062] Step 5: The present application can realize five kinds of loading control methods. Control method one: manually adjust the position of the limiting rod 2 to control the acceleration distance of the launched experimental bullet 5, change the loading pressure of the gas storage tank 8, and realize single impact loading experiment; control method two: set the impact times and interval time to realize automatic multiple same peak impact loading experiment; control method three: set the automatic adjustment of the moving limiting rod distance, set the impact times and interval time, and realize automatic multiple different peak impact loading experiment. Control method four: set the impact times and interval time of three-axis simultaneous launching to realize continuous three-axis simultaneous loading. Control method five: set the sequence and interval time of three-directional sequential firing to realize sequential single-axis loading cycle impact. According to the three-axis Hopkinson bar impact test working condition, the corresponding control method is selected to execute the steps 6, 7, 8, 9 and 10 corresponding to the five control methods respectively to carry out Hopkinson bar impact test under the corresponding working condition. The control method one corresponds to step 6, the control method two corresponds to step 7, the control method three corresponds to step 8, the control method four corresponds to step 9, and the control method five corresponds to step 10. The Hopkinson bar impact test working condition parameters include impact loading times, acceleration distance, loading pressure and interval time.

[0063] Step 6: Single impact loading experiment with arbitrary acceleration distance and arbitrary air pressure is carried out through the control method one in step 5. Referring to Figure 7, select the axis 1 by the axial selection button, rotate the position adjustment knob, realize the manual adjustment of the target position of the limiting rod 2, that is: with the rotation of the position adjustment knob, the linear motor 1 moves automatically forward and backward, moves the limiting rod 2 to the set target position, and the position display screen displays the distance from the starting position of the front end of the limiting rod to the origin in real time. The experimental bullet 5 is automatically reset and falls to the end of the limiting rod 2 under the action of gravity. Rotate the pressure loading knob clockwise to control the one-way valve, slowly charge the air tank 8 to the target air pressure, and the pressure display screen displays the pressure in the air tank 8 in real time. If the pressure exceeds the expected target air pressure of the loading, rotate the pressure unloading knob counterclockwise, and slowly release the gas through the air valve. Click the acquisition button of the data acquisition software on the computer, and the data acquisition device and the data acquisition software enter the acquisition preparation state, and when the trigger signal comes, it will automatically store and record the test data. When the acquisition software is in the acquisition preparation state, press the launch button quickly to start the experimental bullet 5, realize the collision between the experimental bullet 5 and the Hopkinson bar 12, that is: when the launch button is pressed, the compressed air in the air tank 8 is quickly released through the air outlet valve 9, the compressed air is suddenly loaded into the bullet launching cylinder 4 through the gas pipeline 10, and the experimental bullet 5 in the reset state is driven to move forward along the axis, and the end face of the Hopkinson bar 12 has a buffer pad 18, which can adjust the pulse width. The data acquisition device starts the acquisition function, the data acquisition software completes the automatic storage and recording of the test data function, and the data processing software automatically processes the data to display the experimental results and experimental curves on the computer screen.

[0064] Step 7: Perform the automatic multiple same peak impact loading experiment of setting the position of the limiting rod 2 and controlling the acceleration distance of the experimental bullet 5 by the control method two in step 5. Refer to Figure 6 、 Figure 9, first set the number of impacts and interval time, that is: by the number of impact increase and decrease button, the number of experiments to adjust to the expected value, and then click the confirmation button, complete the impact number setting. By the interval time increase and decrease button, the interval time is adjusted to the expected value, and then click the confirmation button, complete the interval time setting. By loading pressure increase and decrease button, the initial value of the loading pressure is adjusted to the expected value, and the step pressure increase value is set to zero, that is, the pressure is constant and does not increase, and then click the confirmation button, complete the loading pressure setting in the gas tank 8. Finally, the acceleration distance setting of the experimental bullet 5 is performed, that is: by the acceleration distance increase and decrease button, the initial value of the acceleration distance is adjusted to the expected value, and the step acceleration distance increase value is set to zero, that is, the acceleration distance is constant and does not increase, and finally click the confirmation button, complete the position adjustment setting of the limit rod 2. After the above four initial parameters are set, enter the experimental preparation state. Click the acquisition button of the data acquisition software on the computer, and the data acquisition device and the data acquisition software enter the acquisition preparation state, and when the trigger signal comes, it will automatically store and record the test data. When the acquisition software is in the acquisition preparation state, press the firing button quickly to start the experimental bullet 5, realize the collision between the experimental bullet 5 and the Hopkinson bar 12, and the end face of the Hopkinson bar 12 has a buffer pad 18, which can adjust the pulse width. The experimental bullet 5 collides with the Hopkinson bar 12 for the first time, and a trigger signal is generated. The data acquisition device starts the acquisition function. After completing a shot, the experimental bullet 5 is automatically reset to the initial firing position under the action of gravity. According to the set impact number, interval time, loading pressure, and acceleration distance parameters, the next shot experiment is automatically performed until the set impact number is completed. The two gas tanks 8 of each bullet firing cylinder 4 work alternately, which can reduce the interval time of the next shot. Click the manual stop data acquisition button, and the data acquisition software will automatically store and record the test data to the computer hard disk. Click the manual data processing software button to display the experimental results and experimental curves on the computer screen.

[0065] Step 8: Set the automatic adjustment of the limit rod 2 position, set the initial value of the loading pressure and the step pressure increase value, set the impact number and interval time by the control method three in step 5, and perform automatic multiple different peak impact loading experiments. Refer to Figure 8 、 Figure 9, first select the axis 1 by the axial selection button, set the impact number and interval time, that is, adjust the experiment number to the expected value by the impact number increase and decrease button, then click the confirmation button to complete the impact number setting. Adjust the interval time to the expected value by the interval time increase and decrease button, then click the confirmation button to complete the interval time setting. Adjust the initial value of the loading pressure to the expected value by the loading pressure increase and decrease button, set the step pressure increase value to the expected value, that is, the pressure increases by one step pressure each time, and finally click the confirmation button to complete the loading pressure setting in the gas storage tank 8. Finally, set the acceleration distance of the experimental bullet 5, that is, adjust the initial value of the acceleration distance to the expected value by the acceleration distance increase and decrease button, set the step acceleration distance increase value to the expected value, that is, the acceleration distance increases by one step distance each time, and finally click the confirmation button to complete the position adjustment setting of the limit rod 2. After the above four initial parameters are set, enter the experiment preparation state. Click the acquisition button of the data acquisition software on the computer, and the data acquisition device and the data acquisition software enter the acquisition preparation state. When the trigger signal arrives, the test data will be automatically stored and recorded. When the acquisition software is in the acquisition preparation state, press the firing button quickly to start the experimental bullet 5, realize the collision between the experimental bullet 5 and the Hopkinson bar 12, and the end face of the Hopkinson bar 12 has a buffer pad 18 in front of it, which can adjust the pulse width and generate a trigger signal. The data acquisition device starts the acquisition function. After completing one firing, the experimental bullet 5 is automatically reset to the initial firing position under the action of gravity. According to the parameters such as the impact number, interval time, loading pressure increase value, and acceleration distance increase value, the next firing experiment is automatically performed until the set impact number is completed. The two gas storage tanks 8 connected to each bullet firing cylinder 4 work alternately, which can reduce the interval time of the next firing. Click the manual stop data acquisition button, and the data acquisition software will automatically store and record the test data to the computer hard disk. Click the manual data processing software button to display the experimental results and experimental curves on the computer screen.

[0066] Step 9: Perform continuous three-axis simultaneous loading impact control by the control method four in step 5. Set the positions of the three limit rods 2 respectively to control the acceleration distance of the experimental bullet 5, and complete the automatic multiple same peak value impact loading experiment. Refer to Figure 10 、 Figure 9, first set the number of impacts and interval time, that is: by the number of impact increase and decrease button, the number of experiments to adjust to the desired value, and then click the confirmation button, complete the impact number setting. By the interval time increase and decrease button, the interval time is adjusted to the desired value, and then click the confirmation button, complete the interval time setting. By loading pressure increase and decrease button, the initial value of the loading pressure is adjusted to the expected value, and the step pressure increase value is set to zero, that is, the pressure is constant and does not increase, and then click the confirmation button, complete the loading pressure setting in the gas tank 8. Finally, the acceleration distance setting of the experimental bullet 5 is performed, that is: by the acceleration distance increase and decrease button, the initial value of the acceleration distance is adjusted to the expected value, and the step acceleration distance increase value is set to zero, that is, the acceleration distance is constant and does not increase, and finally click the confirmation button to complete the position adjustment setting of the three limit rods 2. After the above four initial parameters are set, enter the experimental preparation state. Click the acquisition button of the three-axis impact test data acquisition software on the computer, and the three-channel data acquisition device and the data acquisition software enter the acquisition preparation state. When the trigger signal arrives, it will automatically store and record the test data. When the acquisition software is in the acquisition preparation state, press the three-axis synchronous firing button quickly, and the three axes start the experimental bullet 5 at the same time, so that the three experimental bullets 5 and the three orthogonal directions of the Hopkinson bar 12 are synchronized to collide, that is: when the three-axis synchronous firing button is pressed, the compressed air in the three gas tanks 8 of the three axes is quickly released through the respective air outlet valves 9, and the compressed air is suddenly loaded into the three bullet launch tubes 4 through the gas pipeline 10, driving the experimental bullet 5 in the reset state to move forward along the axis, and the three experimental bullets 5 and the end face of the three Hopkinson bars 12 collide synchronously. The end face of the Hopkinson bar 12 has a buffer pad 18 in front of it, which can adjust the pulse width. The experimental bullet 5 and the Hopkinson bar 12 collide for the first time, generating a trigger signal, and the three-channel data acquisition device starts the acquisition function. After completing a shot, the experimental bullet 5 falls on the end of the limit rod 2 due to gravity and returns to the initial launch position. According to the set impact number, interval time, loading pressure, and acceleration distance parameters, the next shot experiment is automatically performed until the set impact number is reached. The two gas tanks 8 of each axis work alternately to reduce the interval time for the next shot. Click the manual stop data acquisition button, and the three-axis impact test data acquisition software will automatically store and record the test data to the computer hard disk. Click the manual data processing software button to display the experimental results and experimental curves on the computer screen.

[0067] Step 10: Perform three-direction single-axis sequential loading multi-cycle impact control by the control method five in step 5. Refer to Figure 11 、 Figure 9, respectively set the position of the three limit rods 2, control the acceleration distance of the experimental bullet 5, and complete the automatic multiple three-axis different peak impact loading experiment. First, set the impact number and interval time, that is, adjust the experimental number to the expected value by increasing and decreasing the impact number button, then press the confirmation button to complete the impact number setting. Adjust the interval time to the expected value by increasing and decreasing the interval time button, then press the confirmation button to complete the interval time setting. Adjust the initial value of the loading pressure to the expected value by increasing and decreasing the loading pressure button, set the step pressure increase value to zero, that is, the pressure is constant and does not increase, then press the confirmation button to complete the loading pressure setting in the gas tank 8. Finally, set the acceleration distance of the experimental bullet 5, that is, adjust the initial value of the acceleration distance to the expected value by increasing and decreasing the acceleration distance button, set the step acceleration distance increase value to zero, that is, the acceleration distance is constant and does not increase, and finally press the confirmation button to complete the position adjustment setting of the three limit rods 2. After the above four initial parameters are set, enter the experimental preparation state. Click the acquisition button of the three-axis impact test data acquisition software on the computer, and the three-channel data acquisition device and the data acquisition software enter the acquisition preparation state. When the trigger signal arrives, it will automatically store and record the test data. When the acquisition software is in the acquisition preparation state, press the multi-round single-axis sequential cycle firing button quickly, the three gas tanks 8 release compressed air in sequence, the single-axis starts the experimental bullet 5 in sequence, and the three experimental bullets 5 collide with the three orthogonal directions of the Hopkinson bar 12 in sequence, that is, when the multi-round single-axis sequential cycle firing button is pressed, the compressed air in the three gas tanks 8 is released in sequence through the respective air release valve 9, the compressed air is loaded into the three bullet launch tubes 4 through the gas pipeline 10 in sequence, and the experimental bullet 5 in the reset state is driven to move forward along the axis, and the three experimental bullets 5 collide with the end face of the three Hopkinson bars 12 in sequence. The end face of the Hopkinson bar 12 has a buffer pad 18 in front of it, which can adjust the pulse width. The experimental bullet 5 collides with the Hopkinson bar 12 for the first time, generating a trigger signal, and the three-channel data acquisition device starts the acquisition function. After completing a round of firing, the experimental bullet 5 falls on the end of the limit rod 2 due to gravity and returns to the initial firing position. According to the set impact number, interval time, loading pressure, and acceleration distance parameters, the next round of firing experiment is automatically performed until the set impact number is completed. The two gas tanks 8 of each axis work alternately to reduce the interval time for the next firing. Click the manual stop data acquisition button, and the three-channel data acquisition software automatically stores and records the test data of the multi-round single-axis sequential cycle experiment to the computer hard disk, and clicks the manual data processing software button to display the experimental results and experimental curves on the computer screen.

[0068] The above detailed description of the specific description, the purpose, technical scheme and beneficial effects of the application are further described in detail, it should be understood that the above description is only a specific embodiment of the present application, and is not used to limit the protection scope of the present application, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A loading control device for a triaxial hopkinson bar impact test, characterized by: It comprises a linear motor, a limiting rod, an end cover, a bullet launching cylinder, an experimental bullet, an air compressor, an air storage tank, a control console, a three-axis Hopkinson bar, a buffer gasket, and a gasket clamping plate. The air outlet of the air compressor is divided into three air passages via a four-way joint, each air passage is connected with an air inlet valve and an air storage tank, and the air outlet of each air storage tank is connected with the air holes on the end covers of three bullet launching cylinders via an air outlet valve and a gas pipeline. The end cover is located at the end of the bullet launching cylinder and is connected with the bullet launching cylinder. The limiting rod is inserted into the three bullet launching cylinders via the limiting holes on the three end covers, and the other ends of the three limiting rods are connected with three linear motors. The bullet launching cylinder is located on the device support of the three-axis Hopkinson bar, is a cylindrical structure with a cylindrical through hole, is provided with an end cover at one end and is open at the other end, and faces the end surface of the Hopkinson bar. The experimental bullet is cylindrical, is located in the three bullet launching cylinders, is provided with a circular truncated cone at the front end, and is provided with a closed air ring groove at both ends. The two ends of the experimental bullet are provided with a closed air ring groove, and a sealing ring is installed in the groove. The sealing ring has two functions: one is to seal the gap between the experimental bullet and the inner cavity of the bullet launching cylinder, and the other is to reduce the friction between the experimental bullet and the bullet launching cylinder. The triaxial Hopkinson bar and device support overall profile is a right rectangular tetrahedron structure, which is composed of three Hopkinson bars, and the three Hopkinson bars are vertically distributed in pairs; the tested piece is installed at the intersection of the three Hopkinson bars; the three Hopkinson bars can apply impact of different strengths to the tested piece from three main stress directions of the test piece, and can realize true triaxial impact test loading; since the direction of the triaxial Hopkinson bar is obliquely upward, the experimental bullet in the bullet launching cylinder will automatically fall back to the initial launching position under the action of gravity after impacting the Hopkinson bar, thereby realizing the automatic resetting function of the experimental bullet; The buffer gasket is a rectangular strip-shaped sheet, and the two ends of the buffer gasket are clamped by the gasket clamping plate fixed on the device support, the buffer gasket plane is perpendicular to the Hopkinson bar axis, and is tightly attached to the impact end surface of the Hopkinson bar; when the experimental bullet collides with the Hopkinson bar, the pulse width is adjusted through the buffer gasket.

2. The loading control device of a triaxial Hopkinson bar impact test according to claim 1, characterized by: Each bullet launching cylinder is connected with multiple gas storage tanks side by side, and the multiple gas storage tanks work alternately, which can reduce the interval time of the next firing.

3. The loading control device of a triaxial Hopkinson bar impact test according to claim 1, characterized by: The air vents are symmetrically distributed on both sides of the limiting hole; the symmetrically distributed air vents can uniformly act on the bottom of the experimental bullet to drive the experimental bullet to move linearly along the axis of the bullet launching cylinder, thereby avoiding eccentric motion.

4. The loading control device of a triaxial Hopkinson bar impact test according to claim 1, characterized by: The limiting rod is used to determine and control the launching position of the experimental bullet, and the purpose is achieved by the following process: the limiting rod is moved to the specified position in the bullet launching cylinder by the linear motor, and then the experimental bullet in the bullet launching cylinder automatically falls to the end of the limiting rod under the action of gravity, and contacts the limiting rod, thereby controlling the launching position of the experimental bullet; and then the accelerating distance of the experimental bullet can be accurately controlled according to the distance of the linear motor controlling the movement of the limiting rod, thereby improving the experimental precision of the triaxial Hopkinson bar impact test.

5. The loading control device of a triaxial Hopkinson bar impact test according to claim 1, characterized by: The rectangular strip-shaped buffer gasket material is selected from flexible sheet-shaped long strip materials.

6. The loading control device of a triaxial Hopkinson bar impact test according to claim 5, characterized by: The flexible sheet-shaped long strip material includes nylon, rubber and wool felt.

7. A loading control method of a triaxial Hopkinson bar impact test, implemented based on the loading control device of the triaxial Hopkinson bar impact test according to claim 1, 2, 3, 4, 5 or 6, characterized in that: The method comprises the following steps: Step 1: fix the bullet launching cylinder and the corresponding diameter Hopkinson bar on the device support respectively, connect and install the data measurement device of the Hopkinson bar after debugging; Step 2: install the sealing ring of the experimental bullet, and install the experimental bullet in the bullet launching cylinder; the sealing ring can seal the gap between the experimental bullet and the bullet launching cylinder, form a closed cavity, sufficiently reduce the friction between the experimental bullet and the bullet launching tube, and make the experimental bullet accelerate faster; install the end cover of all bullet launching cylinders; Step 3: insert the limiting rod connected with the linear motor into the limiting hole of the end cover; the linear motor can drive the limiting rod to move forward and backward, control the length of the limiting rod inserted into the bullet launching cylinder, thereby determine and control the accelerating distance of the experimental bullet; seal and connect the interface of the gas pipeline with the air vent of the end cover; the air vents are symmetrically distributed around the limiting hole; the symmetrically distributed air vents can uniformly act on the bottom of the experimental bullet when launching and resetting the experimental bullet, so that the bullet can move linearly and avoid eccentric motion; Step 4: sequentially connect and check the air compressor, gas tank and corresponding gas pipeline; connect the control console with the valve of each gas tank, and detect whether each part can work normally, so that the experimental system is ready; Turn on the air compressor, adjust the pressure control knob, and the pressure display instrument displays the pressure in real time. The gas tank is inflated to the specified pressure, and the experimental bullet is in a ready-to-fire state; Step 5: the next five impact experiment loading control methods can be realized. Control method one: manually adjust the position of the limiting rod to control the acceleration distance of the experimental bullet, change the loading pressure of the gas tank, and realize single impact loading experiment; control method two: set the impact number and interval time to realize automatic multiple same peak impact loading experiment; control method three: set the automatic adjustment of the moving limiting rod distance, set the impact number and interval time, and realize automatic multiple different peak impact loading experiment; control method four: set the impact number and interval time of three-axis simultaneous firing to realize continuous three-axis simultaneous loading; control method five: set the sequence and interval time of three-directional sequential firing to realize sequential single-axis loading cycle impact; according to the three-axis Hopkinson bar impact test working condition, select the corresponding control method, and execute steps 6, 7, 8, 9 and 10 corresponding to the five control methods respectively to perform Hopkinson bar impact test under the corresponding working condition; the control method one corresponds to step 6, the control method two corresponds to step 7, the control method three corresponds to step 8, the control method four corresponds to step 9, and the control method five corresponds to step 10; the Hopkinson bar impact test working condition parameters include impact loading number, acceleration distance, loading pressure and interval time; Step 6: single impact loading experiment with arbitrary acceleration distance and arbitrary gas pressure is carried out through control method one in step 5; Clockwise or counterclockwise rotation of the position adjusting knob realizes manual adjustment control function of the target position of the limiting rod, that is, with the rotation of the position adjusting knob, the linear motor automatically moves forward and backward to move the limiting rod to the set target position, and the position display screen displays the distance from the front end of the limiting rod to the starting position in real time; the experimental bullet is automatically reset and falls to the end of the limiting rod under the action of gravity; clockwise rotation of the pressure loading knob controls the one-way valve, slowly inflates the gas tank to the target gas pressure, and the pressure display screen displays the pressure in the gas tank; if the pressure exceeds the target gas pressure of the expected loading, rotate the pressure unloading knob counterclockwise, and slowly release the gas through the gas valve; adjust the pressure in the gas tank to the target gas pressure by cooperating the pressure loading knob and the pressure unloading knob. Click on the data acquisition software on the computer acquisition button, data acquisition device and data acquisition software into the acquisition preparation state, trigger signal to come, will automatically store record test data; When the acquisition software acquisition preparation state, press the launch button quickly, start the experimental bullet firing, realize the experimental bullet and Hopkinson bar collision, that is: when the launch button is pressed, the compressed air in the gas tank is quickly released through the valve, the compressed air is suddenly loaded to the launch cylinder through the pipeline, the reset state of the launch bullet is quickly moved forward along the axis, and the collision with the end face of the Hopkinson bar occurs. The end face of the Hopkinson bar has a buffer pad in front of it, which can adjust the pulse width; The experimental bullet collides with the Hopkinson bar instantaneously, a trigger signal is generated, the data acquisition device starts the acquisition function, the data acquisition software completes the automatic storage and recording of test data function, and the data processing software automatically processes the data. The experimental results and experimental curves are displayed on the computer screen; Step 7: Set the position of the limiting rod, control the acceleration distance of the experimental bullet, and perform automatic multiple identical peak impact loading experiments by the control method two in step 5; first, set the impact number and interval time, i.e., adjust the experimental number to the desired value by increasing and decreasing the impact number keys, then click the confirmation button to complete the impact number setting; adjust the interval time to the desired value by increasing and decreasing the interval time keys, then click the confirmation button to complete the interval time setting; adjust the initial value of the loading pressure to the desired value by increasing and decreasing the loading pressure keys, set the step pressure increase value to zero, i.e., the pressure is constant and does not increase, then click the confirmation button to complete the loading pressure setting in the gas tank; set the acceleration distance of the experimental bullet, i.e., adjust the initial value of the acceleration distance to the desired value by increasing and decreasing the acceleration distance keys, set the step acceleration distance increase value to zero, i.e., the acceleration distance is constant and does not increase, and finally click the confirmation button to complete the limiting rod position adjustment setting; after the four initial parameters are set, enter the experimental preparation state; click the data acquisition button of the data acquisition software on the computer, and the data acquisition device and data acquisition software enter the acquisition preparation state, which will automatically store the test data when the trigger signal arrives; when the acquisition software is in the acquisition preparation state, press the launch button quickly to start the experimental bullet firing and realize the collision of the experimental bullet with the Hopkinson bar, i.e., when the launch button is pressed, the compressed air in the gas tank is rapidly released through the outlet valve, and the compressed air is suddenly loaded into the bullet launch cylinder through the gas pipeline, driving the experimental bullet in the reset state to move forward along the axis and collide with the end face of the Hopkinson bar; the end face of the Hopkinson bar has a buffer pad in front of it, which can adjust the pulse width; the experimental bullet and the Hopkinson bar collide for the first time, generating a trigger signal, and the data acquisition device starts the acquisition function; after completing one firing, the experimental bullet is automatically reset to the initial launch position under the action of gravity; the next firing experiment is automatically performed according to the set impact number, interval time, loading pressure, and acceleration distance parameters until the set impact number is completed; click the manual stop data acquisition button, and the data acquisition software automatically stores the test data to the computer hard disk, and click the manual data processing software button to display the experimental results and experimental curves on the computer screen; Step 8: Set the automatic adjustment of the mobile limit rod position, set the initial value and step pressure increase value of the loading pressure, set the impact number and interval time by the control method three in step 5, and carry out the automatic multiple different peak impact loading experiment; first, set the impact number and interval time, that is, adjust the experiment number to the expected value by increasing and decreasing the impact number keys, then click the confirmation button, complete the impact number setting; adjust the interval time to the expected value by increasing and decreasing the interval time keys, then click the confirmation button, complete the interval time setting; adjust the initial value of the loading pressure to the expected value by increasing and decreasing the loading pressure keys, set the step pressure increase value to the expected value, that is, the pressure increases by one step pressure each time, and finally click the confirmation button to complete the loading pressure setting in the gas tank; finally, set the acceleration distance of the launched bullet, that is, adjust the initial value of the acceleration distance to the expected value by increasing and decreasing the acceleration distance keys, set the step acceleration distance increase value to the expected value, that is, the acceleration distance increases by one step distance each time, and finally click the confirmation button to complete the limit rod position adjustment setting; after the four initial parameters are set, enter the experiment preparation state; click the acquisition button of the data acquisition software on the computer, and the data acquisition device and the data acquisition software enter the acquisition preparation state, which will automatically store the test data when the trigger signal arrives; when the acquisition software is in the acquisition preparation state, press the launch button quickly to start the experiment bullet firing and realize the collision between the experiment bullet and the Hopkinson bar, that is, when the launch button is pressed, the compressed air in the gas tank is quickly released through the valve, the compressed air is suddenly loaded into the bullet launch cylinder through the gas pipeline, and the reset state of the launched bullet is quickly moved forward along the axis to collide with the end face of the Hopkinson bar; the end face of the Hopkinson bar has a buffer pad in front of it, which can adjust the pulse width; the experiment bullet collides with the Hopkinson bar for the first time, and a trigger signal is generated, and the data acquisition device starts the acquisition function; after completing one firing, the experiment bullet is automatically reset to the initial launch position under the action of gravity; according to the set impact number, interval time, loading pressure increase value and acceleration distance increase value parameters, the next firing experiment is automatically carried out until the set impact number is completed; click the manual stop data acquisition button, and the data acquisition software automatically stores the test data to the computer hard disk, and click the manual data processing software button to display the experimental results and experimental curves on the computer screen; Step 9: continuous triaxial simultaneous loading impact control is carried out through the control method four in step 5; the positions of the three limit rods are respectively set to control the acceleration distance of the test bullet, and automatic multiple same peak impact loading experiments are completed; first, the impact number and interval time are set, that is, the experiment number is adjusted to the expected value through the impact number increase and decrease buttons, then the confirm button is clicked to complete the impact number setting; the interval time is adjusted to the expected value through the interval time increase and decrease buttons, then the confirm button is clicked to complete the interval time setting; the initial value of the loading pressure is adjusted to the expected value through the loading pressure increase and decrease buttons, the step pressure increase value is set to zero, that is, the pressure is constant and does not increase, then the confirm button is clicked to complete the loading pressure setting in the gas storage tank; finally, the acceleration distance of the test bullet is set, that is, the initial value of the acceleration distance is adjusted to the expected value through the acceleration distance increase and decrease buttons, the step acceleration distance increase value is set to zero, that is, the acceleration distance is constant and does not increase, and finally the confirm button is clicked to complete the position adjustment setting of the three limit rods; after the four initial parameters are set, the experiment preparation state is entered; the acquisition button of the triaxial impact test data acquisition software on the computer is clicked, the three-channel data acquisition device and the data acquisition software enter the acquisition preparation state, and when the trigger signal comes, the test data will be automatically stored and recorded; when the acquisition software is in the acquisition preparation state, the triaxial synchronous firing button is pressed quickly, the three experimental bullets are fired, and the three experimental bullets and the three orthogonal Hopkinson bars are synchronously collided, that is, when the triaxial synchronous firing button is pressed, the compressed air in the three gas storage tanks is quickly released through the respective valves, the compressed air is suddenly loaded to the three bullet launch tubes through the pipeline, the reset experimental bullets are quickly moved forward along the axis, and the three experimental bullets and the three Hopkinson bars are synchronously collided; the front end of the Hopkinson bar has a buffer pad, which can adjust the pulse width; the experimental bullet and the Hopkinson bar are collided for the first time, a trigger signal is generated, and the three-channel data acquisition device starts the acquisition function; after one firing is completed, the experimental bullet falls on the end of the limit rod due to gravity and returns to the initial firing position; the next firing experiment is automatically carried out according to the set impact number, interval time, loading pressure and acceleration distance parameters until the set impact number is completed; the manual stop data acquisition button is clicked, the triaxial impact test data acquisition software automatically stores and records the test data of multiple experiments to the computer hard disk, and the experimental results and experimental curves are displayed on the computer screen by clicking the manual data processing software data processing button; Step 10: Three-direction single-axis sequential loading multi-cycle impact control is performed by the control method five in step 5; three limit rod positions are set respectively to control the acceleration distance of the experimental bullet, and automatic multiple three-axis impact loading experiments with different peak values are completed; first, the impact number and interval time are set, that is, the experimental number is adjusted to the expected value by increasing and decreasing the impact number keys, and then the confirmation button is pressed to complete the impact number setting; the interval time is adjusted to the expected value by increasing and decreasing the interval time keys, and then the confirmation button is pressed to complete the interval time setting; the initial value of the loading pressure is adjusted to the expected value by increasing and decreasing the loading pressure keys, the step pressure increase value is set to zero, that is, the pressure is constant and does not increase, and then the confirmation button is pressed to complete the loading pressure setting in the gas storage tank; the acceleration distance of the launched experimental bullet is set, that is, the initial value of the acceleration distance is adjusted to the expected value by increasing and decreasing the acceleration distance keys, the step acceleration distance increase value is set to zero, that is, the acceleration distance is constant and does not increase, and finally the confirmation button is pressed to complete the adjustment and setting of the positions of the three limit rods; after the four initial parameters are set, the experimental preparation state is entered; the acquisition button of the three-axis impact test data acquisition software on the computer is clicked, the three-channel data acquisition device and the data acquisition software enter the acquisition preparation state, and when the trigger signal arrives, the test data will be automatically stored and recorded; when the acquisition software is in the acquisition preparation state, the multi-cycle single-axis sequential firing button is pressed quickly, the three gas storage tanks release compressed air in sequence, the single-axis sequential firing of the experimental bullet is started, and the collision of the three experimental bullets with the three orthogonal Hopkinson bars is realized, that is, when the multi-cycle single-axis sequential firing button is pressed, the compressed air in the three gas storage tanks is released quickly in sequence through the respective air release valves, the compressed air is loaded into the three bullet launch barrels through the gas pipeline in sequence, the experimental bullets in the reset state are driven to move forward along the axis, and the three experimental bullets collide with the end faces of the three Hopkinson bars in sequence; the end face of the Hopkinson bar has a buffer pad in front of it, which can adjust the pulse width; the first collision of the experimental bullet with the Hopkinson bar generates a trigger signal, and the three-channel data acquisition device starts the acquisition function; after one round of firing is completed, the experimental bullet falls on the end of the limit rod due to gravity and returns to the initial firing position; the next round of firing experiment is automatically performed according to the set impact number, interval time, loading pressure, and acceleration distance parameters until the set impact number is completed; the manual stop data acquisition button is clicked, the three-channel data acquisition software automatically stores and records the multi-cycle single-axis sequential experimental data to the computer hard disk, and the experimental results and experimental curves are displayed on the computer screen by clicking the manual data processing software button.

8. The method of controlling loading in a triaxial Hopkinson bar impact test according to claim 7, characterized in that: Each bullet launch barrel is connected with multiple gas storage tanks side by side, and the multiple gas storage tanks work alternately, which can reduce the interval time for the next firing.

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