A multi-degree-of-freedom random vibration test device and test method

Abstract

The present invention discloses a multi-degree-of-freedom random vibration test device and a test method. The device includes a vibration test bench, a vibration control system, and a power amplifier connected to the vibration control system. The vibration test bench includes a horizontal vibration table, a base, a central excitation device, a side excitation device, and a corner excitation device. The vibration acceleration signal is input through the vibration control system and, through the power amplifier, the input signal is amplified and converted into a voltage signal and a current signal for driving an electric vibrator to achieve vibration. The present invention realizes that the vibration table truly restores the random vibrations suffered by various automotive parts during vehicle driving. The random vibration test method checks and confirms the vibration signals of the vibration test device, the test fixture, and the parts to be tested, maximizing the avoidance of errors in the transmission process of the vibration signals, ensuring that the vibration signals can be accurately transmitted to the parts to be tested, and guaranteeing that the test has high accuracy and reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration test, and particularly relates to a multi-degree-of-freedom random vibration test device and test method for automotive parts. Background Art

[0002] Random vibration test is mainly to simulate the vibration conditions of automotive parts during vehicle driving from the road surface, engine, motor, etc., so as to determine the fatigue life of automotive parts and provide a basis for evaluating the service life and driving mileage of the whole vehicle. Random vibration test is widely used in the production test links of various automotive parts. It is required that the vibration test device can generate vibration signals identical to the input signals during the test to test whether various automotive parts can withstand the test of random vibration within the life cycle.

[0003] Most of the existing random vibration test benches are single-degree-of-freedom vibration test benches. For example, the utility model patent "A vibration table for product testing" with the publication number of "CN214471641U" introduces a single-degree-of-freedom vibration test bench. The test bench can only vibrate independently in the X or Y or Z direction. The test method is to convert the random vibration received by the part into single-degree-of-freedom vibrations in the X, Y, and Z directions, and then perform random vibrations in the X, Y, and Z horizontal directions in sequence during the test to restore the random vibration received by the part during the working process. However, in actual situations, the vibration received by automotive parts during vehicle driving is a multi-compound vibration, not only including horizontal vibrations in various directions, but also including rotations around the axis. At the same time, currently most random vibration tests directly start the test after connecting the parts to be tested to the vibration table without checking the transmission of vibration signals, and it is impossible to ensure that the input vibration signals are accurately transmitted to the parts to be tested. Summary of the Invention

[0004] In order to at least solve one of the technical defects in the prior art, the present invention provides a multi-degree-of-freedom random vibration test device and test method. The test device can simulate the random vibration conditions received by various automotive parts during vehicle driving and is used for the random vibration test of automotive parts. The random vibration test method can check the vibration signals during the vibration test process to ensure that the input vibration signals are accurately transmitted to the parts to be tested.

[0005] In order to achieve the object of the present invention, a multi-degree-of-freedom random vibration test device provided by the present invention includes a vibration test bench frame, a vibration control system, and a power amplifier connected to the vibration control system.

[0006] The vibration test bench includes a horizontal vibration table, a base, a central excitation device, side excitation devices, and corner excitation devices. The horizontal vibration table and the base are oppositely arranged. The central excitation device, side excitation devices, and corner excitation devices are detachably arranged between the horizontal vibration table and the base. A right-handed XYZ coordinate system is established with the horizontal vibration table as the origin. Among them, the XOY plane is parallel to the plane of the horizontal vibration table, the X-axis direction and the Y-axis direction are respectively parallel to two mutually perpendicular sides of the horizontal vibration table, and the Z-axis direction is vertically upward. Among them, the central excitation device is used to provide Z-direction vibration to the workpiece, the side excitation devices are used to provide vibration to the workpiece in the X and Y horizontal directions and rotation around the Z-axis, and the corner excitation devices are used to provide rotation to the workpiece around the X-axis and around the Y-axis;

[0007] The vibration control system is used to input the random vibration power spectral density to be simulated and transmit the vibration signal to the power amplifier to be converted into voltage signals and current signals. The power amplifier transmits the converted signals to each excitation device.

[0008] The vibration acceleration signal is input through the vibration control system. Through the power amplifier, the input signal is amplified and transformed into a voltage signal or a current signal, which is used to drive the electric vibrator to achieve vibration.

[0009] Furthermore, it also includes a cooling cabinet. The cooling cabinet is connected to each excitation device through cooling pipelines and is used to cool the excitation devices.

[0010] Furthermore, the outlet pipeline of the cooling cabinet is connected to the water-cooling pipelines at the bottom of the base. The water-cooling pipelines include multiple water-cooling branch pipelines, which respectively lead to each excitation device. The multiple water-cooling branch pipelines finally converge at the water outlet at the bottom of the base and are connected to the water inlet of the cooling cabinet to form a loop. Each vibrator is provided with a water-cooling branch pipeline, and the heat generated by the movement of the vibrator is carried away by the cooling water.

[0011] Furthermore, the central excitation device is arranged at the exact center position of the horizontal vibration table. There are four side excitation devices, which are respectively located around the horizontal vibration table. There are four corner excitation devices, which are respectively located at the four corners of the horizontal vibration table.

[0012] Furthermore, workpiece mounting holes are evenly arranged on the horizontal vibration table and are used to connect with the parts to be tested.

[0013] Furthermore, buffer blocks are arranged at the bottom end of the base.

[0014] The horizontal vibration table is evenly arranged with threaded holes for connecting with the parts to be tested or with the tooling fixture; vertical baffle fixing bolt holes are distributed around the horizontal vibration table for installing and fixing the vertical baffles in the four side excitation devices; guide sleeve fixing bolt holes are distributed at the four corners of the horizontal vibration table for installing and fixing the guide sleeves in the four corner excitation devices; a spherical receiving cavity matching the universal ball head is provided at the center of the horizontal vibration table, and the ball head can rotate in the spherical receiving cavity.

[0015] Furthermore, a spherical receiving cavity is concavely arranged at the bottom of the horizontal vibration table;

[0016] The central excitation device includes a universal ball head, a double ball joint decoupling device, a central electric exciter and a central exciter base. The central exciter base is detachably connected to the base. The central electric exciter is fixed on the central exciter base. The output end of the central electric exciter is connected to the universal ball head through the double ball joint decoupling device. The universal ball head is movably arranged in the spherical receiving cavity. The horizontal vibration table can be rotated in any direction through the universal ball head.

[0017] Furthermore, the side vibration device includes a vertical baffle, a horizontal connecting rod, a first ball joint, a side electric vibrator and a side base. The side base is detachably connected to the base. The side electric vibrator is rotatably arranged on the side base to rotate around the X-axis or the Y-axis. The output end of the side electric vibrator is connected to the horizontal connecting rod through the first ball joint. The free end of the horizontal connecting rod is connected to the vertical baffle. The vertical baffle is detachably connected to the horizontal vibration table for transmitting the horizontal exciting force transmitted from the horizontal connecting rod, so that the horizontal vibration table can vibrate and rotate in the horizontal direction.

[0018] The side electric vibrator is connected to the horizontal connecting rod through an adapter and a ball joint, and transmits vibration to the horizontal connecting rod, and the horizontal connecting rod can rotate in any direction around the ball joint. The side electric vibrator is connected to the base through a trunnion bracket, and the side electric vibrator can rotate around the trunnion connection hole.

[0019] Furthermore, the angular vibration device includes an angular electric vibrator, a vertical connecting rod, a second ball joint and a guide sleeve. The angular electric vibrator is detachably arranged on the base. The two ends of the vertical connecting rod are respectively connected to the output end of the angular electric vibrator and one end of the guide sleeve through the second ball joint. The other end of the guide sleeve is detachably connected to the horizontal vibration table for transmitting the exciting force in the vertical direction.

[0020] One end of the vertical connecting rod is connected to the guide sleeve through the second ball joint, and the other end is connected to the angular electric vibrator through the second ball joint and the adapter, so that the guide sleeve can rotate and translate in any direction.

[0021] Further, bolt holes are provided at specific positions on the vibration table base for connecting with the bases of each exciter; a buffer block is installed at the bottom end of the base to slow down the transmission of vibration between the ground and the vibration table.

[0022] The vibration control system is used to input vibration signals and monitor the vibration signals in real time during the test. The input vibration power spectral density is processed and then transmitted to the power amplifier, which converts the vibration signal into a voltage signal and a current signal, and finally transmits them to the central excitation device, the side excitation device, and the corner excitation device respectively. At the same time, during the vibration process, the vibration signals measured in real time by the sensors on the component to be tested are collected through the acceleration data collector, which is used to feedback and control the vibration of the vibration table, further ensuring the accuracy of the vibration signal transmission.

[0023] All the electro-excitors are electric exciters, which can provide a wider vibration frequency range and a greater excitation force. The exciters have no interference in all directions and can be controlled independently.

[0024] The present invention also provides a random vibration test method, which includes the following steps:

[0025] (1) Perform no-load frequency sweeping on the vibration table: Uniformly arrange i (i≥1) acceleration sensors on the horizontal vibration table, input the vibration acceleration a0 through the vibration control system, and sequentially perform frequency sweeping on the horizontal vibration table in the X, Y, and Z axial directions, and compare the vibration acceleration a ti measured by the i-th acceleration sensor with the input vibration acceleration a0. If the two are equal, it means that the vibration table can vibrate according to the input vibration acceleration, which proves that the random vibration test device can accurately transmit the vibration signal;

[0026] (2) After fixing the tooling fixture to the vibration table surface, perform no-load frequency sweeping on the tooling fixture: Arrange m (m≥1) acceleration sensors at the connection and fixing positions between the tooling fixture and the component to be tested, input the vibration acceleration a0 through the vibration control system, and sequentially perform frequency sweeping on the tooling fixture in the X, Y, and Z axial directions, and compare the vibration acceleration a fm measured by the m-th acceleration sensor with the input vibration acceleration a0. If the two are equal, it means that the tooling fixture can vibrate according to the input vibration acceleration, which proves that the tooling fixture can accurately transmit the vibration signal;

[0027] (3) After fixing the component to be tested to the tooling fixture, perform frequency sweeping on the component to be tested: Keep the positions of the acceleration sensors in step (2) unchanged, and at the same time select key positions on the component to be tested to arrange n (n≥1) acceleration sensors, and then input the vibration acceleration a0 through the vibration control system, and sequentially perform frequency sweeping on the component to be tested in the X, Y, and Z axial directions, and compare the vibration acceleration afm With the input vibration acceleration \(a_0\), if the two are equal, it indicates that the component to be tested vibrates according to the input vibration acceleration, verifying that after the component to be tested is fixed to the fixture, the fixture can still accurately transmit the vibration signal; at the same time, the frequency response curve during the frequency sweep of the component to be tested is obtained through the \(n\)-th sensor, and the frequency \(\omega\) corresponding to the peak point is recorded. n This is the natural frequency of the component to be tested;

[0028] (4) Random vibration test: Keep the position of the sensor in step (3) unchanged, and then input the vibration acceleration power spectral density curve, i.e., the PSD curve, through the vibration control system to simulate the vibration conditions experienced by the component to be tested in the actual working conditions, and start the random vibration test. Read the acceleration power spectral density curve measured by the \(m\)-th acceleration sensor. If the read curve is consistent with the input PSD curve, it indicates that the component to be tested is performing random vibration according to the input, further verifying the accuracy of the vibration signal transmission;

[0029] (5) Frequency sweep the component to be tested again: After the random vibration test of the component is completed, keep the position of the sensor in step (3) unchanged, input the vibration acceleration \(a_0\) through the vibration control system, and frequency sweep the component to be tested again in the X, Y, and Z axial directions. The frequency response curve during the frequency sweep of the component to be tested is obtained through the \(n\)-th sensor, and the frequency \(\omega'\) corresponding to the peak point is recorded. n This is the natural frequency of the component to be tested after random vibration. If the natural frequency \(\omega\) before random vibration n and the natural frequency \(\omega'\) after random vibration n differ by no more than the preset value, it is verified that the structure of the component to be tested has no obvious damage before and after random vibration; otherwise, it is verified that the structure of the component to be tested is damaged and fails the random vibration test, and further improvement and optimization of the structure are required;

[0030] (6) Conduct a functional inspection on the components that have completed the random vibration test and have no structural damage. If the functions of the components after random vibration are not damaged, it finally indicates that the component to be tested passes the random vibration test; otherwise, it indicates that the component fails the random vibration test and further improvement and optimization are required.

[0031] Compared with the prior art, the beneficial effects of the present invention at least include:

[0032] 1) It is a test device independently developed in the domestic related field, which can accurately and quickly conduct random vibration tests on automotive components, saving test time and improving test efficiency and reliability.

[0033] 2) Compared with the existing vibration test devices, the random vibration test device of the present invention has six mutually independent degrees of freedom. The vibrations in each direction are decoupled, and the vibration direction and parameters are highly controllable. It can accurately simulate the random vibrations suffered by automotive parts during the driving of the whole vehicle, and the test results have high reliability.

[0034] 3) The test operation is simple and convenient, eliminating the process of converting the vibration direction of the test bench. It can efficiently and accurately complete the random vibration test, greatly improving the test efficiency.

[0035] 4) The overall test device adopts a block connection method, which not only ensures that the test bench has sufficient strength but also facilitates disassembly, installation, and transportation.

[0036] 5) The proposed random vibration test method can well check the transmission of vibration signals during the test process, avoiding test errors caused by the distortion of vibration signal transmission, ensuring that the vibration signals can be accurately transmitted to the parts to be tested, and guaranteeing the accuracy and reliability of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic structural diagram of a multi-degree-of-freedom random vibration test device provided by an embodiment of the present invention.

[0038] Figure 2 It is a schematic structural diagram of a multi-degree-of-freedom random vibration test bench frame in an embodiment of the present invention.

[0039] Figure 3 It is a schematic structural diagram of an excitation device of a multi-degree-of-freedom random vibration test bench frame in an embodiment of the present invention.

[0040] Figure 4 It is a top view of a horizontal vibration table of a multi-degree-of-freedom random vibration test bench frame in an embodiment of the present invention.

[0041] Figure 5 It is a schematic structural diagram of a central excitation device of a multi-degree-of-freedom random vibration test bench frame in an embodiment of the present invention.

[0042] Figure 6 It is a schematic structural diagram of a side excitation device of a multi-degree-of-freedom random vibration test bench frame in an embodiment of the present invention.

[0043] Figure 7 It is a schematic structural diagram of a corner excitation device of a multi-degree-of-freedom random vibration test bench frame in an embodiment of the present invention.

[0044] Figure 8 It is a flow chart of a random vibration test method in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The technical solution of the present invention will be further specifically described below in conjunction with the accompanying drawings in the embodiments of the present invention. It should be understood that the exemplary embodiments of the present invention can be implemented in various forms and are not limited to the embodiments described below. The description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Any formal adaptation and / or change made to the present invention will fall within the protection scope of the present invention.

[0046] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "side", "vertical", "horizontal", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0047] As Figure 1 and Figure 2 shown, a multi-degree-of-freedom random vibration test device provided by the present invention includes a vibration test bench, a vibration control system 6, a power amplifier 7, and a cooling cabinet 8. The vibration test bench includes a horizontal vibration table 1, a central excitation device 2, a side excitation device 3, a corner excitation device 4, and a base 5. By inputting the random vibration power spectral density to be simulated through the vibration control system 6, after being processed by the vibration control system 6, it is transmitted to the power amplifier 7, which converts the vibration signal into a voltage signal and a current signal, and finally transmits the electrical signal to each excitation device on the vibration test bench to control each exciter to vibrate, realizing the simulation of random vibration. At the same time, during the random vibration test, by arranging acceleration sensors on the parts to be tested and feeding back the real-time vibration signals of the parts to be tested measured by the acceleration sensors to the vibration control system 6 through the acceleration data collector 61, further feedback control is performed on the vibration signal, further ensuring the accuracy of the random vibration condition. The cooling cabinet 8 is connected to each exciter through a cooling water inlet pipe 81 and a cooling water outlet pipe 82, and the heat generated by the movement of the exciter is taken away by the cooling water.

[0048] As Figure 2 shown, the horizontal vibration table 1, the central excitation device 2, the side excitation device 3, the corner excitation device 4, and the base 5 together constitute the vibration test bench structure. The horizontal vibration table 1 is located at the uppermost end of the vibration test bench, and is used to place and fix the automotive parts to be tested, and receive the vibrations transmitted from each excitation device, and is used to simulate the vibrations received by the automotive parts during actual vehicle driving.

[0049] In some embodiments of the present invention, a rectangular coordinate system XYZ is established with the center of the horizontal vibration table 1 as the origin, where the XOY plane is parallel to the plane of the horizontal vibration table 1, the X-axis direction and the Y-axis direction are respectively parallel to two mutually perpendicular sides of the horizontal vibration table 1, and the Z-axis direction is vertically upward.

[0050] As Figure 3 shown, there are four side excitation devices 3 and four corner excitation devices 4. The base 5 and the horizontal vibration table 1 are arranged relatively parallel. The central excitation device 2, the side excitation devices 3, and the corner excitation devices 4 are all arranged between the base 5 and the horizontal vibration table 1. The central excitation device 2 is located at the exact center of the horizontal vibration table 1 and mainly provides support and Z-direction vibration. The side excitation devices 3 are located on the sides of the horizontal vibration table 1 and are used to provide vibrations in the X and Y horizontal directions and rotation about the Z-axis. The corner excitation devices 4 are arranged at the four corners of the horizontal vibration table 1 and are used to assist in support and provide rotation about the X-axis and rotation about the Y-axis.

[0051] In some embodiments of the present invention, the base 5 has bolt holes for installing and fixing each excitation device, and buffer blocks are installed at the bottom of the base 5 to reduce the vibration between each excitation device and the ground.

[0052] As Figure 4 shown, fixing bolt holes 11 for the workpiece under test are evenly arranged on the horizontal vibration table 1 for fixing the workpiece under test or the fixture; vertical baffle fixing bolt holes 12 are evenly distributed on the side of the horizontal vibration table 1 for installing and fixing the vertical baffle 31 in the side excitation device 3; guide sleeve fixing bolt holes 13 are evenly distributed at the four corners of the horizontal vibration table 1 for installing and fixing the guide sleeves in the corner excitation device 4; a spherical receiving cavity 14 is arranged at the central part of the horizontal vibration table 1 for assembling with the central excitation device 2.

[0053] As Figure 5As shown in the figure, the central excitation device 2 includes a universal ball head 21, a transfer device 22, a double ball hinge decoupling device 23, a central electric exciter 24, and a central exciter base 241. The universal ball head 21 is assembled with the horizontal vibration table 1 through a spherical receiving cavity 14, enabling the horizontal vibration table 1 to rotate around the universal ball head 21 in any direction. The double ball hinge decoupling device 23 is bolted to the universal ball head 21 through the transfer device 22 at the top and to the central electric exciter 24 through bolts at the bottom, transmitting the vibration generated by the central electric exciter 24 to the universal ball head 21 and ultimately to the horizontal vibration table 1. The universal ball head 21 can rotate in any direction through the double ball hinge decoupling device 23, and the double ball hinge decoupling device 23 can rotate in any direction through the transfer device 22. Under the combined action of the universal ball head 21 and the double ball hinge decoupling device 23, the horizontal vibration table 1 can move horizontally, ultimately achieving multi-degree-of-freedom movement of the horizontal vibration table 1. The central electric exciter 24 is fixedly connected to the base 5 through bolts by the central exciter base 241.

[0054] In some embodiments of the present invention, the double ball hinge decoupling device is one of a hydraulic lubrication decoupling device or a mechanical lubrication decoupling device, which includes two spherical joints.

[0055] As Figure 6 As shown in the figure, the side excitation device 3 includes a vertical baffle 31, a horizontal connecting rod 32, a first ball hinge joint 33, a transfer device 34, an ear shaft bracket 35, a side base 36, and a side electric exciter 37. The side electric exciter 37 is connected to the horizontal connecting rod 32 through the first ball hinge joint 33, enabling the horizontal connecting rod 32 to rotate around the first ball hinge joint 33 in any direction. At the same time, the side electric exciter 37 is connected to the side base 36 through the ear shaft bracket 35, and the side electric exciter 37 can rotate around the X-axis or Y-axis through the ear shaft connection hole 351. The side base 36 is fixedly connected to the ear shaft bracket 35 by welding and is bolted to the base 5. The vertical baffle 31 is bolted to the horizontal vibration table 1, and the horizontal connecting rod 32 is bolted to the side of the vertical baffle 31. The excitation force is transmitted to the vertical baffle 31 through the horizontal connecting rod 32, providing force or torque in the X and Y axis directions of the horizontal vibration table 1, and realizing vibration and rotation of the horizontal vibration table in the X and Y axis directions.

[0056] As Figure 7As shown, the angular excitation device 4 includes a guide sleeve 41, a second ball joint 42, a vertical connecting rod 43, a switching device 44, an angular electric vibrator 45 and an angular vibrator base 451. The guide sleeve 41 is vertically fixed to the horizontal vibration table 1 by bolts to ensure that the force applied to the horizontal vibration table 1 is always along the Z-axis direction. The two ends of the vertical connecting rod 43 are respectively connected to the guide sleeve 41 upward through the second ball joint 42 and connected to the angular electric vibrator 45 downward through the switching device 44, so that the vertical connecting rod 43 can rotate in any direction around the second ball joint 42, and at the same time, the exciting force generated by the angular vibrator 45 is smoothly transmitted to the horizontal vibration table 1, which helps to realize the vibration of the horizontal vibration table 1 in the Z direction. The electric vibrator 45 is bolted to the base 5 through the angular vibrator base 451.

[0057] like Figure 8 As shown, the present invention also provides a random vibration method using the vibration test device provided in the above embodiment, which is used to check the transmission of vibration signals during the test and reduce the test error caused by the transmission of vibration signals, which is of great significance. The method comprises the following steps:

[0058] (1) The components to be tested are subjected to various functional and structural inspections. If the structure and function of the components meet the design requirements and there is no damage, they are deemed to have passed the inspection. The components that have passed the inspection are subjected to random vibration tests to verify whether their fatigue properties meet the design requirements.

[0059] (2) Perform no-load frequency sweep on the horizontal vibration table 1: i (i ≥ 1) acceleration sensors are evenly arranged on the horizontal vibration table 1, and the vibration acceleration a0 is input through the vibration control system 6. The horizontal vibration table 1 is swept in the X, Y, and Z axial directions in turn, and the vibration acceleration a0 measured by the i-th acceleration sensor is compared. ti If the two are equal to the input vibration acceleration a0, it means that the horizontal vibration table 1 can vibrate according to the input vibration acceleration, which proves that the random vibration test device can accurately transmit the vibration signal. The vibration signal inspection passes and the next process can be carried out.

[0060] (3) After the jig is fixed to the horizontal vibration table 1, the jig is subjected to no-load frequency sweep: m (m ≥ 1) acceleration sensors are arranged at the connection and fixing position between the jig and the component to be tested, and the vibration acceleration a0 is input through the vibration control system 6. The jig is subjected to frequency sweep in the X, Y, and Z axial directions in turn, and the vibration acceleration a0 measured by the m acceleration sensor is compared. fm If the two are equal to the input vibration acceleration a0, it means that the fixture can vibrate according to the input vibration acceleration, which proves that the fixture can accurately transmit the vibration signal. The vibration signal inspection passes and the next process can be carried out.

[0061] (4) After fixing the component to be tested to the fixture, perform a sweep frequency on the component to be tested: Keep the position of the acceleration sensor in step (3) unchanged. At the same time, select n (n≥1) key positions on the component to be tested to arrange acceleration sensors. Then input the vibration acceleration a0 through the vibration control system 6, and perform a sweep frequency on the component to be tested in the X, Y, and Z axial directions in sequence. Compare the vibration acceleration a measured by the m-th acceleration sensor fm with the input vibration acceleration a0. If the two are equal, it means that the component to be tested vibrates according to the input vibration acceleration, which verifies that after the component to be tested is fixed to the fixture, the fixture can still accurately transmit the vibration signal, and the vibration signal inspection passes, and the next process can be carried out. At the same time, obtain the frequency response curve of the component to be tested during the sweep frequency process through the n-th sensor, and record the frequency ω corresponding to the peak point n which is the natural frequency of the component to be tested.

[0062] (5) Random vibration test: Keep the position of the acceleration sensor in step (4) unchanged, and then input the vibration acceleration power spectral density curve, that is, the PSD curve, through the vibration control system 6 to simulate the vibration condition that the component to be tested is subjected to in the actual working condition, and start the random vibration test. Read the acceleration power spectral density curve measured by the m-th acceleration sensor. If the read curve is consistent with the input PSD curve, it indicates that the component to be tested is performing random vibration according to the input, which once again verifies the accuracy of the vibration signal transmission. After the random vibration test is completed, proceed to the next process.

[0063] (6) Perform a sweep frequency on the component to be tested again: After the random vibration test of the component is completed, keep the position of the sensor in step (4) unchanged, input the vibration acceleration a0 through the vibration control system 6, and perform a sweep frequency on the component to be tested in the X, Y, and Z axial directions again. Obtain the frequency response curve of the component to be tested during the sweep frequency process through the n-th sensor, and record the frequency ω′ corresponding to the peak point n which is the natural frequency of the component to be tested after random vibration. If the natural frequency ω before random vibration n and the natural frequency ω′ after random vibration n differ by no more than a preset value (in some embodiments of the present invention, the preset value is 10 Hz), it is verified that the structure of the component to be tested has no obvious damage before and after random vibration, and the next process can be carried out; otherwise, it is verified that the structure of the component to be tested is damaged and fails the random vibration test. The structure needs to be further improved and optimized, and then return to the first process to restart the vibration test.

[0064] (7) Conduct a functional inspection on the components that have completed the random vibration test and have no structural damage. If the functions of the components are not damaged after random vibration, it finally indicates that the component to be tested passes the random vibration test; otherwise, it indicates that the component fails the random vibration test and needs to be further improved and optimized, then return to the first process and start the vibration test again.

[0065] More specifically, when in use, place or fixedly install the component to be tested on the horizontal vibration table 1, and determine the vibration degrees of freedom and the specific vibration modes to be executed of the present invention according to the requirements of the vibration test work.

[0066] The horizontal vibration table 1 generates a linear reciprocating motion in the Z direction under the action of the central exciter device 2. Further, the four corner exciters 4 can also be controlled to generate vibrations with the same frequency and the same phase as the central exciter 2 at the same time, which can provide a greater exciting force.

[0067] The two side exciter devices 3 symmetrically arranged along the ZOX or ZOY plane generate vibrations with the same frequency and opposite phases, which can make the horizontal vibration table generate a linear reciprocating motion in the Y-axis or X-axis direction.

[0068] The two side exciter devices symmetrically arranged along the ZOX or ZOY plane generate vibrations with the same frequency and the same phase, which can make the vibration table generate a rotation around the Z axis.

[0069] The two pairs of corner exciters 4 symmetrically arranged along the ZOX or ZOY plane generate vibrations with the same frequency but opposite phases, which can make the vibration table generate a rotation around the X axis or the Y axis.

[0070] The various vibration degrees of freedom of each electric exciter mentioned in the foregoing embodiments are relatively independently adjustable and have complete decoupling. Coupling the vibrations generated by the central exciter device 2, the side exciter device 3, and the corner exciter device 4 in space can generate vibrations in any direction and achieve true six-degree-of-freedom vibration.

[0071] A total of nine electric exciters are used in the foregoing embodiments, which can provide a greater exciting force, and the exciting forces in each direction do not interfere with each other. Moreover, the test bench is compact and occupies a small area; and the electric exciter has a high working frequency, up to 2000 Hz at most, a wide dynamic range, high control accuracy, and a good acceleration waveform, which is suitable for generating random waves.

[0072] In the foregoing embodiments, bolt connections are used between each exciter device and the vibration test bench frame structure. While ensuring the strength of the test device, the detachable nature of the test equipment is realized, which is convenient for transportation and installation.

[0073] The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A multi-degree-of-freedom random vibration test device, characterized in that It includes a vibration test bench, a vibration control system (6) and a power amplifier (7) connected to the vibration control system (6); The vibration test bench includes a horizontal vibration table (1), a base (5), a central excitation device (2), a side excitation device (3) and a corner excitation device (4). The horizontal vibration table (1) and the base (5) are arranged oppositely. The central excitation device (2), the side excitation device (3) and the corner excitation device (4) are detachably arranged between the horizontal vibration table (1) and the base (5). A right-handed XYZ coordinate system is established with the horizontal vibration table (1) as the origin. The XOY plane is parallel to the plane of the horizontal vibration table (1), the X-axis direction and the Y-axis direction are respectively parallel to two mutually perpendicular sides of the horizontal vibration table (1), and the Z-axis direction is vertically upward. Among them, the central excitation device (2) is used to provide Z-direction vibration to the workpiece, the side excitation device (3) is used to provide vibration to the workpiece in the X and Y horizontal directions and rotation around the Z-axis, and the corner excitation device (4) is used to provide rotation to the workpiece around the X-axis and around the Y-axis; The vibration control system (6) is used to input the random vibration power spectral density to be simulated, and transmit the vibration signal to the power amplifier (7) to be converted into a voltage signal and a current signal. The power amplifier (7) transmits the converted signal to each excitation device; Among them, the bottom of the horizontal vibration table (1) is concavely provided with a spherical receiving cavity (14); The central excitation device (2) includes a universal ball head (21), a double ball hinge decoupling device (23), a central electric exciter (24) and a central exciter base (241). The central exciter base (241) is detachably connected to the base (5). The central electric exciter (24) is fixed on the central exciter base (241). The output end of the central electric exciter (24) is connected to the universal ball head (21) through the double ball hinge decoupling device (23). The universal ball head (21) is movably arranged in the spherical receiving cavity (14). The horizontal vibration table (1) can rotate in any direction through the universal ball head (21); The side excitation device (3) includes a vertical baffle (31), a horizontal connecting rod (32), a first ball hinge joint (33), a side electric exciter (37) and a side base (36). The side base (36) is detachably connected to the base (5). The side electric exciter (37) is rotatably arranged on the side base (36) to rotate around the X-axis or the Y-axis. The output end of the side electric exciter (37) is connected to the horizontal connecting rod (32) through the first ball hinge joint (33). The free end of the horizontal connecting rod (32) is connected to the vertical baffle (31). The vertical baffle (31) is detachably connected to the horizontal vibration table (1); The corner excitation device (4) includes a corner electric exciter (45), a vertical connecting rod (43), two second ball hinge joints (42) and a guide sleeve (41). The corner electric exciter (45) is detachably arranged on the base (5). The two ends of the vertical connecting rod (43) are respectively connected to the output end of the corner electric exciter (45) and one end of the guide sleeve (41) through the second ball hinge joints (42). The other end of the guide sleeve (41) is detachably connected to the horizontal vibration table (1).

2. The multi-degree-of-freedom random vibration test device according to claim 1, wherein It further includes a cooling cabinet (8), which is connected to each vibration exciter through a cooling pipeline and is used to cool the vibration exciter.

3. A multi-degree-of-freedom random vibration test device according to claim 2, characterized in that, The water outlet pipeline of the cooling cabinet (8) is connected to the water-cooling pipeline located at the bottom of the base (5). The water-cooling pipeline includes multiple water-cooling branch pipelines, which respectively lead to each vibration exciter. The multiple water-cooling branch pipelines finally converge at the water outlet at the bottom of the base and are connected to the water inlet of the cooling cabinet to form a loop.

4. A multi-degree-of-freedom random vibration test device according to claim 1, characterized in that, The central vibration exciter (2) is arranged at the exact center position of the horizontal vibration table (1). There are four side vibration exciters (3), which are respectively located around the horizontal vibration table (1). There are four corner vibration exciters (4), which are respectively located at the four corners of the horizontal vibration table (1).

5. A multi-degree-of-freedom random vibration test device according to claim 1, characterized in that, The workpiece mounting holes are evenly arranged on the horizontal vibration table (1) and are used to connect with the parts to be tested.

6. A multi-degree-of-freedom random vibration test device according to claim 1, characterized in that, Buffer blocks are arranged at the bottom end of the base (5).

7. A random vibration test method, characterized in that, Using the vibration test device according to any one of claims 1-6, the following steps are included: (1)Perform no-load frequency sweep on the horizontal shaking table (1): Uniformly arrange acceleration sensors on the horizontal shaking table, , input vibration acceleration through the vibration control system, and perform frequency sweep on the horizontal shaking table in the X, Y, and Z axial directions in sequence. Compare the vibration acceleration measured by the i-th acceleration sensor with the input vibration acceleration . If the two are equal, it means that the horizontal shaking table (1) can vibrate according to the input vibration acceleration, verifying that the random vibration test device can accurately transmit vibration signals; (2)After fixing the tooling fixture to the vibration tabletop, perform no-load frequency sweeping on the tooling fixture: At the connection and fixing positions between the tooling fixture and the component to be measured, arrange acceleration sensors, , input vibration acceleration through the vibration control system, and perform frequency sweeping on the tooling fixture in the X, Y, and Z axial directions in sequence. Compare the vibration acceleration measured by the m-th acceleration sensor with the input vibration acceleration . If the two are equal, it means that the tooling fixture can vibrate according to the input vibration acceleration, verifying that the tooling fixture can accurately transmit vibration signals; (3) After fixing the component to be tested to the tooling fixture, perform sweep frequency on the component to be tested: Keep the position of the acceleration sensor in step (2) unchanged, and at the same time select key positions on the component to be tested to arrange acceleration sensors, , then input vibration acceleration through the vibration control system, and perform sweep frequency on the component to be tested in the X, Y, and Z axial directions in sequence. Compare the vibration acceleration measured by the m-th acceleration sensor with the input vibration acceleration . If the two are equal, it means that the component to be tested vibrates according to the input vibration acceleration, which proves that after fixing the component to be tested to the tooling fixture, the tooling fixture can still accurately transmit vibration signals. At the same time, obtain the frequency response curve of the component to be tested during the sweep frequency process through the n-th acceleration sensor, and record the frequency corresponding to the peak point, which is the natural frequency of the component to be tested; (4) Random vibration test: Keep the position of the acceleration sensor in step (3) unchanged, and then input the vibration acceleration power spectral density curve, that is, the PSD curve, through the vibration control system to simulate the vibration condition suffered by the parts to be tested in the actual working condition, and start the random vibration test; Read the acceleration power spectral density curve measured by the mth acceleration sensor. If the read curve is consistent with the input PSD curve, it indicates that the parts to be tested are performing random vibration according to the input, and once again verifies the accuracy of the vibration signal transmission; (5)Perform sweep frequency on the component to be tested again: After the random vibration test of the component is completed, keep the position of the acceleration sensor in step (3) unchanged, and input vibration acceleration through the vibration control system. , perform sweep frequency on the component to be tested again in the X, Y, and Z axial directions, obtain the frequency response curve of the component to be tested during the sweep frequency process through the nth acceleration sensor, and record the frequency corresponding to the peak point. This is the natural frequency of the component to be tested after random vibration. If the natural frequency before random vibration and the natural frequency after random vibration do not differ by more than the preset value, it is confirmed that there is no obvious damage to the structure of the component to be tested before and after random vibration. On the contrary, it proves that the structure of the parts to be tested is damaged and fails the random vibration test, and the structure needs to be further improved and optimized; (6) Conduct a functional inspection on the parts that have completed the random vibration test and have no structural damage. If the functions of the parts are not damaged after random vibration, it finally indicates that the parts to be tested pass the random vibration test; on the contrary, it indicates that the parts do not pass the random vibration test and need to be further improved and optimized.

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