Multi-degree-of-freedom vibration test system

Abstract

The invention belongs to the technical field of vibration tests, and discloses a multi-degree-of-freedom vibration test system. The multi-degree-of-freedom vibration test system comprises a test box, a working table, an axial vibration generator and a spherical hinge device, the test box is provided with a test cavity, and environmental factors of the test cavity can be adjusted; the working table is arranged in the test cavity and is used for placing a product; at least two groups of axial vibration generators are arranged outside the test box, and the two groups of axial vibration generators can generate two exciting forces which are perpendicular to each other or opposite in directions and are not collinear; and the spherical hinge device is arranged between the vibration end of each axial vibration generator and the working table. According to the multi-degree-of-freedom vibration test system, the working table is arranged in the test box, and the real working environment of the product is simulated by adjusting the environmental factors of the cavity, so that the multi-degree-of-freedom vibration test is performed on the product in the real working environment, and finally the vibration test requirements of various products in different environments are met.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration testing, and particularly to a multi-degree-of-freedom vibration testing system. Background Art

[0002] Vibration testing is a testing method that simulates the vibration environment that a product may encounter during transportation, installation, and use to evaluate its vibration resistance and reliability. Through vibration testing, the reliability of the product under the vibration environment can be confirmed, defective products can be screened in advance, and failure analysis can be carried out; it can also verify whether the product design and functions meet the requirements.

[0003] Currently, equipment in the fields of vehicles, ships, weapons, aviation, aerospace, etc. faces a complex and harsh mechanical environment and is often affected by comprehensive environmental factors such as temperature, humidity, air pressure, and vibration. Although current testing equipment can perform multi-degree-of-freedom combined vibration testing on products, the test environment of the products is very different from the actual operating environment of the products, making it difficult to comprehensively evaluate the various performances of the products in complex environments. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-degree-of-freedom vibration testing system that can simulate multi-degree-of-freedom combined vibration testing of products in the actual operating environment to meet the vibration testing requirements of various products in different environments and with multiple degrees of freedom.

[0005] To achieve this purpose, the present invention adopts the following technical solutions: A multi-degree-of-freedom vibration testing system, comprising: A test chamber having a test cavity, and the environmental factors of the test cavity can be adjusted; A workbench surface disposed in the test cavity, and the workbench surface is used for placing products; At least two groups of axial vibration generators, and the two groups of axial vibration generators can generate two excitation forces that are perpendicular to each other or in two opposite directions and non-collinear. The axial vibration generators are disposed outside the test chamber; and, A ball hinge device disposed inside the test chamber, and the ball hinge device is disposed between the vibration ends of each axial vibration generator and the workbench surface, and the ball hinge device can transmit the excitation force of the axial vibration generator to the workbench surface.

[0006] Preferably, the ball hinge device includes: A connecting seat having ball grooves at both ends, and the inner cavity of the ball groove is in a spherical crown shape; Ball heads, and one ball head is rotatably disposed inside each ball groove, and avoidance holes are provided on each ball head; A limiting rod is passed through the connecting seat, and the avoidance holes are extended from both ends of the limiting rod, and the avoidance holes and the limiting rod are clearance-matched; and, A limiting head is provided at each of the two ends of the limiting rod, and a side of the limiting head opposite to the ball head abuts against the ball head, and the ball head can move relative to the limiting head.

[0007] Preferably, a limiting groove is provided on the side of the ball head facing away from the connecting seat, the side wall of the limiting groove is parallel to the outer wall of the ball head, the limiting head is placed inside the limiting groove, and the shape of the limiting head is adapted to the shape of the limiting groove.

[0008] Preferably, a through hole is provided on the limit head along the axial direction of the limit rod, both ends of the limit rod extend out of the through hole and are detachably connected with locking pieces, and the locking pieces abut against the limit head.

[0009] Preferably, an end cover is provided on a side of the ball head facing away from the connecting seat, and the end cover covers the opening of the limiting groove.

[0010] Preferably, the environmental factor is temperature, humidity or air pressure.

[0011] Preferably, a transition device is provided between the axial vibration generator and the test box, and the transition device is configured to transmit the exciting force of the axial vibration generator to the ball joint device.

[0012] Preferably, a connecting hole is provided on the test box corresponding to the vibration end of the axial vibration generator, and a flexible sealing tube is provided between the test box and the axial vibration generator, and the sealing tube seals the connecting hole.

[0013] Preferably, the work surface is horizontally arranged, and four groups of axial vibration generators are sequentially arranged along the circumference of the work surface, and two adjacent groups of axial vibration generators are perpendicular to each other, and the exciting force direction of the axial vibration generator on the circumferential side of the work surface is horizontal.

[0014] Preferably, at least two groups of axial vibration generators are arranged at the bottom of the work surface along the horizontal direction, and the exciting force direction of the axial vibration generators at the bottom of the work surface is the vertical direction.

[0015] Beneficial effects of the present invention: The multi-degree-of-freedom vibration test system of the present invention sets the workbench inside the test chamber, and simulates the real working environment of the product by adjusting the environmental factors in the cavity. When the product is subjected to a vibration test, the product is placed on the workbench. At the same time, two sets of axial vibration generators apply two mutually perpendicular or two opposite and non-collinear exciting forces to the workbench through the spherical hinge device, thereby driving the workbench to perform multi-degree-of-freedom motion, so as to perform a multi-degree-of-freedom combined vibration test on the product in a real working environment, thus meeting the vibration test requirements of various products in different environments. In addition, the spherical hinge device is arranged between the axial vibration generator and the workbench, and the installation eccentricity error can be eliminated through the spherical degrees of freedom, ensuring that the exciting force is strictly transmitted along the axis, and avoiding additional bending moments caused by machining deviations and / or assembly deviations. At the same time, the spherical hinge device can achieve a certain angle of yaw, and enable the workbench to perform translation and rotation, with more degrees of freedom. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the layout diagram of the first embodiment of the multi-degree-of-freedom vibration test system of the present invention; Figure 2 is Figure 1 the cross-sectional view along the A-A direction in Figure 3 is the force application schematic diagram of the axial vibration generator when the workbench rotates around the Z axis in the first embodiment of the present invention; Figure 4 is the cross-sectional view of the spherical hinge device along the axial direction of the connecting seat in the first embodiment of the present invention; Figure 5 is the structural schematic diagram of the test chamber and the axial vibration generator in the second embodiment of the present invention.

[0017] In the figure: 1. Test chamber; 11. Test cavity; 12. Connecting hole; 2. Workbench; 3. Axial vibration generator; 4. Spherical hinge device; 41. Connecting seat; 411. Ball groove; 412. First oil passage; 42. Ball head; 421. Avoidance hole; 422. Limit groove; 43. Limit rod; 44. Limit head; 441. Through hole; 442. Second oil passage; 45. Locking part; 46. End cover; 47. Elastic gasket; 5. Transition device; 6. Base; 61. Installation groove; 7. Sealing tube. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that only parts related to the present invention are shown in the drawings for the convenience of description, rather than all the structures.

[0019] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0020] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over", and "on" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "under", and "beneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0021] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "right", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, so it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0022] Next, refer to Figures 1 to 5 to describe the multi-degree-of-freedom vibration test system provided by the present invention. Embodiment 1

[0023] Refer to Figure 1 and Figure 2 , the multi-degree-of-freedom vibration test system includes a base 6, a test chamber 1, a workbench 2, axial vibration generators 3, and a ball joint device 4. The test chamber 1 is arranged on the base 6. The test chamber 1 has a test cavity 11, and the environmental factors in the test cavity 11 can be adjusted. The workbench 2 is arranged inside the test chamber 1 and is used for placing products. At least two groups of axial vibration generators 3 are arranged outside the test chamber 1, and the two groups of axial vibration generators 3 can generate two mutually perpendicular or two excitation forces in opposite directions and not collinear; the ball joint device 4 is connected between the vibration end of each axial vibration generator 3 and the workbench 2, and the ball joint device 4 can transmit the excitation force of the axial vibration generator to the workbench.

[0024] When the product is subjected to a vibration test, the product is placed on the workbench surface 2. By adjusting the environmental factors in the cavity, the real working environment of the product is simulated. At the same time, two sets of axial vibration generators 3 can apply two mutually perpendicular or two opposite and non-collinear exciting forces to the workbench surface, thereby driving the workbench surface 2 to move in two degrees of freedom. More sets of axial vibration generators 3 can drive the workbench surface 2 to move in more degrees of freedom through the ball hinge device 4, so as to conduct a multi-degree-of-freedom vibration test on the product in the real working environment to meet the vibration test requirements of various products under different environments and multiple degrees of freedom.

[0025] It should be noted that the environmental factors refer to the factors that affect the environmental state of the test chamber 11, such as temperature, humidity, air pressure, light, etc. Among them, temperature deviation and fluctuation will affect the performance of materials; humidity affects the hygroscopicity and corrosiveness of materials. Materials are more likely to absorb moisture and expand in a high-humidity environment, affecting their performance; changes in air pressure will cause changes in the concentrations of oxygen and carbon dioxide in the atmosphere, thereby affecting the oxidation reaction and corrosion rate of materials; light mainly affects the light aging test of materials. The radiation characteristics of different light sources (such as carbon arc lamps, xenon lamps, fluorescent lamps) are different, which will affect the photochemical reactions such as fading and aging of materials. Therefore, by adjusting the above environmental factors, the environment in the inner cavity can be made as close as possible to the real working environment of the product to improve the accuracy of the test results.

[0026] Optionally, the specific structure of the test chamber 1 in this embodiment is set with reference to an environmental test chamber. The adjustable environmental factors include temperature, humidity, and air pressure. The specific structure of the test chamber 1 is prior art and will not be elaborated here.

[0027] Exemplarily, the base 6 is horizontally arranged and has an installation groove 61 at the top. The test chamber 1 is located directly above the installation groove 61. The workbench surface 2 is a square plate and is horizontally arranged inside the test chamber 1. In some other embodiments, the base 6 can also be tilted to a certain extent.

[0028] Optionally, four groups of axial vibration generators 3 are sequentially arranged along the circumferential direction of the workbench surface 2, and two adjacent groups of axial vibration generators 3 are mutually perpendicular. The exciting force direction of the axial vibration generators 3 on the circumferential side of the workbench surface 2 is the horizontal direction. Each group of axial vibration generators 3 includes two axially vibrating generators 3 arranged in parallel, that is, two axial vibration generators 3 are horizontally arranged corresponding to each side of the workbench surface 2. In some other embodiments, each group of axial vibration generators 3 can also include only one axial vibration generator 3. One end of each axial vibration generator 3 is fixedly connected to the base 6, and the other end is fixedly connected to the ball hinge device 4.

[0029] It can be understood that a three-dimensional coordinate system is established with the center of gravity of the workbench surface 2 as the coordinate origin. The X-axis and Y-axis of the three-dimensional coordinate system are two mutually perpendicular axes in the horizontal plane, and the Z-axis of the three-dimensional coordinate system is set in the vertical direction. That is, four axial vibration generators 3 are arranged along the X-axis, and four axial vibration generators 3 are arranged along the Y-axis.

[0030] When all the axial vibration generators 3 arranged along the X-axis work simultaneously and the directions of the exciting forces are the same, the workbench surface 2 can be driven to move unidirectionally along the X-axis; when all the axial vibration generators 3 arranged along the Y-axis work simultaneously and the directions of the exciting forces are the same, the workbench surface 2 can be driven to move unidirectionally along the Y-axis; and when all the above-mentioned axial vibration generators 3 work simultaneously in the above-mentioned states, the workbench surface 2 can be driven along the X-axis and Y-axis; thus, the workbench surface 2 can be moved along the X-axis and / or Y-axis.

[0031] Referring to Figure 3 , in addition, when among the four axial vibration generators 3 arranged along the X-axis, the exciting force directions of two coaxial axial vibration generators 3 are opposite to those of the other two coaxial axial vibration generators 3, the workbench surface 2 is driven to rotate around the Z-axis; of course, when among the four axial vibration generators 3 arranged along the Y-axis, the exciting force directions of two coaxial axial vibration generators 3 are opposite to those of the other two coaxial axial vibration generators 3, the workbench surface 2 can also be driven to rotate around the Z-axis. Specifically in this embodiment, all the horizontally arranged axial vibration generators 3 work simultaneously in the above-mentioned manner, so as to drive the workbench surface 2 to rotate around the Z-axis, which can make the force on the workbench surface 2 more uniform.

[0032] Furthermore, at least two groups of axial vibration generators 3 are arranged horizontally at the bottom of the workbench surface 2, and the exciting force directions of the axial vibration generators 3 at the bottom of the workbench surface 2 are in the vertical direction. In this embodiment, two groups of axial vibration generators 3 are arranged horizontally at the bottom of the workbench surface 2, the number of axial vibration generators 3 in each group is two, four axial vibration generators 3 are arranged along the Z-axis, and the four axial vibration generators 3 are evenly distributed around the Z-axis.

[0033] When the axial vibration generators 3 arranged along the Z-axis work simultaneously, the workbench surface 2 can be driven to move along the Z-axis; if the exciting force directions of the axial vibration generators 3 on both sides of the X-axis are opposite, the workbench surface 2 is driven to rotate around the X-axis, and if the exciting force directions of the axial vibration generators 3 on both sides of the Y-axis are opposite, the workbench surface 2 is driven to rotate around the Y-axis. Thus, the workbench surface 2 can move along the Z-axis, rotate around the X-axis and / or rotate around the Y-axis. Coupled with the rotation of the workbench surface 2 around the Z-axis, movement along the X-axis and / or Y-axis, finally the workbench surface 2 has six degrees of freedom, that is, movement in the X, Y, and Z-axis directions, and rotation around the X-axis, Y-axis, and Z-axis.

[0034] As can be seen from the above, when two axial vibration generators 3 with mutually perpendicular exciting force directions are set, the workbench surface 2 can have two degrees of freedom of linear motion. When two axial vibration generators 3 with opposite and non-collinear exciting force directions are set, the workbench surface 2 can have one degree of freedom of linear motion and one degree of freedom of rotation around a straight line. That is, setting two groups of axial vibration generators 3 can enable the workbench surface 2 to have multiple degrees of freedom, and the specific quantity and arrangement position of the axial vibration generators 3 can be selected according to the needs of the test.

[0035] Further, a transition device 5 is provided between the axial vibration generator 3 and the test chamber 1. The transition device 5 is configured to transfer the exciting force of the axial vibration generator 3 to the ball hinge device 4. The transition device 5 in this embodiment is a vibration transmission device in the prior art, which realizes the transmission of the exciting force through the vibration transmission device and seals the test chamber 1.

[0036] Refer to Figure 4 , for example, the ball hinge device 4 includes a connecting seat 41, a ball head 42, a limiting rod 43, and a limiting head 44. The connecting seat 41 is cylindrical, and the connecting seat 41 is coaxially arranged with the axial vibration generator 3. Ball grooves 411 are provided at both ends of the connecting seat 41, and the inner cavity of the ball groove 411 is in the shape of a spherical crown (the part formed after the spherical surface is intercepted by a plane, and its height is less than the radius of the sphere, that is, it does not reach the height of a hemisphere). A ball head 42 is rotatably arranged inside each ball groove 411, and an avoidance hole 421 is provided on each ball head 42. The two ball heads 42 are respectively connected to the workbench surface 2 and the transition device 5. The limiting rod 43 is coaxially arranged with the connecting seat 41, and the limiting rod 43 penetrates through the connecting seat 41, and both ends of the limiting rod 43 extend out of the avoidance hole 421, and there is a clearance fit between the avoidance hole 421 and the limiting rod 43. A limiting head 44 is provided at both ends of the limiting rod 43, and the side of the limiting head 44 opposite to the ball head 42 abuts against the ball head 42, and the ball head 42 can move relative to the limiting head 44.

[0037] Through the above settings, first, the ball hinge device 4 transfers the exciting force transmitted from the axial vibration generator 3 to the transition device 5 to the workbench surface 2, and the ball hinge device 4 can achieve a certain angle of yaw, and enable the workbench surface 2 to perform a certain translation and rotation relative to the transition device 5, so that the workbench surface 2 has six degrees of freedom.

[0038] Secondly, in this embodiment, the movement range of the ball head 42 is limited by the gap between the avoidance hole 421 and the limiting rod 43, that is, the rotation of the ball head 42 is limited to a certain extent by the limiting rod 43 to prevent the ball head 42 from rotating excessively. In this way, the movement range of the workbench surface 2 can be controlled within a normal range to avoid jamming of the ball head 42 due to excessive movement amplitude. At the same time, it can also prevent the surface of the ball head 42 from being overly exposed to the high-temperature and high-pressure environment, preventing the smooth surface of the ball head 42 from being corroded and extending the service life of the ball hinge device 4.

[0039] In addition, the inner cavity of the above-mentioned ball groove 411 is arranged in a spherical crown shape, eliminating the need to process the connecting seat 41 in two parts, facilitating its processing and the installation of the ball head 42.

[0040] It should be noted that the middle section of the limiting rod 43 corresponding to the position of the avoidance hole 421 is arranged parallel to the side wall of the avoidance hole 421. When the ball head 42 rotates to the limit position, the two parallel side walls are in contact with each other, preventing the edge of the avoidance hole 421 from hitting the limiting rod 43 and causing damage to the ball head 42, thus protecting the ball head 42.

[0041] Furthermore, a limiting groove 422 is arranged on the side of the ball head 42 facing away from the connecting seat 41. The side wall of the limiting groove 422 is parallel to the outer wall of the ball head 42, that is, the inner cavity of the limiting groove 422 is also arranged in a spherical crown shape. The limiting head 44 is placed inside the limiting groove 422. The side of the limiting head 44 close to the limiting groove 422 is adapted to the side wall of the limiting groove 422, that is, the limiting head 44 is arranged in a spherical crown shape. Thus, the ball head 42 is abutted against the surface of the ball groove 411 by the limiting head 44, and the contact area between the limiting head 44 and the ball head 42 is large, which can stably limit the ball head 42, prevent a gap from being generated between the ball head 42 and the ball groove 411, prevent the air inside the test chamber 1 from entering between the ball head 42 and the ball groove 411, and at the same time prevent the ball head 42 from detaching from the limiting rod 43. Optionally, in some other embodiments, the limiting head 44 can also be tubular, and the edge of one end thereof is in contact with the side wall of the limiting groove 422.

[0042] To facilitate the installation and maintenance of the ball hinge device 4, a through hole 441 is axially opened on each limiting head 44 along the limiting rod 43. Both ends of the limiting rod 43 extend out of the through hole 441 and are detachably connected with a locking member 45, and the locking member 45 abuts against the limiting head 44. The locking member 45 in this embodiment is a nut and is threadedly connected to the end of the limiting rod 43. Thus, when the nut is tightened, the fixing of the limiting head 44 is completed. When installing the ball hinge device 4, it is only necessary to install the ball head 42 and the limiting head 44 in sequence and then tighten the nut, and the ball head 42 and the limiting head 44 can be maintained and replaced after loosening the nut. Optionally, in some other embodiments, the locking member 45 is a cap nut or a positioning pin, etc.

[0043] It should be noted that in order to prevent the nut from loosening, an elastic gasket 47 is provided between the nut and the limit head 44, so as to apply an elastic force to the nut through the elastic gasket 47, preventing the nut from loosening.

[0044] Furthermore, on the side of each ball head 42 facing away from the connecting seat 41, an end cap 46 is connected. The end cap 46 covers the opening of the limit groove 422. The end cap 46 facilitates the connection between the ball head 42 and other components, and at the same time seals the limit groove 422, protecting the limit head 44.

[0045] In order to make the rotation of the ball head 42 smoother, first oil passages 412 are provided inside the connecting seat 41, and second oil passages 442 are provided inside the limit head 44. Among them, the first oil passage 412 communicates with the ball groove 411, enabling the lubricating oil to flow between the ball head 42 and the ball groove 411, forming an oil film between the ball head 42 and the ball groove 411. The second oil passage 442 communicates with the limit groove 422, enabling the lubricating oil to flow between the limit head 44 and the limit groove 422, forming an oil film between the limit head 44 and the limit groove 422. Thus, the ball head 42 is lubricated through the oil film, making the ball hinge device 4 have the advantages of high stiffness, good uniformity, good universality, and good dynamic performance. The oil film also has good sealing performance, making the gas inside the test chamber 1 not easily enter between the ball head 42 and the ball groove 411. In addition, the oil passage has good airtightness and is not affected by the air pressure and humidity inside the test chamber 1. Embodiment 2

[0046] Refer to Figure 5 In this embodiment, the difference from Embodiment 1 is that: in this embodiment, the transition device 5 is cancelled, and the axial vibration generator 3 is directly connected to the ball hinge device 4. Specifically, connection holes 12 are provided on the test chamber 1 corresponding to the vibration ends of each axial vibration generator 3, and the vibration ends of the axial vibration generators 3 are connected to the ball hinge device 4 through the connection holes 12.

[0047] In addition, a flexible sealing tube 7 is connected between the test chamber 1 and the axial vibration generator 3. The sealing tube 7 is sleeved outside the vibration end of the axial vibration generator 3, thereby sealing the gap between the test chamber 1 and the axial vibration generator 3 through the sealing tube 7 to achieve the sealing inside the test chamber 1, so as to stabilize the air pressure inside the test chamber 1. The sealing tube 7 in this embodiment is a corrugated tube, which can be stretched and bent to a certain extent; optionally, in some other embodiments, the sealing tube 7 can also be a bellows tube or a hose. Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A multi-degree-of-freedom vibration test system, characterized in that include: A test box (1) having a test chamber (11), wherein the environmental factors of the test chamber (11) are adjustable; A work surface (2) is arranged in the test chamber (11), and the work surface (2) is used to place products; at least two groups of axial vibration generators (3), the two groups of axial vibration generators (3) being capable of generating two mutually perpendicular or two mutually opposite and non-collinear exciting forces, the axial vibration generators (3) being arranged outside the test box (1); and A ball joint device (4) is arranged inside the test box (1), and the ball joint device (4) is arranged between the vibration end of each axial vibration generator (3) and the work surface (2). The ball joint device (4) can transmit the exciting force of the axial vibration generator (3) to the work surface (2).

2. The multi-degree-of-freedom vibration test system according to claim 1, wherein The ball joint device (4) comprises: A connecting seat (41) having ball grooves (411) at both ends, wherein the inner cavity of the ball groove (411) is arranged in the shape of a spherical crown; A ball head (42) is rotatably disposed inside each of the ball grooves (411), and each of the ball heads (42) is provided with an avoidance hole (421); A limiting rod (43) is passed through the connecting seat (41), and both ends of the limiting rod (43) extend out of the avoidance holes (421), and a clearance fit is formed between the avoidance holes (421) and the limiting rod (43); and, A limiting head (44) is provided at each end of the limiting rod (43); a side of the limiting head (44) opposite to the ball head (42) abuts against the ball head (42), and the ball head (42) can move relative to the limiting head (44).

3. The multi-degree-of-freedom vibration test system according to claim 2, wherein, A limiting groove (422) is provided on a side of the ball head (42) facing away from the connecting seat (41); a side wall of the limiting groove (422) is parallel to an outer wall of the ball head (42); the limiting head (44) is disposed inside the limiting groove (422); and a shape of the limiting head (44) matches a shape of the limiting groove (422).

4. The multi-degree-of-freedom vibration test system according to claim 3, characterized in that, A through hole (441) is formed on the limiting head (44) along the axial direction of the limiting rod (43); both ends of the limiting rod (43) extend out of the through hole (441) and are detachably connected to locking pieces (45); the locking pieces (45) abut against the limiting head (44).

5. The multi-degree-of-freedom vibration test system according to claim 3, characterized in that, An end cover (46) is provided on a side of the ball head (42) facing away from the connecting seat (41), and the end cover (46) covers the opening of the limiting groove (422).

6. The multi-degree-of-freedom vibration test system according to any one of claims 1-5, characterized in that The environmental factor is temperature, humidity or air pressure.

7. The multi-degree-of-freedom vibration test system according to any one of claims 1-5, characterized in that, A transition device (5) is provided between the axial vibration generator (3) and the test box (1), and the transition device (5) is configured to transmit the exciting force of the axial vibration generator (3) to the ball joint device (4).

8. The multi-degree-of-freedom vibration test system according to any one of claims 1-5, characterized in that, A connection hole (12) is provided on the test box (1) at a vibration end corresponding to the axial vibration generator (3), and a flexible sealing tube (7) is provided between the test box (1) and the axial vibration generator (3), wherein the sealing tube (7) seals the connection hole (12).

9. The multi-degree-of-freedom vibration test system according to any one of claims 1-5, characterized in that, The workbench surface (2) is horizontally arranged, and four groups of axial vibration generators (3) are sequentially arranged along the circumferential direction of the workbench surface (2), and two adjacent groups of the axial vibration generators (3) are perpendicular to each other. The exciting force direction of the axial vibration generator (3) on the circumferential side of the workbench surface (2) is the horizontal direction.

10. The multi-degree-of-freedom vibration test system according to claim 9, wherein At least two groups of axial vibration generators (3) are horizontally arranged at the bottom of the workbench surface (2), and the exciting force direction of the axial vibration generator (3) at the bottom of the workbench surface (2) is the vertical direction.

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