Multi-axial dynamic coupling-based multi-directional fatigue test system and intelligent collaborative loading method

Abstract

The present application relates to a kind of multi-axial dynamic coupling-based multidirectional fatigue test system, intelligent collaborative loading method.Multi-directional fatigue test system includes: test table;Lifting platform;Tensile test system, for applying tensile and compressive load to test piece;Multi-directional bending test system, including the Y direction bending test system being arranged in the side of test area along Y direction, and the Z direction bending test system being arranged on the lifting platform along Z direction;Torsion test system, for applying torsional load to test piece;Slippable support fixture device, installed at the first end of test area and has certain X direction sliding capacity;Fixed support fixture device, installed at the second end of test area;Intelligent collaborative loading control device.The present application uses tensile testing machine, multi-directional bending test machine, torsion test machine to couple tensile, bending and torsional load by intelligent collaborative loading control device, realizes dynamic collaborative loading, simultaneously judges crack propagation path and real-time control bending test machine loading position.

Description

Technical Field

[0001] The present invention relates to the field of fatigue testing technology, in particular to intelligent collaborative loading of a multi-directional fatigue testing machine, in particular in combination with a digital twin engine and an intelligent acquisition algorithm, and specifically to a multi-directional fatigue testing system based on multi-axis dynamic coupling and an intelligent collaborative loading method. Background Art

[0002] Traditional multi-axis fatigue testing machines have fixed loading positions and single loading methods, resulting in low accuracy in collected test data. Loading conflicts between testing machines are prone to occur, leading to force flow hysteresis. As the test specimen deforms, the loading position of the actuator may become eccentric, making it impossible to accurately simulate the synchronous coupled loading of complex loads, with significant limitations. Existing equipment is mostly based on simplified assumptions, making it difficult to reproduce the multi-field coupling effects in a real environment, resulting in large deviations between test results and actual failure modes. During fatigue testing, the load spectrum needs to be manually preset, and the frequency or amplitude needs to be adjusted individually, making it difficult to reproduce the multi-load synergy effects of real working conditions.

[0003] Based on the above problems, a multi-directional fatigue test system based on multi-axis dynamic coupling and an intelligent collaborative loading method are proposed to effectively solve the problems existing in testing and engineering. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the main purpose of the present invention is to provide a multi-directional fatigue testing system and an intelligent collaborative loading method based on multi-axis dynamic coupling, which have solved the problems existing in the current fatigue testing system.

[0005] The technical solutions of the present invention are as follows:

[0006] The present invention first provides a multi-directional fatigue testing system based on multi-axis dynamic coupling, the multi-directional fatigue testing system comprising:

[0007] test bench;

[0008] A lifting platform is installed on the test platform in a lifting and sliding manner, with a test area formed below;

[0009] The tension and compression test system is arranged at the first end of the test area along the X direction;

[0010] A multi-directional bending test system, comprising a Y-direction bending test system arranged on the side of the test area along the Y direction, and a Z-direction bending test system arranged on the lifting platform along the Z direction, capable of applying YZ-direction bending loads to the specimen in a coupled manner;

[0011] a torsion test system, arranged at the second end of the test area along the X direction;

[0012] A slidable support fixture device is installed at the first end of the test area to clamp the specimen and has a certain X-direction sliding ability. When performing tension and compression tests, it is released to allow sliding. When not performing tension and compression tests, it is fixed to limit sliding, assisting the specimen in tension, compression, bending and / or torsion;

[0013] A fixed support fixture device is installed at the second end of the test area to clamp the test piece and assist the test piece in torsion;

[0014] The intelligent collaborative loading control device is used to couple tension, compression, bending and torsion for dynamic collaborative loading, predict the local stress concentration trend of the test specimen, predict the crack propagation path, and adjust the loading position in time according to the deformation of the specimen to avoid eccentricity.

[0015] In some embodiments, the multi-directional fatigue testing system further comprises:

[0016] The vertical support is fixed around the test bench by multiple columns, and the lifting platform is installed on the multiple columns in a lifting and sliding manner.

[0017] In some embodiments, the tensile and compressive testing system comprises:

[0018] The tension and compression testing machine is an electromagnetic linear motor installed at the first end of the test area by bolts;

[0019] A steel compression rod assembly has one end in transmission connection with the tension and compression testing machine and the other end in connection with the slidable support fixture device.

[0020] In some embodiments, the slidable support fixture device includes:

[0021] a slidable support slidably mounted on a first end of the test area;

[0022] a first rod clamp, mounted on one side of the slidable support located on the specimen and adapted to clamp a first end of the specimen;

[0023] The fixing member is detachably mounted on the test bench and is capable of fixing and releasing the slidable support.

[0024] In some embodiments, the slidable support includes a support body and a sliding support rod. The two groups of sliding support rods are symmetrically fixed on the test bench on both sides of the support body along the X direction. The support body is slidably installed on the two groups of sliding support rods. When no tensile and compressive tests are performed, the support body is fixed to the test bench by bolts to limit its sliding on the sliding support rods. When the tensile and compressive tests are performed, the bolts are released to allow it to slide on the sliding support rods.

[0025] In some embodiments, the steel compression rod assembly includes a first steel compression rod and a second steel compression rod axially connected by a steel compression rod anchor, wherein the first steel compression rod is transmission-connected to the tensile and compression testing machine, and the second steel compression rod is fixedly connected to or integrally formed with the slidable support.

[0026] In some embodiments, the torsion testing system comprises:

[0027] The torsion testing machine is a servo motor mounted on the second end of the test area by bolts;

[0028] A transmission rod assembly has one end in transmission connection with the torsion testing machine and the other end in connection with the fixed support fixture device.

[0029] In some embodiments, the fixed support fixture device includes:

[0030] With a harmonic reducer fixed support, installed at the second end of the test area by bolts;

[0031] The second rod fixture is installed on one side of the test piece of the fixing support with harmonic reducer and is suitable for clamping the second end of the test piece.

[0032] In some embodiments, the transmission rod assembly includes a first transmission rod and a second transmission rod axially connected by a transmission rod anchor, wherein the first transmission rod is transmission-connected to the torsion testing machine, the second transmission rod is connected to the high-speed shaft of the reducer with the harmonic reducer fixed support, and the low-speed shaft of the reducer with the harmonic reducer fixed support is connected to the second rod fixture to transmit the regulated torque to the test piece.

[0033] In some embodiments, the first rod clamp and the second rod clamp are multifunctional round rod clamps, each comprising:

[0034] outer ring body;

[0035] An electromagnetic clamp unit, wherein multiple groups of the electromagnetic clamp units are circumferentially installed in the outer ring body. The electromagnetic clamp unit consists of an electromagnetic sleeve, a magnetic round rod, and a round rod chuck. One end of the magnetic round rod is arranged in the electromagnetic sleeve and is retractable, and the other end is connected to the round rod chuck. The electromagnetic sleeve controls the current size through an intelligent collaborative loading and control device to change the internal magnetic field of the electromagnetic sleeve, thereby pushing the magnetic round rod to retract and contract until the round rod chuck clamps the test piece.

[0036] In some embodiments, the Y-direction bending test system comprises:

[0037] The Y-axis bending tester is an electromagnetic linear motor installed on the side of the test area by bolts;

[0038] A steel compression rod assembly, one end of which is transmission-connected to the Y-axis bending tester, and the other end of which is perpendicular to the axis of the specimen and capable of applying transverse bending to the specimen according to the test conditions;

[0039] The Z-direction bending test system includes:

[0040] The Z-direction bending tester is an electromagnetic linear motor installed at the bottom of the lifting platform;

[0041] The steel thin rod assembly has one end drivingly connected to the Z-direction bending testing machine and the other end perpendicular to the axial direction of the specimen and capable of applying vertical bending to the specimen according to test conditions.

[0042] In some embodiments, the lifting platform has an opening at the position corresponding to the test area, and a primary slide rail is provided at the opening, a secondary slide rail perpendicular to the primary slide rail is provided on the primary slide rail, a sliding platform is provided on the secondary slide rail, and the Z-direction bending tester is installed at the bottom of the sliding platform. Through the intelligent collaborative loading and control device, the position of the Z-direction bending tester in the X and Y directions can be adjusted in real time according to the test needs.

[0043] In some embodiments, the test bench is provided with a sealing groove, and a sealing partition is provided around the periphery of the test area. The sealing partition is inserted into the sealing groove to form a multifunctional sealed cabin with a closed test environment. The tensile and compression test system, the torsion test system, and the multi-directional bending test system pass through the corresponding sealing partitions and are sealed and connected;

[0044] A material sprayer is installed in the multifunctional sealed cabin, and a test material storage box and a small induced draft fan are provided on the lifting platform. The material sprayer is used to extract test materials from the test material storage box to apply the material conditions required for the test to the test pieces during the test process. The small induced draft fan is used to extract the test materials in the multifunctional sealed cabin to the test material storage box to realize the circulation of test materials. The material sprayer can adjust the spray angle in real time through the intelligent collaborative loading and control device, thereby changing the position of the sprayed material.

[0045] In some embodiments, a workspace positioning system is further included, specifically including:

[0046] Spatial positioning sensors: Multiple spatial positioning sensors are arranged in three dimensions around the test area to transmit position information in real time;

[0047] A multi-channel fiber Bragg grating sensor with a signal transmitter, wherein multiple multi-channel fiber Bragg grating sensors are symmetrically arranged along the axial and circumferential directions of the test piece; and

[0048] The spatial positioning algorithm and signal receiver contained in the intelligent collaborative loading and control device together form a three-dimensional workspace.

[0049] In some embodiments, the intelligent collaborative loading control device includes:

[0050] The digital twin engine, equipped with an intelligent collaborative loading control algorithm, can convert actual physical field information into test parameters for tension, compression, bending, and torsion fatigue tests through Fourier transform analytical expressions;

[0051] The multi-physics field synchronous acquisition system can collect the stress and strain field data transmitted by the multi-channel fiber Bragg grating sensors during the test and the distance information of each sensor, predict the trend of local stress concentration, predict the crack propagation path, adjust the current transmitted to the fixture to change the magnetic force, and then adjust the clamping force of the specimen. In addition, the distance information can be processed by the digital motion processor to find the loading center position of the deformed specimen, and transmit it to the Z-axis bending test system. The sliding platform repositions the test loading position and adjusts the nozzle position of the material sprayer.

[0052] The present invention further provides an intelligent collaborative loading method according to the multi-directional fatigue testing system, comprising the following steps:

[0053] S10: Assemble the multi-directional fatigue test system;

[0054] S20: Multiple multi-channel fiber Bragg grating sensors with signal transmitters are symmetrically arranged along the axial and circumferential directions of the specimen, multiple spatial positioning sensors are installed on the test bench, and signal receivers are installed on the intelligent collaborative loading and control device to form a three-dimensional working space;

[0055] S30: The digital twin engine converts actual working loads into test parameters for tension, compression, bending, and torsion fatigue tests;

[0056] S40: The multi-channel fiber Bragg grating sensor collects stress and strain field data on the specimen surface and transmits it to the intelligent collaborative loading control device through a signal transmitter;

[0057] S50: The digital motion processor processes stress and strain field data, converts it into corresponding fatigue data, and combines it with a neural network algorithm to predict local stress concentration trends and anticipate crack propagation paths.

[0058] S60: The signal transmitter transmits the distance information of the multi-channel fiber Bragg grating sensor in the three-dimensional workspace to the intelligent collaborative loading control device;

[0059] S70: The digital motion processor calculates the distance information of the sensor as the specimen position information. According to the deformation of the specimen and the test conditions, it adjusts the lifting platform and the sliding platform to adjust the loading position of the Z-axis bending tester and the spraying position of the material sprayer.

[0060] In some embodiments, step S30 specifically includes:

[0061] The digital twin engine is equipped with an intelligent collaborative loading control algorithm, which converts actual physical field information into test parameters for tension, compression, bending and torsion fatigue tests through Fourier transform analytical expressions.

[0062] In some embodiments, step S40 specifically includes:

[0063] The multi-channel fiber Bragg grating sensor is equipped with a signal transmitter, which is symmetrically arranged along the axial and circumferential directions of the test piece. It uses wavelength division multiplexing technology to monitor the stress and strain field on the surface of the test piece in real time, and transmits the stress and strain field data to the multi-physical field synchronous acquisition system in real time.

[0064] In some embodiments, step S50 specifically includes:

[0065] After collecting the test results data, the multi-physics field synchronous acquisition system can predict the crack propagation data and establish a multi-axial fatigue damage evolution model for the specimen. It can also adjust the current transmitted to the multi-functional round rod clamp to change the magnetic force and thus adjust the clamping force of the specimen.

[0066] In some embodiments, step S70 specifically includes:

[0067] The signal position is calculated by a digital motion processor, and the loading center position of the deformed specimen is found after calculation using the symmetry interpolation method or curve fitting algorithm. It is then transmitted to the Z-axis bending test system, and the sliding platform repositions the test loading position and adjusts the nozzle position of the material sprayer.

[0068] The beneficial effects of the present invention over the prior art are as follows: the present invention proposes a multi-directional fatigue test system and an intelligent collaborative loading method based on multi-axis dynamic coupling, which adopts electromagnetic linear motors and harmonic reduction servo motors to reduce test errors, and is combined with slidable supports to couple tension, compression, torsion and bending loads through an intelligent collaborative loading control device according to actual working conditions, thereby realizing dynamic collaborative loading and adjusting the type of applied load, making the test process closer to actual working conditions; providing a multi-functional fixture, which adjusts the clamping force by adjusting the current to change the magnetic force, and is convenient for loading specimens of different shapes and yield strengths; adopting a multi-functional test box, which is convenient for simulating different temperatures and corrosion environments in the test, which is closer to reality. Actual working conditions; Provide a method that can change the position of applied bending load in real time according to test needs, and reduce the error and eccentricity during loading through intelligent collaborative loading control device, workspace positioning system and lifting and sliding device; Provide a method that combines intelligent algorithm system with fatigue test, and through the combination of digital twin engine and multi-physical field synchronous acquisition system with multi-axial dynamic coupling fatigue testing machine, it can convert the actual working condition load into corresponding fatigue parameters and apply them to the specimen, and collect node distance, strain field, crack and other data in the test process in real time, and at the same time analyze the collected test data to predict the local stress concentration trend of the test specimen, predict the crack propagation path and adjust the loading position of the bending testing machine in real time to ensure that the loading device does not eccentric during loading and prevent sudden fracture of the specimen.

[0069] It should be understood that the implementation of any embodiment of the present invention does not mean that multiple or all of the above-mentioned beneficial effects must be possessed or achieved at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can, without inventive effort, derive other implementation drawings based on the provided drawings.

[0071] The structures, proportions, sizes, etc. illustrated in this specification are intended solely to complement the contents disclosed herein and to facilitate understanding and reading by persons skilled in the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, provided they do not affect the efficacy and objectives of the present invention, shall remain within the scope of the technical contents disclosed herein.

[0072] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0073] Figure 2 A detailed schematic diagram of a lifting platform according to an embodiment of the present invention;

[0074] Figure 3 A schematic diagram of fixing a slidable support according to an embodiment of the present invention;

[0075] Figure 4 Schematic diagram of a tension and compression loading test bench according to one embodiment of the present invention;

[0076] Figure 5 Detailed schematic diagram of a multifunctional clamp according to one embodiment of the present invention;

[0077] Figure 6 A partially cutaway schematic diagram of a multifunctional test box according to one embodiment of the present invention;

[0078] Figure 7 This is an overall schematic diagram of a multifunctional test box according to one embodiment of the present invention;

[0079] Figure 8 Schematic diagram of the intelligent collaborative loading control principle of one embodiment of the present invention.

[0080] Markings in the figure:

[0081] Specimen 100;

[0082] Test bench 1, lifting platform 2, vertical support 3, tension and compression testing machine 4, slidable support 5, support body 51, sliding support rod 52, fixing part 53, steel pressure rod assembly 6, first steel pressure rod 61, second steel pressure rod 62, steel pressure rod anchor 63, first rod fixture 7, torsion testing machine 8, fixed support with harmonic reducer 9, transmission rod assembly 10, first transmission rod 101, second transmission rod 102, transmission rod anchor 103, second rod fixture 11, outer ring 12, electromagnetic sleeve 13, magnetic Round rod 14, round rod chuck 15, Y-axis bending testing machine 16, Z-axis bending testing machine 17, primary slide rail 18, secondary slide rail 19, sliding platform 20, sealing partition 21, multi-functional sealing cabin 22, sealing groove 23, material sprayer 24, test material storage box 25, small induced draft fan 26, motor control console 27, cover 28, spatial positioning sensor 29, signal receiver 30, intelligent collaborative loading control device 31, multi-channel fiber grating sensor 32, steel pad 33.

[0083] The same or corresponding symbols in the drawings indicate the same or corresponding parts. DETAILED DESCRIPTION

[0084] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with the embodiments and drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0085] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0086] It should be understood that the terms "comprises / comprising," "consisting of," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product, apparatus, process, or method that includes a list of elements includes not only those elements but also, if necessary, other elements not explicitly listed, or elements inherent to such product, apparatus, process, or method. In the absence of further limitations, elements defined by the phrases "comprises / comprising," "consisting of," do not preclude the presence of additional identical elements in the product, apparatus, process, or method that includes the elements.

[0087] It should also be understood that terms such as "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device, component or structure referred to must have a specific direction, be constructed or operate in a specific direction, and should not be understood as limiting the present invention.

[0088] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0089] The implementation of the present invention is described in detail below in conjunction with preferred embodiments.

[0090] First of all, it should be noted that the conventional three-dimensional coordinate system XYZ mentioned in the present invention, the X direction is the horizontal direction, the Y direction is also the horizontal direction, both are one of the directions in the two-dimensional plane, and are perpendicular to each other to form a two-dimensional plane, and the Z direction is the vertical direction, which is perpendicular to the two-dimensional plane formed by the XY directions. This is easy to understand.

[0091] Overall Figure 1-7 As shown, an embodiment of the present invention provides a multi-directional fatigue test system based on multi-axis dynamic coupling, which mainly includes: a test bench 1, a lifting platform 2, a tension and compression test system, a multi-directional bending test system (Y-axis bending test system, Z-axis bending test system), a torsion test system, a slidable support fixture device, a fixed support fixture device, and an intelligent collaborative loading and control device, wherein the test bench 1 is the main structure of the multi-directional fatigue test system, mainly serving as a base load, and the lifting platform 2 can be installed on the test bench 1 in a lifting and sliding manner, and a test area is formed below the lifting platform 2, that is, a test area is formed on the test bench 1 below the lifting platform 2. In actual implementation, a layer of steel pad 33 can be installed on the test bench 1, and related equipment can be installed on the steel pad 33. The tension and compression test system is arranged along the X direction at the first end of the test area on the test bench 1, as shown in FIG. Figure 1 The left end shown in FIG is used to apply X-direction tension and compression loads to the specimen; the Y-direction bending test system is arranged along the Y direction on the side of the test area of ​​the test bench 1, as shown in FIG. Figure 1 The inner side perpendicular to the paper direction shown in the figure is used to apply the Y-direction bending load to the specimen; the Z-direction bending test system is arranged on the lifting platform 2 along the Z direction to apply the Z-direction bending load to the specimen; the torsion test system is arranged along the X direction at the second end of the test area on the test platform 1, that is, on the opposite side of the tension and compression test system, that is, as shown in the figure. Figure 1 The right end shown in the figure is used to apply a torsional load to the specimen; the sliding support fixture device is installed at the first end of the test area and has a certain X-direction sliding ability, which assists the specimen in tension, compression and torsion. When no tension or compression test is performed, it is fixed to limit sliding. When the tension and compression test is performed, the fixation is released to allow sliding, so that the specimen bears tension and compression loads; the fixed support fixture device is installed at the second end of the test area to assist the specimen in torsion; through the tension and compression test system, the Y-direction and Z-direction bending test system and the torsion test system, the XYZ force flow coupling is realized, and at the same time, through the intelligent collaborative loading control device, the tension, compression, bending and torsion loads can be coupled, and the tension, compression, bending and torsion loads can be controlled in real time to achieve collaborative loading, which can better simulate the actual working conditions, so as to solve the problems of single test and difficulty in applying actual working loads in the existing technology, and ultimately achieve the purpose of predicting the local stress concentration trend of the test specimen and predicting the crack propagation path.

[0092] In some embodiments, the test bench 1 can be a square or rectangular structure. The multi-directional fatigue testing system also includes vertical supports 3, which are fixed to the corners of the test bench 1 by multiple columns. The lifting platform 2 is mounted on these columns so that it can be raised and lowered and slidably moved. The multiple columns are supported by cylindrical columns, and the four corners of the lifting platform 2 are slidably connected to the cylindrical supports via welded or integrally molded sliders, allowing for free lifting and sliding. It can be precisely raised and lowered by motor power and system control to be fixed at any height.

[0093] In some embodiments, as Figure 3 、 Figure 4 As shown, the main body of the tension and compression test system adopts a tension and compression test machine 4, which is an electromagnetic linear motor to realize linear tension and compression loading. The electromagnetic linear motor is installed at one end of the test area on the test bench 1, namely the left end, by bolts.

[0094] Furthermore, the tensile and compressive testing machine 4 simultaneously applies tensile and compressive loads in the X direction to the specimen 100 with the help of the slidable support 5, the steel pressure rod assembly 6 and the first rod clamp 7. The figure shows that the specimen 100 is a round rod, which is arranged axially along the X direction. The slidable support 5 is slidably installed on the first end of the specimen 100 on the test bench 1, specifically, it is installed between the tensile and compressive testing machine 4 and the first end of the specimen 100. One end of the steel pressure rod assembly 6 is connected to the tensile and compressive testing machine 4 in a transmission manner and can be driven by the tensile and compressive testing machine 4, and the other end is connected to one side of the slidable support 5. The steel pressure rod assembly 6 is used to apply tensile and compressive loads to the slidable support 5 and thus to the specimen 100. It is easy to understand that if the specimen 100 is loaded directly, eccentricity may occur and the applied force field may be uneven. The slidable support 5 acts as a pad to ensure central loading.

[0095] At this corresponding end of the specimen 100, the present invention is designed with a first rod clamp 7. This first rod clamp 7 is mounted on the other side of the slidable support 5, i.e., on the side opposite the steel compression rod assembly 6, and is fixedly connected to the slidable support 5. The first rod clamp 7 clamps the first end of the specimen 100. During testing, the first rod clamp 7 clamps the first end of the specimen 100. The tensile and compressive testing machine 4 drives the slidable support 5 in the X-direction via the steel compression rod assembly 6. The slidable support 5 drives the first rod clamp 7 fixed thereto, thereby applying tensile and compressive loads to the specimen 100.

[0096] In some embodiments, you may continue to see Figure 3 、 Figure 4, a specific slidable support 5 is provided, including a support body 51 and a sliding support rod 52. The sliding support rod 52 is provided on the left and right sides of the support body 51, that is, on both sides of the steel base plate 33. The two groups of sliding support rods 52 are symmetrically arranged along the X direction, so that the support body 51 can be slidably mounted on the two groups of sliding support rods 52. By fixing the slidable support 5 on the sliding rod, it is possible to avoid eccentricity of the loading force after the specimen is deformed, so that the tensile and compressive forces are always kept perpendicular to the cross section of the specimen during the loading process. The sliding support rod 52 can be mounted on the steel base plate 33 through two fixing seats. The two fixing seats are arranged along the X direction and can be fixed specifically by bolt connection or welding. Through holes are preset on the fixing seats, and the two ends of the sliding support rod 52 are inserted through the through holes for installation. The sliding support rod 52 is a round rod. One or more of them can be provided according to actual requirements. Through holes are correspondingly provided on both sides of the support body 51 and inserted on the sliding support rod 52. During the non-tension and compression test, the support body 51 is fixed to the steel plate 33 by bolts to limit its sliding on the sliding support rod 52. Figure 3 As shown, two fixing members 53 are specifically used and fixed to the steel base plate 33 by bolts. When a tension or compression test is required, the bolts are released to allow the support body 51 to slide on the sliding support rod 52, so that the test specimen 100 can withstand the tension and compression loads. The fixing members 53 are preferably special-shaped fixing frames. In this embodiment, they are specifically L-shaped members or angle steels, with appropriate reinforcement at the corners to provide sufficient support strength while maintaining the fixation.

[0097] See also Figure 3 In some embodiments, the steel compression rod assembly 6 includes a first steel compression rod 61 and a second steel compression rod 62 axially connected by a steel compression rod anchor 63. The first steel compression rod 61 is in transmission connection with the tension and compression testing machine 4, and the second steel compression rod 62 is fixedly connected to or integrally formed with the support body 51 of the slidable support 5. The two steel compression rods, secured by the anchor, transmit the motor drive to the support, facilitating maintenance and replacement, as well as adjusting the motor's mounting position. Furthermore, the system delays force transmission to ensure effective force transmission, overcoming the problem of inaccurate force transmission to the test piece caused by directly connecting the support, thereby improving accuracy and stability.

[0098] In some embodiments, the torsion testing system mainly uses a torsion testing machine 8 , which uses a servo motor and is installed on the other end of the test area on the test bench 1 by bolts, that is, on the opposite side of the tension and compression testing machine 4 .

[0099] In an embodiment of the present invention, the torsion test system further incorporates a harmonic reducer fixed support 9, a transmission rod assembly 10, and a second rod fixture 11 to achieve torsional loading of the rod 100. The harmonic reducer fixed support 9 is bolted to the second end of the specimen 100 on the steel backing plate 33, that is, it is installed between the torsion testing machine 8 and the second end of the rod 100; one end of the transmission rod assembly 10 is connected to the torsion testing machine 8 for transmission, and the other end is connected to one side of the harmonic reducer fixed support 9; the second rod fixture 11 is installed on the other side of the harmonic reducer fixed support 9, that is, it is installed at the second end of the rod 100 to clamp the second end of the specimen 100.

[0100] In this embodiment, the transmission rod assembly 10 is similar to the steel compression rod assembly 6 and is used to accurately and effectively transmit the torque of the torsion testing machine 8 to the specimen 100. The transmission rod assembly 10 includes a first transmission rod 101 and a second transmission rod 102 axially connected by a transmission rod anchor 103, wherein the first transmission rod 101 is transmission-connected to the torsion testing machine 8, the second transmission rod 102 is connected to the high-speed shaft of the reducer with the harmonic reducer fixed support 9, and the low-speed shaft of the reducer with the harmonic reducer fixed support 9 is connected to the second rod fixture 11 to transmit the regulated torque to the specimen 100. Similarly, with the help of such a transmission rod assembly 10, the force can be transmitted with delay, ensuring the effectiveness of force transmission, overcoming the problem that the direct connection support cannot transmit the force to the specimen in time and the accuracy is insufficient, and can improve accuracy and stability.

[0101] Continue to see Figure 5 As shown, in some embodiments, the first rod clamp 7 and the second rod clamp 11 have the same structure and are multifunctional round rod clamps. They first include an outer ring body 12, which is a circular ring structure, similar to an external gear. At the same time, an electromagnetic clamp unit is arranged inside it. Multiple groups of electromagnetic clamp units are circumferentially installed in the outer ring body 12. Each group of electromagnetic clamp units consists of an electromagnetic sleeve 13, a magnetic round rod 14, and a round rod clamp 15. The magnetic round rod 14 is arranged in the electromagnetic sleeve 13 and is retractable. The end of the magnetic round rod 14 is connected to the round rod clamp 15. A coil can be set in the electromagnetic sleeve 13 to form magnetism with the help of current. The current size is controlled by the intelligent collaborative loading and control device to change the internal magnetic field of the electromagnetic sleeve 13, thereby pushing the magnetic round rod 14 to retract and retract until the round rod clamp 15 clamps the end of the specimen 100. It is suitable for clamping various special-shaped specimens such as round rod specimens, thin plate specimens and non-standard components (such as welded joints), and the clamping force can be adjusted by electromagnetics to avoid excessive clamping force affecting the test.

[0102] In this embodiment, each group of electromagnetic clamp units can be provided with multiple electromagnetic sleeves 13, three of which are shown in the figure, and three corresponding magnetic round rods 14 are provided. The round rod clamp 15 adopts a short round rod, and the short round rod is along the X direction, that is, the axial direction of the rod 100. One side of the rod body of the short round rod is connected to the ends of the three magnetic round rods 14, and the other side of the rod body axially clamps the end of the rod 100 to ensure stable and effective clamping.

[0103] See also Figure 3 、 Figure 4 In some embodiments, the Y-axis bend test system includes a Y-axis bend tester 16 and a steel compression rod assembly. The Y-axis bend tester 16 is an electromagnetic linear motor bolted to the side of the test area of ​​the test bench, i.e., to the side of the vertical rod 100. One end of the steel compression rod assembly is connected to the Y-axis bend tester 16, and the other end is perpendicular to the axis of the specimen 100 and can apply lateral bending to the specimen according to test conditions. The steel compression rod assembly is similar to the above description and will not be repeated here.

[0104] See also Figure 2 In some embodiments, the Z-direction bending test system includes a Z-direction bending tester 17 and a thin steel rod assembly. The Z-direction bending tester 17 is an electromagnetic linear motor installed at the bottom of the lifting platform 2, that is, directly above the test piece 100 in the test area, and can be controlled by the motor control console 27. One end of the thin steel rod assembly is connected to the Z-direction bending tester 17 (see Figure 1 ), and the other end is perpendicular to the axial direction of the specimen 100, and can apply vertical bending to the specimen 100 according to the test conditions, thereby realizing dynamic coupling loading of various complex load spectra, such as dynamic coupling loading of complex load spectra such as sine, triangular wave, and random spectrum.

[0105] In some embodiments, the lifting platform 2 is provided with an opening at the position corresponding to the test area, and a primary slide rail 18 is provided at the opening, a secondary slide rail 19 perpendicular thereto is provided on the primary slide rail 18, a sliding platform 20 is provided on the secondary slide rail 19, and the Z-direction bending tester 17 is installed at the bottom of the sliding platform 20. By virtue of the two-stage slide rails being perpendicular to each other, bidirectional sliding is achieved, and the position of the Z-direction bending tester 17 in the X and Y directions can be adjusted in real time according to the test needs through the intelligent collaborative loading and control device. In this embodiment, the primary slide rail 18 is arranged along the X direction, that is, the axial direction of the specimen 100, to adjust the position of the Z-direction bending tester 17 in the axial direction of the specimen 100, and the secondary slide rail 19 is arranged along the Y direction, that is, perpendicular to the axial direction of the specimen 100, to adjust the position of the Z-direction bending tester 17 in the Y direction.

[0106] Specifically, the first sliding rail 18 can be mounted on opposite edges of the hole or can be formed on the edges of the hole. The second sliding rail 19 can be connected and slid, and in the embodiment, pulleys are further arranged at both ends of the second sliding rail 19 to slide on the first sliding rail 18. The sliding platform 20 can have a box type or a box type structure, is sleeved on the second sliding rail 19, bears the reaction force when loaded, and pulleys are arranged in the box type or the box type structure to slide on the second sliding rail 19.

[0107] In addition, a cover plate 28 is additionally arranged above the hole to close the test area inside, so as to form the multifunctional sealed cabin 22 of the closed test environment (which will be described in detail below).

[0108] Continuing to refer to Figure 6 , Figure 7 In some embodiments, the multifunctional sealed cabin 22 of the closed test environment is further formed by the sealing partition plates 21 arranged around the periphery of the test area, and the compression test system, the torsion test system and the multi-directional bending test system pass through the corresponding sealing partition plates 21 and are sealingly connected.

[0109] Specifically, the sealing groove 23 is arranged on the test bench 1 and surrounds the periphery of the test area, and the multifunctional sealed cabin 22 of the closed test environment is formed by inserting the sealing partition plates 21 into the sealing groove 23.

[0110] With the multifunctional sealed cabin 22, a multifunctional test area is formed inside, and in combination with Figure 1 , Figure 2 In the embodiment, the material sprayer 24 is installed in the multifunctional sealed cabin 22, and the test material storage box 25 and the small air blower 26 are arranged on the lifting platform 2, wherein the test material storage box 25 stores test materials, the material sprayer 24 is used to extract the test materials in the test material storage box 25 to apply the required material conditions (including refrigerant gas, corrosive gas, etc.) to the test piece 100 during the test, and the small air blower 26 is used to extract the test materials in the multifunctional sealed cabin 22 to the test material storage box 25 to realize the circulation of the test materials.

[0111] The material sprayer 24 can be provided with multiple groups according to test conditions, such as Figure 2 four groups are symmetrically arranged around the test area to ensure sufficient and uniform spraying, and the material sprayer 24 has a connecting circular shaft and a mechanical arm, which can be adjusted in real time by the intelligent collaborative loading control device, that is, the spraying angle is adjusted to change the position of the sprayed materials.

[0112] In addition, the present invention also includes a workspace positioning system, specifically including: a spatial positioning sensor, a multi-channel fiber grating sensor with a signal transmitter, and a spatial position algorithm and a signal receiver included in the intelligent collaborative loading and control device, which together form a three-dimensional workspace. Figure 3 、 Figure 4 As shown, multiple spatial positioning sensors 29 are provided, specifically three in this embodiment, which are arranged in a three-dimensional manner around the test area to transmit position information in real time. Multi-channel fiber grating sensors 32 with signal transmitters are arranged symmetrically along the axial and circumferential directions of the test piece 100. The signal receiver 30 is arranged on the intelligent collaborative loading and control device 31 to facilitate data transmission. Combined with the spatial position algorithm contained in the intelligent collaborative loading and control device 31, a three-dimensional workspace is formed together.

[0113] In the present invention, the intelligent collaborative loading and control device 31 includes a digital twin engine and a multi-physical field synchronous acquisition system to realize multi-directional bending coupling and intelligent collaborative loading and control of the tensile and compression test system, the torsion test system, and the multi-directional bending test system.

[0114] Among them, the digital twin engine has an intelligent collaborative loading control algorithm, which can convert actual physical field information into test parameters for tension, compression, bending and torsion fatigue tests through Fourier transform analytical expressions;

[0115] The multi-channel fiber Bragg grating sensors 32 are equipped with signal transmitters and are arranged symmetrically along the axial and circumferential directions of the test piece 100. Wavelength division multiplexing technology is used to monitor the strain field on the test piece surface in real time. The signal transmitter built into each multi-channel fiber Bragg grating sensor 32 transmits distance information. After data calculation and processing, the position information of each sensor node of the test piece before the test is obtained. The position data and strain field data can be transmitted in real time to the multi-physics field synchronous acquisition system.

[0116] The multi-physics field synchronous acquisition system can collect the strain field data transmitted by the multi-channel fiber grating sensor 32 during the test and the position information of each sensor, predict the local stress concentration trend, predict the crack propagation path, and establish a multi-axis fatigue damage evolution model of the specimen. It adjusts the current transmitted to the multi-function fixture to change the magnetic force, thereby adjusting the clamping force of the specimen. In addition, it can process the distance information through the digital motion processor to calculate the signal position, find the loading center position of the deformed specimen after calculation through the symmetry interpolation method or curve fitting algorithm, and transmit it to the Z-axis bending test system. The sliding platform repositions the test loading position and adjusts the nozzle position of the material sprayer.

[0117] The multi-directional fatigue test system installation method provided by the present invention comprises the following steps:

[0118] S10: First, install four columns of vertical supports 3 around the test table 1, and install a layer of steel base plate 33, install a slidable support 5, install a material sprayer 24 under the top of the lifting platform 2 according to the test area, install a layer of sealing partition plate 21 around it, install a sealing groove 23 in the corresponding test table 1 area, so that the sealing partition plate 21 can be tightly inserted into the sealing groove 23 to form a closed space, that is, a multifunctional sealed cabin 22, install a small air blower 26 and a test material storage box 25 on the lifting platform 2;

[0119] S20: Install the first rod clamp 7 and the second rod clamp 11 on the slidable support 5 and the harmonic reducer fixed support 9 respectively, then install the slidable support 5 through the sliding support rod 52 on the steel base plate 33, and fix it on the steel base plate 33 with the fixing piece 53, then bolt the harmonic reducer fixed support 9 to the steel base plate 33, install the torsion testing machine 8, and connect the transmission rod anchor 103 of the torsion testing machine 8 to the harmonic reducer fixed support 9, and keep the connection part of the multifunctional sealed cabin 22 sealed;

[0120] S30: Install the tensile testing machine 4 opposite to the steel base plate 33 of the torsion testing machine 8, connect the steel pressing rod anchor 63 of the steel pressing rod to the slidable support 5, and keep the connection part of the multifunctional sealed cabin 22 sealed;

[0121] S40: Install the multi-directional bending testing machine, install the electromagnetic linear motor of the Z-directional bending testing machine 17 on the secondary slide rail 19 through the sliding platform 20, then install the secondary slide rail 19 on the primary slide rail 18 arranged on both sides of the hole of the lifting platform 2, and finally install a cover plate 28 on the top of the sliding platform 20, install the lifting platform 2 on the four columns of vertical supports 3, and install the Y-directional bending testing machine 16 on the side of the test table 1, which is perpendicular to the test piece axis, and keep the connection part of the multi-directional bending testing machine and the multifunctional sealed cabin 22 sealed.

[0122] S50: Install the intelligent collaborative loading control device 31 on the end of the test table 1 that does not affect the test, and connect it with the three testing machines.

[0123] S60: Before the test, arrange the multi-channel fiber grating sensor 32 on the surface of the test piece 100 along the test piece axis and the circumferential direction, and connect it with the intelligent collaborative loading control device 31.

[0124] As shown in Figure 8 The intelligent collaborative loading method of the multi-directional fatigue test system of the application comprises the following steps:

[0125] S10: Assemble the multi-directional fatigue test system;

[0126] S20: Multiple multi-channel fiber Bragg grating sensors with signal transmitters are symmetrically arranged along the axial and circumferential directions of the specimen, multiple spatial positioning sensors are installed on the test bench, and signal receivers are installed on the intelligent collaborative loading and control device to form a three-dimensional working space;

[0127] S30: The digital twin engine converts actual working loads into test parameters for tension, compression, bending, and torsion fatigue tests;

[0128] S40: The multi-channel fiber Bragg grating sensor collects stress and strain field data on the specimen surface, such as specimen elongation data and torsion angle, and transmits the data to the intelligent collaborative loading control device through a signal transmitter;

[0129] S50: The digital motion processor processes stress and strain field data and converts it into corresponding fatigue data, such as loading times and damage rate. It also uses a neural network algorithm to predict local stress concentration trends and anticipate crack propagation paths.

[0130] S60: The signal transmitter transmits the distance information of the multi-channel fiber Bragg grating sensor in the three-dimensional workspace to the intelligent collaborative loading control device;

[0131] S70: The digital motion processor calculates the distance information of the sensor as the specimen position information. According to the deformation of the specimen and the test conditions, it adjusts the lifting platform and the sliding platform to adjust the loading position of the Z-axis bending tester and the spraying position of the material sprayer.

[0132] In particular, in step S30, the digital twin engine has an intelligent collaborative loading control algorithm, which converts the actual physical field information into test parameters of tension, compression, bending and torsion fatigue tests through Fourier transform analytical expressions.

[0133] In step S40, a multi-channel fiber Bragg grating sensor is provided with a signal transmitter, which is symmetrically arranged along the axial and circumferential directions of the test piece, and uses wavelength division multiplexing technology to monitor the stress and strain field on the surface of the test piece in real time, and transmits the stress and strain field data to the multi-physics field synchronous acquisition system in real time.

[0134] In step S50, after the multi-physics field synchronous acquisition system collects the test result data, it can predict the crack propagation data and establish a multi-axis fatigue damage evolution model of the specimen. It can adjust the current transmitted to the multi-functional round rod clamp to change the magnetic force and thus adjust the clamping force of the specimen.

[0135] In step S60, the distance information includes the distance between each multi-channel fiber Bragg grating sensor and the intelligent collaborative loading and control device, as well as the distance between each multi-channel fiber Bragg grating sensor and the three-dimensional spatial coordinate axis. It is easy to understand that the three spatial positioning sensors 29 form the three-dimensional workspace coordinate system. The signal receiver 30 in the intelligent collaborative loading and control device 31 is equivalent to a satellite, and the spatial positioning sensor 29 within the three-dimensional workspace coordinate system is equivalent to a locator, which locates the position of the multi-channel fiber Bragg grating sensor 32 in the three-dimensional workspace coordinate system and the distance to each coordinate axis of the three-dimensional workspace coordinate system.

[0136] In step S70, the digital motion processor calculates the signal position. Using symmetric interpolation or a curve fitting algorithm, the center of the specimen's loading position after deformation is determined. This position is then transmitted to the Z-axis bending test system. The sliding platform repositions the test loading position and adjusts the material applicator's nozzle position. Specifically, the distance information is used to algorithmically calculate the position of each multi-channel fiber Bragg grating sensor in the three-dimensional workspace coordinates. This position information is then used to derive the specimen's contour and establish a specimen model. As the specimen deforms, the position of each sensor changes, and the corresponding model also changes. Using a fitting method, the center of the specimen's loading position is determined after deformation.

[0137] In summary, the present invention combines the tension and compression test system, the multi-directional bending test system and the torsion test system to realize XYZ force flow coupling, and realizes coordinated loading by real-time control of the tension, compression, torsion and bending loads through the intelligent collaborative loading control device, which can better simulate the actual working conditions; the sliding support is combined with the tension and compression testing machine to make the test conditions more diversified and the test parameters closer to the actual load conditions; the electromagnetic linear motor is used for higher control accuracy, which can directly generate linear motion and eliminate the mechanical loss of intermediate conversion devices such as gears; the multi-functional fixture is used to make the test not limited to a single specimen; the installation of a multi-functional test box (multi-functional sealed cabin) makes the fatigue test not limited to a single loading environment, close to the actual working conditions, and easy to install; the working space positioning system is combined with the lifting sliding plate to make the bending testing machine (Z direction) able to adjust the loading position in real time according to the deformation of the specimen, thereby improving the test accuracy; The "digital twin engine" is set up through a high-fidelity time domain mapping algorithm to convert the complex load data collected by the test sensors into real-time multi-directional fatigue test parameters, coordinate the collaborative loading of the testing machines in all directions, avoid mutual interference and improve the test accuracy, integrate the deep learning model to analyze the strain gradient distribution, and predict the local stress concentration area in advance to prevent accidental fracture of the specimen; multi-channel fiber Bragg grating sensors are symmetrically distributed to cover the surface of the specimen, combined with the transient strain field reconstruction algorithm to achieve higher-precision strain capture; a multi-physical field synchronous acquisition system is used to combine the real-time position information transmitted by the multi-channel fiber Bragg grating sensors with the workspace positioning system to promptly detect the deformation of the specimen, and the lifting platform adjusts the loading position of the bending testing machine (Z direction) to reduce the test error. Based on the field-field coupling mapping algorithm, the measured physical field data is converted into a laboratory controllable load spectrum, the non-proportional and random characteristics of multi-axial loads are reproduced, and a multi-axial fatigue damage evolution model is established. According to the above conditions and intelligent algorithms required by the multi-axis fatigue test system, it is imperative to improve the test accuracy, collect test parameters in real time, increase the test research conditions, improve the versatility of the specimen clamping system, and conduct research on the accuracy, convenience, real-time performance, diversification and combination of the multi-axis fatigue test system with intelligent algorithms.

[0138] The above-mentioned several specific implementation details should not be interpreted as limiting the scope of the present invention. Certain features described in the context of separate embodiments can also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented in multiple implementations individually or in any suitable sub-combination.

[0139] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A multi-directional fatigue test system based on multi-axis dynamic coupling, characterized in that: The multi-directional fatigue testing system includes: test bench; A lifting platform is installed on the test platform in a lifting and sliding manner, with a test area formed below; The tension and compression test system is arranged at the first end of the test area along the X direction; A multi-directional bending test system, comprising a Y-direction bending test system arranged on the side of the test area along the Y direction, and a Z-direction bending test system arranged on the lifting platform along the Z direction, capable of applying YZ-direction bending loads to the specimen in a coupled manner; a torsion test system, arranged at the second end of the test area along the X direction; A slidable support fixture device is installed at the first end of the test area to clamp the specimen and has a certain X-direction sliding ability. When performing tension and compression tests, it is released to allow sliding. When not performing tension and compression tests, it is fixed to limit sliding, assisting the specimen in tension, compression, bending and / or torsion; a fixed support fixture device, installed at the second end of the test area to clamp the test piece and assist the test piece in torsion; The workspace positioning system forms the three-dimensional workspace of the multi-directional fatigue test system; The intelligent collaborative loading control device is used to couple tension, compression, bending and torsion for dynamic collaborative loading, predict the local stress concentration trend of the test piece, predict the crack propagation path, and adjust the loading position in time according to the deformation of the test piece to avoid eccentricity; The slidable support fixture device comprises: a slidable support slidably mounted on a first end of the test area; a first rod clamp, mounted on one side of the slidable support located on the specimen and adapted to clamp a first end of the specimen; a fixing member, detachably mounted on the test bench and capable of fixing and releasing the slidable support; and The workspace positioning system includes: Spatial positioning sensors: Multiple spatial positioning sensors are arranged in three dimensions around the test area to transmit position information in real time; A multi-channel fiber Bragg grating sensor with a signal transmitter, wherein multiple multi-channel fiber Bragg grating sensors are symmetrically arranged along the axial and circumferential directions of the test piece; and the spatial position algorithm and signal receiver contained in the intelligent collaborative loading control device.

2. The multi-directional fatigue testing system according to claim 1, characterized in that: The tension and compression test system comprises: The tension and compression testing machine is an electromagnetic linear motor installed at the first end of the test area by bolts; A steel compression rod assembly, one end of which is transmission-connected to the tension and compression testing machine, and the other end of which is connected to the slidable support fixture device; And / or, the Y-direction bending test system includes: The Y-axis bending tester is an electromagnetic linear motor installed on the side of the test area by bolts; A steel compression rod assembly, one end of which is transmission-connected to the Y-axis bending tester, and the other end of which is perpendicular to the axis of the specimen and capable of applying transverse bending to the specimen according to the test conditions; And / or, the Z-direction bending test system includes: The Z-direction bending tester is an electromagnetic linear motor installed at the bottom of the lifting platform; A thin steel rod assembly, one end of which is connected to the Z-axis bending tester, and the other end of which is perpendicular to the axis of the specimen and can apply vertical bending to the specimen according to the test conditions; And / or, the torsion testing system comprises: The torsion testing machine is a servo motor mounted on the second end of the test area by bolts; A transmission rod assembly has one end in transmission connection with the torsion testing machine and the other end in connection with the fixed support fixture device.

3. The multi-directional fatigue testing system according to claim 1, characterized in that: The slidable support includes a support body and a sliding support rod. Two groups of the sliding support rods are symmetrically fixed on the test bench on both sides of the support body along the X direction. The support body is slidably installed on the two groups of the sliding support rods. When no tensile and compressive tests are performed, the support body is fixed to the test bench by fixing parts and bolts to limit its sliding on the sliding support rods. When performing tensile and compressive tests, the bolt fixation is released to allow it to slide on the sliding support rods.

4. The multi-directional fatigue testing system according to claim 1, characterized in that: The fixed support fixture device comprises: With a harmonic reducer fixed support, installed at the second end of the test area by bolts; The second rod fixture is installed on one side of the test piece of the fixing support with harmonic reducer and is suitable for clamping the second end of the test piece.

5. The multi-directional fatigue testing system according to claim 1 or 4, characterized in that: The first rod clamp and the second rod clamp are multifunctional round rod clamps, each comprising: outer ring body; An electromagnetic clamp unit, wherein multiple groups of the electromagnetic clamp units are circumferentially installed in the outer ring body. The electromagnetic clamp unit consists of an electromagnetic sleeve, a magnetic round rod, and a round rod chuck. One end of the magnetic round rod is arranged in the electromagnetic sleeve and is retractable, and the other end is connected to the round rod chuck. The electromagnetic sleeve controls the current size through an intelligent collaborative loading and control device to change the internal magnetic field of the electromagnetic sleeve, thereby pushing the magnetic round rod to retract and contract until the round rod chuck clamps the test piece.

6. The multi-directional fatigue testing system according to claim 5, characterized in that: The lifting platform has an opening at the position corresponding to the test area, and a primary slide rail is provided at the opening, a secondary slide rail perpendicular to the primary slide rail is provided on the primary slide rail, a sliding platform is provided on the secondary slide rail, and the Z-direction bending tester is installed at the bottom of the sliding platform. Through the intelligent collaborative loading and control device, the position of the Z-direction bending tester in the X and Y directions can be adjusted in real time according to the test needs.

7. The multi-directional fatigue testing system according to claim 1, characterized in that: The test bench is provided with a sealing groove, and a sealing partition is provided around the periphery of the test area. The sealing partition is inserted into the sealing groove to form a multifunctional sealed cabin with a closed test environment. The tensile and compression test system, the torsion test system, and the multi-directional bending test system pass through the corresponding sealing partitions and are sealed and connected; A material sprayer is installed in the multifunctional sealed cabin, and a test material storage box and a small induced draft fan are provided on the lifting platform. The material sprayer is used to extract the test material from the test material storage box and apply the material conditions required for the test to the test pieces during the test. The small induced draft fan is used to extract the test material in the multifunctional sealed cabin to the test material storage box to realize the circulation of the test material. The material sprayer can adjust the spray angle in real time through the intelligent collaborative loading and control device, thereby changing the position of the sprayed material.

8. The multi-directional fatigue testing system according to claim 6, characterized in that: The intelligent collaborative loading control device includes: The digital twin engine, equipped with an intelligent collaborative loading control algorithm, can convert actual physical field information into test parameters for tension, compression, bending, and torsion fatigue tests through Fourier transform analytical expressions; The multi-physics field synchronous acquisition system can collect the stress and strain field data transmitted by the multi-channel fiber Bragg grating sensors during the test and the distance information of each sensor, predict the local stress concentration trend, predict the crack propagation path, adjust the current transmitted to the fixture to change the magnetic force, and then adjust the clamping force of the specimen. In addition, the distance information can be processed by the digital motion processor to find the loading center position of the deformed specimen, and transmit it to the Z-axis bending test system. The sliding platform repositions the test loading position and adjusts the nozzle position of the material sprayer.

9. An intelligent collaborative loading method for a multi-directional fatigue testing system according to any one of claims 1 to 8, characterized in that: The steps include: S10: Assemble the multi-directional fatigue test system; S20: Multiple multi-channel fiber Bragg grating sensors with signal transmitters are symmetrically arranged along the axial and circumferential directions of the specimen, multiple spatial positioning sensors are installed on the test bench, and signal receivers are installed on the intelligent collaborative loading and control device to form a three-dimensional working space; S30: The digital twin engine converts actual working loads into test parameters for tension, compression, bending, and torsion fatigue tests; S40: The multi-channel fiber Bragg grating sensor collects stress and strain field data on the specimen surface and transmits it to the intelligent collaborative loading control device through a signal transmitter; S50: The digital motion processor processes stress and strain field data, converts it into corresponding fatigue data, and combines it with a neural network algorithm to predict local stress concentration trends and anticipate crack propagation paths. S60: The signal transmitter transmits the distance information of the multi-channel fiber Bragg grating sensor in the three-dimensional workspace to the intelligent collaborative loading control device; S70: The digital motion processor calculates the distance information of the sensor as the specimen position information. According to the deformation of the specimen and the test conditions, it adjusts the lifting platform and the sliding platform to adjust the loading position of the Z-axis bending tester and the spraying position of the material sprayer.

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