A magnetostrictive material multi-physics field coupling mechanical parameter testing system and method

Abstract

The application provides a magnetostrictive material multi-physical field coupling mechanical parameter testing system and method, the testing system comprises a mechanical loading unit, a magnetic field loading unit, a thermal field control unit, a boundary control unit, a synchronous acquisition unit and a parameter identification unit; the boundary control unit is used for adapting sample installation and loading boundary control under different testing conditions; the mechanical loading unit is used for applying tensile load, compression load or bending load to the sample; the magnetic field loading unit is used for applying static magnetic field and / or dynamic magnetic field to the sample; the thermal field control unit is used for heating and keeping warm the working area of the sample; the synchronous acquisition unit is used for synchronously acquiring multi-source physical signals; and the parameter identification unit is used for identifying mechanical performance parameters and magneto-mechanical coupling characteristic parameters under multi-physical field coupling. The application can realize stable testing of magnetostrictive material mechanical key parameters under the coupling conditions of magnetic field, thermal field and force field, and improve testing accuracy, repeatability and engineering applicability.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, and in particular to a multi-physics field coupled mechanical parameter testing system and method for magnetostrictive materials. Background Technology

[0002] Magnetostrictive materials are typically subjected to a non-single physical field environment during service, simultaneously experiencing mechanical loads, bias magnetic fields, alternating magnetic fields, and temperature changes. Under these coupled conditions, the material's strength, stiffness, fracture behavior, and magnetomechanical coupling response all change.

[0003] Existing universal testing machines can perform conventional mechanical property tests such as tension, compression, and bending, and their mechanical loading functions are relatively complete. Some testing platforms can also superimpose temperature fields through heating devices, thereby achieving a certain degree of force-thermal field coupling testing. However, for magnetostrictive materials, especially small-sized, brittle samples that are sensitive to boundary conditions, it is difficult to accurately reflect the behavior characteristics of magnetostrictive materials under real service conditions by relying solely on mechanical property data obtained under normal temperature, no magnetic field, or single static load conditions.

[0004] CN121254157B discloses a multi-physics field coupled dynamic characteristic monitoring system for supermagnetic-strictive rods. This system enables high-speed synchronous acquisition of multi-source signals such as magnetic, force, acoustic, and temperature signals, comprehensively characterizing the material's dynamic response process and achieving synchronous control of the external magnetic field, force field, and ambient temperature of the rod, realistically reproducing the material's working state under complex service conditions. However, this system can only perform dynamic magnetic property tests related to compression and cannot perform conventional dynamic mechanical property tests such as compression, tension, and bending under multi-physics fields. During compression, tension, and bending tests, eccentric loading, additional bending moments, or localized stress concentrations are easily introduced into the sample, leading to increased test result deviations and decreased repeatability. Especially under the combined action of dynamic magnetic fields and mechanical loads, these additional errors are easily amplified, further affecting the reliable acquisition of material mechanical parameters and coupling parameters. Summary of the Invention

[0005] In order to achieve stable testing of key mechanical parameters of magnetostrictive materials under the coupling conditions of magnetic field, thermal field and force field, this invention provides a multi-physics field coupled mechanical parameter testing system and method for magnetostrictive materials.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical method: a multi-physics field coupled mechanical parameter testing system for magnetostrictive materials, including a mechanical loading unit, a magnetic field loading unit, a thermal field control unit, a synchronous acquisition unit, and a parameter identification unit. The synchronous acquisition unit is connected to the mechanical loading unit, the magnetic field loading unit, and the thermal field control unit. The parameter identification unit is connected to the synchronous acquisition unit. The testing system also includes a boundary control unit. The boundary control unit is placed in the force path of the mechanical loading unit to adapt to the sample installation and loading boundary control under different test conditions; The mechanical loading unit is used to drive the boundary control unit to apply tensile load, compressive load or bending load to the specimen; The magnetic field loading unit is used to apply a static magnetic field and / or a dynamic magnetic field to the sample; The thermal control unit is used to heat the working area of ​​the sample and maintain a set temperature; The synchronous acquisition unit is used to synchronously acquire multi-source physical signals of the sample and system response; The parameter identification unit is connected to the synchronous acquisition unit and is used to identify the mechanical property parameters and magnetomechanical coupling characteristic parameters of the sample under the multi-physics field coupling based on the synchronously acquired data. The sample is a magnetostrictive material.

[0007] Furthermore, the boundary control unit includes a tension clamp, a compression clamp, or a three-point bending clamp; The tensile fixture includes a clamping structure for mounting the specimen. A buffer contact layer is provided on the clamping surface of the clamping structure to homogenize the clamping pressure of the clamping structure on the specimen and reduce local stress concentration at the end of small-sized brittle specimens. The compression fixture includes an upper pressure plate symmetrically distributed vertically and a self-aligning structure. The self-aligning structure includes a concave spherical seat and a convex spherical seat symmetrically distributed vertically and cooperating with each other. The sample can be vertically mounted on the concave spherical seat. The three-point bending fixture includes an upper loading head and a lower support roller seat. The lower support roller seat is provided with two lower support rollers for horizontally mounting the sample, and the upper loading head is used to apply a downward load to the center of the sample.

[0008] Furthermore, the force-bearing components in the boundary control unit that come into contact with the sample are all made of martensitic stainless steel, mold steel, or other metallic materials that combine magnetic response characteristics and structural stiffness.

[0009] Furthermore, the magnetic field loading unit surrounds the boundary control unit and is embedded in the center of the thermal field control unit, which is an enclosed constant temperature structure.

[0010] Furthermore, the magnetic field loading unit includes an upper electromagnetic pole and a lower electromagnetic pole arranged symmetrically vertically, as well as a left electromagnetic pole and a right electromagnetic pole arranged symmetrically horizontally. The upper electromagnetic pole, lower electromagnetic pole, left electromagnetic pole, and right electromagnetic pole form an encircling magnetic field structure surrounding the boundary control unit. The upper electromagnetic pole and lower electromagnetic pole can move vertically to achieve axial dynamic magnetic field loading, and the left electromagnetic pole and right electromagnetic pole can move horizontally to achieve lateral dynamic magnetic field loading. The frequency of the dynamic magnetic field is 50 Hz to 1500 Hz. The magnetic field loading unit and the mechanical loading unit adopt a synchronous and coordinated control method.

[0011] Furthermore, the thermal field control unit and the magnetic field loading unit are each equipped with independent cooling structures.

[0012] Preferably, the synchronous acquisition unit includes a force sensor, a displacement sensor, a strain sensor, a magnetic field sensor, a magnetic induction intensity sensor, and a temperature sensor, which are used to acquire load signals, displacement signals, strain signals, magnetic field signals, magnetic induction intensity signals, and temperature signals from multi-source physical signals, respectively. The mechanical performance parameters identified by the parameter identification unit include at least one of tensile strength, compressive strength, elastic modulus, and fracture toughness. The magnetomechanical coupling characteristic parameters identified by the parameter identification unit include at least one of dynamic stiffness, magnetomechanical coupling coefficient, and stiffness change rate.

[0013] As another aspect of the present invention, a method for testing multi-physics coupled mechanical parameters of magnetostrictive materials is provided, which uses the aforementioned multi-physics coupled mechanical parameter testing system for magnetostrictive materials. The method includes: S1, Sample preparation: Select the sample type and the fixture type of the boundary control unit according to the test target, install the sample in the fixture corresponding to the boundary control unit, adjust the sample position and fixture status, so that the sample test area is located in the effective working area of ​​the magnetic field loading unit, and establish a stable test boundary. S2, Set Multiple Field Boundaries: Set mechanical loading parameters, magnetic field mode, magnetic field parameters, and thermal field temperature conditions according to test requirements. Start the magnetic field loading unit and thermal field control unit. After the magnetic field and temperature reach a stable state, start the mechanical loading unit to apply mechanical load to the sample and establish a coupled test environment of magnetic field, thermal field and force field. S3, Synchronous signal acquisition: During the test, the multi-source physical signals of the sample and system response are synchronously acquired through the synchronous acquisition unit, and the test data acquisition and storage are completed according to the preset termination conditions. S4, Parameter Identification and Output: Preprocess and analyze the synchronously acquired data, identify the mechanical performance parameters and magnetomechanical coupling characteristic parameters of the sample under the multi-physics coupling effect, and output the test results.

[0014] Compared with the prior art, the present invention has at least the following effects: 1. This invention constructs a system architecture that coordinates mechanical loading, magnetic field loading, thermal field control, boundary control, synchronous acquisition, and parameter identification to meet the parameter testing needs of magnetostrictive materials. It can complete the dynamic mechanical performance testing of magnetostrictive materials under multi-physics coupling conditions on the same platform.

[0015] 2. This invention incorporates the compression fixture, tension fixture, and three-point bending fixture into the same error suppression chain by setting a boundary control unit. The self-aligning structure in the compression fixture can compensate for the additional displacement and end-face attitude deflection of the specimen caused by magnetostriction under the action of a magnetic field, reducing eccentric loading and additional bending moment; the low-stress-concentration clamping structure in the tension fixture can reduce local stress concentration at the ends of small-sized brittle specimens; the three-point bending fixture can keep the test area stably within the effective area of ​​the magnetic field working region, thereby improving the consistency of the test boundary.

[0016] 3. In this invention, the magnetic field loading unit and the mechanical loading unit can coordinate and control the time synchronization or phase coordination between dynamic magnetic field loading and mechanical loading, which is beneficial to obtaining consistent data between magnetic field response and mechanical response under dynamic working conditions and improving the reliability of dynamic parameter testing. Attached Figure Description

[0017] Figure 1 This is a front view of the universal testing machine according to Embodiment 1 of the present invention; Figure 2 This is a side view of the universal testing machine according to Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the magnetic field loading unit assembly according to Embodiment 1 of the present invention; Figure 4 These are schematic diagrams of the tension clamp structures of Embodiments 1 and 3 of the present invention; Figure 5 These are schematic diagrams of the compression clamp structures of Embodiments 1 and 4 of the present invention; Figure 6 These are schematic diagrams of the three-point bending fixtures of Embodiments 1 and 5 of the present invention; Figure 7 This is a block diagram illustrating the principle of the multi-physics coupling mechanical parameter testing method for magnetostrictive materials according to Embodiment 2 of the present invention. Figure 8 This is a flowchart of the multi-physics field coupling mechanical parameter testing method for magnetostrictive materials according to Embodiment 2 of the present invention; Figure 9 This is a physical image of the universal testing machine according to Embodiment 1 of the present invention; Figure 10 The stress-strain curves are shown for the conventional tensile test and the multiphysics coupled tensile test in Embodiment 3 of the present invention. Figure 11 The stress-strain curves are shown for the conventional compression test and the multiphysics field coupled compression test in Embodiment 4 of the present invention. Figure 12 This is a force-displacement curve diagram of the conventional three-point bending test and the multi-physics field coupled three-point bending test in Embodiment 5 of the present invention.

[0018] In the attached diagram: 1. Top beam; 2. Middle crossbeam; 3. Upper top rod; 4. Aluminum side cover; 5. Heating chamber; 6. Cooling structure of the magnetic field loading unit; 7. Electromagnet support plate; 8. Lower top rod; 9. Base; 10. Chamber door; 11. Heat-insulating glass cover; 12. Electromagnet support leg; 13. Chamber; 14. Movable bracket; 15. Movable bracket base; 16. Upper electromagnetic pole head; 17. Left electromagnetic coil; 18. Left electromagnetic pole head; 19. Right electromagnetic pole head 20. Lifting ring; 21. Upper electromagnetic coil; 22. Right electromagnetic coil; 23. Lower electromagnetic pole head; 24. Lower electromagnetic coil; 25. Locking nut; 26. Upper clamping part; 27. Tensile sample; 28. Buffer contact layer; 29. ​​Lower clamping part; 30. Upper pressure plate; 31. Compression sample; 32. Convex spherical seat; 33. Concave spherical seat; 34. Fixing block; 35. Upper loading head; 36. Pre-cracked three-point bending sample; 37. Lower support roller. Detailed Implementation

[0019] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0020] Example 1 This invention provides a multi-physics coupling mechanical parameter testing system for magnetostrictive materials. The testing system is mounted on a mechanical loading platform. Preferably, in this embodiment, the mechanical loading platform is a universal testing machine, used to provide stable axial tensile loads, compressive loads, and three-point bending loads. The universal testing machine in this embodiment is described below. Figure 1 , 2 As shown in Figures 9 and 10. The testing system involved in this invention includes: The boundary control unit, located in the force path of the mechanical loading unit, is used to adapt to the sample installation and loading boundary control under different test conditions. This enables the sample to suppress additional deformation errors caused by magnetostriction during multi-physics field coupling tests involving magnetic fields, thermal fields, and force fields, reduce clamping stress concentration, and control magnetic field boundary disturbances in the sample's working area.

[0021] The mechanical loading unit is used to drive the boundary control unit to apply tensile, compressive, or bending loads to the specimen.

[0022] The magnetic field loading unit is used to apply a static magnetic field and / or a dynamic magnetic field to the sample.

[0023] The thermal control unit is used to heat the working area of ​​the sample and maintain the set temperature.

[0024] The synchronous acquisition unit is used to synchronously acquire multi-source physical signals of the sample and system response.

[0025] The parameter identification unit is used to identify the mechanical property parameters and magnetomechanical coupling characteristic parameters of the sample under the action of multi-physics field coupling based on synchronously acquired data.

[0026] The aforementioned synchronous acquisition unit is connected to the mechanical loading unit, magnetic field loading unit, and thermal field control unit, while the parameter identification unit is connected to the synchronous acquisition unit. In this embodiment, the mechanical loading unit, magnetic field loading unit, thermal field control unit, boundary control unit, synchronous acquisition unit, and parameter identification unit are not isolated from each other, but rather work collaboratively within the same sample working area under the control of the control system in the universal testing machine to obtain the capability for testing coupled parameters for magnetostrictive materials.

[0027] To apply both static and dynamic magnetic fields to the sample and ensure a stable thermal environment during testing, in this embodiment, the magnetic field loading unit surrounds the boundary control unit and is embedded in the center of the thermal field control unit. Specifically, as shown... Figure 1 and Figure 2 As shown: In this embodiment, the universal testing machine includes a base 9, on which two aluminum side covers 4 are symmetrically installed. The tops of the two aluminum side covers 4 are fixedly connected by a horizontal top beam 1. The top beam 1, the aluminum side covers 4, and the base 9 are interconnected to form the sample working area of ​​the universal testing machine.

[0028] In this embodiment, the thermal field control unit is a heating chamber 5 with an enclosed constant temperature structure. The heating chamber 5 includes a chamber body 13, a chamber door 10, a movable support 14, and a movable support base 15. The movable support base 15 is placed in front of the base 9, and the movable support 14 is fixed on the movable support base 15. The chamber body 13 is slidably connected to the movable support 14, and the movable support 14 is provided with guide rails that allow the chamber body 13 to enter and exit the sample working area of ​​the universal testing machine. The heating chamber 5 of the thermal field control unit can be heated by electric heating, constant temperature chamber heating, or other methods suitable for forming a stable thermal environment. In order to reduce the impact of thermal overflow on system stability, sensor accuracy, and structural reliability, the thermal field control unit is equipped with an independent cooling structure. Preferably, a heat-insulating glass cover 11 is embedded in the center of the chamber door 10.

[0029] like Figure 3As shown, in this embodiment, the magnetic field loading unit includes an electromagnetic device, which includes electromagnetic poles. These electromagnetic poles consist of an upper electromagnetic pole 16 and a lower electromagnetic pole 23 symmetrically arranged vertically, and a left electromagnetic pole 18 and a right electromagnetic pole 19 symmetrically arranged horizontally. The upper electromagnetic pole 16, lower electromagnetic pole 23, left electromagnetic pole 18, and right electromagnetic pole 19 form an encircling magnetic field structure surrounding the boundary control unit. The electromagnetic device also includes electromagnetic coils surrounding the electromagnetic poles. These electromagnetic coils consist of an upper electromagnetic coil 21, a lower electromagnetic coil 24, a left electromagnetic coil 17, and a right electromagnetic coil 22. The upper, lower, left, and right electromagnetic coils are located above, below, left, and right of the upper electromagnetic pole 16, lower electromagnetic pole 23, left electromagnetic pole 18, and right electromagnetic pole 19, respectively. To reduce the impact of electromagnetic coil heating on system stability, sensor accuracy, and structural reliability, preferably, the upper, lower, left, and right electromagnetic coils all have water-cooling structures. Preferably, the magnetic field loading unit can achieve at least one of axial dynamic magnetic field loading and lateral dynamic magnetic field loading. Therefore, the upper electromagnetic pole head 16, lower electromagnetic pole head 23, upper electromagnetic coil 21, and lower electromagnetic coil 24 can move up and down to achieve axial dynamic magnetic field loading, and the left electromagnetic pole head 18, right electromagnetic pole head 19, left electromagnetic coil 17, and right electromagnetic coil 22 can move left and right to achieve lateral dynamic magnetic field loading (note that when the positions of the upper, lower, left, and right electromagnetic pole heads and the upper, lower, left, and right electromagnetic coils remain unchanged, static magnetic field loading of the magnetic field loading unit can be achieved). The frequency of the dynamic magnetic field is 50 Hz to 1500 Hz. To improve the data correspondence during dynamic testing, the magnetic field loading unit and the mechanical loading unit are coordinated and controlled by the control system of the universal testing machine. In addition, in this embodiment, the magnetic field loading unit also includes an electromagnet support plate 7 for supporting the electromagnetic device, four electromagnet support legs 12 fixed to the four corners of the electromagnet support plate 7, and a lifting ring 20 fixed to the top of the electromagnetic device for easy carrying. In this embodiment, the magnetic field loading unit is located inside the heating cavity 5, and the four electromagnet support legs 12 of the magnetic field loading unit can all pass through the bottom of the heating cavity 5 and stand on the base 9 when the cavity 13 enters the sample working area of ​​the universal testing machine.

[0030] The testing system provided by this invention needs to perform conventional mechanical property tests such as tensile, compression, and bending. Therefore, for ease of explanation, the specimens mentioned below are preferably Terfenol-D or other rare-earth super magnetostrictive materials, or related composite materials. The specimen type can be tensile specimen 27, compression specimen 31, or pre-cracked three-point bending specimen 36, depending on the test target. To adapt to specimen installation and loading boundary control under different test conditions, the boundary control unit in this embodiment 1 includes any one of the following clamps: tensile clamp, compression clamp, and three-point bending clamp. The universal testing machine includes an upper push rod 3 and a lower push rod 8. One end of the clamp is detachably connected to the upper push rod 3 via a pin, and the other end is detachably connected to the lower push rod 8 via a pin. Since the pin cannot lock the clamp to the upper push rod 3 and the lower push rod 8, there are gaps between them. Therefore, locking nuts 25 are respectively fitted on the upper push rod 3 and the lower push rod 8 to eliminate the gaps between the clamp and the upper push rod 3 and the lower push rod 8, making the overall equipment more stable. The top end of the upper push rod 3 protrudes from the center of the top of the cavity 13 of the heating chamber 5 and is fixedly connected to the mechanical loading unit, while the bottom end of the lower push rod 8 protrudes from the center of the bottom of the cavity 13 of the heating chamber 5 and abuts against the base 9. It is worth mentioning that in this invention, the boundary control unit not only undertakes the functions of sample installation and force transmission, but also suppresses additional deformation errors, stress concentrations, and magnetic field boundary disturbances of the magnetostrictive material during the coupling test process. It is an important error control module in the testing system of this invention.

[0031] like Figure 1 and Figure 4 As shown, the tensile clamp in this embodiment includes a clamping structure. An encircling magnetic field structure formed by the upper electromagnetic pole 16, lower electromagnetic pole 23, left electromagnetic pole 18, and right electromagnetic pole 19 of the magnetic field loading unit surrounds the clamping structure. Specifically, in this embodiment, the clamping structure consists of an upper clamping part 26 and a lower clamping part 29. The upper end of the upper clamping part 26 is detachably connected to the upper push rod 3, and the lower end is used to clamp and fix the upper part of the tensile sample 27. The lower end of the lower clamping part 29 is detachably connected to the lower push rod 8, and the upper end is used to clamp and fix the lower part of the tensile sample 27. The upper clamping part 26 and the lower clamping part 29 are arranged symmetrically, one above the other, to reduce the eccentric load during the tensile process. The clamping surfaces of the upper clamping part 26 and the lower clamping part 29 preferably use transition fillets, gradient clamping surfaces, arc-shaped clamping surfaces, or combinations thereof, to reduce local stress concentration at the ends of small-sized brittle specimens. In addition, a buffer contact layer 28 is provided on the clamping surfaces of the upper clamping part 26 and the lower clamping part 29. Preferably, the buffer contact layer 28 is a metal pad made of stainless steel to homogenize the clamping pressure of the tensile jig on the tensile sample 27 and reduce the risk of local crushing, crack initiation or premature fracture of the tensile sample 27 at the clamping end.

[0032] like Figure 5As shown, the compression clamp in this embodiment includes an upper pressure plate 30 symmetrically distributed vertically and a self-aligning structure. The self-aligning structure includes a convex spherical seat 32 and a concave spherical seat 33 symmetrically distributed vertically and mutually cooperating. The lower end of the upper push rod 3 is detachably connected to the upper end face of the upper pressure plate 30, and the upper end of the lower push rod 8 is detachably connected to the concave spherical seat 33. The compression sample 31 can be vertically mounted on the convex spherical seat 32. During the compression of the sample 31, when the sample 31 undergoes axial micro-extension and end face deflection due to magnetostriction, the self-aligning structure can perform angle compensation within a preset range, thereby keeping the main force axis basically consistent with the axis of the compression sample 31, thus reducing eccentric loading and additional bending moment. Preferably, the compression clamp can also be provided with a limiting guide structure to limit the lateral movement of the self-aligning structure. The compression clamp can also be provided with a reset structure to restore the clamp to its initial alignment state after unloading. The above-mentioned limiting guide structure and reset structure can be implemented using conventional structures in the art.

[0033] like Figure 6 As shown, the three-point bending fixture in this embodiment includes an upper loading head 35 and a lower support roller seat. The lower support roller seat has two lower support rollers 37 for horizontally placing the pre-cracked three-point bending sample 36. The upper loading head 35 applies a downward load to the center of the pre-cracked three-point bending sample 36. For the pre-cracked three-point bending sample 36, by adjusting the spacing of the lower support rollers 37, the position of the upper loading head 35, and the relative position of the pre-cracked three-point bending sample 36, the crack tip region can be placed within the effective working area of ​​the magnetic field loading unit, thereby improving the consistency of the crack tip boundary conditions during fracture testing. Therefore, the two lower support rollers 37 and the upper loading head 35 are arranged symmetrically with respect to the center of the pre-cracked three-point bending sample 36 so that the test area of ​​the sample is located within the effective working area of ​​the magnetic field loading unit. The three-point bending fixture also includes a fixing block 34, and the upper loading head 35 can be vertically installed below the fixing block 34. The upper end face of the fixing block 34 is detachably connected to the lower end of the upper push rod 3, and the upper end of the lower push rod 8 is detachably connected to the lower support roller seat.

[0034] The force-bearing components in the boundary control unit that come into contact with the sample are preferably made of a metallic material that combines structural stiffness and magnetic response characteristics, such as martensitic stainless steel or mold steel. In this embodiment, S136 steel is preferred. Using this type of metallic material can reduce the random disturbance of the fixture to the magnetic field boundary of the sample's working area while meeting the requirements of stress stability and machining accuracy, thereby improving the consistency of boundary conditions between different batches of tests.

[0035] like Figure 1 and Figure 9As shown, the mechanical loading unit in this embodiment includes a hydraulic device and a middle crossbeam 2 that is slidably connected between the two aluminum side covers 4 and located below the top beam 1. The lower part of the upper push rod 3 extends into the electromagnetic device of the magnetic field loading unit, and the upper part passes through the top center of the cavity 13 of the heating chamber 5 and is connected to the middle crossbeam 2. The hydraulic device can drive the middle crossbeam 2 to move up and down, so as to drive the upper push rod 3 and the upper clamping part 26 or the upper pressure plate 30 or the upper loading head 35 in the boundary control unit to move up and down synchronously, thereby transmitting pressure to the sample fixed in the tensile fixture, compression fixture or three-point bending fixture, so that the sample is under load.

[0036] Preferably, the synchronous acquisition unit in this embodiment includes a force sensor, a displacement sensor, a strain sensor, a magnetic field sensor, a magnetic induction intensity sensor, and a temperature sensor. The force sensor is located on the loading transmission chain of the universal testing machine (e.g., between the upper loading end and the upper clamping part 26 during tensile testing), or at the force measuring unit built into the universal testing machine, for acquiring load signals. The displacement sensor is located at the middle crossbeam 2 of the universal testing machine for acquiring axial displacement signals or bending deflection signals of the specimen. The strain sensor is located on the surface of the effective working section of the specimen; for tensile and compressive strength tests, it is preferably located in the middle gauge length section of the specimen, and for fracture toughness tests, it is preferably located in the middle gauge length section. The magnetic field sensor is located near the crack tip or crack opening location of the sample to collect strain signals or crack opening displacement related signals; the magnetic field sensor is located near the effective working area of ​​the sample, preferably in a position on the outer side of the middle of the sample that does not affect the loading, to collect magnetic field intensity signals; the magnetic induction intensity sensor is located around the effective working area of ​​the sample, preferably an induction coil sleeved on the outer periphery of the effective working section of the sample, or located in a magnetic circuit position close to the working area of ​​the sample, to collect magnetic induction intensity signals; the temperature sensor is located on the sample surface, near the sample, or in the heating chamber 5 near the working area of ​​the sample, preferably near the middle working section of the sample, to collect sample temperature signals.

[0037] In this embodiment, the mechanical performance parameters identified by the parameter identification unit include at least one of tensile strength, compressive strength, elastic modulus, and fracture toughness, and the magnetomechanical coupling characteristic parameters identified by the parameter identification unit include at least one of dynamic stiffness, magnetomechanical coupling coefficient, and stiffness change rate.

[0038] 1) In tensile strength testing, engineering stress and engineering strain They respectively satisfy: (1) (2) in, For load signals, The initial cross-sectional area of ​​the sample. This represents the change in displacement of the gauge length segment. This is the initial gauge length.

[0039] Therefore, tensile strength The expression is: (3) in, F max This represents the maximum load during the tensile process.

[0040] 2) Elastic modulus It can be obtained from the slope of the linear segment of the stress-strain curve, that is: (4) 3) In the compressive strength test, compressive stress and compressive strain They respectively satisfy: (5) (6) Therefore, compressive strength The expression is: (7) in, This represents the maximum load during the compression process.

[0041] 4) For fracture toughness testing of pre-cracked three-point bending samples, the fracture toughness parameters can be obtained based on the load-displacement curve, the pre-crack size, and the sample geometry. Preferably, the linear elastic fracture toughness parameters... The expression is: (8) in, For characteristic loads, To support the span, For the sample thickness, The width of the sample. The length of the pre-crack. This is a correction function related to the sample geometry.

[0042] Preferred: (9) in, express .

[0043] When the corresponding validity conditions are met It can be further confirmed as plane strain fracture toughness. .

[0044] 5) Dynamic stiffness It can be obtained from dynamic load signals and dynamic displacement signals, and is preferably expressed as: (10) in, For dynamic load amplitude, This represents the dynamic displacement amplitude.

[0045] 6) The magnetomechanical coupling coefficient can be obtained by jointly calculating at least two of the magnetic field signal, displacement signal, strain signal, and load signal. Preferably, it is characterized by the response rate of change, for example: (11) in, or These represent the magnetomechanical coupling coefficients under changes in displacement or strain response, respectively. This is the change in magnetic field. The change in displacement response. This represents the change in strain response.

[0046] 7) Stiffness variation rate The expression is: (12) in, Stiffness under reference working conditions This represents the dynamic stiffness under the current operating conditions.

[0047] Example 2 This invention provides a method for testing the multi-physics coupled mechanical parameters of magnetostrictive materials, using the aforementioned multi-physics coupled mechanical parameter testing system for magnetostrictive materials. Figure 7 and Figure 8 As shown, the method includes: S1, Sample Preparation: Select the sample type and the fixture type of the boundary control unit according to the test objectives. The test objectives include three conventional mechanical property tests: tension, compression, and three-point bending. The selected test samples for these three tests are tensile sample 27, compression sample 31, and pre-cracked three-point bending sample 36, respectively. The selected boundary control unit fixtures are tensile fixture, compression fixture, and three-point bending fixture, respectively. Install the sample in the fixture corresponding to the boundary control unit, adjust the sample position and fixture status, ensuring that the test area of ​​the sample is within the effective working area of ​​the magnetic field loading unit, and establish a stable test boundary.

[0048] S2, Set Multiple Field Boundaries: Set mechanical loading parameters, magnetic field mode, magnetic field parameters, and thermal field temperature conditions according to test requirements. Start the magnetic field loading unit and thermal field control unit. After the magnetic field and temperature reach a stable state, start the mechanical loading unit to apply mechanical load to the sample and establish a coupled test environment of magnetic field, thermal field and force field.

[0049] S3, Synchronous signal acquisition: During the test, the synchronous acquisition unit synchronously acquires multi-source physical signals of the sample and system response. Specifically, the load signal, displacement signal, strain signal, magnetic field signal, magnetic induction intensity signal and temperature signal of the system are acquired through force sensor, displacement sensor, DIC strain sensor, Hall element, magnetic induction intensity sensor and temperature sensor respectively, and the test data acquisition and storage are completed according to the preset termination conditions.

[0050] S4, Parameter Identification and Output: Preprocess and analyze the synchronously acquired data to identify the mechanical performance parameters and magnetomechanical coupling characteristic parameters of the sample under the multi-physics field coupling effect. The mechanical performance parameters include at least one of tensile strength, compressive strength, elastic modulus, and fracture toughness. The magnetomechanical coupling characteristic parameters identified by the parameter identification unit include at least one of dynamic stiffness, magnetomechanical coupling coefficient, and stiffness change rate. Output parameter results and test report.

[0051] Example 3 Tensile strength test under coupled magnetic, thermal, and force fields: This embodiment uses a tensile fixture to test the tensile strength of a specimen under coupled magnetic, thermal, and force fields. During the test, a small-sized brittle magnetostrictive specimen (see...) is first placed... Figure 4 The tensile sample 27 is installed between the upper clamping part 26 and the lower clamping part 29 of the tensile fixture, so that the sample is located at the center of the effective working area of ​​the magnetic field loading unit. The clamping surface in the tensile fixture adopts a low stress concentration clamping structure, and a buffer contact layer 28 is provided between the clamping surface and the sample to reduce stress concentration at the clamping end and homogenize the clamping pressure.

[0052] According to the test requirements, the axial magnetic field mode or transverse magnetic field mode is set through the control system, and the static magnetic field parameters and / or dynamic magnetic field parameters are set, wherein the frequency range of the dynamic magnetic field is preferably 50 Hz to 1500 Hz. Then, the thermal field control unit is activated to heat the sample to the set temperature and maintain a constant temperature throughout the test. After the sample temperature and magnetic field stabilize, the mechanical loading unit applies an axial tensile load to the sample sequentially through the middle crossbeam 2, the upper top rod 3, and the clamping structure (upper clamping part 26 and lower clamping part 29). At the same time, the load, displacement, strain, temperature, and magnetic field signals are synchronously acquired through the synchronous acquisition unit.

[0053] Based on the synchronously acquired stress-strain data, the tensile strength of the specimen under a set magnetic field and temperature conditions can be obtained. Simultaneously, the elastic modulus can be calculated from the slope of the linear segment, tangent slope, or secant slope of the stress-strain curve. Under dynamic magnetic field and dynamic tensile load conditions, dynamic stiffness and magnetomechanical coupling characteristic parameters can be further identified based on the synchronously acquired load, displacement, strain, and magnetic field signals.

[0054] In this embodiment, both dynamic magnetic field loading and mechanical loading are coordinated and controlled by the control system to achieve preset time synchronization or phase relationship. The thermal field control unit and the magnetic field loading unit each adopt independent cooling structures to reduce the impact of coil heating and thermal overflow on the temperature stability of the sample working area and signal accuracy.

[0055] To verify the testing capabilities of the system in Example 3 and its ability to identify changes in material mechanical parameters under the coupling effects of magnetic and thermal fields, a comparative test was conducted using a self-developed Terfenol-D tensile specimen. The tensile specimen adopted a small-sized plate structure, with a total length of approximately 28 mm, an effective section length of approximately 15 mm, a thickness of approximately 5 mm, and a transition radius of R2.5. Before the test, burrs on the specimen surface were removed, and the dimensions of the specimen clamping end and the effective section were measured to determine the initial cross-sectional area of ​​the specimen.

[0056] The comparative test used conventional tensile test conditions, i.e., tensile loading at 25 ℃ without an external magnetic field. Example 3 employed multi-physics coupled tensile test conditions, i.e., tensile loading at 35 ℃ with external transverse magnetic fields of 150 mT and 250 mT respectively. All three sets of tests used Terfenol-D specimens of the same geometric dimensions, the same tensile fixtures, and the same loading regime to ensure comparability of the test results. Load, displacement, strain, temperature, and magnetic field signals were simultaneously acquired during the tests, and parameters such as tensile strength, tensile modulus of elasticity, and fracture strain were calculated by the parameter identification unit. The stress-strain curves obtained under different conditions are shown below. Figure 10 As shown in Table 1, the mechanical parameters obtained under different working conditions are shown in Table 1.

[0057] Table 1. Comparison of mechanical parameters between conventional tensile tests and multiphysics coupled tensile tests. .

[0058] Example 4 Compressive strength test under coupled magnetic, thermal, and force fields: This embodiment uses a compression clamp on the sample (see...). Figure 5The compressive strength of the compressed sample 31) under the coupled conditions of magnetic field, thermal field and force field was tested. Before the test, the sample was installed on the self-aligning structure of the compression fixture and the position of the sample was adjusted so that the sample was located at the center of the effective working area of ​​the magnetic field loading unit.

[0059] During testing, the magnetic field direction, magnitude, and loading method are set via the control system, and either a static or dynamic magnetic field is selected according to the test requirements. The thermal field control unit is then activated to heat the sample to the set temperature and maintain it constant. Once the sample temperature and magnetic field have stabilized, the mechanical loading unit applies an axial compressive load to the sample sequentially through the middle crossbeam 2, upper push rod 3, and upper pressure plate 30. Simultaneously, the load, displacement, strain, temperature, and magnetic field signals are recorded synchronously by the synchronous acquisition unit.

[0060] During the compression process of the specimen, when the specimen undergoes slight axial expansion and contraction and end face tilting due to the magnetostrictive effect, the self-aligning structure can adaptively compensate for the attitude, thereby reducing eccentric loading and additional bending moment and improving the consistency of the test boundary. Based on the stress-strain curve obtained from the test, the compressive strength of the specimen under the coupled action of magnetic and thermal fields can be obtained; at the same time, the elastic modulus can be obtained from the slope of the linear segment, tangent slope, or secant slope of the curve.

[0061] Under dynamic magnetic field and / or dynamic compressive load conditions, the dynamic stiffness of the specimen can be obtained based on synchronously acquired dynamic load signals, dynamic displacement signals, and / or dynamic strain signals; furthermore, magnetomechanical coupling characteristic parameters can be identified based on at least two of the magnetic field signals, displacement signals, strain signals, and load signals. This embodiment is applicable to studying the compressive bearing capacity and coupling stiffness variation laws of giant magnetostrictive materials under different magnetic field directions, different temperature levels, and different dynamic working conditions.

[0062] To verify the testing capabilities of the system in Example 4 and its ability to identify changes in material mechanical parameters under the coupling effects of magnetic and thermal fields, a compression comparison test was conducted on a self-developed Terfenol-D cylindrical specimen. The specimen dimensions were 10 mm in diameter and 20 mm in height, with an initial cross-sectional area of ​​78.54 mm².

[0063] The comparative test used conventional compression test conditions, i.e., compression loading at 25 ℃ without an external magnetic field; this Example 4 uses multi-physics coupled compression test conditions, i.e., compression loading at 50 ℃ with an external longitudinal magnetic field of 175 mT. Both sets of tests used specimens of the same geometric dimensions, the same compression fixture, and the same loading regime to ensure the comparability of the results. During the test, load, displacement, strain, temperature, and magnetic field signals were simultaneously acquired, and parameters such as compressive strength and compressive modulus were calculated by the parameter identification unit. The stress-strain curves obtained under different working conditions are shown below. Figure 11As shown in Table 2, the mechanical parameters obtained under different working conditions are shown in Table 2.

[0064] Table 2 Comparison of mechanical parameters between conventional compression test and multiphysics coupled compression test .

[0065] Example 5 Fracture toughness testing under coupled magnetic, thermal, and force fields: This embodiment uses a three-point bending fixture for the sample (see...). Figure 6 The fracture toughness of a pre-cracked three-point bending sample 36 under coupled magnetic, thermal, and force fields was tested. Before the test, the sample was mounted on two lower support rollers 37, and the position of the upper loading head 35 was adjusted so that the crack location was on the loading symmetry plane, and the crack tip was located at the center or within the effective working area of ​​the magnetic field loading unit. The thermal field control unit was located outside the magnetic field loading unit, providing a surrounding constant temperature environment for the sample.

[0066] During testing, the axial or transverse magnetic field mode is set via the control system, and static and / or dynamic magnetic field parameters are set according to the test requirements. The thermal field control unit is then activated to heat the sample to the set temperature and maintain it constant. After the temperature and magnetic fields stabilize, the mechanical loading unit applies a three-point bending load to the sample sequentially through the middle crossbeam 2, the upper push rod 3, and the upper loading head 35. Simultaneously, the load, displacement, temperature, and magnetic field signals are synchronously acquired by the synchronous acquisition unit.

[0067] Based on the load-displacement curve, the pre-existing crack size, and the specimen's geometric parameters, the fracture toughness parameters of the specimen under the coupled field can be obtained. By controlling the positional relationship between the lower support roller 37, the upper loading head 35, and the crack zone of the specimen, the consistency of the boundary conditions at the crack tip can be improved, thereby enhancing the repeatability and reliability of the fracture test. Furthermore, by comparing the fracture response data obtained under different magnetic field and temperature conditions, the variation patterns of crack propagation resistance and response dispersion of the material under the coupled field can be analyzed.

[0068] This embodiment is applicable to analyzing the crack propagation resistance variation characteristics of giant magnetostrictive materials under the combined action of magnetic field and temperature. During the test, the magnetic field loading unit and the thermal field control unit are cooled by independent cooling structures to ensure the stable operation of the coil, heating chamber, and related structural components during the fracture test.

[0069] To verify the testing capabilities of the system in Example 5 and its ability to identify changes in material mechanical parameters under the coupling effects of magnetic and thermal fields, a comparative test was conducted using a self-developed Terfenol-D pre-cracked three-point bending specimen. The specimen adopted a rectangular beam structure, and the specimen thickness was... =4 mm, sample width =8 mm, machining length is 40 mm, pre-crack length =4 mm, crack width less than 0.2 mm. During the test, the specimen was placed horizontally on the two lower support rollers 37 of the three-point bending fixture, the upper loading head 35 was located at the mid-span of the specimen, the pre-crack was located near the mid-span loading symmetry plane, and the specimen position was adjusted so that the crack tip area was within the effective working area of ​​the magnetic field loading unit, and the support span was... It is 33.6 mm.

[0070] The comparative test used conventional three-point bending fracture test conditions, i.e., loading at 25 ℃ without an external magnetic field; this Example 5 used multi-physics field coupled three-point bending fracture test conditions, i.e., loading at 25 ℃ with an external lateral magnetic field of 100 mT. Both sets of tests used specimens with the same geometric dimensions, the same support span, the same three-point bending fixture, and the same loading regime to ensure the comparability of the test results.

[0071] Based on the force-displacement curve output by the universal testing machine, parameters such as the slope of the linear segment of the load-displacement curve can be obtained. The stress-strain curve output by the universal testing machine is a nominal bending stress-nominal bending strain curve derived from the three-point bending beam theory. It can be used to characterize the macroscopic bending response of the specimen and further calculate the flexural modulus and bending strength. For pre-cracked specimens, candidate fracture toughnesses are calculated. K Q This is used to compare the changes in crack propagation resistance of Terfenol-D materials under different magnetic field conditions. The force-displacement curves obtained under different working conditions are shown below. Figure 12 As shown in Table 3, the mechanical parameters obtained under different working conditions are shown in Table 3.

[0072] Table 3 Comparison of mechanical parameters between conventional three-point bending test and multiphysics coupled three-point bending test .

[0073] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present technical solution are within the protection scope of the present invention.

[0074] To facilitate understanding by those skilled in the art of the improvements of this invention over the prior art, some of the accompanying drawings and descriptions have been simplified, and for clarity, some other elements have been omitted from this application. Those skilled in the art should realize that these omitted elements may also constitute the content of this invention.

Claims

1. A multi-physics coupling mechanical parameter testing system for magnetostrictive materials, comprising a mechanical loading unit, a magnetic field loading unit, a thermal field control unit, a synchronous acquisition unit, and a parameter identification unit, wherein the synchronous acquisition unit is connected to the mechanical loading unit, the magnetic field loading unit, and the thermal field control unit, and the parameter identification unit is connected to the synchronous acquisition unit, characterized in that, It also includes a boundary control unit; The boundary control unit is placed in the force path of the mechanical loading unit to adapt to the sample installation and loading boundary control under different test conditions; The mechanical loading unit is used to drive the boundary control unit to apply tensile load, compressive load or bending load to the specimen; The magnetic field loading unit is used to apply a static magnetic field and / or a dynamic magnetic field to the sample. The magnetic field loading unit includes an upper electromagnetic pole (16) and a lower electromagnetic pole (23) symmetrically arranged vertically, and a left electromagnetic pole (18) and a right electromagnetic pole (19) symmetrically arranged horizontally. The upper electromagnetic pole (16), the lower electromagnetic pole (23), the left electromagnetic pole (18), and the right electromagnetic pole (19) form an enclosed magnetic field structure surrounding the boundary control unit. The upper electromagnetic pole (16) and the lower electromagnetic pole (23) can move vertically to achieve axial dynamic magnetic field loading, and the left electromagnetic pole (18) and the right electromagnetic pole (19) can move horizontally to achieve transverse dynamic magnetic field loading. The frequency of the dynamic magnetic field is 50 Hz to 1500 Hz. The magnetic field loading unit and the mechanical loading unit adopt a synchronous and coordinated control method. The thermal control unit is used to heat the working area of ​​the sample and maintain a set temperature; The synchronous acquisition unit is used to synchronously acquire multi-source physical signals of the sample and system response; The parameter identification unit is connected to the synchronous acquisition unit and is used to identify the mechanical property parameters and magnetomechanical coupling characteristic parameters of the sample under the multi-physics field coupling based on the synchronously acquired data. The sample is a magnetostrictive material.

2. The multi-physics coupled mechanical parameter testing system for magnetostrictive materials according to claim 1, characterized in that: The boundary control unit includes a tension clamp, a compression clamp, or a three-point bending clamp; The tensile fixture includes a clamping structure for mounting the specimen. A buffer contact layer (28) is provided on the clamping surface of the clamping structure to homogenize the clamping pressure of the clamping structure on the specimen and reduce the local stress concentration at the end of the small-sized brittle specimen. The compression clamp includes an upper pressure plate (30) symmetrically distributed vertically and a self-aligning structure. The self-aligning structure includes a convex spherical seat (32) and a concave spherical seat (33) symmetrically distributed vertically and cooperating with each other. The sample can be vertically mounted on the convex spherical seat (32). The three-point bending fixture includes an upper loading head (35) and a lower support roller seat that are symmetrically distributed on the upper and lower sides. The lower support roller seat is provided with two lower support rollers (37) for horizontally mounting the sample. The upper loading head (35) is used to apply a downward load to the center of the sample.

3. The multi-physics coupled mechanical parameter testing system for magnetostrictive materials according to claim 2, characterized in that: The force-bearing components in the boundary control unit that come into contact with the sample are all made of martensitic stainless steel, mold steel, or other metallic materials that combine magnetic response characteristics and structural stiffness.

4. The multi-physics coupled mechanical parameter testing system for magnetostrictive materials according to claim 3, characterized in that: The magnetic field loading unit surrounds the boundary control unit and is embedded in the center of the thermal field control unit, which is an enclosed constant temperature structure.

5. The multi-physics coupled mechanical parameter testing system for magnetostrictive materials according to claim 4, characterized in that: The thermal field control unit and the magnetic field loading unit are each equipped with an independent cooling structure.

6. The multi-physics coupled mechanical parameter testing system for magnetostrictive materials according to claim 5, characterized in that: The synchronous acquisition unit includes a force sensor, a displacement sensor, a strain sensor, a magnetic field sensor, a magnetic induction intensity sensor, and a temperature sensor, which are used to acquire load signals, displacement signals, strain signals, magnetic field signals, magnetic induction intensity signals, and temperature signals from multi-source physical signals, respectively. The mechanical performance parameters identified by the parameter identification unit include at least one of tensile strength, compressive strength, elastic modulus, and fracture toughness. The magnetomechanical coupling characteristic parameters identified by the parameter identification unit include at least one of dynamic stiffness and stiffness change rate.

7. A method for testing the multi-physics coupled mechanical parameters of magnetostrictive materials, characterized in that: The test is performed using the multi-physics coupled mechanical parameter testing system for magnetostrictive materials as described in any one of claims 1-6, the method comprising: S1, Sample preparation: Select the sample type and the fixture type of the boundary control unit according to the test target, install the sample in the fixture corresponding to the boundary control unit, adjust the sample position and fixture status, so that the sample test area is located in the effective working area of ​​the magnetic field loading unit, and establish a stable test boundary. S2, Set Multiple Field Boundaries: Set mechanical loading parameters, magnetic field mode, magnetic field parameters and thermal field temperature conditions according to test requirements, start the magnetic field loading unit and thermal field control unit, and after the magnetic field and temperature reach a stable state, start the mechanical loading unit to apply mechanical load to the sample and establish a coupled test environment of magnetic field, thermal field and force field. S3, Synchronous signal acquisition: During the test, the multi-source physical signals of the sample and system response are acquired synchronously through the synchronous acquisition unit, and the test data acquisition and storage are completed according to the preset termination conditions. S4, Parameter Identification and Output: Preprocess and analyze the synchronously acquired data, identify the mechanical performance parameters and magnetomechanical coupling characteristic parameters of the sample under the multi-physics coupling effect, and output the test results.

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