Electroacoustic transducer output characteristic test method and system considering bar inconsistency

Abstract

The invention discloses an electroacoustic transducer output characteristic test method and system considering bar inconsistency. The method for testing the output characteristics of the electroacoustic transducer comprises the following steps of: A, enabling the electroacoustic transducer to be in a single output mode, and determining the strain of each bar based on a strain model formula according to the prestress applied to the bars and the body magnetization intensity corresponding to each bar; b, according to the strain, obtained in the step A, of each bar, the output force corresponding to each bar is determined; and C, according to the pre-stress borne by the bars and the output force corresponding to each bar obtained in the step B, constructing a kinetic equation reflecting the relation between the output displacement of the electroacoustic transducer and the time so as to obtain the relation between the output displacement of the electroacoustic transducer in the single output mode and the time.

Description

Technical Field

[0001] This invention relates to the field of testing the output characteristics of super magnetostrictive material rods in electroacoustic transducers, and particularly to a method and system for testing the output characteristics of electroacoustic transducers considering rod inconsistencies. Background Technology

[0002] Giant magnetostrictive electroacoustic transducers, with their significant advantages such as fast response speed, high energy density, and large output force, have been widely used in underwater sonar, long-range detection, and non-destructive testing. To further meet the engineering requirements of high load and high thrust, the structure of multiple giant magnetostrictive rods driven in parallel has become the mainstream design for high-power electroacoustic transducers. For such parallel electroacoustic transducers, establishing an accurate output characteristic model is a prerequisite for achieving high-precision control. Most current theoretical models are based on idealized assumptions, assuming that all giant magnetostrictive rods within the parallel system have completely identical physical properties and magnetization characteristics. This simplifies the output of the multi-rod system to a linear superposition of the properties of individual rods, severely limiting its application and promotion.

[0003] In practical fabrication and engineering applications, due to factors such as the randomness of crystal growth orientation, inhomogeneity of heat treatment processes, and material cutting errors, even giant magnetostrictive rods of the same batch and specifications still exhibit significant individual differences (i.e., inconsistencies) in key performance parameters such as magnetization curves and saturation magnetostriction coefficients. In rigid coupling structures with two or more rods in parallel, this inconsistency leads to uneven output of the rods in each branch, causing impedance shifts and changes in resonance characteristics. Existing modeling methods based on the assumption of "rod consistency" cannot characterize this objectively existing difference, resulting in a large deviation between the displacement-time curve predicted by the model and the actual output displacement-time curve, severely restricting the application and performance optimization of parallel giant magnetostrictive electroacoustic transducer structures. Summary of the Invention

[0004] The problem this invention aims to solve is that in the modeling of existing structures driven by multiple parallel magnetostrictive rods, the use of a modeling method based on the consistency of rod performance leads to a large deviation between the displacement-time curve predicted by the model and the actual output displacement-time curve. The invention provides a method for testing the output characteristics of an electroacoustic transducer that takes into account the inconsistency of rod performance.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for testing the output characteristics of an electroacoustic transducer considering the inconsistency of rods, wherein the electroacoustic transducer includes J rods arranged in parallel with each other, wherein the rods are magnetostrictive rods; J≥2; an excitation coil is wound around the outer side of each rod; and the excitation coils are connected in series to form a series circuit. The electroacoustic transducer has a single output mode; when the electroacoustic transducer is in single output mode, the electroacoustic transducer includes a first output rod, each rod abuts against the first output rod, and the end of the first output rod away from the rod forms the output end of the electroacoustic transducer; on a projection plane perpendicular to the axial direction of the rod, the projections of J rods are evenly arranged in the circumferential direction of the projection of the first output rod. The method for testing the output characteristics of the electroacoustic transducer includes: Step A: Set the electroacoustic transducer to single-output mode, apply the same prestress to each rod, and determine the strain of each rod based on the prestress and the volume magnetization of each rod, using the strain model formula. Step B: Based on the strain of each bar obtained in Step A, determine the output force corresponding to each bar; Step C: Based on the prestress on the rod and the output force corresponding to each rod obtained in Step B, construct a dynamic equation reflecting the relationship between the output displacement and time of the electroacoustic transducer, thereby obtaining the relationship between the output displacement and time of the electroacoustic transducer in single-output mode.

[0006] Based on the same inventive concept, the present invention also provides a test system for the output characteristics of an electroacoustic transducer that takes into account the inconsistency of the rod material, comprising: A computer device or processor configured or programmed to perform the steps of the above-described method for testing the output characteristics of an electroacoustic transducer. The pre-tensioning mechanism is used to apply prestress to each bar. A power module is used to supply power to the series circuit; When the electroacoustic transducer is in single-output mode, the electroacoustic transducer also includes a first pressure sensor for measuring the prestress on the rod.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention proposes a method for testing output characteristics considering the inconsistencies in the rod materials. Unlike traditional models that simplify two rods to a single rod multiplier, the proposed method establishes independent dynamic magnetization and strain models for each rod, introduces eddy current loss and abnormal loss corrections, and finally achieves mechanical coupling through dynamic equations. This method can effectively capture the performance differences of the rods caused by manufacturing processes, improving the prediction accuracy of the output displacement of the electroacoustic transducer under different frequencies and power supply excitations. This invention provides guidance for the optimized design of parallel-type giant magnetostrictive electroacoustic transducers.

[0008] 2. This invention designs a unique testing system for an electroacoustic transducer employing multiple rods connected in parallel. Its output mechanism can flexibly switch between a "dual-output mode" and a "single-output mode." In dual-output mode, the displacement and prestress data of the two rods can be acquired independently for corresponding tests. In single-output mode, the overall performance after coupling can be verified. This design provides a reliable hardware foundation for solving the consistency problem in multi-rod parallel structures. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the electroacoustic transducer output characteristic testing system considering rod material inconsistency according to an embodiment of the present invention. Figure 2 It is a display Figure 1 A schematic diagram of the switching between single-output and dual-output modes of the electroacoustic transducer; Figure 3 This is a three-dimensional structural schematic diagram of a single-output mode electroacoustic transducer according to an embodiment of the present invention; Figure 4 yes Figure 3 A sectional view; Figure 5 This is a three-dimensional structural schematic diagram of a dual-output mode electroacoustic transducer according to an embodiment of the present invention. Figure 6 yes Figure 5 A sectional view; Figure 7 This is an enlarged schematic diagram of the rod and permanent magnet portion in the electroacoustic transducer of an embodiment of the present invention; Figure 8 These are the current-displacement curves of multiple bars of the same specifications obtained in the embodiments of the present invention under static conditions; Figure 9 These are the current-displacement curves of multiple bars of the same specifications obtained in an embodiment of the present invention under dynamic conditions; Figure 10 This is a comparison chart of the displacement-time curve obtained by the output characteristic test method of this invention and the measured curve; Figure 11 This is a comparative diagram of voltage-current relationship curves obtained from experimental results, the method of this invention, and a common equivalent circuit model when the frequency is set to 100Hz in an embodiment of the present invention. Figure 12This is a comparative diagram of voltage-current relationship curves obtained from experimental results, the method of this invention, and a common equivalent circuit model when the frequency is set to 300Hz in an embodiment of the present invention. Figure 13 This is a comparative diagram of voltage-current relationship curves obtained from experimental results, the method of this invention, and a common equivalent circuit model when the frequency is set to 600Hz in an embodiment of the present invention. Figure 14 This is a comparative diagram of the current-displacement relationship curves obtained from experimental results, the method of this invention, and the existing superposition model when the frequency is set to 100Hz in an embodiment of the present invention. Figure 15 This is a comparative diagram of the current-displacement relationship curves obtained from experimental results, the method of this invention, and the existing superposition model when the frequency is set to 200Hz in an embodiment of the present invention. Figure 16 This is a comparative diagram of the current-displacement relationship curves obtained from experimental results, the method of this invention, and the existing superposition model when the frequency is set to 300Hz in this embodiment of the invention. Figure 17 This is a schematic diagram comparing the current-displacement relationship curves obtained from experimental results, the method of this invention, and existing superposition models when the frequency is set to 500Hz in this embodiment of the invention.

[0011] In the above attached figures: 111. First pad; 112. Second pad; 121. First magnetic block; 122. Second magnetic block; 13. Rod; 14. Permanent magnet; 15. Magnetic yoke; 17. Induction coil; 21. First displacement sensor; 22. Second displacement sensor; 20. Sensor mounting bracket; 31. First output rod; 310. First mounting base; 32. Second output rod; 320. Second mounting base; 4. Pre-tightening bolts; 51. First pre-tightening end cap; 52. Second pre-tightening end cap; 510. First through hole; 520. Second through hole; 6. Excitation coil; 7. Magnetic circuit cover plate; 8. Base; 81. Base plate; 82. Top plate; 83. Vertical plate; 91. First pressure sensor; 92. Second pressure sensor; 101. First disc spring; 102. Second disc spring. Detailed Implementation

[0012] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0013] This invention provides a method for testing the output characteristics of an electroacoustic transducer considering the inconsistency of rod materials. The electroacoustic transducer includes J parallel rod materials 13, wherein the rod materials 13 are magnetostrictive rod materials, preferably super magnetostrictive rod materials; J≥2; each rod material 13 has an excitation coil 6 wound around its outer side; the excitation coils 6 are connected in series to form a series circuit. The electroacoustic transducer has a single output mode; when the electroacoustic transducer is in single output mode, the electroacoustic transducer includes a first output rod 31, and each rod 13 abuts against the first output rod 31. The end of the first output rod 31 away from the rod 13 forms the output end of the electroacoustic transducer; on the projection plane perpendicular to the axial direction of the rod 13, the projections of J rods 13 are evenly arranged in the circumferential direction of the projection of the first output rod 31. The method for testing the output characteristics of the electroacoustic transducer includes: Step A: Set the electroacoustic transducer to a single output mode, apply the same prestress to each rod 13, and determine the strain of each rod based on the prestress on the rod 13 and the corresponding bulk magnetization intensity of each rod, using the strain model formula. Step B: Based on the strain of each bar obtained in Step A, determine the output force corresponding to each bar; Step C: Based on the prestress on rod 13 and the output force corresponding to each rod obtained in step B, construct a dynamic equation reflecting the relationship between the output displacement and time of the electroacoustic transducer, thereby obtaining the relationship between the output displacement and time of the electroacoustic transducer in single-output mode.

[0014] According to the above-described scheme of the present invention, considering the inconsistency of the rods, the bulk magnetization of each rod is calculated, the strain of the rod is calculated, the output force corresponding to the rod is calculated based on the strain, and then a dynamic equation is constructed based on the output force of each rod, thereby determining the relationship between output displacement and time based on the dynamic equation.

[0015] When the electroacoustic transducer is in single-output mode, the extension direction of the rod 13 is parallel to the extension direction of the first output rod 31. When the electroacoustic transducer is in multi-output mode, the extension direction of the rod 13 is parallel to the extension direction of the second output rod 32.

[0016] Each bar 13 has the same specifications.

[0017] The dynamic equation is: Formula Eq1: ; Where: M eq C eq K eq These correspond to the equivalent mass, equivalent damping, and equivalent stiffness of the axially vibrating component, respectively; x is the output displacement of the electroacoustic transducer; t is time; σ is the prestress on the rod 13; A r F is the cross-sectional area of ​​bar 13. G,j The output force corresponding to the j-th rod 13 obtained in step B; j = 1, 2, ..., J; J is the number of rods 13 in the electroacoustic transducer; J ≥ 2; the axial vibration component is the whole structure of the electroacoustic transducer that moves in the axial direction of the rod 13.

[0018] The number of J is preferably even. Preferably, the magnetic fields of two adjacent rods form a magnetic focusing circuit, that is, the magnetic poles of the magnetic fields corresponding to the two adjacent rods are opposite, one of which forms a magnetic field with an upper N pole and a lower S pole, and the other forms a magnetic field with an upper S pole and a lower N pole, thus forming a magnetic focusing circuit.

[0019] Furthermore, permanent magnets 14 are fixedly connected to both ends of the rod 13 in the axial direction.

[0020] Furthermore, when the electroacoustic transducer is in single-output mode: the electroacoustic transducer further includes a first pre-tightening end cap 51 detachably connected to the transducer base; the first pre-tightening end cap 51 has a first through hole 510 corresponding to the first output rod 31; the first output rod 31 is fixed to the first mounting base 310, and each rod 13 abuts against the first output rod 31 by abutting against the end of the first mounting base 310 away from the first output rod 31; the first output rod 31 extends away from the rod 13 in the axial direction of the rod 13 and passes through the first through hole 510; the rod The end of rod 13 near the first mounting base 310 is connected to the first mounting base 310 in sequence via a permanent magnet 14 and a magnetic guide block; the first pre-tightening end cap 51 abuts against the first mounting base 310 through an annular structure sleeved on the outside of the first output rod 31, thereby applying the same prestress to each rod 13; the annular structure includes a first disc spring 101 and a first pressure sensor 91 arranged in sequence; the magnetic guide block, rod 13, permanent magnet 14 fixedly connected to rod 13, the annular structure, and the first output rod 31 constitute the axial vibration component. In this embodiment, the end of rod 13 near the first mounting base 310 is connected to the first mounting base 310 in sequence via a permanent magnet 14 and a first magnetic guide block 121, and the magnetic guide block arranged between rod 13 and the first mounting base 310 is the first magnetic guide block 121.

[0021] With the above configuration, prestress can be applied to each rod using the first prestressing end cap, and the first output rod 31 passes through the first through hole 510, so that the axial vibration component will not be disturbed by the first prestressing end cap during movement. The first mounting base 310 applies prestress to each rod simultaneously and receives the output force of each rod, and a single output can be formed through the first output rod 31.

[0022] The formula for the output force corresponding to the j-th bar is: Formula Eq2: F G,j =A r E H,j λ j ; Among them: A r E is the cross-sectional area of ​​bar 13. H,j Let λ be the Young's modulus of the j-th bar 13; j Let be the strain of the j-th bar 13 obtained in step A; wherein the Young's modulus of different bars can be measured using existing methods.

[0023] When σ≤σ s When the strain model formula is: Formula Eq31: ; When σ>σ s When the strain model formula is: Formula Eq32: ; Where: λ j Let σ be the strain of the j-th bar. s For bar 13, σ is the saturated prestress. max The maximum stress that bar 13 can withstand is tanh(2σ / σ), which is the maximum stress that the bar material can withstand. s ) is 2σ / σ s The hyperbolic tangent function, λ s,j M represents the saturation magnetostriction coefficient of the j-th rod 13. j M is the bulk magnetization of the j-th rod 13. s,j Let be the saturation magnetization of the j-th rod 13.

[0024] With the above settings, the strain of each bar in a multi-bar parallel structure can be calculated based on the corresponding parameters of different bars, thus taking into account the differences in the performance of different bars in a multi-bar parallel structure.

[0025] Furthermore, J is an even number: the two permanent magnets 14 corresponding to the rod 13 are fixedly connected to the upper and lower surfaces of the rod 13 respectively; each excitation coil 6 has the same number of turns; for two adjacent excitation coils 6 in the circumferential direction, the N pole of the magnetic field generated by one excitation coil and the N pole of the magnetic field generated by the other excitation coil are located on opposite sides in the height direction; the N poles of the two permanent magnets 14 corresponding to the same rod are located on the same side in the height direction; for two adjacent rods 13 in the circumferential direction, the N poles of the permanent magnets 14 corresponding to one rod and the N poles of the permanent magnets 14 corresponding to the other rod are located on opposite sides in the height direction; For example, the N pole and S pole of each permanent magnet 14 corresponding to the same rod are located at the bottom and top respectively, or the N pole and S pole are located at the top and bottom respectively.

[0026] For example, if the N pole and S pole generated by an excitation coil 6 are at the top and bottom respectively, then the N pole and S pole generated by the excitation coil 6 adjacent to it in the circumferential direction are at the bottom and top respectively.

[0027] For example, for two adjacent rods 13 in the circumferential direction, the N pole and S pole of the permanent magnet 14 corresponding to one of the rods are at the top and bottom respectively, and the N pole and S pole of the permanent magnet 14 corresponding to the other rod are at the bottom and top respectively.

[0028] In this configuration, for the excitation coil 6 and the permanent magnet 14 corresponding to the same rod, the N poles of the magnetic field generated by the excitation coil 6 and the permanent magnet 14 can be located on the same side or opposite sides in the height direction. For example, the N poles of the magnetic field generated by the excitation coil 6 and the permanent magnet 14 can both be at the bottom end, or both at the bottom end, or at opposite ends.

[0029] Furthermore, by simultaneously solving the following formulas, the bulk magnetization M corresponding to the j-th rod can be determined. j : Formula Eq41: M an,j =M s,j [coth(H e,j / as j )-(as j / H e,j )]; Formula Eq42: H e,j =H+αr j M j -(H eddy,j +H anom,j ); Formula Eq43: αr j =α j +9λ s,j σM j / 2μ0(Ms,j ) 2 ; Formula Eq44: M j =M rev,j +M irr,j ; Formula Eq45: M rev,j =c j (M an,j -M irr,j ); Formula Eq46: dM irr,j / dH=(M an,j -M irr,j ) / [k j δ-αr j (M an,j -M irr,j )]; Formula Eq47: ; Where: M j M is the bulk magnetization of the j-th rod 13; rev,j M is the reversible magnetization of the j-th rod 13. irr,j c is the irreversible magnetization of the j-th rod 13; j M is the reversibility coefficient of the j-th bar 13; an,j H is the hysteresis-free magnetization of the j-th rod 13; H is the effective axial magnetic field strength of rod 13; k j Here are the pinning parameters for the j-th bar 13; αr j The mean field parameters of the corrected interdomain coupling for the j-th rod 13 are given; the current flowing through the excitation coil 6 is a function of time t, denoted as the input current i. ac (t); G M B is the magnetoresistive correction factor, where N is the number of 6 turns of the excitation coil; r L represents the remanent magnetic flux density of permanent magnet 14. GMM L represents the dimension of bar 13 along its axial direction, i.e., the length of the bar; PM μ represents the dimension of the permanent magnet 14 along the axial direction of the rod 13, i.e., the length of the permanent magnet; GMM Let μ be the relative permeability of rod 13. PM M is the relative permeability of permanent magnet 14, μ0 is the permeability of free space; s,j H represents the saturation magnetization of the j-th rod 13; e,j Let be the magnetic field strength of the effective field inside the j-th rod 13; as j Let λ be the shape factor of the hysteresis-free magnetization of the j-th rod 13. s,j H represents the saturation magnetostriction coefficient of the j-th rod 13; eddy,jH is the eddy current loss magnetic field strength of the j-th rod 13; anom,j It is the abnormal loss magnetic field strength of the j-th rod 13; α j Let be the mean field parameter of the interdomain coupling of the j-th rod 13; δ is the direction parameter; when dH / dt≥0, δ=1; when dH / dt<0, δ=-1.

[0030] By performing independent calculations on each rod, the volume magnetization intensity corresponding to each rod can be determined, thus taking into account the differences in the performance of different rods in a structure with multiple rods connected in parallel.

[0031] Furthermore, the electroacoustic transducer also has multiple output modes; When the electroacoustic transducer is in multi-output mode, the electroacoustic transducer includes a second output rod 32 corresponding to each rod 13. The rod 13 abuts against the corresponding second output rod 32. The end of each second output rod 32 away from the corresponding rod 13 forms one of the output ends of the electroacoustic transducer. Each output end of the electroacoustic transducer is independent of each other. The rod 13 and the corresponding second output rod 32 are coaxially arranged. Furthermore, step PA1 and step PA2 are included before step A; Step PA1: Set the electroacoustic transducer to multi-output mode, apply prestress to each rod 13, and measure the displacement of each second output rod 32 in the axial direction of the rod 13. Step PA2: Based on the prestress on each bar 13 and the displacement of the corresponding second output rod 32 in the axial direction of the bar 13, determine the reversibility coefficient c corresponding to each bar 13. j Pinning parameter k j Saturation magnetization M s,j The shape factor as of hysteresis-free magnetization j saturation magnetostriction coefficient λ s,j Eddy current loss magnetic field strength H eddy,j Abnormal loss magnetic field strength H anom,j The mean field parameter α of interdomain coupling j This allows us to determine the volume magnetization intensity of each rod. In step A, each bar 13 is adjusted to a single output mode.

[0032] Through the above settings, the electroacoustic transducer can switch between single-output and multi-output modes. In multi-output mode, each rod can output independently, allowing independent measurement of the prestress on each rod 13 and the displacement of the corresponding second output rod 32 in the axial direction of the rod 13, thereby determining the corresponding parameters of each rod and consequently the bulk magnetization intensity of the rod. In step A, adjusting the electroacoustic transducer to single-output mode enables testing of the output characteristics of the electroacoustic transducer in single-output mode.

[0033] In step PA2, the method of determining the aforementioned parameters for each rod based on the prestress experienced by each rod and the displacement of the corresponding second output rod in the axial direction of the rod is existing technology. Furthermore, the number of turns of the excitation coil 6, the axial dimensions of the rod, the axial dimensions of the permanent magnet, the remanent magnetic induction of the permanent magnet 14, the vacuum permeability, the relative permeability of the rod 13, and the relative permeability of the permanent magnet 14 are all known parameters. The meaning of the magnetoresistance correction factor is: in addition to the magnetoresistance already considered in the calculation, the magnetic field lines also have leakage magnetic flux. By introducing the magnetoresistance correction factor, these leakage magnetic fluxes can be corrected, thereby improving the accuracy of the magnetic field calculation. The magnetoresistance correction factor can be approximately calculated using finite element simulation with COMSOL simulation software. The calculation of the magnetoresistance correction factor is existing technology.

[0034] The current flowing through the excitation coil 6 is a function of time t, denoted as the input current i. ac (t); Furthermore, the method for testing the output characteristics of the electroacoustic transducer also includes: based on the input current i ac The expression for (t), the relationship between the output displacement and time of the electroacoustic transducer obtained in step C, and the relationship between the input current and the output displacement are obtained.

[0035] With the above settings, the relationship between input current and output displacement can also be obtained during output characteristic testing.

[0036] Each rod 13 has the same specifications; each excitation coil 6 has the same number of turns; J is an even number; two permanent magnets 14 corresponding to the rod 13 are fixedly connected to the upper and lower surfaces of the rod 13, respectively; for two adjacent excitation coils 6 in the circumferential direction, the N poles of the magnetic field generated by one excitation coil and the N poles of the magnetic field generated by the other excitation coil are located on opposite sides in the height direction; the N poles of two permanent magnets 14 corresponding to the same rod are located on the same side in the height direction; for two adjacent rods 13 in the circumferential direction, the N poles of the permanent magnets 14 corresponding to one rod and the N poles of the permanent magnets 14 corresponding to the other rod are located on opposite sides in the height direction. In this invention, "each rod 13 has the same specifications" means that the shape, size, material, and manufacturing process parameters of each rod 13 are consistent.

[0037] Furthermore, the input current i is determined according to the following formula. ac The expression for (t); Formula Eq5: ; Wherein, the voltage applied across the series circuit is a function of time t, denoted as u(t); R is the equivalent impedance of all excitation coils 6; N is the number of turns of excitation coil 6; A r Let μ be the cross-sectional area of ​​rod 13, μ0 be the free permeability, and δ be the cross-sectional area of ​​rod 13. M,j These are the magnetization state switching parameters corresponding to the j-th rod 13; When (dH / dt)(M) an,j -M j When )≤0, δ M,j =0; when (dH / dt)(M an,j -M j When )>0, δ M,j =1.

[0038] In existing technologies, the input current is generally calculated using a common equivalent circuit model, that is, by dividing the voltage applied across the series circuit by the equivalent impedance of the series circuit. In contrast, this invention determines the input current using the aforementioned formula Eq5, taking into account electro-magnetic nonlinear coupling. This reflects the current distortion caused by the nonlinearity of the magnetic core and solves the problem of inaccurate output characteristic prediction due to current distortion.

[0039] Based on the same inventive concept, the present invention also provides a test system for the output characteristics of an electroacoustic transducer that takes into account the inconsistency of the rod material, comprising: A computer device or processor configured or programmed to perform the steps of the above-described method for testing the output characteristics of an electroacoustic transducer. The pre-stressing mechanism is used to apply prestress to each of the bars 13; A power module is used to supply power to the series circuit; When the electroacoustic transducer is in single-output mode, the electroacoustic transducer also includes a first pressure sensor 91 for measuring the prestress on the rod 13.

[0040] Furthermore, the electroacoustic transducer includes a transducer base; When the electroacoustic transducer is in single-output mode, the pre-tightening mechanism is a first pre-tightening end cap 51 detachably connected to the transducer base; the first pre-tightening end cap 51 has a first through hole 510 corresponding to the first output rod 31; the first output rod 31 is fixed to the first mounting base 310, and each rod 13 abuts against the first output rod 31 by abutting against the end of the first mounting base 310 away from the first output rod 31; the first output rod 31 extends away from the rod 13 in the axial direction of the rod 13 and passes through the first through hole 510; the first pre-tightening end cap 51 abuts against the first mounting base 310 through a first disc spring 101 sleeved on the outside of the first output rod 31, and a first pressure sensor 91, thereby applying the same prestress to each rod 13; A first pad 111 can be provided between the first disc spring 101 and the corresponding first pressure sensor 91 to accommodate the distance between the first pre-tightening end cap 51 and the first mounting base 310.

[0041] The electroacoustic transducer also has multiple output modes; When the electroacoustic transducer is in multi-output mode: the pre-tightening mechanism is a second pre-tightening end cap 52 detachably connected to the transducer base; the electroacoustic transducer also includes a second output rod 32, a second pressure sensor 92, a second disc spring 102, and a displacement sensor corresponding to the rod 13; the second pre-tightening end cap 52 has a second through hole 520 corresponding to each of the second output rods 32; the displacement sensor is used to measure the displacement of the corresponding second output rod 32 in the axial direction of the rod 13; the second output rod 32 is fixed to the corresponding second mounting base 320, and the rod 13 abuts against the end of the corresponding second mounting base 320 away from the corresponding second output rod 32. The second pre-tightening end cap 52 abuts against the corresponding second output rod 32; the second output rod 32 extends away from the rod 13 in the axial direction of the rod 13 and passes through the corresponding second through hole 520; the second pre-tightening end cap 52 abuts against the second mounting base 320 corresponding to the second output rod 32 through the corresponding second disc spring 102 and the corresponding second pressure sensor 92 sleeved on the outside of each second output rod 32, thereby applying prestress to each rod 13; the end of each second output rod 32 away from the corresponding rod 13 forms one of the output ends of the electroacoustic transducer, and the output ends of the electroacoustic transducer are independent of each other; the rod 13 and the corresponding second output rod 32 are coaxially arranged. A second pad 112 can be provided between the second disc spring 102 and the corresponding second pressure sensor 92 to accommodate the distance between the second pre-tightening end cap 52 and the second mounting base 320.

[0042] Among them, the multi-output mode means that the electroacoustic transducer has at least two independent outputs.

[0043] There is a gap between the first output rod 31 and the wall surface of the corresponding first through hole 510, so that when the axially vibrating rod 13 drives the first output rod 31 to vibrate, the first pre-tightening end cap 51 will not interfere with the movement of the first output rod 31.

[0044] There is a gap between the second output rod 32 and the wall of the corresponding second through hole 520, so that when the axially moving rod 13 drives the second output rod 32 to vibrate, the second pre-tightening end cap 52 will not interfere with the movement of the second output rod 32.

[0045] like Figures 3-6 As shown, a transducer base is mounted on the base 8. The transducer base can be a frame structure formed by a base plate 81, a top plate 82, and two upright plates 83 on either side. Of course, the transducer base is not limited to this structural form and other commonly used base forms can also be used. The inner side of the frame structure accommodates the oscillator module, i.e., the rod 13 and the corresponding permanent magnet 14. The pre-tightening end cap can be detachably connected to the transducer base via pre-tightening bolts 4. Figure 3 , Figure 4As shown, the first pre-tightening end cap 51 is detachably connected to the upright plate 83 via pre-tightening bolts 4. Figure 5 , Figure 6 As shown, the second pre-tightening end cap 52 is detachably connected to the upright plate 83 via pre-tightening bolts 4.

[0046] like Figures 3-6 As shown, the base plate 81, top plate 82, and two side uprights 83 are all provided with grooves for accommodating the magnetic yoke 15, and a magnetic circuit cover plate 7 can be provided on the corresponding magnetic yoke 15. The magnetic circuit cover plate 7 can be an epoxy resin board to prevent the magnetic yoke below the permanent magnet from being attracted during disassembly and assembly.

[0047] exist Figures 3-6 In the structure, the rod 13, permanent magnet 14, magnetic yoke 15, first magnetic guide block 121, second magnetic guide block 122, and magnetic yoke 15 form a magnetic circuit. The rod 13 is connected to the transducer base sequentially through the permanent magnet 14 and the second magnetic guide block 122 located below the rod 13. The transducer base supports the rod 13 by supporting the second magnetic guide block 122. The second magnetic guide block 122 only contacts the permanent magnet 14 above it, but is not fixedly connected to the permanent magnet 14.

[0048] Both the first displacement sensor and the second displacement sensor can be fixedly installed using the sensor mounting bracket 20.

[0049] The first pre-tightening end cap 51 abuts against the first mounting base 310 in sequence via the first disc spring 101, the first pad 111, and the first pressure sensor 91, so that the first mounting base 310 abuts against each of the bars 13, thereby providing prestress.

[0050] This invention presents a uniquely structured electroacoustic transducer testing system whose output mechanism can flexibly switch between a "dual-output mode" and a "single-output mode." In dual-output mode, the displacement and prestress data of the two rods can be acquired independently, thereby accurately identifying two sets of differing material parameters and visually demonstrating the inconsistency of the rods. In single-output mode, the overall performance after coupling can be verified. This design provides a reliable hardware foundation for solving the consistency problem in multi-rod parallel structures.

[0051] Unlike traditional models that simplify a system with two parallel rods to a single rod multiplication, this method establishes independent dynamic magnetization and strain models for each rod, introduces eddy current loss and abnormal loss corrections, and finally achieves mechanical coupling through dynamic equations. This invention demonstrates the inconsistency between the rods in a parallel two-rod structure, effectively quantifies the performance differences, and predicts the overall output characteristics of the electroacoustic transducer based on these differential parameters. This method effectively captures performance differences in the rods caused by manufacturing processes, improves the prediction accuracy of the output displacement of the electroacoustic transducer under different frequencies and current excitations, and provides guidance for the optimized design of parallel-type giant magnetostrictive electroacoustic transducers.

[0052] The present invention will be further described in detail below.

[0053] like Figures 1-7 As shown, this invention proposes a method and system for testing the output characteristics of an electroacoustic transducer considering the inconsistency of the rod material. The testing system can be configured in single-output mode or dual-output mode to obtain the characteristics of a single rod and the overall characteristics, adapting to different testing needs. This embodiment uses two rods as an example, and the multi-output mode is the dual-output mode.

[0054] Figure 1 This is a schematic diagram of the electroacoustic transducer output characteristic testing system considering rod material inconsistency according to an embodiment of the present invention. Figure 2 It is a display Figure 1 A schematic diagram of the switching between single-output and dual-output modes of the electroacoustic transducer.

[0055] like Figure 5 , Figure 6 As shown, the parallel dual-bar electroacoustic transducer includes an oscillator module, a magnetic circuit module, a preload mechanism, an output module, and an excitation module. The testing system includes a signal acquisition module and a signal processing module. The oscillator module consists of two bars 13 and corresponding permanent magnets 14; the magnetic circuit module includes a first magnetic guide block 121, a second magnetic guide block 122, and a magnetic yoke 15; the preload mechanism includes a preload bolt 4, a second preload end cap 52, and a second disc spring 102. The excitation module includes an excitation coil 6. The excitation coil 6 can be supported by a base plate 81 and does not vibrate with the bars.

[0056] In the oscillator module, permanent magnets 14 are symmetrically distributed at both ends of the two rods 13 along their axial direction, providing a relatively uniform bias magnetic field for the magnetostrictive rods. The two rods 13 can be symmetrically distributed, and the rods 13, permanent magnets 14, excitation coils 6, the first magnetically conductive block 121, the second magnetically conductive block 122, and the yoke 15 together form a magnetic focusing circuit. The excitation coils are connected in series to ensure that their excitation currents are the same, thereby ensuring that the magnetic field strength of the two rods is the same. Preferably, the four permanent magnets corresponding to the two rods and the two excitation coils are arranged with their N and S poles facing each other, forming a magnetic focusing circuit. For example... Figure 4 In the diagram, the permanent magnet bonded to the left rod and the corresponding excitation coil form magnetic poles with an S pole at the top and a N pole at the bottom. Similarly, the permanent magnet bonded to the right rod and the corresponding excitation coil form magnetic poles with an N pole at the top and an S pole at the bottom. This creates a magnetic field between the two rods. Figure 4 The magnetic circuit loop is shown in the direction of the arrow.

[0057] like Figure 3 , Figure 4 As shown, in the electroacoustic transducer in single-output mode, the pre-tensioning mechanism includes a threaded connector for adjusting the pre-tension force, a first pre-tensioning end cap 51, and a first disc spring 101 disposed between the first pre-tensioning end cap 51 and the rod. The threaded connector is a pre-tensioning bolt 4. The axial prestress applied to the rod can be adjusted by rotating the pre-tensioning bolt 4. A first pressure sensor 91 is installed below the first disc spring 101 to monitor the magnitude of the prestress. The pre-tensioning mechanism is used to apply axial prestress to two magnetostrictive rods.

[0058] like Figure 3 , Figure 4 As shown, in the electroacoustic transducer in single-output mode, the output module includes a first output rod 31.

[0059] like Figure 3 , Figure 4 As shown, in the single-output mode of the electroacoustic transducer, the signal acquisition module includes a displacement measurement unit and a force measurement unit. The force measurement unit includes a first pressure sensor 91, used to monitor the axial prestress applied to the rod and ensure the accuracy of the prestress. The displacement measurement unit includes a first displacement sensor 21 mounted on a sensor mounting bracket 20. The measuring end of the displacement sensor is positioned opposite the output end of the electroacoustic transducer in the axial direction of the rod, used to measure the dynamic displacement of the output end in the axial direction. The displacement of the first output rod 31 can be measured by the first displacement sensor, thereby allowing the measured displacement to be compared with the output characteristics obtained by testing, verifying the effectiveness of the output characteristic testing method of the present invention. In this invention, the displacement sensor can be a laser displacement sensor. The signal acquisition module also includes a current sensor for monitoring the excitation current, which can measure the current magnitude in the excitation coil 6. The current sensor can be a current probe. Preferably, the signal acquisition module also includes an induction coil 17 for measuring the induced electromotive force of the rod, which can measure the change in magnetic induction intensity within the rod. The change in magnetic flux density within the rod can be determined based on the measurement results of induction coil 17, thus verifying the accuracy of the simulated magnetic flux density. Induction coil 17 is tightly wound around the surface of the giant magnetostrictive rod. Since induction coil 17 is lightweight, its weight can be neglected when determining the equivalent mass, equivalent damping, and equivalent stiffness.

[0060] like Figure 3 , Figure 4 As shown, in single-output mode, the transducer adopts a dual-rod parallel structure, with both rods 13 rigidly connected to the first output rod 31, jointly driving the same first output rod 31. The two rods are coupled together, outputting power externally. In single-output mode, two sets of differentiated material parameters are invoked to execute the output characteristic test method steps to predict the overall output characteristics after parallel connection. At this time, the overall output displacement after the two rods are coupled is measured. This mode is used to verify the actual output performance of the electroacoustic transducer with dual-rod parallel structure, as well as the impact of rod inconsistency.

[0061] The single-output electroacoustic transducer includes a first output rod 31, a preload bolt 4, a first preload end cap 51, an excitation coil 6, a magnetic circuit cover plate 7, a base 8, a first pressure sensor 91, a first disc spring 101, a first pad 111, a first magnetic guide block 121, a second magnetic guide block 122, a rod 13, a permanent magnet 14, a magnetic yoke 15, and an excitation coil 6. The magnetic yoke 15 can be made of silicon steel sheet.

[0062] like Figure 5 , Figure 6 As shown, in the dual-output mode, the two rods 13 are rigidly connected to the two second output rods 32 respectively, and the two rods are decoupled, so the outputs do not affect each other. In the dual-output mode, the two magnetostrictive rods drive independent output ends to vibrate axially. The two second pressure sensors 92 monitor the prestress on the two rods respectively, and the two second displacement sensors 22 at the top collect the independent displacement data of the two rods respectively, identifying the different material parameters of the two rods, thereby reflecting the performance inconsistency between the two magnetostrictive rods. In the dual-output mode, the same or different prestresses can be applied to different rods. The electroacoustic transducer in the dual-output mode includes the second output rod 32, the pre-tightening bolt 4, the second pre-tightening end cap 52, the excitation coil 6, the magnetic circuit cover plate 7, the base 8, the second pressure sensor 92, the second disc spring 102, the second pad 121, the first magnetic guide block 121, the second magnetic guide block 122, the rod 13, the permanent magnet 14, the magnetic yoke 15, and the excitation coil 6.

[0063] like Figure 5 , Figure 6 As shown, in the electroacoustic transducer in dual-output mode, the output module includes a second output rod 32.

[0064] Both single-output and dual-output electroacoustic transducers share the same excitation drive module. This module includes a programmable AC power supply, a capacitor matching board, and a DC power supply, providing a mixed AC / DC excitation current. The capacitor matching board within the module contains multiple capacitors, as well as multiple plug-in interfaces and connecting wires. These interfaces allow for rapid capacitor adjustment to match the test system under different operating conditions. The pluggable and adjustable capacitor matching board enables rapid capacitor matching for the inductive load characteristics of the test system under various conditions, improving power supply efficiency and system stability. The excitation drive module is electrically connected to the excitation coil, providing AC, DC, or a mixed AC / DC excitation current. The programmable AC power supply uses an existing AC power supply. Therefore, the excitation drive module is essentially the power supply module.

[0065] The signal processing module is used to process, visualize, and compare the acquired signals. The signal processing module includes a host computer, which is electrically connected to the excitation drive module and the signal acquisition module. It processes and visualizes the acquired signals and compares the extracted parameters. The host computer can process and visualize test data in real time, extract parameters of the supermagnetostrictive rod under corresponding operating conditions, and compare them, providing a clear indication of the rod's inconsistencies. The host computer can be electrically connected to each sensor via a data acquisition card.

[0066] The method for testing the output characteristics of a giant magnetostrictive electroacoustic transducer is implemented based on the aforementioned electroacoustic transducer output characteristic testing system. The output characteristic testing method runs within the signal processing module.

[0067] The testing method of this invention abandons the assumption of uniform rod performance. First, a parallel magnetic circuit model is established; second, differentiated dynamic magnetization models are established for the two rods respectively, and their respective magnetization intensities are calculated; finally, by combining a nonlinear strain model and a single-degree-of-freedom dynamic equation, the output forces of the two rods are vector-coupled to solve for the overall displacement. This invention effectively solves the prediction error problem caused by differences in rod performance by combining systematic experimental testing with differentiated modeling, significantly improving the prediction accuracy of the output characteristics of electroacoustic transducers, and providing a reliable basis and theoretical support for the utilization of giant magnetostrictive materials and the performance optimization of such electroacoustic transducers.

[0068] Specifically, the testing method of the present invention includes the following steps: Step 1: Establish a parallel magnetic circuit model: Based on the input current applied to the series circuit by the excitation drive module and the permanent magnet parameters, introduce a magnetoresistive correction factor G. M The effective axial magnetic field strength H acting on the rod is calculated using the formula Eq47.

[0069] Wherein, the input current i acThe expression for (t) is: Formula Eq50: ; By combining formulas Eq50, Eq48, and Eq49, the input current i can be obtained. ac Formula 5 for (t); Among them, B j (t) represents the magnetic flux density in the region where the j-th rod 13 is located. u(t) can be a DC voltage, an AC voltage, or a voltage resulting from the superposition of DC and AC voltages. u(t) is the voltage applied to the series circuit by the power supply module.

[0070] Step 2: Establish differentiated dynamic magnetization models; for two physically parallel supermagnetostrictive rods, abandon the assumption of performance consistency and establish independent magnetization models, such as the dynamic Jiles-Atherton magnetization model.

[0071] Introducing abnormal loss magnetic field strength H anom,j Eddy current loss magnetic field strength H eddy,j This is used to correct the effective magnetic field. The specific expression of the Jiles-Atherton magnetization model for the corrected nonlinear magnetization process includes the above formulas Eq41 to Eq47, and also includes: Formula Eq48: B j =μ0(H+M j ); Formula Eq49: ; δ is a direction parameter that ensures energy is always dissipated. The parameter δ is introduced. M,j This is to avoid non-physical negative magnetic susceptibility phenomena in the calculation.

[0072] Step 3: Calculate the independent output force; establish a nonlinear magnetostrictive strain model, and calculate the output force F of the two rods based on their magnetization intensities M1 and M2. G,1 and F G,2 The strain model formulas are Eq31 and Eq32.

[0073] Step 4: Dynamic Coupling Solution: Establish a single-degree-of-freedom dynamic equation that includes the load mass, damping, and stiffness, and determine the output force F corresponding to the two bars respectively. G,1 F G,2 By performing vector superposition as the driving force of the system, the overall output displacement x of the electroacoustic transducer can be obtained, thus yielding the dynamic equation: ; Among them, M eq C eq K eqThese represent the system's equivalent mass, equivalent damping, and equivalent stiffness, including the load, respectively. r Let be the cross-sectional area of ​​the bar.

[0074] This embodiment plots static current-displacement curves and dynamic current-displacement curves for different bars. For example... Figure 8 As shown, for a gradually increasing current under static conditions, there is an inconsistency in the relationship between the output displacement and the input current for bars of the same specifications, and the performance varies significantly. For example... Figure 9 As shown, under dynamic conditions where an AC voltage is applied across both ends of a series circuit, there is a significant inconsistency between the output displacement and input current of bars of the same specifications. Figure 8 In the diagram, B1, B2, ..., B8 represent eight different bars of the same specification. Figure 9 In the diagram, B1, B2, ..., B6 represent six different bars of the same specification.

[0075] like Figure 10 As shown, the displacement-time curve obtained by the output characteristic test method according to the present invention is basically consistent with the actual test results, and the curves match well, which confirms the effectiveness of the output characteristic test method of the present invention.

[0076] To verify the effectiveness of the input current calculation formula Eq5 of this invention, the operating frequencies were set to 100Hz, 300Hz, and 600Hz. At each frequency, a comparative diagram of the voltage-current relationship curves was obtained based on experimental results, the method of this invention, and a common equivalent circuit model, as shown below. Figures 11-13 As shown. The experimental results are voltage-current relationship curves obtained from the input current measured by the set input voltage and current sensors. The curve corresponding to the method of this invention is the voltage-current relationship curve obtained from the input current and the actual measured voltage according to the above formula Eq5 of this invention. From Figure 11 , Figure 12 , Figure 13 It can be seen that at different frequencies, the existing ordinary equivalent circuit model (which divides the voltage by the equivalent impedance of the series line as the input current) deviates significantly from the experimental results. However, the voltage-current relationship curve obtained based on the above formula Eq5 of this invention is closer to the experimental results. In other words, in terms of the degree of closeness to the actual experimental results, it is significantly better than the voltage-current relationship curve obtained based on the existing ordinary equivalent circuit model.

[0077] Figures 14-17This diagram compares the current-displacement curves obtained from experiments, the method of this invention, and existing superposition models when the operating frequencies are set to 100Hz, 200Hz, 300Hz, and 500Hz. The experimental results are current-displacement curves obtained from the input current measured by the current sensor and the output displacement measured by the first displacement sensor. Existing superposition models assume that the material parameters and properties of the two bars are completely identical, simplifying the system to a linear superposition of the properties of individual bars. From... Figure 14 , Figure 15 , Figure 16 , Figure 17 It can be seen that there is a significant difference between the experimental results obtained using the existing superposition model and the current-displacement relationship curves obtained through current and displacement tests. In contrast, at different frequencies, the current-displacement relationship curves obtained based on the method of this invention show little difference from the experimental results, and are significantly better than the existing superposition model.

[0078] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for testing the output characteristics of an electroacoustic transducer considering rod material inconsistency, characterized in that, The electroacoustic transducer includes J parallel rods (13), which are magnetostrictive rods; J≥2; each rod (13) has an excitation coil (6) wound around its outer side; the excitation coils (6) are connected in series to form a series circuit; The electroacoustic transducer has a single output mode; when the electroacoustic transducer is in single output mode, the electroacoustic transducer includes a first output rod (31), each rod (13) abuts against the first output rod (31), and the end of the first output rod (31) away from the rod (13) forms the output end of the electroacoustic transducer; on the projection plane perpendicular to the axial direction of the rod (13), the projections of J rods (13) are evenly arranged in the circumferential direction of the projection of the first output rod (31). The method for testing the output characteristics of the electroacoustic transducer includes: Step A: Set the electroacoustic transducer to single output mode, apply the same prestress to each rod (13), and determine the strain of each rod based on the prestress of the rod (13) and the volume magnetization intensity corresponding to each rod, according to the strain model formula. Step B: Based on the strain of each bar obtained in Step A, determine the output force corresponding to each bar; Step C: Based on the prestress on the rod (13) and the output force corresponding to each rod obtained in step B, construct a dynamic equation that reflects the relationship between the output displacement and time of the electroacoustic transducer, thereby obtaining the relationship between the output displacement and time of the electroacoustic transducer in single output mode.

2. The method for testing the output characteristics of an electroacoustic transducer according to claim 1, characterized in that, Each bar (13) has the same specifications; the kinetic equation is: ； Where: M eq C eq K eq These correspond to the equivalent mass, equivalent damping, and equivalent stiffness of the axially vibrating component, respectively; x is the output displacement of the electroacoustic transducer; t is time; σ is the prestress on the rod (13); A r F is the cross-sectional area of ​​the bar (13). G,j The output force corresponding to the j-th rod (13) obtained in step B; j = 1, 2, ..., J; the axial vibration component is the whole structure of the electroacoustic transducer that moves in the axial direction of the rod (13).

3. The method for testing the output characteristics of an electroacoustic transducer according to claim 2, characterized in that, The electroacoustic transducer includes a transducer base; both ends of the rod (13) in the axial direction are fixedly connected to permanent magnets (14). When the electroacoustic transducer is in single-output mode: the electroacoustic transducer further includes a first pre-tightening end cap (51) detachably connected to the transducer base; the first pre-tightening end cap (51) has a first through hole (510) corresponding to the first output rod (31); the first output rod (31) is fixed to the first mounting base (310), and each rod (13) abuts against the first output rod (31) by abutting the end of the first mounting base (310) away from the first output rod (31); the first output rod (31) extends away from the rod (13) in the axial direction of the rod (13) and passes through the first through hole (510); the rod (13) of The end near the first mounting base (310) is connected to the first mounting base (310) in sequence via a permanent magnet (14) and a magnetic guide block; the first pre-tightening end cap (51) abuts against the first mounting base (310) through an annular structure sleeved on the outside of the first output rod (31), thereby applying the same prestress to each rod (13); the annular structure includes a first disc spring (101) and a first pressure sensor (91) arranged in sequence; the magnetic guide block, the rod (13), the permanent magnet (14) fixedly connected to the rod (13), the annular structure, and the first output rod (31) constitute the axial vibration component.

4. The method for testing the output characteristics of an electroacoustic transducer according to claim 2, characterized in that, The formula for the output force corresponding to the j-th bar is: F G,j =A r E H,j l j ; Among them: A r E is the cross-sectional area of ​​the bar (13). H,j Let λ be the Young's modulus of the j-th bar (13); j Let be the strain of the j-th bar (13) obtained in step A; When σ≤σ s When the strain model formula is: ； When σ > σ s When the strain model formula is: ； Where: λ j Let σ be the strain of the j-th bar. s For the saturated prestress corresponding to bar (13), σ max The maximum stress that the bar (13) can withstand is tanh(2σ / σ). s ) is 2σ / σ s The hyperbolic tangent function, λ s,j M represents the saturation magnetostriction coefficient of the j-th rod (13). j M is the bulk magnetization of the j-th rod (13). s,j Let be the saturation magnetization of the j-th rod (13).

5. The method for testing the output characteristics of an electroacoustic transducer according to claim 4, characterized in that, J is an even number: two permanent magnets (14) corresponding to the rod (13) are fixedly connected to the upper and lower surfaces of the rod (13) respectively; each excitation coil (6) has the same number of turns; for two adjacent excitation coils (6) in the circumferential direction, the N pole of the magnetic field generated by one excitation coil and the N pole of the magnetic field generated by the other excitation coil are located on opposite sides in the height direction; the N poles of two permanent magnets (14) corresponding to the same rod are located on the same side in the height direction; for two adjacent rods (13) in the circumferential direction, the N poles of the permanent magnets (14) corresponding to one rod and the N poles of the permanent magnets (14) corresponding to the other rod are located on opposite sides in the height direction; By combining the following formulas, the bulk magnetization M corresponding to the j-th rod can be determined. j : M an,j =M s,j [nutrition(H e,j / from j )-(from j / H e,j )]; H e,j =H+αr j M j -(H eddy,j +H anom,j ); ar j =a j +9min s,j sM j / 2μ0(M s,j ) 2 ; M j =M rev,j +M irr,j ; M rev,j =c j (M an,j -M irr,j ); dM irr,j / dH=(M an,j -M irr,j ) / [k j δ-αr j (M an,j -M irr,j )]; ； in: M rev,j M is the reversible magnetization of the j-th rod (13). irr,j c is the irreversible magnetization of the j-th rod (13); j M is the reversibility coefficient of the j-th bar (13); an,j H is the hysteresis-free magnetization of the j-th rod (13); H is the effective axial magnetic field strength of the rod (13); k j Let αr be the pinning parameter of the j-th bar (13); j The mean field parameter of the domain coupling after correction for the j-th rod (13); The current flowing through the excitation coil (6) is a function of time t, denoted as the input current i. ac (t); G M B is the magnetoresistive correction factor, N is the number of turns of the excitation coil (6); r L represents the remanent magnetic flux density of the permanent magnet (14); GMM L is the dimension of the bar (13) along its axial direction. PM μ is the dimension of the permanent magnet (14) along the axial direction of the rod (13). GMM Let μ be the relative permeability of the rod (13). PM M is the relative permeability of the permanent magnet (14), μ0 is the permeability of free space; s,j H is the saturation magnetization of the j-th rod (13); e,j The magnetic field strength of the effective field inside the j-th rod (13); as j Let λ be the shape factor of the hysteresis-free magnetization of the j-th rod (13). s,j H represents the saturation magnetostriction coefficient of the j-th rod (13); eddy,j H is the eddy current loss magnetic field strength of the j-th rod (13); anom,j It is the abnormal loss magnetic field strength of the j-th rod (13); α j δ is the average field parameter of the interdomain coupling of the j-th rod (13); δ is the direction parameter; when dH / dt≥0, δ=1; when dH / dt<0, δ=-1.

6. The method for testing the output characteristics of an electroacoustic transducer according to claim 5, characterized in that, The electroacoustic transducer also has multiple output modes; When the electroacoustic transducer is in multi-output mode, the electroacoustic transducer includes a second output rod (32) corresponding to each rod (13). The rod (13) abuts against the corresponding second output rod (32). The end of each second output rod (32) away from the corresponding rod (13) forms one of the output ends of the electroacoustic transducer. Each output end of the electroacoustic transducer is independent of each other. The rod (13) and the corresponding second output rod (32) are coaxially arranged. The steps preceding step A include steps PA1 and PA2; Step PA1: Set the electroacoustic transducer to multi-output mode, apply prestress to each rod (13), and measure the displacement of each second output rod (32) in the axial direction of the rod (13); Step PA2: Based on the prestress of each rod (13) and the displacement of the corresponding second output rod (32) in the axial direction of the rod (13), determine the reversibility coefficient, pinning parameters, saturation magnetization, shape factor of hysteresis-free magnetization, saturation magnetostriction coefficient, eddy current loss magnetic field strength, abnormal loss magnetic field strength, and average field parameters of interdomain coupling for each rod (13), thereby determining the bulk magnetization of each rod.

7. The method for testing the output characteristics of an electroacoustic transducer according to claim 1, characterized in that, The current flowing through the excitation coil (6) is a function of time t, denoted as the input current i. ac (t); The method for testing the output characteristics of the electroacoustic transducer further includes: based on the input current i ac The expression for (t), the relationship between the output displacement and time of the electroacoustic transducer obtained in step C, and the relationship between the input current and the output displacement are obtained.

8. The method for testing the output characteristics of an electroacoustic transducer according to claim 5 or 7, characterized in that, Each rod (13) has the same specifications; J is an even number; two permanent magnets (14) corresponding to the rod (13) are fixedly connected to the upper and lower surfaces of the rod (13) respectively; each excitation coil (6) has the same number of turns; for two adjacent excitation coils (6) in the circumferential direction, the N pole of the magnetic field generated by one excitation coil and the N pole of the magnetic field generated by the other excitation coil are located on opposite sides in the height direction; the N poles of two permanent magnets (14) corresponding to the same rod are located on the same side in the height direction; for two adjacent rods (13) in the circumferential direction, the N poles of the permanent magnets (14) corresponding to one rod and the N poles of the permanent magnets (14) corresponding to the other rod are located on opposite sides in the height direction; The input current i is determined according to the following formula. ac The expression for (t); ； Wherein, the voltage applied across the series circuit is a function of time t, denoted as u(t); R is the equivalent impedance of all excitation coils (6); N is the number of turns of the excitation coil (6); A r Let μ be the cross-sectional area of ​​the rod (13), μ0 be the vacuum permeability; j = 1, 2, ..., J; H is the effective axial magnetic field strength of the rod (13); t is time; k j c is the pinning parameter of the j-th bar (13); j α is the reversibility coefficient of the j-th bar (13); j M represents the mean field parameter of interdomain coupling in the j-th rod (13); j M is the bulk magnetization of the j-th rod (13); an,j H is the hysteresis-free magnetization of the j-th rod (13); e,j δ is the magnetic field strength of the effective field inside the j-th rod (13); δ is the direction parameter; δ M,j It is the magnetization state switching parameter corresponding to the j-th rod (13); when dH / dt≥0, δ=1; when dH / dt<0, δ=-1; when (dH / dt)(M an,j -M j When )≤0, δ M,j =0; when (dH / dt)(M an,j -M j When )>0, δ M,j =1.

9. A test system for the output characteristics of an electroacoustic transducer considering the inconsistency of rod material, characterized in that, include: A computer device or processor configured or programmed to perform the steps of the method for testing the output characteristics of an electroacoustic transducer as described in any one of claims 1-8; A pre-stressing mechanism is used to apply prestress to each bar (13); A power module is used to supply power to the series circuit; When the electroacoustic transducer is in single-output mode, the electroacoustic transducer also includes a first pressure sensor (91) for measuring the prestress on the rod (13).

10. The electroacoustic transducer output characteristic testing system according to claim 9, characterized in that, The electroacoustic transducer includes a transducer base; When the electroacoustic transducer is in single-output mode: the pre-tightening mechanism is a first pre-tightening end cap (51) detachably connected to the transducer base; the first pre-tightening end cap (51) has a first through hole (510) corresponding to the first output rod (31); the first output rod (31) is fixed to the first mounting base (310), and each rod (13) abuts against the first output rod (31) by abutting against the end of the first mounting base (310) away from the first output rod (31); the first output rod (31) extends away from the rod (13) in the axial direction of the rod (13) and passes through the first through hole (510); the first pre-tightening end cap (51) abuts against the first mounting base (310) by a first disc spring (101) sleeved on the outside of the first output rod (31) and a first pressure sensor (91), thereby applying the same prestress to each rod (13); The electroacoustic transducer also has multiple output modes; When the electroacoustic transducer is in multi-output mode: the pre-tightening mechanism is a second pre-tightening end cap (52) detachably connected to the transducer base; the electroacoustic transducer also includes a second output rod (32), a second pressure sensor (92), a second disc spring (102), and a displacement sensor corresponding to the rod (13); the second pre-tightening end cap (52) has a second through hole (520) corresponding to each of the second output rods (32); the displacement sensor is used to measure the displacement of the corresponding second output rod (32) in the axial direction of the rod (13); the second output rod (32) is fixed to the corresponding second mounting base (320), and the rod (13) abuts against the end of the corresponding second mounting base (320) away from the corresponding second output rod (32). Thus, it abuts against the corresponding second output rod (32); the second output rod (32) extends away from the rod (13) in the axial direction of the rod (13) and passes through the corresponding second through hole (520); the second pre-tightening end cap (52) abuts against the second mounting base (320) corresponding to the second output rod (32) through the corresponding second disc spring (102) and the corresponding second pressure sensor (92) sleeved on the outside of each second output rod (32), thereby applying prestress to each rod (13); the end of each second output rod (32) away from the corresponding rod (13) forms one of the output ends of the electroacoustic transducer, and each output end of the electroacoustic transducer is independent of each other; the rod (13) and the corresponding second output rod (32) are coaxially arranged.

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