Electromagnetic loading test method and system for simulating stress and strain in a wheel rotating state

Abstract

The present application relates to the technical field of material and engine structure strength test, and specifically relates to an electromagnetic loading test method and system for simulating stress and strain under rotating state of a wheel disc, comprising the following steps: S1, magnetic field design for simulating stress and strain distribution of the wheel disc under rotating state; S2, electromagnetic loading device design; S3, electromagnetic load feedback and control; S4, real-time monitoring of full-field strain, the electromagnetic loading test method and system for simulating stress and strain under rotating state of the wheel disc can realize static loading of the test disc piece, the full-field stress and strain distribution of the wheel disc is consistent with that in the rotating state, the real-time monitoring of crack propagation behavior and full-field strain of the wheel disc under the load can be realized, and the method has the characteristics of simple operation, strong controllability, high energy conversion efficiency, low cost, short cycle, good compatibility and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of material and engine structure strength testing, and particularly relates to an electromagnetic loading test method and system for simulating stress and strain in a rotating state of a wheel disc. BACKGROUND

[0002] As a dangerous part of the wheel disc, the tenon and groove of the gas turbine engine has a fine geometric structure and complex stress in the working process. During the service period, the tenon and groove simultaneously bear high temperature, blade centrifugal force and tangential air resistance, as well as complex thermal-mechanical alternating load and high-low cycle fatigue load, and are often the key area of fatigue failure. In order to prevent structural failure and ensure safe and reliable operation of the wheel disc and the blade, structural strength testing is an indispensable part of the wheel disc structure strength design.

[0003] The load loading of the gas turbine engine wheel disc is the basis of the wheel disc structure strength testing. Whether it is an over-speed experiment, a low-cycle fatigue crack propagation experiment or a damage tolerance design, the overall or local load needs to be applied to the test piece. The current wheel disc load test method includes engine whole machine test, high-speed rotating test based on whole disc simulation piece, whole disc local loading test based on Phil wheel device and wheel disc feature part simulation piece test. The load loading methods of different test methods have the following shortcomings:

[0004] 1) The cost of engine whole machine test is extremely high: the object of the engine whole machine test is the real wheel disc component. The gas turbine engine loaded with the wheel disc to be tested is started to the real working condition, and the real load is applied to the whole structure of the wheel disc under high temperature and high pressure. Although the whole machine test can restore the real load of the wheel disc to the greatest extent, a large amount of energy is consumed during the starting and running of the engine, and most of the energy is used to load other parts inside the engine, and the energy utilization rate is extremely low. At the same time, the wheel disc is wrapped in the complex structure of the casing, and it is difficult to observe the whole test process.

[0005] 2) The test cycle of high-speed rotating test is long: the object of the high-speed rotating test is the whole disc simulation piece of the wheel disc. In the vertical high-speed rotating test bed, the motor is used to accelerate the rotation of the single wheel disc component, and the external heating furnace is used to heat the disc piece to simulate the stress distribution inside the wheel disc under the real condition. Since the test speed is high, the acceleration process of the test bed is slow, and the test cycle of this method is long when the fatigue test is carried out, and the crack propagation process cannot be observed in real time.

[0006] 3) The Philon device can only apply the load at the rim: The test object of the Philon device is the local structure of the mortise and tenon structure of the entire disc, a false blade with a standard tenon is installed on the mortise and connected with a hydraulic cylinder to simulate the low-cycle centrifugal load of the blade. The Philon device can only simulate the local centrifugal load of the blade at the rim, and cannot simulate the load distribution of the entire disc during rotation, so the Philon device is only suitable for load application of local structure of the disc, and cannot be applied in the field of strength testing of the entire disc.

[0007] 4) The test of the simulation piece of the feature part of the disc can only simulate the stress and strain distribution of the real disc within a smaller size: The test of the simulation piece is to design the configuration of the simulation piece to simulate the stress and strain distribution near the specific dangerous part of the disc under the simple load of uniaxial tension generated by the hydraulic machine, which has the characteristics of low cost and simple test. However, this test can only represent the local strength performance characteristics of the disc, and the simulation piece needs to be matched with the real disc in all aspects, which has a long design cycle and a complicated design path.

[0008] Therefore, a wheel disc load loading method is provided, which can meet the load loading requirements of the wheel disc in various tests, can realize real-time observation of full-field strain distribution, can track and record the entire process of crack tip expansion, can reduce test cost and energy consumption, and can shorten the test cycle, thereby providing a basis for wheel disc structure strength testing, and is one of the technical problems to be solved by the person skilled in the art. SUMMARY

[0009] The purpose of the present application is to provide an electromagnetic loading test method and system for simulating stress and strain in a rotating state of a disc to meet the load loading requirements of the disc in various tests, realize real-time observation of full-field strain distribution, track and record the entire process of crack tip expansion, reduce test cost and energy consumption, and shorten the test cycle.

[0010] Therefore, the present application provides an electromagnetic loading test method for simulating stress and strain in a rotating state of a disc, comprising the steps of:

[0011] S1, magnetic field design for simulating stress and strain distribution of the disc in a rotating state: analyzing the characteristics of the rotating centrifugal load suffered by the real disc structure during rotation to obtain the distribution of the rotating centrifugal load suffered by the real disc structure in a rotating state; then designing the distribution of the magnetic field vector in space based on the distribution of the rotating centrifugal load suffered by the real disc structure during rotation to obtain a target space magnetic field capable of simulating the stress and strain distribution of the real disc structure in a rotating state, wherein the test disc is subjected to consistent stress and strain distribution in the target space magnetic field.

[0012] S2, electromagnetic loading device design: first, use machine learning to train the proxy model between the input parameter combination of the electromagnetic coil array and the final magnetic field output form, then substitute the magnetic field parameters of the target space magnetic field designed in step S1 into the proxy model, and obtain the electromagnetic coil array parameters required for the test by back propagation;

[0013] S3, electromagnetic load feedback and control: according to the electromagnetic coil array parameters obtained by back propagation in step S2, arrange the electromagnetic coil array around the test disc piece, and set a probe in the space magnetic field, obtain and feed back the local magnetic field intensity signal through the probe, control the electromagnetic coil excitation current according to the local magnetic field intensity signal, and generate a space magnetic field meeting the test requirements;

[0014] S4, real-time monitoring of full-field strain: during the magnetic field load loading process in step S3, the dynamic strain field and crack size of the test disc piece are monitored in real time based on digital image correlation technology, and the surface strain distribution and crack propagation behavior of the test disc piece at each time during the load loading process are analyzed.

[0015] Further, in the step S1, when the disc structure is an equal-thickness disc type disc, the direction of the target space magnetic field is divergent outward along the radius from the center of the disc structure, the strength of the target space magnetic field is linearly distributed along the radial direction, and the magnetic field form is a ring-shaped radial magnetic field.

[0016] Further, the step S2 comprises:

[0017] S21, setting different coil input parameters;

[0018] S22, training the proxy model by adjusting the coil input parameter combination, and outputting the space magnetic field distribution form corresponding to each coil input parameter combination through the proxy model;

[0019] S23, substitute the magnetic field parameters of the target space magnetic field designed in step S1 into the proxy model, obtain the electromagnetic coil array parameters required for the test by back propagation, arrange the electromagnetic coil array according to the electromagnetic coil array parameters obtained by back propagation, and generate a space electromagnetic field meeting the design requirements.

[0020] Further, in the step S4, a speckle image is pre-prepared on the test disc piece, the speckle image on the surface of the test disc piece is continuously photographed by a camera during real-time monitoring of the full-field strain; and the speckle image photographed during the test is compared with the speckle image on the surface of the disc simulation piece photographed before the test, the dynamic strain field and crack size of the test disc piece are monitored in real time based on digital image correlation technology, and the surface strain distribution and crack propagation behavior of the test disc piece at each time during the load loading process are analyzed.

[0021] An electromagnetic loading test system for simulating stress and strain in a rotating wheel state, the electromagnetic loading test system is used to implement the electromagnetic loading test method, the electromagnetic loading test system comprises:

[0022] A test disc made of ferromagnetic material, the test disc has the same structure as a real wheel disc, and a pre-crack and a speckle image are arranged on the test disc;

[0023] An electromagnetic loading device for forming a spatial magnetic field around the test disc;

[0024] An electromagnetic load feedback and control device comprising a plurality of probes arranged in the spatial magnetic field, the local magnetic field intensity signals can be obtained through the probes, the electromagnetic load feedback and control device can control the electromagnetic coil excitation current according to the local magnetic field intensity signals to generate a spatial magnetic field meeting the test requirements;

[0025] A measurement and analysis device for real-time monitoring of the full-field dynamic strain field and crack size of the test disc based on digital image correlation technology during the magnetic field load loading process, and analyzing the surface stress and strain distribution and crack propagation behavior of the test disc at each moment during the load loading process.

[0026] Further, the electromagnetic loading device comprises:

[0027] An electromagnetic coil array comprising a plurality of electromagnetic coils, the plurality of electromagnetic coils are distributed in the test system space according to the test requirements, the electromagnetic coils can exert magnetic field force on the test disc under the excitation of current, and the spatial electromagnetic field meeting the test requirements is generated through the cooperation of each electromagnetic coil in the electromagnetic coil array.

[0028] Further, the electromagnetic load feedback and control device comprises:

[0029] A direct current power supply, which is an adjustable direct current stabilized power supply, the direct current power supply is used to provide current to the electromagnetic coil;

[0030] An electromagnetic relay connected in series with the direct current power supply, the electromagnetic relay is used to control the direct current power supply according to the test requirements;

[0031] The electromagnetic coils in the electromagnetic coil array are connected in series with the electromagnetic relay and the direct current power supply;

[0032] The electromagnetic load feedback and control device can control the size of the magnetic field force generated by the electromagnetic coil by adjusting the output power of the direct current power supply; the electromagnetic load feedback and control device can control the generation frequency of the magnetic field force load by adjusting the power-on delay length of the electromagnetic relay.

[0033] Further, the feedback and control device of the electromagnetic load further comprises:

[0034] a plurality of probes arranged in the spatial magnetic field to acquire the local magnetic field strength signal;

[0035] a control module connected with the probes, the DC power supply and the electromagnetic relay respectively, the control module being capable of controlling the size of the DC power supply output current and the energization delay length of the electromagnetic relay; the control module being further capable of receiving the local magnetic field strength signal monitored by the probes and performing electromagnetic loading on the test disc according to the local magnetic field strength signal and different electromagnetic loading parameters required by different tests.

[0036] Further, the measuring and analyzing device comprises:

[0037] a camera arranged opposite to the test disc, the camera being used to continuously shoot the speckle images on the surface of the test disc during the test;

[0038] a computer having software for crack propagation analysis based on the speckle images shot by the camera installed therein.

[0039] Further, the electromagnetic loading test system for simulating the stress and strain in the rotating state of the disc further comprises a protective device in the form of a ring, the protective device wrapping the test disc and the electromagnetic coil array.

[0040] The present application has the following advantages:

[0041] The electromagnetic loading test method and system for simulating the stress and strain in the rotating state of the disc can realize the static loading of the test disc, the disc full-field stress and strain distribution is consistent with that in the rotating state, the real-time monitoring of the disc crack propagation behavior and full-field strain under the load can be realized, and the method and system have the characteristics of simple operation, strong controllability, high energy conversion efficiency, low cost, short cycle, good compatibility and the like. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a schematic diagram of the magnetic field distribution form of the equal-thickness disc-type disc according to the present application;

[0043] Figure 2 is a structural schematic diagram of the electromagnetic loading test system for simulating the stress and strain in the rotating state according to the present application;

[0044] Figure 3 is a schematic diagram of the design process of the electromagnetic loading device according to the present application;

[0045] Figure 4 is a schematic diagram of the real-time monitoring process of the full-field strain according to the present application;

[0046] The marks in the figure are as follows:

[0047] 1 test tray; 2 array of solenoids; 3 video camera; 4 computer; 5 guard; 6 base. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art are within the scope of the present application.

[0049] In the description of the present application, it should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. For ease of description, the sizes of the various parts shown in the drawings are not drawn in accordance with the actual proportional relationship. The techniques, methods and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as part of the authorized description. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of exemplary embodiments can have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0050] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application are used to distinguish similar objects, and are not intended to describe a specific order or chronological sequence. It should be understood that the data used in this way can be exchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated or described herein, and the objects distinguished by "first", "second" and the like are generally a class, and do not limit the number of objects, for example, the first object can be one or more. In addition, the specification and claims "and / or" indicate at least one of the connected objects, and the character " / ", generally indicates that the front and rear associated objects are in a "or" relationship.

[0051] It should be noted that in the description of the present application, the terms of orientation such as "front, back, up, down, left, right", "circumferential, radial, vertical, horizontal" and "top, bottom" and the like indicated orientation or position relationship are generally based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, without making the opposite statement, these orientation terms do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the scope of protection of the present application; the orientation terms "inner, outer" refer to the inner and outer of the contour of each component itself.

[0052] It should be noted that in the present application, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or device. Without more limitation, the element defined by the sentence "including a…" does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but can also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0053] As shown in Figures 1 to 4 An electromagnetic loading test method for simulating stress and strain in a rotating state of a wheel disc, comprising the steps of:

[0054] S1, magnetic field design for simulating stress and strain distribution of wheel disc in rotating state: analyzing the characteristics of the rotating centrifugal load suffered by the real wheel disc structure when rotating, obtaining the distribution of the rotating centrifugal load suffered by the real wheel disc structure in rotating state; then designing the distribution of the magnetic field vector in space based on the distribution of the rotating centrifugal load suffered by the real wheel disc structure when rotating, obtaining a target space magnetic field capable of simulating the stress and strain distribution of the real wheel disc structure in rotating state, in which the test disc is subjected to consistent stress and strain distribution as in the rotating state of the real wheel disc structure;

[0055] S2, electromagnetic loading device design: first, use machine learning means to train the proxy model between each input parameter combination of the electromagnetic coil array and the final magnetic field output form, then substitute the magnetic field parameters of the target space magnetic field designed in step S1 into the proxy model, and obtain the electromagnetic coil array parameters required for the test by back calculation;

[0056] S3, electromagnetic load feedback and control: according to the step S2, the electromagnetic coil array parameters are obtained, the electromagnetic coil array is arranged around the test disc piece, the probe is arranged in the space magnetic field, the local magnetic field intensity signal is obtained through the probe, the electromagnetic coil excitation current is controlled according to the local magnetic field intensity signal, and the space magnetic field meeting the test requirements is generated;

[0057] S4, real-time monitoring of full-field strain: during the magnetic field load loading process in step S3, the digital image correlation technology is used to monitor the full-field dynamic strain field and crack size of the test disc piece in real time, and the surface strain distribution and crack propagation behavior of the test disc piece at each moment during the load loading process are analyzed.

[0058] It should be noted that in step S1, in actual application, considering the complex and variable characteristics of the rotating centrifugal load suffered by the real disc structure during rotation, when designing the distribution of the magnetic field vector in space based on the distribution of the rotating centrifugal load suffered by the real disc structure during rotation, it is appropriate to make the test disc piece in the magnetic field suffer similar overall stress and strain distribution, and the dangerous part of the test disc piece suffer the same local stress and strain distribution as in the rotating state.

[0059] It can be understood that the closer the stress and strain distribution of the test disc piece in the magnetic field to the actual situation, the more accurate the test results will be. In the present application, the similar overall stress and strain distribution means that the maximum difference between the stress and strain distribution of the test disc piece in the magnetic field and the actual stress and strain distribution of the real disc structure is not more than ± 10%, preferably ± 6%; and the same local stress and strain distribution means that the maximum difference between the stress and strain distribution of the dangerous part of the test disc piece in the magnetic field and the actual stress and strain distribution of the real disc structure is not more than ± 5%, preferably ± 3%.

[0060] As some examples of the present application, in the step S1, when the disc structure is an equal-thickness disc type disc, according to the stress and strain distribution of the disc structure in the simulated rotating state, the distribution of the magnetic field vector in space, i.e. the form of the target space magnetic field, is designed as shown in the following formula: Figure 1 The direction of the target space magnetic field is diverged outward from the center of the disc structure along the radius, the strength of the target space magnetic field is linearly distributed along the radial direction, and the magnetic field form is a ring-shaped radial magnetic field.

[0061] The following takes the design process of the target space magnetic field of the equal-thickness disc type disc as an example to illustrate the specific implementation process of step S1:

[0062] 1) Analysis of the characteristics of the rotating centrifugal load on the rotating disc structure, and design of the distribution of the magnetic field vector in space according to the analysis: the example selects the commonly used equal-thickness disc type disc as the characteristic structure of the disc, which can be used as the turbine disc, compressor disc, gas turbine disc, etc. of the engine. When the centrifugal load acts on the disc structure, the centrifugal force acting on each microelement in the volume of the disc is directed radially outward. According to the force direction of the magnetic material in the magnetic field, i.e. the magnetic force direction is the magnetic induction line direction, a radial magnetic field with a shape as shown in Fig. 1 is obtained, and the magnetic field direction radiates from the center hole of the disc structure to the disc rim along the radial direction. Figure 1

[0063] 2) On this basis, the magnetic field intensity distribution is designed:

[0064] Analysis shows that: when the temperature is constant, the radial and circumferential stress distributions of the equal-thickness disc in the plane polar coordinate system parallel to the disc surface in the rotating state satisfy the following analytical expressions (a) and (b) respectively:

[0065]

[0066] Where E is the elastic modulus of the disc material, v is the Poisson's ratio, u is the displacement component in the radial direction, and r is the radial coordinate of the polar coordinate system.

[0067] And the volume force density of the magnetic material in the magnetic field can be represented by the following formula (c):

[0068]

[0069] Where, is the current density inside the material, is the magnetic induction intensity, H is the local magnetic field intensity, μ is the magnetic permeability of the material, and τ is the volume density.

[0070] Then, the volume force of the radial magnetic field is substituted into the stress distribution calculation method of the rotating disc, and the magnetic field intensity that simulates the stress and strain distribution of the disc structure in the rotating state should satisfy:

[0071] The magnetic field intensity and the magnetic field radius are linearly related, i.e. the target space magnetic field takes the center of the radial magnetic field as the origin, and the intensity of the magnetic field is linearly distributed along the radial direction.

[0072] Specifically, in the plane polar coordinate system parallel to the magnetic field direction, the distribution of the magnetic field intensity should satisfy the following formula (d):

[0073]

[0074] ​Wherein, H(r) represents the magnetic field strength everywhere in space, r is the radial coordinate of the polar coordinate system, omega is the angular velocity corresponding to the rotating disc, and p is the density of the disc material.

[0075] Thus, when the wheel disc structure is an equal-thickness disc wheel, the direction of the target space magnetic field diverges outward along the radius from the center of the wheel disc structure, the strength of the target space magnetic field is linearly distributed along the radial direction, and the magnetic field form is a ring-shaped radial magnetic field.

[0076] On the basis of the above analysis, for an equal-thickness disc wheel, the electromagnetic field can be designed according to the different wheel disc materials and different required loads according to the above formula.

[0077] In the present application, the distribution of the rotating centrifugal load of the wheel disc structure in the rotating state is obtained by analyzing the characteristics of the rotating centrifugal load of the wheel disc structure in the rotating state according to the structural characteristics of the wheel disc. This is well known to those skilled in the art, and only the most commonly used equal-thickness disc wheel is taken as an example to analyze the characteristics of the rotating centrifugal load. Other types of wheel discs are not described one by one.

[0078] Further, the implementation process of step S2 is as shown in Figure 3 For the design of the electromagnetic loading device, the arrangement of the electromagnetic coil array is mainly designed, which specifically includes the following steps:

[0079] S21, different coil input parameters are set, including but not limited to: coil number, excitation current, arrangement radius, coil gap, gap between coil and test disc, etc. It can be understood that the more comprehensive the coil input parameter setting is, the more influencing factors it contains, the more diversified the spatial magnetic field distribution form is, and the more accurate and comprehensive the electromagnetic coil array parameters required by the test obtained by back calculation will be. Therefore, the stress and strain distribution of the test disc in the finally obtained test space magnetic field will be closer to the stress and strain distribution of the real wheel disc structure in the rotating state, and the test result will be more accurate.

[0080] S22, train the agent model by adjusting the coil input parameter combination, and output the spatial magnetic field distribution form corresponding to each coil input parameter combination through the agent model;

[0081] S23, the magnetic field parameters of the target space magnetic field designed in step S1 are substituted into the agent model, and the characteristic parameters of the electromagnetic loading device required by the test, especially the electromagnetic coil array parameters, are obtained by back calculation. Therefore, after arranging the electromagnetic coil array according to the back-calculated electromagnetic coil array parameters, the spatial electromagnetic field meeting the design requirements can be generated.

[0082] Further, in the step S23, the magnetic field parameters of the target space magnetic field include but are not limited to the shape, direction and intensity distribution of the magnetic field; the magnetic field parameters of the target space magnetic field can be obtained according to the target space magnetic field designed in the step S1.

[0083] It should be noted that in the step S23, after the electromagnetic coil array parameters are determined and the electromagnetic coil array is arranged according to the parameters, the generated space magnetic field is consistent with the target space magnetic field, but the intensity and frequency of the space magnetic field often change during the test process due to the change of the test load loading demand, so the intensity and frequency of the space magnetic field need to be adjusted according to the method described in the step S3 according to the test requirements.

[0084] The design principle of the electromagnetic loading device described in the application is as follows: first, the electromagnetic coil array design process is as shown in Figure 3 The number, excitation current, arrangement radius and other parameters of different electromagnetic coils are taken as inputs, and the corresponding magnetic field space distribution is taken as output, and the proxy model between the electromagnetic coil array and the magnetic field is trained by machine learning method. For disc pieces of different geometric sizes and geometric configurations, the corresponding electromagnetic coil array parameters in the electromagnetic loading device are inversely deduced according to this proxy model, such as the number of electromagnetic coil arrangement, the size of excitation current, the arrangement radius and other characteristic parameters, to obtain a space electromagnetic coil array that meets the requirements of the test device, as shown in Figure 2 At the same time, for different test piece sizes and different test parameters, the variables in the design process can be adjusted at any time, which retains the ability of the electromagnetic loading test method and system described in the application to simulate the centrifugal load of various different specifications of disc test pieces.

[0085] Further, in the step S3, probes can be arranged in different regions of the space magnetic field, and the local magnetic field intensity signals can be obtained by the probes to carry out the space magnetic field intensity monitoring, and the field intensity signals are fed back to the input end of the electromagnetic coil array parameters to realize the control of the magnetic field frequency and the field intensity.

[0086] Further, in the step S4, the speckle image can be pre-prepared on the test disc piece, and the speckle image of the surface of the test disc piece can be continuously shot by the camera during the real-time monitoring of the full-field strain; and the speckle image shot during the test process is compared with the speckle image of the surface of the disc simulation piece shot before the test, and the digital image correlation technology is used to monitor the full-field dynamic strain field and crack size of the test disc piece in real time, and the surface strain distribution and crack propagation behavior of the test disc piece at each moment during the load loading process are analyzed.

[0087] Specifically, the step S4 is implemented as follows: before the test, the speckle is sprayed on the surface of the test disc, during the electromagnetic loading, the speckle image change is captured by the camera and transmitted into the computer in real time, as shown in the figure, the digital image correlation analysis method is used in the computer to compare each frame of image with the initial speckle reference image, the disc full-field strain distribution is calculated, the real-time observation of the strain and the real-time monitoring of the crack size in the example are realized, and the surface strain distribution and crack propagation behavior of the test disc at each moment during the loading process are analyzed. Figure 4

[0088] In addition, the application also provides an electromagnetic loading test system for simulating the stress and strain in the rotating state of a wheel disc, which is used to implement the electromagnetic loading test method, and comprises:

[0089] a test disc 1 made of ferromagnetic material, which has the same structure as a real wheel disc, and has a pre-prepared crack and a speckle image arranged thereon;

[0090] an electromagnetic loading device for forming a spatial magnetic field around the test disc 1;

[0091] a feedback and control device of the electromagnetic load, which comprises a plurality of probes arranged in the spatial magnetic field, the local magnetic field intensity signal can be obtained through the probes, and the feedback and control device of the electromagnetic load can control the excitation current of the electromagnetic coil according to the local magnetic field intensity signal to generate a spatial magnetic field meeting the test requirements;

[0092] a measurement and analysis device for monitoring the full-field dynamic strain field and crack size of the test disc 1 in real time during the magnetic field load loading process, and analyzing the surface stress and strain distribution and crack propagation behavior of the test disc 1 at each moment during the load loading process based on the digital image correlation technology.

[0093] As some embodiments of the application, a plurality of pre-prepared cracks with different positions, directions and sizes can be designed on the test disc 1, and the pre-preparation of multiple cracks coupling in the real situation can also be carried out.

[0094] Further, the test disc 1 has the same size and structure as a real wheel disc, or the test disc 1 is prepared according to the real wheel disc structure by equal proportion magnification or reduction.

[0095] Further, the electromagnetic loading device comprises:

[0096] ​An electromagnetic coil array 2 comprising a plurality of electromagnetic coils, which are distributed in the test system space according to test requirements, and are arranged in an array in a certain number in the circumferential direction of the system, and the electromagnetic coils can exert magnetic field force on the test disc 1 under the excitation of electric current, and a spatial electromagnetic field meeting the test requirements is generated by the cooperation of each electromagnetic coil in the electromagnetic coil array 2.

[0097] And a fixing and supporting device for arranging each electromagnetic coil in the electromagnetic coil array 2 in the test system space.

[0098] As some examples of the present application, the fixing and supporting device for the electromagnetic coil array 2 can be an annular support arranged on the surface of the test disc 1 and in the surrounding space.

[0099] As some examples of the present application, the electromagnetic coils in the electromagnetic coil array 2 are distributed in the test system space, the electromagnetic coils are distributed on the disc edge of the test disc 1, and the electromagnetic coils are arranged in an array in a certain number in the circumferential direction of the test system and in a certain number in the radial direction of the test disc 1, and a spatial magnetic field distribution form required by the test, such as a radial spatial magnetic field, is generated by the cooperation of the plurality of electromagnetic coils, wherein the field strength, direction and shape of the magnetic field are determined by relevant parameters such as the arrangement position of each coil in the electromagnetic coil, the gap size between the coil and the test disc 1, and the excitation current intensity. When loading, the above parameters are used as input, and the magnetic field vector is used as output, and a proxy model between the coil input and the magnetic field output is trained using machine learning. Then, for different geometric parameters of the test disc 1, the proxy model can be used to inversely deduce the input parameters such as the arrangement of the electromagnetic coil array 2 corresponding to the stress and strain distribution under the rotating state of the wheel disc.

[0100] Further, the electromagnetic load feedback and control device is connected with the electromagnetic loading device, and the electromagnetic load feedback and control device comprises:

[0101] A direct current power supply, which is an adjustable direct current stabilized power supply, and is used to provide electric current to the electromagnetic coil;

[0102] An electromagnetic relay connected in series with the direct current power supply, which is used to control the direct current power supply according to test requirements;

[0103] The electromagnetic coil in the electromagnetic coil array 2 is connected in series with the electromagnetic relay and the direct current power supply.

[0104] Preferably, each electromagnetic coil in the electromagnetic coil array 2 is connected in series with the electromagnetic relay and the direct current power supply, so that the size of the electric current in each electromagnetic coil can be individually regulated.

[0105] As some examples of the present application, the feedback and control device of the electromagnetic load can control the size of the magnetic field force generated by the electromagnetic coil by adjusting the output power of the direct current power supply; the feedback and control device of the electromagnetic load can control the generation frequency of the magnetic field force load by adjusting the energization delay of the electromagnetic relay, thereby achieving rapid control of the frequency of the magnetic field force.

[0106] Furthermore, the feedback and control device of the electromagnetic load further comprises:

[0107] a plurality of probes arranged in the spatial magnetic field to obtain and feedback the local magnetic field strength signal;

[0108] a control module connected with the probes, the direct current power supply and the electromagnetic relay, respectively, the control module being capable of controlling the size of the output current of the direct current power supply and the energization delay of the electromagnetic relay, in addition, the control module being capable of receiving the local magnetic field strength signal monitored by the probes and performing electromagnetic loading on the test disc 1 according to the local magnetic field strength signal and different test requirements by using different electromagnetic loading parameters, wherein the electromagnetic loading parameters include: load frequency, load amplitude, etc.

[0109] In this way, the electromagnetic loading test system can realize low cycle fatigue test of the test disc 1, and at the same time, the electromagnetic loading test system can also have the ability to observe the full-field strain distribution and crack propagation process of the disc in real time.

[0110] As some examples of the present application, the feedback and control device of the electromagnetic load comprises a Tesla meter probe, a direct current power supply, an electromagnetic relay and a control module, the Tesla meter probe arranged in the spatial magnetic field obtains the local magnetic field strength signal, which is fed back to the control module, the control module controls the excitation current of the electromagnetic coil through the direct current power supply to generate a stable electromagnetic field meeting the test requirements of the disc. At the same time, the direct current power supply and the electromagnetic relay are connected in series to control the change frequency of the magnetic field, thereby realizing diversification of the electromagnetic load, so that low cycle fatigue test, fatigue / creep test, etc. of the disc can be performed.

[0111] Further, the measurement and analysis device comprises:

[0112] a camera 3 arranged opposite to the test disc 1, the camera 3 being used to continuously shoot speckle images on the surface of the test disc 1 during the test;

[0113] a computer 4 having software for crack propagation analysis based on the speckle images shot by the camera 3 installed therein.

[0114] As some examples of the present application, the software required for crack propagation analysis based on the speckle images taken by the camera 3 includes image analysis software, stress and strain analysis software, such as DIC strain analysis software, ANSYS stress and strain analysis software, etc. Among them, the process and method of crack propagation analysis and stress and strain distribution analysis through relevant computer analysis software based on the speckle images obtained during the crack propagation process are well known to those skilled in the art, and the analysis process will not be described in detail here.

[0115] As some examples of the present application, during the test process, a shooting space for the camera 3 is reserved directly above the test disc 1, as shown in detail in Figure 4 During the process of load loading, the speckle image changes are continuously taken and transmitted into the computer 4 in real time. At the same time, using the digital image correlation method, each frame of image taken is compared with the initial speckle as the reference image, the local stress and strain distribution at each moment is analyzed, the crack length is judged according to the stress concentration phenomenon at the crack tip, and the real-time observation of crack propagation in this example is realized.

[0116] In addition, the electromagnetic loading test system for simulating the stress and strain under the rotating state of the disc further comprises a protective device 5 which is annular, and the protective device 5 wraps the test disc 1 and the electromagnetic coil array 2 inside to prevent damage caused by the magnetic field force flying out after the test disc 1 breaks, and at the same time, the electromagnetic coil or the support for fixing it can be installed on the protective device 5 to support each electromagnetic coil.

[0117] At present, in the application of motor, the magnetic field is built by current load electromagnetic coil to convert energy, which has the characteristics of high energy conversion efficiency and fast conversion frequency. The principle is that the stator coil and the rotor coil inside the motor are passed through alternating current or direct current to produce high-intensity magnetic field, and the stator winding magnetic field and the rotor winding magnetic field interact with each other, so as to directly convert electric energy into kinetic energy of the rotor. The large load generated in this process can drive some large machinery. Based on this, the electromagnetic loading test method and system for simulating the stress and strain under the rotating state of the disc proposed by the present application puts forward a load loading test method using electromagnetic exciter for high-frequency load application in the field of engine structure strength test, which designs an electromagnetic loading test method for load application in the process of disc test, and according to the principle of interaction between magnetic field and ferromagnetic material, an electromagnetic loading test method for simulating the stress and strain distribution under the rotating state of the disc is designed.

[0118] Compared with the prior art, the electromagnetic loading test method and system for simulating the stress and strain under the rotating state of the disc has the characteristics of simple operation, strong controllability, high energy conversion efficiency, low cost, short cycle, good compatibility, real-time observation of full-field strain and real-time tracking record of crack tip expansion, etc., which is specifically shown in the following aspects:

[0119] 1) The electromagnetic loading method of the application has wide applicability: for different geometric sizes and shapes of power machinery wheel discs, such as aircraft engine wheel discs, gas turbine wheel discs and other structures that need to be tested for different types of strength tests, the method can be used to load the required load after the simulation piece is made.

[0120] 2) The electromagnetic loading method can realize real-time observation of the full-field strain of the wheel disc and real-time tracking of the crack tip expansion: based on the digital image correlation technology, the application can realize real-time observation of the full-field strain of the wheel disc and real-time tracking of the crack tip expansion during crack expansion of the feature simulation piece structure. Compared with traditional loading test devices, the application solves the problem that cameras cannot be used to observe high-speed rotating discs during the test process.

[0121] 3) The electromagnetic loading method has strong controllability: during the loading process of the electromagnetic load, multiple links can be adjusted to meet the test requirements. For example, during the load control stage, the DC power supply can adjust the amplitude of the electromagnetic load, and the electromagnetic relay can control the frequency of the electromagnetic load loading. During the crack expansion process, the frequency and amplitude of the cyclic loading load can also be adjusted at any time according to the observation results, and the test process is controllable.

[0122] 4) The electromagnetic loading method has high energy conversion efficiency and low energy consumption: for some traditional test devices, the acceleration period from the static state of the wheel disc test piece to the working speed is long, the energy consumption is large, and the energy conversion efficiency is low. The electromagnetic loading method only involves energy conversion between electric energy and magnetic field energy, has high energy conversion efficiency, and greatly reduces the required energy compared to traditional methods.

[0123] 5) The electromagnetic loading method is clean, environmentally friendly and non-polluting: the processing methods of each link of the application have multiple options, and environmentally friendly materials can be selected for testing without generating or releasing harmful substances, and the test process is clean and environmentally friendly.

[0124] In summary, the electromagnetic loading test method and system for simulating the stress and strain of a rotating wheel disc can achieve static loading of the test disc 1, the full-field stress and strain distribution of the wheel disc is consistent with that in the rotating state, the crack propagation behavior and full-field strain of the wheel disc under the load can be monitored in real time, and the method has the characteristics of simple operation, strong controllability, high energy conversion efficiency, low cost, short cycle, good compatibility and the like.

[0125] The embodiments of the present application are described above with reference to the drawings, and the embodiments and features in the embodiments of the present application can be combined with each other without conflict, and the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are only illustrative but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and all belong to the protection of the present application.

Claims

1. An electromagnetic loading test method for simulating stress-strain in a wheel rotating state, characterized by, Comprising steps of: S1, magnetic field design for simulating stress and strain distribution of a wheel disc in a rotating state: analyzing characteristics of a rotating centrifugal load borne by a real wheel disc structure in rotation to obtain a distribution of the rotating centrifugal load borne by the real wheel disc structure in the rotating state; and then designing a distribution of a magnetic field vector in space based on the distribution of the rotating centrifugal load borne by the real wheel disc structure in rotation to obtain a target space magnetic field capable of simulating stress and strain distribution of the real wheel disc structure in the rotating state, wherein the test disc is subjected to consistent stress and strain distribution in the target space magnetic field as in the rotating state of the real wheel disc structure; In the step S1, when the wheel disc structure is an equal-thickness disc wheel, a direction of the target space magnetic field diverges outward from a center of the wheel disc structure along a radius, and a strength of the target space magnetic field linearly distributes along the radius, and the magnetic field is in a form of a ring-shaped radial magnetic field; The process of designing the magnetic field strength distribution is as follows: When the temperature is constant, the radial and circumferential stress distributions of the equal-thickness disc in the rotating state in a plane polar coordinate system parallel to a surface of the disc satisfy the following analytical expressions (a) and (b): wherein E is the modulus of elasticity of the disc material, In the magnetic field, a volume force density of the magnetic material is expressed by the following expression (c): is the Poisson's ratio, u is the displacement component in the radial direction, r is the radial coordinate in the polar coordinate system; The magnetic field strength of the radial magnetic field should satisfy the following expression (d) after the volume force of the radial magnetic field is substituted into a stress distribution calculation method of the rotating wheel disc: wherein, is the current density inside the material, is the magnetic induction, H is the local magnetic field strength, The target space magnetic field takes a center of the radial magnetic field as an origin, and the strength of the magnetic field linearly distributes along the radius; is the magnetic permeability of the material, and τ is the volume density; In the plane polar coordinate system parallel to the direction of the magnetic field, the distribution of the magnetic field strength should satisfy the following expression (d): S2, electromagnetic loading device design: first, training an agent model between each input parameter combination of an electromagnetic coil array and a final magnetic field output form by using machine learning, and then substituting magnetic field parameters of the target space magnetic field designed in the step S1 into the agent model to obtain electromagnetic coil array parameters required by the test by backstepping; S3, electromagnetic load feedback and control: arranging the electromagnetic coil array in a space around the test disc according to the electromagnetic coil array parameters obtained by backstepping in the step S2, and setting a probe in the space magnetic field to obtain and feed back local magnetic field strength signals through the probe, and controlling an electromagnetic coil excitation current according to the local magnetic field strength signals to generate a space magnetic field meeting test requirements; in, H ( r () represents the magnetic field strength at various points in space. r For the radial coordinates in the polar coordinate system, S4, real-time monitoring of full-field strain: monitoring a full-field dynamic strain field and a crack size of the test disc in real time based on a digital image correlation technique during the magnetic field load loading process in the step S3, and analyzing surface strain distribution and crack propagation behavior of the test disc at each time during the load loading process. To correspond to the angular velocity of the rotating disk, The step S2 comprises: The density of the disk material; S21, setting different coil input parameters; S22, training the agent model by adjusting the coil input parameter combination, and outputting a space magnetic field distribution form corresponding to each coil input parameter combination through the agent model; S23, substituting the magnetic field parameters of the target space magnetic field designed in the step S1 into the agent model to obtain electromagnetic coil array parameters required by the test by backstepping, arranging the electromagnetic coil array according to the electromagnetic coil array parameters obtained by backstepping, and generating a space electromagnetic field meeting design requirements.

2. The electromagnetic loading test method according to claim 1, characterized by, ​ ​ ​ ​ 3. The electromagnetic loading test method according to claim 1, characterized by, In the step S4, the speckle image is pre-prepared on the test disc, and the speckle image of the surface of the test disc is continuously captured by using the camera in the real-time monitoring of the full-field strain; and the speckle image captured in the test process is compared with the speckle image of the surface of the test disc captured before the test, the dynamic strain field and the crack size of the test disc are monitored in real time based on the digital image correlation technology, and the surface strain distribution and the crack propagation behavior of the test disc at each moment in the load loading process are analyzed.

4. An electromagnetic loading test system for simulating stress-strain in a wheel rotating state, characterized by, The electromagnetic loading test system is used to implement the electromagnetic loading test method in any one of claims 1-3, and the electromagnetic loading test system comprises: a test disc (1) made of ferromagnetic material, the test disc (1) having the same structure as a real disc, and a pre-prepared crack and a speckle image being arranged on the test disc (1); an electromagnetic loading device for forming a spatial magnetic field around the test disc (1); an electromagnetic load feedback and control device comprising a plurality of probes arranged in the spatial magnetic field, the local magnetic field intensity signals being acquired by the probes, and the electromagnetic load feedback and control device being capable of controlling the electromagnetic coil excitation current according to the local magnetic field intensity signals to generate a spatial magnetic field meeting the test requirements; a measurement and analysis device for monitoring the dynamic strain field and the crack size of the test disc (1) in real time based on the digital image correlation technology in the magnetic field load loading process, and analyzing the surface stress and strain distribution and the crack propagation behavior of the test disc (1) at each moment in the load loading process.

5. The electromagnetic loading test system of claim 4, wherein, The electromagnetic loading device comprises: an electromagnetic coil array (2) comprising a plurality of electromagnetic coils, the plurality of electromagnetic coils being distributed in the test system space according to the test requirements, the electromagnetic coils being capable of applying a magnetic field force to the test disc (1) under the excitation of the current, and the spatial electromagnetic field meeting the test requirements being generated by the cooperation of each electromagnetic coil in the electromagnetic coil array (2).

6. The electromagnetic loading test system of claim 5, wherein, The electromagnetic load feedback and control device comprises: a direct current power supply, which is an adjustable direct current stabilized power supply, and is used to provide the current to the electromagnetic coil; an electromagnetic relay connected in series with the direct current power supply, and used to control the direct current power supply according to the test requirements; the electromagnetic coils in the electromagnetic coil array (2) are connected in series with the electromagnetic relay and the direct current power supply; the electromagnetic load feedback and control device is capable of controlling the size of the magnetic field force generated by the electromagnetic coil by adjusting the output power of the direct current power supply, and is capable of controlling the generation frequency of the magnetic field force load by adjusting the energization delay length of the electromagnetic relay.

7. The electromagnetic loading test system of claim 6, wherein, The electromagnetic load feedback and control device further comprises: a plurality of probes arranged in the spatial magnetic field to acquire and feed back the local magnetic field intensity signals. A control module is connected with the probe, the direct current power supply and the electromagnetic relay respectively, and is capable of controlling the size of the direct current power supply output current and the energizing delay length of the electromagnetic relay; the control module is also capable of receiving the local magnetic field intensity signal monitored by the probe, and performing electromagnetic loading on the test disc piece (1) according to the local magnetic field intensity signal and different electromagnetic loading parameters required by different tests.

8. The electromagnetic loading test system of claim 4, wherein, The measuring and analyzing device comprises: A camera (3) is arranged opposite to the test disc piece (1), and is used for continuously shooting speckle images on the surface of the test disc piece (1) during the test; A computer (4) is internally installed with software for crack propagation analysis based on the speckle images shot by the camera (3).

9. The electromagnetic loading test system of claim 4, wherein, The electromagnetic loading test system for simulating the stress and strain of the rotating state of the disc further comprises a protection device (5) which is annular, and the protection device (5) wraps the test disc piece (1) and the electromagnetic coil array (2) inside.

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