Cold and hot impact test method and system for synchronously applying multi-dimensional stress

Abstract

The invention discloses a cold and hot impact test method and system for synchronously applying multi-dimensional stress, and relates to the technical field of material tests.The method comprises the steps that space time temperature distribution of a test material in the cold and hot impact process is obtained, and a thermal stress field is established; superposing the external mechanical stress field and the thermal stress field to obtain a comprehensive stress field, coupling thermal stress and mechanical stress, and calculating comprehensive strain; and acquiring real-time monitoring data of the test material in cold and hot impact and multi-dimensional stress environments, calculating an experiment monitoring index, performing threshold judgment, and when the experiment monitoring index is greater than a preset threshold, performing accumulative analysis on the test material, outputting an accumulative damage measure, and completing the test. By comprehensively considering the superimposed effect of mechanical stress and thermal stress, damage accumulation in a multi-dimensional stress environment is monitored in real time, and the fatigue life and the potential failure mode of the material are scientifically predicted through a multi-factor coupling damage assessment method, so that the accuracy of reliability assessment of the material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of material testing, and in particular to a method and system for performing a hot and cold shock test by synchronously applying multi-dimensional stress. Background Art

[0002] In many engineering applications, metal materials are often in an alternating hot and cold environment, and are subjected to external mechanical loads and internal and external temperature changes at the same time. This complex stress state has an important impact on the performance and life of metal materials, especially under the alternating action of complex loads and temperature changes, which may cause fatigue, crack propagation or other failure modes of metal materials. Therefore, it is very important to understand the behavior of metal materials under the simultaneous action of hot and cold shocks and mechanical stresses.

[0003] Traditional thermal shock test methods usually only consider the effect of temperature on metal materials, ignoring the effect of external mechanical stress on the performance of metal materials. Most of the existing composite load test methods are static and cannot truly reflect the comprehensive performance of metal materials under dynamic thermal shock conditions. These test methods cannot provide accurate experimental data to a certain extent, resulting in inaccurate reliability evaluation of metal materials in practical engineering applications.

[0004] At present, there is no unified standard for the test method for this kind of multi-factor, multi-dimensional stress synchronization. Especially in actual engineering tests, how to accurately simulate and simultaneously apply hot and cold shocks and mechanical loads, how to comprehensively analyze the test data, and how to evaluate the damage and performance degradation of metal materials are still technical challenges. Summary of the invention

[0005] Based on the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a hot and cold shock test method and system with simultaneous application of multi-dimensional stress to solve the above-mentioned technical problems.

[0006] To achieve the above object, the present invention provides the following technical solution: a hot and cold shock test method with simultaneous application of multi-dimensional stress, comprising:

[0007] Obtain the spatial and temporal temperature distribution of the test material during the thermal shock process, and establish the thermal stress field based on the spatial and temporal temperature distribution;

[0008] The external mechanical stress field is superimposed on the thermal stress field to obtain a comprehensive stress field, the thermal stress is coupled with the mechanical stress, and the comprehensive strain is calculated based on the stress-strain relationship of the material;

[0009] Acquire real-time monitoring data of the test material under cold and hot shock and multi-dimensional stress environment, and calculate the experimental monitoring index according to the real-time monitoring data;

[0010] A threshold value is judged for the experimental monitoring index. When it is greater than a preset threshold value, a cumulative analysis is performed on the damage of the test material in multiple cold and hot shocks, and a cumulative damage metric is output to complete the test.

[0011] The present invention is further configured such that, in the thermal stress field, the thermal stress tensor σ ij =αE(T(x,y,z,t)-T ref )δ ij , where σ ij is the thermal stress tensor, α is the thermal expansion coefficient, E is the elastic modulus, T(x, y, z, t) is the temperature distribution function in time and space, which is used to describe the temperature change of the test material during the test. ref is the reference temperature, is the initial temperature of the test material, δ ij is Kronecker's delta, a mathematical constant used to represent the diagonal elements in the identity matrix,

[0012] The present invention is further configured that the acquisition logic of the temperature distribution function T(x, y, z, t) in time and space includes:

[0013] Establishing a three-dimensional geometric model according to the actual size and shape of the sample material, and meshing the three-dimensional geometric model;

[0014] Setting a convection heat transfer coefficient, a radiation emissivity and a thermal conductivity coefficient for the surface of the three-dimensional geometric model;

[0015] Input the initial temperature value, use the time discretization method to solve the transient heat conduction control equation, and obtain the temperature distribution function of time and space at different times. The transient heat conduction control equation is: ρ is the material density, c p is the specific heat capacity and k is the thermal conductivity.

[0016] The present invention is further configured to: in, is the mechanical stress field, and the mechanical stress field Transformed into a multi-directional distribution in time and space, γ k is the mechanical stress amplitude, Ψ ijk (x, y, z, t) is the space-time stress distribution function.

[0017] The present invention is further configured such that the calculation logic of the comprehensive strain is: Among them, ∈ ij is the comprehensive strain, ν is the Poisson's ratio, which is used to describe the contraction ratio in the perpendicular direction when the test material is stretched in one direction. is the trace of the stress field, that is, the sum of all principal stresses, which is used to reflect the overall stress state.

[0018] The present invention is further configured such that the real-time monitoring data includes real-time stress, real-time strain, real-time temperature, real-time vibration amplitude, acoustic emission amplitude and real-time magnetic response signal.

[0019] The present invention is further configured to calculate the experimental monitoring index according to the real-time monitoring data, including:

[0020] Calculating a mechanical load factor based on the real-time stress and real-time strain;

[0021] Calculating a thermal magnetic coupling factor according to the real-time temperature and the real-time magnetic response signal;

[0022] Calculating the vibro-acoustic-magnetic coupling factor according to the real-time vibration amplitude, the acoustic emission amplitude and the real-time magnetic response signal;

[0023] The experimental monitoring index is calculated according to the mechanical load factor, the thermal magnetic coupling factor and the vibro-acoustic magnetic coupling factor.

[0024] The present invention is further configured such that the calculation logic of the mechanical load factor is: Among them, MLF(t) is the mechanical load factor at time t, ST(u) is the stress at time u, SR(u) is the strain at time u, cA and cB are constant coefficients, which are used to adjust the overall magnitude of the mechanical load factor and the exponential amplification effect of the strain respectively;

[0025] The calculation logic of the thermal magnetic coupling factor is: Wherein, TMC(t) is the thermomagnetic coupling factor at time t, TP(u) is the temperature at time u, MG(u) is the magnetic response signal at time u, and cC is a constant coefficient used to adjust the proportion of temperature magnetic coupling in the thermomagnetic coupling factor;

[0026] The calculation logic of the vibro-acoustic magnetic coupling factor is: Wherein, VAM(t) is the vibration-acoustic-magnetic coupling factor at time t, VB(u) is the vibration amplitude at time u, AC(u) is the acoustic emission amplitude at time u, MG(u) is the magnetic response signal at time u, and cD is the amplification factor, which is used to adjust the overall magnitude of the vibration-acoustic-magnetic coupling factor;

[0027] The calculation logic of the experimental monitoring index is: MHF(t) = [MLF(t)] f1 ×[TMC(t)] f2 ×[VAM(t)] f3, where MHF(t) is the experimental monitoring index at time t, and f1, f2 and f3 are exponential coefficients used to determine the relative influence of the factor in the experimental monitoring index.

[0028] The present invention is further configured such that the calculation logic of the cumulative damage metric is: Where D is the cumulative damage metric, N is the total number of hot and cold cycles, is the total stress of the nth thermal cycle, S ij is the fatigue strength of the test material in each direction, and m is the fatigue damage index.

[0029] The present invention also provides a hot and cold shock test system with synchronous multi-dimensional stress application, which is used to implement the above-mentioned hot and cold shock test method with synchronous multi-dimensional stress application, and the system includes:

[0030] Acquisition module: obtain the space-time temperature distribution of the test material during the hot and cold shock process, and establish the thermal stress field according to the space-time temperature distribution;

[0031] The first calculation module is: superimposing the external mechanical stress field with the thermal stress field to obtain a comprehensive stress field, coupling the thermal stress with the mechanical stress, and calculating the comprehensive strain based on the stress-strain relationship of the material;

[0032] The second calculation module is used to obtain real-time monitoring data of the test material under the cold and hot shock and multi-dimensional stress environment, and calculate the experimental monitoring index according to the real-time monitoring data;

[0033] Output module: perform threshold judgment on the experimental monitoring index. When it is greater than the preset threshold, perform cumulative analysis on the damage of the test material in multiple cold and hot shocks, output the cumulative damage measurement, and complete the test.

[0034] The present invention provides a method and system for a hot and cold shock test with synchronous multi-dimensional stress application. The method acquires the spatial-temporal temperature distribution of a test material during a hot and cold shock process, establishes a thermal stress field according to the spatial-temporal temperature distribution; superimposes an external mechanical stress field with the thermal stress field to obtain a comprehensive stress field, couples thermal stress with mechanical stress, and calculates the comprehensive strain based on the stress-strain relationship of the material; acquires real-time monitoring data of the test material under hot and cold shock and multi-dimensional stress environments, and calculates experimental monitoring indicators according to the real-time monitoring data; performs threshold judgment on the experimental monitoring indicators, and when the threshold is greater than a preset threshold, performs cumulative analysis on the damage of the test material in multiple hot and cold shocks, outputs a cumulative damage metric, and completes the test, and the beneficial effects produced include:

[0035] 1. Accurately simulate the stress state of materials in complex environments: It can comprehensively consider the superposition effect of mechanical stress and thermal stress, and accurately simulate the stress state of materials under the simultaneous action of cold and hot shock and multi-dimensional stress by establishing a comprehensive stress field. This method can more realistically reflect the stress state of materials in extreme environments, and effectively make up for the deficiency of traditional test methods that fail to consider the coupling effect of mechanical stress and thermal stress;

[0036] 2. Enhance the accuracy of material damage prediction: By obtaining real-time monitoring data of test materials under hot and cold shock and multi-dimensional stress environment, the present invention can calculate the experimental monitoring index in real time and make judgments based on thresholds, so as to accurately evaluate the damage accumulation of materials during multiple hot and cold shock processes. This provides a more scientific basis for material fatigue life prediction and reliability assessment.

[0037] 3. Damage assessment of multi-factor coupling: Through the joint calculation of thermal magnetic coupling factor, mechanical load factor and vibro-acoustic magnetic coupling factor, the damage state of the material under the action of different physical fields can be fully reflected, avoiding the one-sided evaluation of material performance by a single physical factor. Through comprehensive monitoring and analysis, the potential failure modes that may occur in the material in actual application can be more accurately identified.

[0038] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0040] Figure 1 A flow chart of a method for a thermal shock test with simultaneous application of multi-dimensional stresses is shown as an exemplary embodiment of the present invention;

[0041] Figure 2 The schematic diagram of the structure of a thermal shock test system for synchronously applying multi-dimensional stresses is shown as an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0043] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0044] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0045] Embodiment 1

[0046] A thermal shock test method with simultaneous application of multi-dimensional stresses, such as Figure 1 As shown, including:

[0047] Obtain the spatial and temporal temperature distribution of the test material during the thermal shock process, and establish the thermal stress field based on the spatial and temporal temperature distribution;

[0048] The external mechanical stress field is superimposed on the thermal stress field to obtain a comprehensive stress field, the thermal stress is coupled with the mechanical stress, and the comprehensive strain is calculated based on the stress-strain relationship of the material;

[0049] Acquire real-time monitoring data of the test material under cold and hot shock and multi-dimensional stress environment, and calculate the experimental monitoring index according to the real-time monitoring data;

[0050] A threshold value is judged for the experimental monitoring index. When it is greater than a preset threshold value, a cumulative analysis is performed on the damage of the test material in multiple cold and hot shocks, and a cumulative damage metric is output to complete the test.

[0051] The present invention is further configured such that, in the thermal stress field, the thermal stress tensor σ ij =αE(T(x,y,z,t)-T ref )δ ij , where σ ijis the thermal stress tensor, α is the thermal expansion coefficient, E is the elastic modulus, T(x, y, z, t) is the temperature distribution function in time and space, which is used to describe the temperature change of the test material during the test. ref is the reference temperature, is the initial temperature of the test material, δ ij is Kronecker's delta, a mathematical constant used to represent the diagonal elements in the identity matrix, Specifically, σ ij Represents the thermal stress tensor. Thermal stress is generated because the material expands or contracts when the temperature changes. However, due to the boundary or shape restrictions of the material, it cannot change freely, thus forming stress; the subscript ij in the thermal stress tensor represents the direction and action surface of the stress; the thermal expansion coefficient α is a physical quantity that measures the degree of linear expansion caused by a unit temperature change of the material. Different materials have different thermal expansion coefficients. Usually, this coefficient changes with temperature, but within a small temperature range, it can usually be regarded as a constant, which is confirmed by the composition of the material to be tested; the elastic modulus E represents the material's ability to resist deformation. The larger the elastic modulus, the smaller the deformation of the material when subjected to external force or temperature changes; in the above calculation logic, Kronecker δ is used to ensure that the stress tensor σ ij Independence between different directions. When i = j, δ ij =1, indicating that this is stress in the same direction; when i≠j, δ ij =0, indicating that there is no direct stress between different directions; the temperature distribution function T(x, y, z, t) in time and space is the temperature distribution function of the material during the test, taking into account the changes in space and time, and describes the temperature changes of the test material at different positions and times.

[0052] The present invention is further configured that the acquisition logic of the temperature distribution function T(x, y, z, t) in time and space includes:

[0053] A three-dimensional geometric model is established according to the actual size and shape of the sample material, and the three-dimensional geometric model is meshed; specifically, according to the actual size and shape of the sample material, a three-dimensional geometric model of the material is first established to accurately describe the shape and size of the material in practical applications, and to provide a basis for subsequent heat conduction simulations. The three-dimensional geometric model should not only reflect the physical shape of the sample, but also include boundary conditions, including the boundaries of heat sources and heat flows; the established three-dimensional geometric model is meshed, that is, the model is divided into several small units. The temperature on each unit will be used as the basic unit for solution. The finer the mesh, the higher the accuracy of the solution, but the amount of calculation will also increase. Meshing is usually adjusted based on the complexity of the model and the required calculation accuracy. For more complex structures or occasions requiring high-precision results, the mesh should be finer;

[0054] Convective heat transfer coefficient, radiation emissivity and thermal conductivity coefficient are set for the surface of the three-dimensional geometric model; specifically, thermal boundary conditions such as convection heat transfer coefficient, radiation emissivity and thermal conductivity coefficient are set on the surface of the three-dimensional geometric model. The convection heat transfer coefficient indicates the heat exchange capacity between the material surface and the surrounding fluid. It is usually obtained through fluid mechanics analysis or experiments; the radiation emissivity indicates the ability of the material surface to radiate heat. Different materials have different radiation emissivities, and for materials such as metals and ceramics, the radiation emissivity will be significantly different. The thermal conductivity coefficient describes the ability of the material to conduct heat inside. The thermal conductivity of different materials varies greatly;

[0055] Input the initial temperature value, use the time discretization method to solve the transient heat conduction control equation, and obtain the temperature distribution function of time and space at different times. The transient heat conduction control equation is: ρ is the material density, c p is the specific heat capacity, and k is the thermal conductivity. Specifically, the initial temperature of the input material is the starting point of the simulation, and the subsequent temperature changes will be calculated based on this value; the transient heat conduction control equation is solved in a time-discrete manner, which means that the time is divided into several small time steps, and the temperature distribution is calculated at each time step; by solving the above heat conduction equation, the temperature distribution function at different time and spatial positions is obtained, which not only reflects the temperature distribution of the test material in space, but also considers the change of temperature over time, calculates the process of temperature change over time on each grid unit, and gradually approaches the final state of the temperature distribution. By establishing a three-dimensional geometric model and setting the physical boundary conditions of heat conduction, the temperature change of the material during the test can be accurately calculated, especially the temperature distribution under complex conditions; by solving the transient heat conduction control equation in a time-discrete manner, a high-precision temperature distribution function can be obtained, so that the dynamic behavior of heat conduction can be tracked in detail, thereby providing more accurate data support for the thermal stress analysis of the material; by setting the convection heat transfer coefficient, radiation emissivity and thermal conductivity coefficient on the surface, it can adapt to the heat exchange characteristics of different materials and different environmental conditions, making the temperature calculation results more universal and applicable.

[0056] The present invention is further configured to: in, is the mechanical stress field, and the mechanical stress field Transformed into a multi-directional distribution in time and space, γ k is the mechanical stress amplitude, Ψ ijk (x, y, z, t) is the space-time stress distribution function. Specifically, the comprehensive stress field It represents the comprehensive stress field of the material during the thermal shock process, that is, the superposition of the thermal stress field and the mechanical stress field. The construction of the comprehensive stress field first considers the thermal stress field σ ij , that is, the stress caused by temperature change. Secondly, consider the mechanical stress field The stress field reflects the influence of mechanical load on the material under the action of external force. By adding the two, a comprehensive stress field is formed. Furthermore, the mechanical stress field It represents the stress generated by external forces (including tension, compression and shear) in the material. In order to accurately describe the distribution of mechanical stress field in time and space, the space-time stress distribution function Ψ is used. ijk (x, y, z, t) is used to represent the change of mechanical stress field. This function characterizes the distribution of stress field in space coordinates and time, and is fitted by numerical simulation (including finite element analysis) to accurately describe the influence of mechanical load on material. The specific implementation steps are similar to the logic of obtaining temperature distribution function in time and space, and will not be elaborated here. By introducing mechanical stress field and thermal stress field and combining them into a comprehensive stress field, the present invention can comprehensively reflect the stress state of material under multi-dimensional stress environment. This coupling of multiple physical fields provides more accurate simulation data for the performance analysis of test materials; the mechanical stress field is described in the form of space-time stress distribution function, which can accurately reflect the change of mechanical load at different spatial points and time. This makes the stress state of material more realistically reproduced and provides a reliable basis for subsequent strain and damage analysis; by comprehensively considering the superposition effect of thermal stress and mechanical stress, the present invention provides a more scientific and accurate material performance evaluation method. This has important application value in fatigue life prediction, reliability analysis and other aspects of materials.

[0057] The present invention is further configured such that the calculation logic of the comprehensive strain is: Among them, ∈ ij is the comprehensive strain, ν is the Poisson's ratio, which is used to describe the contraction ratio in the perpendicular direction when the test material is stretched in one direction. is the trace of the stress field, that is, the sum of all principal stresses, which is used to reflect the overall stress state. Specifically, according to the above calculation logic, the comprehensive strain can be divided into two parts: the strain caused by the comprehensive stress field This term represents the strain caused by the combined effect of mechanical stress field and thermal stress field. The strain calculation of this part is based on the elastic modulus E of the material and takes into account the proportional relationship of the deformation of the material in different directions (i.e. Poisson effect); the strain α caused by temperature change (TT ref )δ ij, which represents the thermal strain caused by temperature change, taking into account the thermal expansion effect of the material, α is the thermal expansion coefficient, which represents the proportion of material length change caused by unit temperature change; by combining the calculation of mechanical stress and thermal stress, the influence of various factors on material strain can be more comprehensively considered. This comprehensive strain calculation method can truly reflect the deformation state of the material in a complex stress field; by introducing Poisson's ratio and thermal expansion coefficient, the present invention can accurately describe the deformation behavior of the material when it is subjected to external force (mechanical stress) and temperature change (thermal stress) at the same time. Especially in extreme environments such as cold and hot shocks, it can provide more accurate strain predictions.

[0058] The present invention is further configured such that the real-time monitoring data includes real-time stress, real-time strain, real-time temperature, real-time vibration amplitude, acoustic emission amplitude and real-time magnetic response signal. Specifically, real-time stress indicates the stress value of the material under external loading or thermal stress at each moment during the test. Stress is the internal force per unit area, which is used to evaluate the bearing capacity and damage risk of the material; real-time strain is the percentage of the deformation (i.e., length or volume change) of the material caused by external force or temperature change relative to the original state. Strain is proportional to stress and reflects the degree of deformation of the material; real-time temperature refers to the temperature of the material at each moment during the test. The temperature of the material has an important influence on its performance (including thermal expansion, thermal conductivity and thermal stress), and temperature changes may cause deformation, damage or even destruction of the material; real-time vibration amplitude refers to the vibration intensity of the material under external mechanical force or internal stress during the test. Vibration amplitude is a quantitative description of the vibration amplitude of the material, which can reflect the dynamic response of the material; acoustic emission amplitude refers to the intensity of the sound wave signal emitted by the internal structure when the material is subjected to stress or heat, and microcrack expansion, plastic deformation and other processes occur. Acoustic emission signals can reflect the internal damage process and destruction process of materials; real-time magnetic response signals refer to the magnetic changes caused by external forces, temperature changes or internal defects of materials during the test. This signal is usually related to the microstructural changes, stress state and damage accumulation of the material. The above parameters reflect the state of the material under hot and cold shocks and multi-dimensional stresses from different aspects. These data are obtained through a variety of sensors and detection technologies, including stress sensors, strain gauges, temperature sensors, accelerometers, acoustic emission sensors and magnetic response sensors, which can capture the dynamic response and damage state of the material in real time and accurately. Through the analysis of these real-time monitoring data, the performance of the material in a complex environment can be more comprehensively evaluated, providing guarantees for the accuracy of the test results and the reliability of the material.

[0059] The present invention is further configured to calculate the experimental monitoring index according to the real-time monitoring data, including:

[0060] The mechanical load factor is calculated according to the real-time stress and real-time strain; the present invention is further configured such that the calculation logic of the mechanical load factor is: Among them, MLF(t) is the mechanical load factor at time t, ST(u) is the stress at time u, SR(u) is the strain at time u, cA and cB are constant coefficients, which are used to adjust the overall magnitude of the mechanical load factor and the exponential amplification effect of the strain respectively; specifically, the mechanical load factor quantifies the impact of the mechanical load on the material by comprehensively considering the stress and strain of the material at different times. The constant coefficient cA controls the overall amplitude of the mechanical load factor and affects the contribution of stress to the mechanical load factor. cB controls the influence of strain, especially by amplifying the influence of strain on the mechanical load factor through the exponential function exp(cB×SR(u)), indicating that when the strain increases, its contribution to the mechanical load factor increases exponentially; through comprehensive consideration of stress and strain, the mechanical load factor can provide more accurate predictions of the mechanical properties of the material and help better evaluate the reliability, durability and fatigue life of the material. Especially under dynamic and complex loads, it can accurately predict the failure mode of the material;

[0061] The thermomagnetic coupling factor is calculated according to the real-time temperature and the real-time magnetic response signal; the calculation logic of the thermomagnetic coupling factor is: Among them, TMC(t) is the thermomagnetic coupling factor at time t, TP(u) is the temperature at time u, MG(u) is the magnetic response signal at time u, and cC is a constant coefficient, which is used to adjust the proportion of temperature magnetic coupling in the thermomagnetic coupling factor; specifically, thermomagnetic coupling refers to the interaction between thermal effect and magnetic effect. When a material is subjected to temperature changes, its magnetism may change. Conversely, an external magnetic field may also affect the thermal response of the material. In the present invention, the thermomagnetic coupling factor quantifies this interaction by combining real-time temperature and real-time magnetic response signals, and the constant coefficient cC is used to adjust the coupling strength of temperature and magnetic response signals. By adjusting cC, the relative contribution of temperature and magnetic response signals in the thermomagnetic coupling factor can be controlled. When calculating the thermomagnetic coupling factor, the temperature and magnetic response signals from the start of the experiment to the current moment are integrated. This process accumulates the influence of temperature and magnetic response signals on the thermomagnetic coupling effect of the material, reflects the thermomagnetic coupling state of the material at different time points, and the magnetic response signal reflects the magnetic change of the material under the action of the magnetic field. It is usually related to the microstructure, stress state and temperature change of the material. The thermomagnetic coupling factor can fully reflect the combined effects of temperature and magnetic field on material performance. The thermomagnetic coupling factor can help predict the performance of materials under thermomagnetic coupling conditions, especially in environments that require high temperatures or strong magnetic fields. By calculating the thermomagnetic coupling factor in real time, the stability, durability and performance changes of materials can be evaluated in real time, thereby improving the accuracy of material reliability evaluation.

[0062] The vibro-acoustic-magnetic coupling factor is calculated according to the real-time vibration amplitude, the acoustic emission amplitude and the real-time magnetic response signal; the calculation logic of the vibro-acoustic-magnetic coupling factor is: Among them, VAM(t) is the vibration-acoustic-magnetic coupling factor at time t, VB(u) is the vibration amplitude at time u, AC(u) is the acoustic emission amplitude at time u, MG(u) is the magnetic response signal at time u, and cD is the amplification factor, which is used to adjust the overall magnitude of the vibration-acoustic-magnetic coupling factor; specifically, vibration-acoustic-magnetic coupling refers to the phenomenon of interaction between vibration, sound waves and magnetic fields in materials. When materials are subjected to mechanical loads, temperature changes or internal forces, their vibration, acoustic emission and magnetic response signals are often interrelated. Microcracks or deformations in materials may cause joint changes in vibration, acoustic emission and magnetic response; VB(u)×AC(u)×MG(u) indicates that the coupling effects of vibration, acoustic emission and magnetic response signals in time are interrelated, and the changes of the three will jointly affect the overall state of the material; by integrating the signal over time, the comprehensive effects of vibration, acoustic emission and magnetic response signals on the material are accumulated from the start of the experiment to the current moment. This process can reflect the vibration-acoustic-magnetic coupling effect of the material over a period of time; by introducing the vibration-acoustic-magnetic coupling factor, it can fully reflect the coupling effect between the material's vibration, acoustic emission and magnetic response. This is of great significance for material status monitoring and damage assessment. The calculation of the vibration-acoustic-magnetic coupling factor can help evaluate the comprehensive state of the material during stress and damage, especially when the material undergoes cracks, plastic deformation or other microstructural changes. This provides more comprehensive data support for material damage accumulation, fatigue life prediction, etc.

[0063] The experimental monitoring index is calculated according to the mechanical load factor, the thermal magnetic coupling factor and the vibro-acoustic magnetic coupling factor; the calculation logic of the experimental monitoring index is: MHF(t) = [MLF(t)] f1 ×[TMC(t)] f2 ×[VAM(t)] f3, where MHF(t) is the experimental monitoring index at time t, and f1, f2 and f3 are exponential coefficients used to determine the relative influence of factors in the experimental monitoring index. Specifically, the experimental monitoring index reflects the comprehensive state of the material by combining three independent factors. These three factors correspond to the effects of different physical fields (mechanical field, thermal magnetic field, vibro-acoustic magnetic field), which are multi-dimensional evaluations of the overall performance of the material. The experimental monitoring index comprehensively considers the synergistic effect between the mechanical load factor, the thermal magnetic coupling factor and the vibro-acoustic magnetic coupling factor. If the value of a certain factor is large (such as the material is in an abnormal state under a specific physical field), the value of the experimental monitoring index will increase rapidly, thereby reflecting the changes or abnormalities of the material in the current state; the experimental monitoring index can reflect the state changes of the material in real time during the test, especially when the material is damaged, deformed or performance degraded, the experimental monitoring index will change rapidly, thereby realizing dynamic monitoring of the material state.

[0064] The present invention is further configured such that the calculation logic of the cumulative damage metric is: Where D is the cumulative damage metric, N is the total number of hot and cold cycles, is the total stress of the nth thermal cycle, S ij is the fatigue strength of the test material in each direction, and m is the fatigue damage index. Specifically, under the conditions of thermal shock or stress cycling, the material will gradually accumulate damage as the number of cycles increases. The cumulative damage metric quantifies the degree of damage accumulation of the material during the entire experiment by adding up the damage contribution in each cycle. is the square of the total stress, reflecting the contribution of stress to damage, It is equivalent to the square of the Frobenius norm of the stress tensor, which is used to quantify the overall strength of the entire stress field. The introduction of stress square reflects the nonlinear aggravation effect of high stress on damage. The stress is normalized to indicate the ratio of the current total stress to the fatigue strength of the material. This normalization process makes the quantification of damage have material-specific physical meaning. The introduction of the fatigue damage index m reflects the nonlinear characteristics of the material during the damage accumulation process. The larger the m value, the more sensitive the material is to high stress, that is, the damage accumulation caused by high stress will grow exponentially. The damage contribution of each hot and cold cycle is summed to obtain the cumulative damage value of the material during the entire experiment, which can fully consider the comprehensive impact of multiple cycles on material properties; by defining the cumulative damage metric, the degree of damage accumulation of the material under multiple hot and cold shocks and stress cycles can be quantified, providing a scientific basis for the fatigue life prediction of the material.

[0065] Embodiment 2

[0066] See also Figure 2The exemplary multi-dimensional stress synchronously applied hot and cold shock test system is used to implement the above-mentioned multi-dimensional stress synchronously applied hot and cold shock test method, including:

[0067] Acquisition module: obtain the spatial and temporal temperature distribution of the test material during the thermal shock process, and establish the thermal stress field based on the spatial and temporal temperature distribution;

[0068] The first calculation module is: superimposing the external mechanical stress field with the thermal stress field to obtain a comprehensive stress field, coupling the thermal stress with the mechanical stress, and calculating the comprehensive strain based on the stress-strain relationship of the material;

[0069] The second calculation module is used to obtain real-time monitoring data of the test material under the cold and hot shock and multi-dimensional stress environment, and calculate the experimental monitoring index according to the real-time monitoring data;

[0070] Output module: perform threshold judgment on the experimental monitoring index. When it is greater than the preset threshold, perform cumulative analysis on the damage of the test material in multiple cold and hot shocks, output the cumulative damage measurement, and complete the test.

[0071] It should be noted that the hot and cold shock test system with synchronous application of multi-dimensional stress provided in the above embodiment and the hot and cold shock test method with synchronous application of multi-dimensional stress provided in the above embodiment belong to the same concept, wherein the specific manner in which each module and unit performs the operation has been described in detail in the method embodiment and will not be repeated here. In actual application, the hot and cold shock test system with synchronous application of multi-dimensional stress provided in the above embodiment can allocate the above functions to different functional modules as needed, that is, divide the internal structure of the system into different functional modules to complete all or part of the functions described above, and this is not limited here.

[0072] The above embodiments can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0073] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0074] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0075] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0076] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0077] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0078] In the several embodiments provided in the present application, it should be understood that the disclosed system can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0079] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0080] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0081] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage media include: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks or optical disks.

[0082] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A hot and cold shock test method with simultaneous application of multi-dimensional stress, characterized in that: include: Obtain the spatial and temporal temperature distribution of the test material during the thermal shock process, and establish the thermal stress field based on the spatial and temporal temperature distribution; The external mechanical stress field is superimposed on the thermal stress field to obtain a comprehensive stress field, the thermal stress is coupled with the mechanical stress, and the comprehensive strain is calculated based on the stress-strain relationship of the material; Acquire real-time monitoring data of the test material under cold and hot shock and multi-dimensional stress environment, and calculate the experimental monitoring index according to the real-time monitoring data; A threshold value is judged for the experimental monitoring index. When it is greater than a preset threshold value, a cumulative analysis is performed on the damage of the test material in multiple cold and hot shocks, and a cumulative damage metric is output to complete the test.

2. A thermal shock test method with simultaneous multi-dimensional stress application according to claim 1, characterized in that: In the thermal stress field, the thermal stress tensor σ ij =αE(T(x,y,z,t)-T ref )δ ij , where σ ij is the thermal stress tensor, α is the thermal expansion coefficient, E is the elastic modulus, T(x, y, z, t) is the temperature distribution function in time and space, which is used to describe the temperature change of the test material during the test. ref is the reference temperature, is the initial temperature of the test material, δ ij is Kronecker's delta, a mathematical constant used to represent the diagonal elements in the identity matrix, 3. A thermal shock test method with simultaneous multi-dimensional stress application according to claim 2, characterized in that: The acquisition logic of the temperature distribution function T(x,y,z,t) in time and space includes: Establishing a three-dimensional geometric model according to the actual size and shape of the sample material, and meshing the three-dimensional geometric model; Setting a convection heat transfer coefficient, a radiation emissivity and a thermal conductivity coefficient for the surface of the three-dimensional geometric model; Input the initial temperature value, use the time discretization method to solve the transient heat conduction control equation, and obtain the temperature distribution function of time and space at different times. The transient heat conduction control equation is: ρ is the material density, c p is the specific heat capacity and k is the thermal conductivity.

4. The method for thermal shock testing with simultaneous multi-dimensional stress application according to claim 2, characterized in that: Comprehensive stress field in, is the mechanical stress field, and the mechanical stress field Transformed into a multi-directional distribution in time and space, γ k is the mechanical stress amplitude, Ψ ijk (x, y, z, t) is the space-time stress distribution function.

5. A thermal shock test method with simultaneous multi-dimensional stress application according to claim 4, characterized in that: The calculation logic of the comprehensive strain is: Among them, ∈ ij is the comprehensive strain, ν is the Poisson's ratio, which is used to describe the contraction ratio in the perpendicular direction when the test material is stretched in one direction. is the trace of the stress field, that is, the sum of all principal stresses, which is used to reflect the overall stress state.

6. The method for thermal shock testing with simultaneous multi-dimensional stress application according to claim 1, characterized in that: The real-time monitoring data includes real-time stress, real-time strain, real-time temperature, real-time vibration amplitude, acoustic emission amplitude and real-time magnetic response signal.

7. A thermal shock test method with simultaneous multi-dimensional stress application according to claim 6, characterized in that: Calculating experimental monitoring indicators based on the real-time monitoring data includes: Calculating a mechanical load factor based on the real-time stress and real-time strain; Calculating a thermal magnetic coupling factor according to the real-time temperature and the real-time magnetic response signal; Calculating the vibro-acoustic-magnetic coupling factor according to the real-time vibration amplitude, the acoustic emission amplitude and the real-time magnetic response signal; The experimental monitoring index is calculated according to the mechanical load factor, the thermal magnetic coupling factor and the vibro-acoustic magnetic coupling factor.

8. A thermal shock test method with simultaneous multi-dimensional stress application according to claim 7, characterized in that: The calculation logic of the mechanical load factor is: Among them, MLF(t) is the mechanical load factor at time t, ST(u) is the stress at time u, SR(u) is the strain at time u, cA and cB are constant coefficients, which are used to adjust the overall magnitude of the mechanical load factor and the exponential amplification effect of the strain respectively; The calculation logic of the thermal magnetic coupling factor is: Wherein, TMC(t) is the thermomagnetic coupling factor at time t, TP(u) is the temperature at time u, MG(u) is the magnetic response signal at time u, and cC is a constant coefficient used to adjust the proportion of temperature magnetic coupling in the thermomagnetic coupling factor; The calculation logic of the vibro-acoustic magnetic coupling factor is: Wherein, VAM(t) is the vibration-acoustic-magnetic coupling factor at time t, VB(u) is the vibration amplitude at time u, AC(u) is the acoustic emission amplitude at time u, MG(u) is the magnetic response signal at time u, and cD is the amplification factor, which is used to adjust the overall magnitude of the vibration-acoustic-magnetic coupling factor; The calculation logic of the experimental monitoring index is: MHF(t) = [MLF(t)] f1 ×[TMC(t)] f2 ×[VAM(t)] f3 , where MHF(t) is the experimental monitoring index at time t, and f1, f2 and f3 are exponential coefficients used to determine the relative influence of the factor in the experimental monitoring index.

9. A thermal shock test method with simultaneous multi-dimensional stress application according to claim 8, characterized in that: The calculation logic of the cumulative damage metric is: Where D is the cumulative damage metric, N is the total number of hot and cold cycles, is the total stress of the nth thermal cycle, S ij is the fatigue strength of the test material in each direction, and m is the fatigue damage index.

10. A hot and cold shock test system with synchronous multi-dimensional stress application, used to implement a hot and cold shock test method with synchronous multi-dimensional stress application as claimed in any one of claims 1 to 9, characterized in that: include: Acquisition module: obtain the space-time temperature distribution of the test material during the hot and cold shock process, and establish the thermal stress field according to the space-time temperature distribution; The first calculation module is: superimposing the external mechanical stress field with the thermal stress field to obtain a comprehensive stress field, coupling the thermal stress with the mechanical stress, and calculating the comprehensive strain based on the stress-strain relationship of the material; The second calculation module is used to obtain real-time monitoring data of the test material under the cold and hot shock and multi-dimensional stress environment, and calculate the experimental monitoring index according to the real-time monitoring data; Output module: perform threshold judgment on the experimental monitoring index. When it is greater than the preset threshold, perform cumulative analysis on the damage of the test material in multiple cold and hot shocks, output the cumulative damage measurement, and complete the test.

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