Material fatigue test method and system integrating environmental thermal aging and motion pose fatigue

Abstract

The invention relates to the technical field of material simulation tests, and discloses a material fatigue test method and system fusing environmental thermal aging and motion pose fatigue, and the method comprises the following steps: preparing a plurality of groups of same samples, and carrying out environmental high-temperature thermal aging treatment on each group of samples for different ages to obtain sample groups corresponding to different service ages; applying multiple cyclic fatigue loads with different motion poses to each group of samples subjected to thermal aging treatment; monitoring and recording fatigue damage data of each sample in the cyclic loading process in real time until the sample loses efficacy, and obtaining fatigue cycle times corresponding to each sample; according to the fatigue cycle times and the corresponding torsion angle parameters per unit length, fitting to obtain S-N curves under different thermal aging service lives; and through overlay analysis of a plurality of groups of S-N curves, a coupling relation model of the environmental thermal aging age limit and the motion pose fatigue life is established and is used for predicting the fatigue life of the material under the action of high temperature and dynamic load.

Description

Technical Field

[0001] The present invention relates to the technical field of material simulation tests, and particularly to a material fatigue test method and system that integrates environmental thermal aging and motion pose fatigue. Background Art

[0002] The fatigue behavior of materials refers to the phenomenon that materials gradually accumulate damage under repeated or alternating stress, and finally lead to crack generation and fracture. Stress-life curve (S-N curve) analysis is a classical fatigue analysis method used to describe the life of materials after a certain number of cyclic loadings under different stress levels. The S-N curve is usually obtained through tests, and the test process will be designed according to factors such as material type, stress amplitude, and load frequency. Existing S-N curve tests are usually carried out at room temperature, and the test loads are unidirectional or simple multi-axial loadings. In actual engineering applications, materials often work under complex environmental conditions. Especially under the dual action of high temperature and dynamic motion poses, the fatigue performance of materials may be very different from the test results under conventional conditions. Therefore, the existing S-N curve test methods cannot fully reflect the true fatigue behavior of materials under complex working conditions, especially under high temperature environments and complex dynamic loadings.

[0003] Although some studies have begun to focus on the effects of high temperature and motion poses on the fatigue life of materials, there is still a lack of a systematic fatigue test method that can simultaneously consider high temperature and dynamic pose changes. Existing studies usually analyze and study these two aspects separately, lacking a test method that comprehensively considers the combined action of high temperature and dynamic loads. For example, some literatures discuss the influence of high temperature on the fatigue life of metal materials, while others focus on the multi-axial loading fatigue behavior under complex working conditions, but these studies lack a systematic analysis of the interaction between the two.

[0004] Considering the deficiencies in the prediction of fatigue life under the combined action of high temperature and motion poses in the existing technology, the present invention proposes a new fatigue test method that can integrate environmental high-temperature thermal aging and motion pose fatigue, and simulate the fatigue behavior of materials under real working conditions by comprehensively controlling high temperature and dynamic pose loading. This method can carry out S-N curve tests under high temperature and dynamic motion poses, and accurately evaluate the fatigue life of materials. Summary of the Invention

[0005] The present invention provides a material fatigue test method and system that integrates environmental thermal aging and motion pose fatigue to solve the problem of low evaluation accuracy in existing material fatigue test methods.

[0006] To achieve the above object, the present invention is realized through the following technical solutions: In a first aspect, the present invention provides a material fatigue test method that combines environmental thermal aging and motion posture fatigue, including: Preparing multiple groups of identical specimens, and subjecting each group of specimens to environmental high-temperature thermal aging treatment for different years to obtain specimen groups corresponding to different service years; Applying cyclic fatigue loading with multiple different motion postures to each group of specimens after thermal aging treatment, where the motion posture is defined by the torsional angle parameter per unit length; Real-time monitoring and recording the fatigue damage data of each specimen during the cyclic loading until the specimen fails, and obtaining the corresponding fatigue cycle times of each specimen; According to the fatigue cycle times and the corresponding torsional angle parameters per unit length, fitting the S-N curves for different thermal aging service years; Through the superposition analysis of multiple groups of S-N curves, establishing a coupling relationship model between the environmental thermal aging years and the motion posture fatigue life, which is used to predict the fatigue life of materials under the action of high temperature and dynamic load.

[0007] Optionally, the step of subjecting each group of specimens to environmental high-temperature thermal aging treatment for different years includes: Placing each group of specimens in different high-temperature thermal aging test chambers to simulate the thermal aging states of materials under service years of year, year, year, year, and year.

[0008] Optionally, the motion posture includes at least five different torsional angle parameters per unit length , and each torsional angle corresponds to a dynamic load mode.

[0009] Optionally, the fitting method of the S-N curve is an exponential function model, and its function model satisfies the following relationship: ; In the formula, is the torsional angle per unit length, is the fatigue cycle times, , both represent fitting parameters.

[0010] Optionally, linearizing the exponential function model corresponding to the S-N curve, and the linearization includes: Taking the natural logarithm of both sides of the equation of the exponential function model and transforming it into a linear equation, and the linear equation satisfies the following relationship: ; Constructing a linear equation set in matrix form and solving the fitting parameters using the least squares method.

[0011] Optionally, the method for establishing the coupling relationship model between the environmental thermal aging life and the motion posture fatigue life includes: By plotting the corresponding relationship curve between the high-temperature thermal aging life and the motion fatigue life, determining the number of cycles when the two are strictly equal , , , , , and then constructing a comprehensive S-N curve that couples environmental thermal aging and motion posture fatigue; And taking the constructed comprehensive S-N curve that couples environmental thermal aging and motion posture fatigue as the coupling relationship model between the environmental thermal aging life and the motion posture fatigue life.

[0012] Optionally, the method is applicable to the fatigue performance testing of metal materials, polymer composite materials or ceramic materials.

[0013] In a second aspect, an embodiment of the present application provides a material fatigue test system that integrates environmental thermal aging and motion posture fatigue, including a processor and a memory; The memory is used to store computer programs; The processor is configured to implement any of the method steps in the first aspect when executing the programs stored on the memory.

[0014] Beneficial effects: The material fatigue test method that integrates environmental thermal aging and motion posture fatigue provided by the present invention sets multiple service years (such as 0 year, year, year, year, year, etc.) during the test process for comprehensive comparison. The present invention can show the performance degradation trend of the material in different service time periods, as well as the influence of the combined action of environmental high temperature and motion posture fatigue on the material life. By coupling high-temperature thermal aging and motion posture fatigue, a test method that can better simulate the performance of the material in a complex use environment is designed. This enables the experimental results to truly reflect the material performance in the actual service environment, making up for the neglect of various environmental factors in traditional test methods; By comprehensively considering the dual effects of high-temperature thermal aging and motion posture fatigue, the present invention can obtain a more accurate S-N curve, which is of great significance for accurately predicting the fatigue life of the material. Traditional fatigue tests usually only consider one of the factors (such as temperature or loading), ignoring the coupling effect of the two. The present invention makes up for this deficiency, making the prediction result of the fatigue life closer to the actual application scenario. Description of the drawings

[0015] Figure 1 Flow chart of the material fatigue test method integrating environmental thermal aging and motion posture fatigue according to the preferred embodiment of the present invention; Figure 2 Schematic diagram of S-N curves with different environmental thermal aging service life according to the preferred embodiment of the present invention; Figure 3 For the torsional angle in the preferred embodiment of the present invention Graph of the corresponding relationship between the thermal aging life and the cyclic posture fatigue life; Figure 4 For the torsional angle in the preferred embodiment of the present invention Strict corresponding points of the thermal aging life and the cyclic posture fatigue life of the torsional angle Schematic diagram. Specific implementation mode

[0016] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0017] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the art to which the present invention belongs. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, terms such as "a" or "one" do not denote a quantity limitation, but mean that there is at least one. The terms "connected" or "coupled" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right" and the like are only used to represent relative positional relationships, and when the absolute position of the object to be described changes, the relative positional relationship also changes accordingly.

[0018] Please refer to Figure 1 , the embodiments of the present application provide a material fatigue test method integrating environmental thermal aging and motion posture fatigue, including: Prepare multiple groups of identical specimens, and perform environmental high-temperature thermal aging treatment on each group of specimens for different years to obtain specimen groups corresponding to different service lives; Apply cyclic fatigue loading with multiple different motion postures to each group of specimens after thermal aging treatment, wherein the motion posture is defined by the torsional angle parameter per unit length; Real-time monitor and record the fatigue damage data of each specimen during the cyclic loading process until the specimen fails, and obtain the corresponding fatigue cycle times of each specimen; According to the fatigue cycle times and the corresponding unit length torsional angle parameters, the S-N curves under different thermal aging service years are obtained by fitting; Through the superposition analysis of multiple groups of S-N curves, a coupling relationship model between the environmental thermal aging years and the fatigue life of the motion pose is established to predict the fatigue life of the material under the action of high temperature and dynamic load.

[0019] In this embodiment, taking the cable material as an example, fatigue tests are carried out on different groups of cable materials. The cable materials here are only examples in the embodiment and are not limited. The fatigue tests of other materials can also apply this test method, and the specific steps are as follows: First, the same specimens are processed to different environmental high-temperature thermal aging service years through a high-temperature thermal aging test chamber , and then a same brand-new specimen is taken to obtain five groups of specimens, which are specimens with service year, service year, service year, service year, and service year. Through cyclic fatigue loading of five different motion poses (the unit length torsional angles are respectively ) for each group of specimens in these five groups of specimens, different actual use states are simulated, and fatigue loads are applied to each specimen. Five different test curves are obtained after cyclic fatigue loading of five different motion poses for each group of specimens. The fatigue damage, strain and other data of the specimens at different stages are recorded by sensors. The fatigue cycle times corresponding to the failure conditions of each specimen are recorded, and a scatter plot of the unit length torsional angle and the cycle times can be obtained. The S-N curve is fitted through the scatter plot. There are 5 scatter points corresponding to each service year, and 5 S-N curves corresponding to different service years can be fitted. The S-N curve equation is usually in exponential form, and the specific fitting process is as follows: We know five data points , and need to fit them into an exponential function model: (1) Among them, is the unit length torsional angle, is the fatigue cycle times.

[0020] To linearize this model, take the logarithm of both sides of the exponential equation: (2) In this way, we define: (3) Then the exponential equation is transformed into a linear equation, and the fitting problem becomes: (4) This problem can be solved by the least squares method, which transforms the problem into a system of linear equations. For the convenience of matrix operations, we represent the data points in matrix form.

[0021] Construct matrices and : (5) (6) Set as the column vector of the coefficients to be solved : (7) In this way, we can represent the original problem as a system of linear equations: (8) The purpose of the least squares method is to find an optimal coefficient vector such that the sum of the squares of the residuals is minimized. To this end, the solution of the least squares method is: (9) Calculate the matrix : (10) where the summation is carried out over all data points .

[0022] Normally, the obtained is non-singular, and its inverse can be obtained.

[0023] Calculate : (11) Calculate the coefficient through the matrix formula , and then calculate the coefficient .

[0024] (12) (13) The S-N curve equation shown in Figure 2 can be obtained.

[0025] By performing the above fitting on each group of scattered points respectively, five S-N curves under different thermal aging service life can be obtained. As shown in Figure 2 , taking the unit torsional angle as a fixed quantity, the corresponding number of cycles of service can be obtained. To more intuitively and conveniently observe the relationship between the service life of thermal aging and the service life of motion fatigue, the dimensions of the fatigue times and the service life of thermal aging are unified and both are expressed in years, but they have the same practical meaning. Thus, five scatter points can be obtained again, namely 。By fitting the five scatter points again through the above fitting method, the functional relationship between the service life of high-temperature thermal aging and the service life of motion fatigue can be obtained at the unit torsional angle 。As shown, to obtain the points where the service life of high-temperature thermal aging and the service life of motion fatigue are strictly corresponding and equal, we plot the Figure 3 function image in the figure. The points where the service life of high-temperature thermal aging and the service life of motion fatigue are strictly corresponding and equal are obtained, as shown. By performing the above operations on the torsional angle per unit length Figure 4 respectively, the number of cycles corresponding to the service life of high-temperature thermal aging and the service life of motion fatigue being equal can be obtained for the torsional angle . Thus, five scatter points are obtained again. Through the above fitting steps, the S-N curve of the coupling of high-temperature environmental thermal aging and motion pose fatigue can be obtained This embodiment of the present application also provides a material fatigue test system integrating environmental thermal aging and motion pose fatigue, which is characterized by including a processor and a memory; The memory is used to store computer programs; The processor, when executing the programs stored on the memory, realizes any of the method steps in the material fatigue test method integrating environmental thermal aging and motion pose fatigue. The above-mentioned material fatigue test system integrating environmental thermal aging and motion pose fatigue can implement each embodiment of the above-mentioned material fatigue test method integrating environmental thermal aging and motion pose fatigue, and can achieve the same beneficial effects. Here, it will not be elaborated.

[0026] The above has described in detail the preferred specific embodiments of the present invention. It should be understood that those of ordinary skill in the art can make many modifications and variations according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

[0027] ​

Claims

1. A material fatigue test method that combines environmental thermal aging and motion posture fatigue, characterized in that Comprising: Preparing multiple groups of identical specimens, and subjecting each group of specimens to environmental high-temperature thermal aging treatment for different years to obtain specimen groups corresponding to different service years; Applying cyclic fatigue loading with different motion postures to each group of specimens after thermal aging treatment, wherein the motion posture is defined by the torsional angle parameter per unit length; Real-time monitoring and recording the fatigue damage data of each specimen during the cyclic loading until the specimen fails, and obtaining the corresponding fatigue cycle times of each specimen; Fitting the S-N curves under different thermal aging service years according to the fatigue cycle times and the corresponding torsional angle parameters per unit length; Through the superposition analysis of multiple groups of S-N curves, establishing a coupling relationship model between the environmental thermal aging years and the fatigue life of the motion posture, which is used to predict the fatigue life of materials under the action of high temperature and dynamic load; 2. The method for material fatigue test integrating environmental thermal aging and motion posture fatigue according to claim 1, wherein The step of subjecting each group of specimens to environmental high-temperature thermal aging treatment for different years includes: Place each group of specimens in different high-temperature thermal aging test chambers to simulate the thermal aging state of the material under service life of year, year, year, year, and years.

3. The fatigue test method for materials integrating environmental thermal aging and motion postural fatigue according to claim 1, wherein The motion pose includes at least five different unit length torsional angle parameters , and each torsional angle corresponds to a dynamic load mode.

4. The method for material fatigue test integrating environmental thermal aging and motion posture fatigue according to claim 1, characterized in that The fitting method of the S-N curve is an exponential function model, and its function model satisfies the following relationship: ； In the formula, is the torsional angle per unit length, is the number of fatigue cycles, , both represent fitting parameters.

5. The method for material fatigue test integrating environmental thermal aging and motion posture fatigue according to claim 4, characterized in that, Performing linearization processing on the exponential function model corresponding to the S-N curve, and the linearization processing includes: Taking the natural logarithm of both sides of the equation of the exponential function model and transforming it into a linear equation, and the linear equation satisfies the following relationship: ； By constructing a linear equation system in matrix form and solving the fitting parameters using the least squares method; 6. The material fatigue test method integrating environmental thermal aging and motion posture fatigue according to claim 1, characterized in that The step of establishing a coupling relationship model between the environmental thermal aging years and the fatigue life of the motion posture includes: By plotting the corresponding relationship curve between the high-temperature thermal aging years and the motion fatigue years, determine the number of cycles when the two are strictly equal , , , , , and then construct a comprehensive S-N curve that couples environmental thermal aging and motion posture fatigue; And taking the constructed comprehensive S-N curve coupling environmental thermal aging and motion posture fatigue as the coupling relationship model between the environmental thermal aging years and the fatigue life of the motion posture; 7. The material fatigue test method integrating environmental thermal aging and motion posture fatigue according to claim 1, wherein The method is applicable to the fatigue performance test of metal materials, polymer composite materials or ceramic materials; 8. A material fatigue test system integrating environmental thermal aging and motion posture fatigue, characterized in that, Comprising a processor and a memory; The memory is used for storing computer programs; The processor is used to implement the method steps described in any one of claims 1-7 when executing the programs stored on the memory.

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