Fatigue life prediction method under multi-axis vibration test and related equipment

Abstract

The invention provides a fatigue life prediction method under a multi-axis vibration test and related equipment. The method comprises the following steps: acquiring test parameters of a device under a single-axis vibration test; determining a damage correction factor corresponding to the device based on the number of axes and test parameters in the multi-axis vibration test, and determining uniaxial damage strength corresponding to the device based on the test parameters; in response to determining that the vibration load of the multi-axis vibration test in each axial direction has no correlation, determining a first multi-axis fatigue life corresponding to the device based on the single-axis damage strength and the damage correction factor; in response to determining that the vibration load of the multi-axis vibration test in each axial direction has correlation, determining a damage ratio corresponding to the device based on the test parameters, and determining a second multi-axis fatigue life corresponding to the device based on the damage ratio, the single-axis damage strength and the damage correction factor, the technical problem in the prior art that the fatigue life of a device under a multi-axis vibration test is not accurately predicted by using a single-axis vibration test is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of data processing, and in particular to a method for predicting fatigue life under multi-axis vibration test and related equipment. BACKGROUND

[0002] In the design and service process of engineering structures, fatigue failure caused by multi-axis random vibration is a major challenge faced by the fields of aerospace, automobile manufacturing, nuclear power equipment, etc. For example, aircraft engine supports bear X, Y, Z three-axis synchronous vibration loads in flight, and automobile chassis undergoes multi-directional dynamic excitation on rough roads. These complex load environments cause multi-axis alternating stress inside the structure, accelerating crack initiation and propagation. Multi-axis vibration test is the authoritative method for evaluating the fatigue life of structures under complex vibration environment, and its core is to simulate multi-directional, non-stationary vibration loads in real working conditions.

[0003] Due to the complexity of multi-axis vibration test equipment, the engineering industry generally uses sequential single-axis vibration test to replace multi-axis test, that is, vibration loads are applied on each main axis of the structure one by one, and it is assumed that multi-axis damage is a linear superposition of each single-axis damage. However, a large number of studies have shown that this simplified method has significant defects: most methods assume that multi-axis damage is a linear superposition of each axis damage (such as Dmulti=DX+DY+DZ), but in reality there may be nonlinear coupling, the phase coupling, frequency coherence of multi-axis loads and the spatial interaction of stress state are completely ignored, resulting in a life prediction error of up to 30%-50%. Therefore, it is an urgent need in the industry to develop an equivalent method for predicting the fatigue life of devices under multi-axis vibration based on single-axis vibration test. SUMMARY

[0004] In view of the above, the purpose of the present application is to provide a method for predicting fatigue life under multi-axis vibration test and related equipment to overcome all or part of the deficiencies in the prior art.

[0005] To achieve the above purpose, the present application provides a method for predicting fatigue life under multi-axis vibration test, comprising: obtaining test parameters of a device under single-axis vibration test; determining a damage correction factor corresponding to the device based on the number of axes in multi-axis vibration test and the test parameters, and determining a single-axis damage intensity corresponding to the device based on the test parameters; in response to determining that there is no correlation between the vibration loads in each axis direction of the multi-axis vibration test, determining a first multi-axis fatigue life corresponding to the device based on the single-axis damage intensity and the damage correction factor; in response to determining that there is correlation between the vibration loads in each axis direction of the multi-axis vibration test, determining a damage ratio corresponding to the device based on the test parameters, and determining a second multi-axis fatigue life corresponding to the device based on the damage ratio, the single-axis damage intensity and the damage correction factor.

[0006] Optionally, the damage correction factor comprises a first damage correction factor and a second damage correction factor, the test parameter comprises a first test parameter and a second test parameter, wherein a number of parameters in the second test parameter is greater than a number of parameters in the first test parameter, and the second test parameter comprises the first test parameter; and the determining of the damage correction factor corresponding to the device based on the number of axes in the multi-axis vibration test and the test parameter comprises: in response to determining that the number of axes in the multi-axis vibration test is two axes, determining the first damage correction factor based on the first test parameter; and in response to determining that the number of axes in the multi-axis vibration test is three axes, determining the second damage correction factor based on the second test parameter.

[0007] Optionally, the determining of the first damage correction factor based on the first test parameter comprises: determining the first damage correction factor by the following formula: wherein λ1 is the first damage correction factor, is a forward zero-crossing rate under a multi-axis vibration test condition, m 0-y is an m-order spectral moment of y-axis vibration, m 0-x is an m-order spectral moment of x-axis vibration, is a forward zero-crossing rate of x-axis vibration, is a forward zero-crossing rate of y-axis vibration, and k is a material fatigue strength index.

[0008] Optionally, the determining of the second damage correction factor based on the second test parameter comprises: determining the second damage correction factor by the following formula: wherein λ2 is the second damage correction factor, is a forward zero-crossing rate under a multi-axis vibration test condition, m 0-x is an m-order spectral moment of x-axis vibration, m 0-y is an m-order spectral moment of y-axis vibration, m 0-z is an m-order spectral moment of z-axis vibration, is a forward zero-crossing rate of x-axis vibration, is a forward zero-crossing rate of y-axis vibration, is a forward zero-crossing rate of z-axis vibration, and k is a material fatigue strength index; or, the determining of the second damage correction factor comprises: determining the second damage correction factor by the following formula:

[0009]

[0010] wherein λ2 is the second damage correction factor, is a forward zero-crossing rate under a multi-axis vibration test condition, m 0-x is an m-order spectral moment of x-axis vibration, m 0-y is an m-order spectral moment of y-axis vibration, m0-z is a spectrum moment of the z-axis vibration, b eq is a bandwidth correction coefficient corresponding to multi-axis damage, b1 is a total bandwidth correction coefficient corresponding to single-axis damage, is an irregularity coefficient corresponding to multi-axis damage, is a positive zero-crossing rate of the x-axis vibration, b x is a bandwidth correction coefficient of the x-axis, is an irregularity coefficient of the x-axis, is a positive zero-crossing rate of the y-axis vibration, b y is a bandwidth correction coefficient of the y-axis, is an irregularity coefficient of the y-axis, is a positive zero-crossing rate of the z-axis vibration, b z is a bandwidth correction coefficient of the z-axis, is an irregularity coefficient of the z-axis, k is a material fatigue strength index.

[0011] Optionally, the determining the first multi-axis fatigue life corresponding to the device based on the single-axis damage intensity and the damage correction factor comprises: calculating a product value of the single-axis damage intensity and the damage correction factor to obtain a first multi-axis damage intensity corresponding to the device; and determining the first multi-axis fatigue life based on the first multi-axis damage intensity.

[0012] Optionally, the determining the damage ratio corresponding to the device based on the test parameter comprises: determining the damage ratio by the following formula: wherein, ξ is the damage ratio, a is a first fitting parameter, γ ij is a correlation coefficient of each-axis vibration, θ ij is a phase difference of each-axis vibration, b2 is a second fitting parameter.

[0013] Optionally, the determining the second multi-axis fatigue life corresponding to the device based on the damage ratio, the single-axis damage intensity and the damage correction factor comprises: correcting the damage correction factor based on the damage ratio; calculating a product value of the single-axis damage intensity and the corrected damage correction factor to obtain a second damage intensity corresponding to the device; and determining the second multi-axis fatigue life based on the second damage intensity.

[0014] Based on the same inventive concept, the application further provides a device for predicting fatigue life under multi-axis vibration test, comprising: an acquisition module configured to acquire test parameters of a device under single-axis vibration test; a first determination module configured to determine a damage correction factor corresponding to the device based on the number of axes in the multi-axis vibration test and the test parameters, and determine a single-axis damage intensity corresponding to the device based on the test parameters; a second determination module configured to, in response to determining that vibration loads in each axis direction of the multi-axis vibration test are not correlated, determine a first multi-axis fatigue life corresponding to the device based on the single-axis damage intensity and the damage correction factor; and a third determination module configured to, in response to determining that vibration loads in each axis direction of the multi-axis vibration test are correlated, determine a damage ratio corresponding to the device based on the test parameters, and determine a second multi-axis fatigue life corresponding to the device based on the damage ratio, the single-axis damage intensity and the damage correction factor.

[0015] Based on the same inventive concept, the application further provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable by the processor, wherein the processor implements the method described above when executing the computer program.

[0016] Based on the same inventive concept, the application further provides a non-transitory computer-readable storage medium storing computer instructions for causing a computer to execute the method described above.

[0017] As can be seen from the above, the method for predicting fatigue life under multi-axis vibration test and the related device provided by the application, the method comprises acquiring test parameters of a device under single-axis vibration test; determining a damage correction factor corresponding to the device based on the number of axes in the multi-axis vibration test and the test parameters, and determining a single-axis damage intensity corresponding to the device based on the test parameters, ensuring the accuracy of the determined damage correction factor and single-axis damage intensity of the device. In response to determining that vibration loads in each axis direction of the multi-axis vibration test are not correlated, a first multi-axis fatigue life corresponding to the device is determined based on the single-axis damage intensity and the damage correction factor, achieving the purpose of accurately predicting the first multi-axis fatigue life of the device under multi-axis vibration test using single-axis vibration test. In response to determining that vibration loads in each axis direction of the multi-axis vibration test are correlated, a damage ratio corresponding to the device is determined based on the test parameters, and a second multi-axis fatigue life corresponding to the device is determined based on the damage ratio, the single-axis damage intensity and the damage correction factor, achieving the purpose of accurately predicting the second multi-axis fatigue life of the device under multi-axis vibration test using single-axis vibration test. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the application or the related art, the drawings needed to be used in the embodiments or the related art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0019] Figure 1 A flowchart of the fatigue life prediction method under multi-axis vibration test of the embodiments of the application;

[0020] Figure 2 A schematic diagram of the device of the embodiments of the application;

[0021] Figure 3 A schematic diagram of the finite element calculation model of the device of the embodiments of the application;

[0022] Figure 4 A comparison schematic diagram of the predicted fatigue life and the tested fatigue life of the device of the embodiments of the application under triaxial vibration test;

[0023] Figure 5 A schematic diagram of the vibration fatigue life of the device of the embodiments of the application under each working condition of multi-axis vibration;

[0024] Figure 6 A comparison schematic diagram of the predicted fatigue life and the tested fatigue life of the device of the embodiments of the application under biaxial vibration test;

[0025] Figure 7 A structural schematic diagram of the fatigue life prediction device under multi-axis vibration test of the embodiments of the application;

[0026] Figure 8 An electronic device hardware structure schematic diagram of the embodiments of the application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the application more clear, the application will be further described in detail below with reference to specific embodiments and drawings.

[0028] It should be noted that the technical terms or scientific terms used in the embodiments of the present application should be the general meanings understood by those skilled in the art to which the embodiments of the present application belong, unless otherwise defined. The terms "first", "second", and similar words used in the embodiments of the present application do not represent any order, number, or importance, but are only used to distinguish different components. The terms "include" or "contain" and similar words mean that the elements or objects before the words cover the elements or objects listed after the words and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right", and the like are only used to represent relative positional relationships, and when the absolute positions of the described objects change, the relative positional relationships may also change accordingly.

[0029] As described in the background section, during the design and service of engineering structures, fatigue failure caused by multi-axial random vibration is a major challenge faced by the fields of aerospace, automobile manufacturing, nuclear power equipment, etc. For example, aircraft engine supports are subjected to X, Y, Z three-axis synchronous vibration loads during flight, and automobile chassis undergoes multi-directional dynamic excitation on rough roads. These complex load environments cause multi-axial alternating stresses inside the structure, accelerating crack initiation and propagation. Multi-axial vibration testing is the authoritative method for evaluating the fatigue life of structures under complex vibration environments, and its core is to simulate multi-directional, non-stationary vibration loads in real working conditions. However, this technology faces significant challenges in engineering applications: multi-axial vibration tables need to independently control the excitation ability of X, Y, Z three directions, usually using six-degree-of-freedom vibration tables, which are difficult to prepare. In addition, the synchronization control of multi-axial vibration needs to solve the problems of phase matching, amplitude coordination, etc. For example, in spacecraft launch vibration simulation, it is necessary to ensure that the phase difference of X, Y, Z axis vibration is consistent with the actual working condition, which has very high requirements for the real-time performance and accuracy of the control algorithm.

[0030] Due to the complexity of the equipment used in multi-axial vibration testing, the engineering community generally uses sequential single-axis vibration testing instead of multi-axial vibration testing, that is, vibration loads are applied on each principal axis of the structure one by one, and it is assumed that multi-axial damage is the linear superposition of single-axis damage. However, a large number of studies have shown that this simplified method has significant defects: most methods assume that multi-axial damage is the linear superposition of single-axis damage (such as Dmulti = DX + DY + DZ), but in reality there may be nonlinear coupling, the phase coupling, frequency coherence of multi-axial loads, and the spatial interaction of stress states are completely ignored, resulting in a life prediction error of up to 30%-50%.

[0031] Specifically, there are the following shortcomings: 1) single-axis vibration test only generates a single principal stress, while the structure may simultaneously bear complex stress states such as tension, compression and shear under multi-axis vibration test. 2) the PSD of multi-axis vibration test may present asymmetric distribution in different axial directions. Single-axis vibration test cannot reflect the difference in frequency domain distribution if only matching the total energy. 3) the phase difference of each axial load in multi-axis vibration test directly affects the damage superposition mode. For example, when the phase difference of X and Y axis vibration is 180°, the structure may produce resonance amplification effect; single-axis vibration test cannot simulate such dynamic coupling. The synergistic effect of X and Y axis damage may cause the damage value to exceed simple addition, or to be reduced due to mutual inhibition. These defects make the prediction error of the existing method often exceed 20%, which is difficult to meet the engineering precision requirements.

[0032] Therefore, the engineering field urgently needs a high-precision multi-axis life prediction method, which can quickly construct a multi-axis damage correction model through single-axis test data and numerical simulation, and fill the technical gap in the standardized process.

[0033] Therefore, the engineering field urgently needs a high-precision multi-axis life prediction method, which can quickly construct a multi-axis damage correction model through single-axis test data and numerical simulation, and fill the technical gap in the standardized process. Figure 1 , comprising the following steps:

[0034] Step 101, obtaining test parameters of the device under single-axis vibration test.

[0035] In this step, the test parameters of the device under single-axis vibration test are obtained, so that there is a data basis for predicting the fatigue life of the device under multi-axis vibration test through single-axis vibration test, wherein the single-axis vibration test is single-axis vibration test or single-axis vibration simulation. In order to make the test parameters more accurate, the device can be a fatigue test standard specimen, for example, the device is a LY12CZ aluminum alloy notched specimen. The device is subjected to fatigue loading, that is, the device is subjected to single-axis stress, and the S-N curve of the device based on the Basquin law is obtained:

[0036] σ k ·N=C formula (1),

[0037] Wherein, σ is the stress amplitude, N is the fatigue life of the device, k is the material fatigue strength index of the device, and C is the fatigue strength coefficient of the device.

[0038] The material S-N curve and the Basquin law parameters obtained by single-axis vibration test can be combined with digital image correlation technology to measure the displacement field to calibrate the material constitutive relation. The test parameters are obtained during the single-axis vibration test, which comprehensively includes the parameters used for subsequent multi-axis vibration test prediction, wherein the test parameters include the test parameters corresponding to the fatigue life of the device.

[0039] In step 102, based on the number of axes in the multi-axis vibration test and the test parameter, a damage correction factor corresponding to the device is determined, and based on the test parameter, a single-axis damage intensity corresponding to the device is determined.

[0040] In this step, due to the different number of axes in the multi-axis vibration test, for example, the number of axes is x-axis, y-axis and z-axis, or the number of axes is x-axis and y-axis, resulting in different stresses suffered by the device during fatigue loading, thereby affecting the multi-axis fatigue life of the device. Therefore, in addition to the test parameter, the damage correction factor corresponding to the device needs to be determined based on the number of axes in the multi-axis vibration test. There is a difference in damage intensity between the multi-axis vibration test and the single-axis vibration test. The damage correction factor is used to correct the damage difference between the multi-axis damage intensity and the single-axis damage intensity. The damage correction factor λ is defined as the ratio of the multi-axis damage intensity to the single-axis damage intensity: wherein D 3-D is the multi-axis damage intensity, and D 1-D is the single-axis damage intensity. Based on the test parameter, the single-axis damage intensity corresponding to the device is determined. The test parameter includes single-axis fatigue life. The single-axis damage intensity is a parameter describing the degree of cumulative damage of the device under cyclic loading. The single-axis fatigue life refers to the number of cycles before the device fails under a specific load condition. The greater the single-axis damage intensity, the shorter the single-axis fatigue life. The single-axis damage intensity and the single-axis fatigue life have an inverse proportional linear relationship. The single-axis fatigue life of the device can be determined through single-axis vibration test. Based on the single-axis fatigue life, the inverse proportional linear relationship between the predetermined single-axis damage intensity and the single-axis fatigue life is used to determine the single-axis damage intensity corresponding to the device. The test parameter in this application is obtained through single-axis vibration test, ensuring the reliability of the test parameter, and taking into account the influence of the number of axes in the multi-axis vibration test. Therefore, the determined damage correction factor and single-axis damage intensity of the device are accurate.

[0041] In step 103, in response to determining that the vibration loads in each axis direction in the multi-axis vibration test do not have correlation, based on the single-axis damage intensity and the damage correction factor, a first multi-axis fatigue life corresponding to the device is determined.

[0042] In this step, there are vibration loads in each axis direction in the multi-axis vibration test. The vibration loads affect the fatigue life of the device. To predict the fatigue life of the device under multi-axis vibration test, the relationship between the vibration loads in each axis direction needs to be considered. If the vibration loads in each axis direction affect each other, it will cause the stress suffered by the device to change, thereby causing the fatigue life of the device to change. Therefore, the multi-axis fatigue life of the device is predicted in two cases: the vibration loads in each axis direction do not have correlation and the vibration loads in each axis direction have correlation. In actual application, according to user demand, it is selected to predict the multi-axis fatigue life of the device through which case.

[0043] In the case that the multi-axis vibration test has no correlation between the vibration loads in each axis, a first multi-axis fatigue life of the device is determined based on a uniaxial damage strength and a damage correction factor. The correlation refers to a change in the vibration load in one axis causing a change in the vibration load in another axis. In the case that the multi-axis vibration test has no correlation between the vibration loads in each axis, the vibration loads in each axis are independent of each other, and a change in the vibration load in one axis does not cause a change in the vibration load in another axis. Since there is no mutual influence between the vibration loads at this time, the first multi-axis fatigue life of the device can be determined based on the uniaxial damage strength and the damage correction factor. The damage correction factor is used to correct the damage difference between the multi-axis damage strength and the uniaxial damage strength. After the uniaxial damage strength is accurately determined through experimental data, the uniaxial damage strength is corrected through the damage correction factor, the relationship between the uniaxial vibration test and the multi-axis vibration test is established, the first multi-axis fatigue life is determined based on the corrected result, and the purpose of accurately predicting the first multi-axis fatigue life of the device in the multi-axis vibration test by using the uniaxial vibration test is achieved.

[0044] In step 104, in response to determining that the multi-axis vibration test has correlation between the vibration loads in each axis, a damage ratio of the device is determined based on the test parameters, and a second multi-axis fatigue life of the device is determined based on the damage ratio, the uniaxial damage strength, and the damage correction factor.

[0045] In this step, in the case that the multi-axis vibration test has correlation between the vibration loads in each axis, it means that a change in the vibration load in one axis causes a change in the vibration load in another axis. It should be noted that the correlation between the vibration loads in each axis means that a change in the vibration load in one axis causes a change in the vibration load in another axis. Since there is a correlation between the vibration loads in each axis at this time, it will affect the fatigue life of the device, and therefore the damage ratio of the device needs to be determined based on the test parameters. The damage ratio is used to correct the damage correction factor. The second multi-axis fatigue life of the device is determined based on the damage ratio, the uniaxial damage strength, and the damage correction factor. The damage correction factor is corrected through the damage ratio, so that the corrected damage correction factor can take into account the influence of the correlation between the vibration loads in each axis. Then, the uniaxial damage strength is corrected through the corrected damage correction factor, the relationship between the uniaxial vibration test and the multi-axis vibration test is established, the second multi-axis fatigue life is determined based on the corrected result, and the purpose of accurately predicting the second multi-axis fatigue life of the device in the multi-axis vibration test by using the uniaxial vibration test is achieved.

[0046] The present invention combines uniaxial test data with finite element simulation to establish damage correction factors and damage ratios, thereby achieving rapid and high-precision prediction of multi-axial life. It is suitable for fatigue life prediction of notched structures in multi-axial vibration environments, filling the gap in the existing technology in the field of multi-axial vibration fatigue life prediction, and providing a solution that is both economical and highly accurate for engineering practice. By introducing damage correction factors, damage ratio damage correction factors, and a derivation method for predicting multi-axial fatigue life using uniaxial fatigue life, the present invention solves the accuracy contradiction between uniaxial and multi-axial damage equivalence, and provides a high-precision innovative solution for structural reliability assessment in complex vibration environments.

[0047] Through the above scheme, the test parameters of the device under uniaxial vibration testing are obtained; based on the number of axes in the multiaxial vibration testing and the test parameters, the damage correction factor corresponding to the device is determined, and, based on the test parameters, the uniaxial damage intensity corresponding to the device is determined, ensuring the accuracy of the determined damage correction factor and uniaxial damage intensity of the device. In response to determining that there is no correlation between the vibration loads in each axial direction of the multiaxial vibration test, the first multiaxial fatigue life corresponding to the device is determined based on the uniaxial damage intensity and the damage correction factor, achieving the purpose of accurately using the uniaxial vibration test to predict the first multiaxial fatigue life of the device under the multiaxial vibration test. In response to determining that there is a correlation between the vibration loads in each axial direction of the multiaxial vibration test, the damage ratio corresponding to the device is determined based on the test parameters, and based on the damage ratio, the uniaxial damage intensity and the damage correction factor, the second multiaxial fatigue life corresponding to the device is determined, achieving the purpose of accurately using the uniaxial vibration test to predict the second multiaxial fatigue life of the device under the multiaxial vibration test.

[0048] In some embodiments, the damage correction factor includes a first damage correction factor and a second damage correction factor, and the test parameters include a first test parameter and a second test parameter, wherein the number of parameters in the second test parameter is greater than the number of parameters in the first test parameter, and the second test parameter includes the first test parameter; determining the damage correction factor corresponding to the device based on the number of axes in the multi-axis vibration test and the test parameters includes: in response to determining that the number of axes in the multi-axis vibration test is two axes, determining the first damage correction factor based on the first test parameter; in response to determining that the number of axes in the multi-axis vibration test is three axes, determining the second damage correction factor based on the second test parameter.

[0049] In the embodiment, the number of axes in the multi-axis vibration test is different, the stress of the device subjected to fatigue loading is different, and the multi-axis fatigue life of the device is different. Therefore, when the number of axes in the multi-axis vibration test is different, different damage correction factors are applied to determine the multi-axis fatigue life of the device. When the number of axes in the multi-axis vibration test is two, it is referred to as a two-axis vibration test, for example, only the x-axis and the y-axis, based on the first test parameters, a first damage correction factor is determined. When the number of axes in the multi-axis vibration test is three, it is referred to as a three-axis vibration test, for example, there are x-axis, y-axis and z-axis, based on the second test parameters, a second damage correction factor is determined. Since the three-axis vibration test has one more axial vibration load than the multi-axis vibration test, the number of parameters of the second test parameters is greater than that of the first test parameters, and the second test parameters include the first test parameters. By distinguishing the number of axes in the multi-axis vibration test, and combining the test data obtained by the real single-axis vibration test, the purpose of accurately determining the damage correction factor is achieved.

[0050] In some embodiments, the first damage correction factor is determined based on the first test parameters, comprising: determining the first damage correction factor by the following formula: wherein λ1 is the first damage correction factor, is the positive zero-crossing rate under multi-axis vibration test conditions, m 0-y is the order spectrum moment of y-axis vibration, m 0-x is the order spectrum moment of x-axis vibration, is the positive zero-crossing rate of x-axis vibration, is the positive zero-crossing rate of y-axis vibration, k is the material fatigue strength index.

[0051] In the embodiment, the positive zero-crossing rate is the average number of times that the random vibration signal crosses zero from negative to positive in unit time, which is used to reflect the combined action frequency of multi-axis load, and its physical meaning is directly related to the load cycle frequency, and is one of the key parameters for fatigue life analysis. The zero-crossing rate describes the frequency of load cycles, and the multi-axis zero-crossing rate combines the interaction of x and y axes. The positive zero-crossing rate under multi-axis vibration test conditions is calculated by the positive zero-crossing rate of x-axis vibration and the positive zero-crossing rate of y-axis vibration. The positive zero-crossing rate of x-axis vibration and the positive zero-crossing rate of y-axis vibration are used to provide single-axis reference damage. The order spectrum moment of x-axis vibration and the order spectrum moment of y-axis vibration are used to show the vibration energy distribution, and the ratio quantifies the energy contribution difference between y-axis and x-axis, reflects the relative strength of different axial loads, and corrects the multi-axis coupling effect. Through the energy proportion correction value Map multi-axis vibration energy to a single-axis reference. Material fatigue strength exponent is used to correlate load amplitude to life. k is the slope of the material S-N curve, determining the sensitivity of stress amplitude to life. The exponential form of k / 2 in the equation comes from: the equivalent stress amplitude for multi-axis fatigue is usually related to the square of the uniaxial stress (e.g. von Mises criterion), k / 2 converts the multi-axis energy difference to a life modification. The positive zero-crossing rates of x and y axis vibrations are weighted and superimposed, with the weight being a function of the vibration energy ratio The first damage modification factor is the product of the positive zero-crossing rate under multi-axis vibration test conditions and the energy ratio correction value, divided by the weighted superposition of the positive zero-crossing rates of x and y axis vibrations. The formula of the first damage modification factor is determined by combining the first test parameter with the narrowband random process, and the first damage modification factor is numerized, so that the first damage modification factor has accuracy.

[0052] In some embodiments, the second damage modification factor is determined based on the second test parameter, including: the second damage modification factor is determined by the following formula: Wherein, λ2 is the second damage modification factor, is the positive zero-crossing rate under multi-axis vibration test conditions, m 0-x is the order spectral moment of x-axis vibration, m 0-y is the order spectral moment of y-axis vibration, m 0-z is the order spectral moment of z-axis vibration, is the positive zero-crossing rate of x-axis vibration, is the positive zero-crossing rate of y-axis vibration, is the positive zero-crossing rate of z-axis vibration, k is the material fatigue strength index; or, the second damage modification factor is determined by the following formula:

[0053]

[0054] Wherein, λ2 is the second damage modification factor, is the positive zero-crossing rate under multi-axis vibration test conditions, m 0-x is the order spectral moment of x-axis vibration, m 0-y is the order spectral moment of y-axis vibration, m 0-z is the order spectral moment of z-axis vibration, b eq is the bandwidth correction coefficient corresponding to multi-axis damage, b1 is the total bandwidth correction coefficient corresponding to uniaxial damage, is the irregularity coefficient corresponding to multi-axis damage, is the positive zero-crossing rate of x-axis vibration, b x is the bandwidth correction coefficient of x-axis, is the irregularity coefficient of x-axis, is the positive zero-crossing rate of y-axis vibration, by is the bandwidth correction factor for the y-axis, is the irregularity factor for the y-axis, is the positive zero crossing rate for the z-axis vibration, b z is the bandwidth correction factor for the z-axis, is the irregularity factor for the z-axis, k is the material fatigue strength exponent.

[0055] In the present embodiment, the multi-axis positive zero crossing rate The interaction of x, y, z axes is integrated. The positive zero crossing rate under multi-axis vibration test condition is calculated by the positive zero crossing rate of x-axis vibration, the positive zero crossing rate of y-axis vibration and the positive zero crossing rate of z-axis vibration. The positive zero crossing rate of x-axis vibration, the positive zero crossing rate of y-axis vibration and the positive zero crossing rate of z-axis vibration are used to provide single-axis reference damage. The spectral moments of each order of x-axis vibration, the spectral moments of each order of y-axis vibration and the spectral moments of each order of z-axis vibration are used to show the vibration energy distribution, the ratio is used to quantify the energy contribution difference between y-axis and x-axis, the ratio is used to quantify the energy contribution difference between z-axis and x-axis, reflects the relative strength of different axial loads, and corrects the multi-axis coupling effect. The energy proportion correction value maps the multi-axis vibration energy to single-axis reference. The material fatigue strength exponent is used to correlate the load amplitude and the life. k is the slope of the material S-N curve, which determines the sensitivity of stress amplitude to life. The exponential form of k / 2 in the formula is derived from: the equivalent stress amplitude of multi-axis fatigue is usually in square relationship with single-axis stress (such as von Mises criterion), and k / 2 is used to convert the multi-axis energy difference into life correction. The multi-axis vibration power spectral density (PSD) is extracted by finite element simulation, the correction factor λ is introduced to quantify the multi-axis and single-axis damage ratio, and the Tovo-Benasciutti method (multi-axis fatigue damage assessment method) is combined to distinguish the wide / narrow band vibration characteristics. The formula of the second damage correction factor is determined by using the narrow band random process and combining the first test parameter, as shown in formula (3), and the second damage correction factor is numerized, so that the second damage correction factor has accuracy.

[0056]

[0057] where T represents transposition, C is the fatigue strength coefficient of the device, and Γ is the gamma function, which is used for statistical correction of damage calculation.

[0058] The positive zero crossing rates of x-axis, y-axis and z-axis vibration are weighted and superimposed, and the weight is a function of the vibration energy ratio and The second correction factor determined by the narrow-band random process is the product of the first damage correction factor, the forward zero-crossing rate and the energy proportion correction value under the multi-axis vibration test condition, and is divided by the weighted superposition of the forward zero-crossing rates of the vibrations of the x-axis, the y-axis and the z-axis.

[0059] In addition to determining the second damage correction factor by the narrow-band random process, the second damage correction factor can also be determined by a wide-band random process in combination with the first test parameter. The formula for determining the second damage correction factor is shown in formula (4). The second damage correction factor is numerized so as to have accuracy.

[0060]

[0061] Since the second damage factor is determined by the wide-band random process, the bandwidth correction coefficient is introduced in formula (4), and a process of correcting the forward zero-crossing rates of the axes based on the bandwidth correction coefficient is added.

[0062] In some embodiments, the first multi-axis fatigue life corresponding to the device is determined based on the single-axis damage intensity and the damage correction factor, including: calculating a product value of the single-axis damage intensity and the damage correction factor to obtain a first multi-axis damage intensity corresponding to the device; and determining the first multi-axis fatigue life based on the first multi-axis damage intensity.

[0063] In the present embodiment, the damage correction factor can correct the difference between the single-axis damage intensity and the multi-axis damage intensity. Therefore, a product value of the single-axis damage intensity and the damage correction factor is calculated to obtain a first multi-axis damage intensity corresponding to the device. The multi-axis damage intensity and the multi-axis fatigue life have an inverse proportional linear relationship. In the case where the first multi-axis damage intensity is determined, the first multi-axis fatigue life is determined according to a predetermined inverse proportional linear relationship. The single-axis damage intensity is corrected by the damage correction factor to obtain an accurate first multi-axis damage intensity, and the purpose of accurately determining the first multi-axis fatigue life is achieved.

[0064] In some embodiments, the damage ratio corresponding to the device is determined based on the test parameter, including: determining the damage ratio by the following formula: wherein, ξ is the damage ratio, a is a first fitting parameter, γ ij is a correlation coefficient of the vibrations of the axes, θ ij is a phase difference of the vibrations of the axes, and b2 is a second fitting parameter.

[0065] In the present embodiment, the damage ratio is defined to represent the difference in damage intensity between the multi-axis related load and the unrelated load, which can be represented by formula (5):

[0066]

[0067] wherein D 3-D，correlated is the damage intensity of the multi-axial correlated loading, D 3-D，uncorrelated is the damage intensity of the multi-axial uncorrelated loading.

[0068] The correlation coefficient of each axis vibration reflects the coupling strength of multi-axial vibration. The phase difference of each axis vibration measures the degree of non-proportional loading, θ ij equals 0 is proportional loading; θ ij equals π / 2 is non-proportional loading. The first fitting parameter and the second fitting parameter are determined by single-axis vibration test, the first fitting parameter is used to adjust the contribution weight of the correlation coefficient to damage, and the second fitting parameter is used to control the nonlinearity degree of damage changing with the phase difference. The damage ratio ξ model of the correlation coefficient of each axis vibration and the phase difference of each axis vibration is established to analyze the influence of multi-axial correlation on life. The damage ratio is numerized by the damage ratio formula, so as to accurately determine the damage ratio.

[0069] In some embodiments, the second multi-axial fatigue life corresponding to the device is determined based on the damage ratio, the single-axis damage intensity, and the damage correction factor, including: correcting the damage correction factor based on the damage ratio; calculating the product value of the single-axis damage intensity and the corrected damage correction factor to obtain the second damage intensity corresponding to the device; and determining the second multi-axial fatigue life based on the second damage intensity.

[0070] In the present embodiment, the damage correction factor is corrected based on the damage ratio, that is, the product value of the damage ratio and the damage correction factor is calculated, so that the corrected damage correction factor can more accurately correct the difference between the single-axis damage intensity and the multi-axial damage intensity.

[0071] The product value of the corrected damage correction factor is determined by using a narrow-band random process:

[0072]

[0073] wherein D 1-D is the single-axis damage intensity, m 0-i is the spectral moment of each order of the i-th axis vibration.

[0074] The product value of the corrected damage correction factor is determined by using a wide-band random process:

[0075]

[0076] The product of the uniaxial damage strength and the modified damage correction factor is calculated to obtain the second damage strength corresponding to the device. The multi-axial damage strength and the multi-axial fatigue life have an inverse linear relationship. After the second multi-axial damage strength is determined, the second multi-axial fatigue life is determined according to the predetermined inverse linear relationship. The uniaxial damage strength is modified by the modified damage correction factor to obtain the accurate second multi-axial damage strength, and then the purpose of accurately determining the second multi-axial fatigue life is achieved.

[0077] In another embodiment provided in the application, after the first multi-axial fatigue life corresponding to the device is determined, the first fatigue life is verified, or after the second multi-axial fatigue life corresponding to the device is determined, the device is subjected to multi-axial vibration test to obtain multi-axial test parameters, and the second fatigue life is verified.

[0078] Firstly, the stress in the multi-axial vibration test is determined:

[0079] The multi-axial stress state is described by the PSD matrix of the stress tensor:

[0080]

[0081] In order to consider the influence of hydrostatic stress, the equivalent Lemaitre stress method is adopted. The expression of the equivalent stress defined by Lemaitre and Desmorat in the time domain in damage mechanics is:

[0082]

[0083] where v is the Poisson's ratio of the material, σ eq is the von Mises stress, σ m is the hydrostatic stress, and the expressions are respectively:

[0084]

[0085] σ m =(σ xx +σ yy +σ zz ) / 3 Formula (11),

[0086] where σ xx , σ yy , σ zz are normal stresses in each direction, and σ xy , σ xz , σ yz are shear stresses in each direction.

[0087] Substitute formula (10) and formula (11) into formula (9) to obtain:

[0088]

[0089] The stress tensor σ(t) = (σ xx (t), σ yy (t), σ zz (t), σ xy (t), σ xz (t), σ yz (t)) T Then, equations (11) and (12) can be written as:

[0090]

[0091] where Trace{.} denotes the trace of a matrix, and Q* is the coefficient matrix corresponding to the Lemaitre stress:

[0092]

[0093] Taking the mathematical expectation of both sides of equation (13), we have

[0094]

[0095] where E[σσ T ] is the covariance matrix of stresses, which can be obtained from the power spectral density function matrix of stresses:

[0096]

[0097] Therefore,

[0098] Thus, the equivalent Lemaitre stress in the frequency domain can be written as:

[0099]

[0100] It can be seen that when v = 0.5, the equivalent Lemaitre stress can be simplified as the equivalent von Mises stress. The equivalent Lemaitre stress defined in the frequency domain by equation (17) is also a zero-mean stationary Gauss process. Therefore, existing mature uniaxial fatigue life prediction models, such as the narrowband approximation model, can also be used. A significant feature of the equivalent Lemaitre stress is that it can take into account the effect of hydrostatic stress, which plays an important role in fatigue fracture. By using the Lemaitre equivalent stress (which incorporates a hydrostatic stress correction term) instead of the traditional von Mises stress, an equivalent relationship between multiaxial stress and uniaxial damage is established. Therefore, compared with the equivalent von Mises stress, the equivalent Lemaitre stress can provide more accurate fatigue life prediction results.

[0101] In addition, the multi-axial vibration damage strength can also be obtained by formula calculation, and the multi-axial damage strength is determined by using a narrow-band random process:

[0102]

[0103] Wherein, Γ is a gamma function, a statistical correction for damage calculation, The root mean square value of the equivalent stress of the dangerous point of the structure under the multi-axial vibration condition, The positive zero-crossing rate under the multi-axial vibration condition, and C is a fatigue strength coefficient.

[0104] The multi-axial damage strength is determined by using a wide-band random process:

[0105]

[0106] Wherein, α1 is a bandwidth parameter, and α2 is an irregularity coefficient,

[0107]

[0108] Through test and simulation verification, the life prediction error of the method is less than or equal to 20%, which is significantly better than the traditional method, and the method can be widely applied to multi-axial vibration fatigue evaluation of complex structures in the fields of aerospace, automobile engineering and the like, and provides key technical support for high-precision and high-efficiency durability design.

[0109] In another embodiment provided in the application, the multi-axial vibration test is not related to the vibration load in each axial direction, and the spectral moment relationship of the multi-axial vibration test is as follows:

[0110] When the input load of each axial direction of the multi-axial vibration is not related to each other, that is, the cross spectrum G ij (f) of the input load spectrum is 0, the response of each point on the structure is the superposition of the responses caused by the vibration in three directions. Then the stress response can be obtained:

[0111]

[0112] Wherein, H σx (f) is the stress frequency response function of the x-axis, H σy (f) is the stress frequency response function of the y-axis, and H σz (f) is the stress frequency response function of the z-axis, G xx (f) is the acceleration power spectral density of the x-axis vibration excitation, G yy (f) is the acceleration power spectral density of the y-axis vibration excitation, and G zz (f) is the acceleration power spectral density of the z-axis vibration excitation. For three-axis loading, the equivalent zero-order moment is:

[0113]

[0114] Potential influence of correlation between multi-axial load components on structural damage. Load correlation power spectral density is defined as:

[0115]

[0116] where,

[0117]

[0118] It can be seen that the response of the structure in a tri-axial vibration environment contains the combination of excitations in three directions and the frequency response functions in different directions. For multi-axial random vibration, a single direction excitation can simultaneously excite the modes of the structure in each direction, and the structure response in the frequency domain has multiple resonance peaks caused by axial excitations. Then the stress response can be obtained as:

[0119]

[0120] At this time, it satisfies

[0121]

[0122] For tri-axial loading, formula (27) can be simplified as

[0123] m 0-3D = m 0-x + m 0-y + m 0-z + m 0-corrected Formula (28), where m 0-corrected is the spectral moment correction value.

[0124] The stress response PSD under multi-axial vibration is obtained by finite element simulation, and the damage intensity is calculated by using the Tovo-Benasciutti method (applicable to wideband) or narrowband approximation (NB) method:

[0125] For narrowband random processes, a spectral moment correction value can also be introduced to calculate the second damage correction factor, Simplifying can obtain:

[0126]

[0127] In order to establish the relationship between λ and θ ij , γ ij , the damage ratio between multi-axial correlated load and uncorrelated load under multi-axial loading is defined as:

[0128] According to related research, the damage ratio ξ between multi-axial correlated load and uncorrelated load under multi-axial loading has the following characteristics:

[0129] Correlation coefficient γ ijWhen equal to 0, the damage ratio ξ between the multi-axial correlated load and the uncorrelated load is always equal to 1. In this case, the load is uncorrelated.

[0130] Phase difference θ ij When equal to 90 degrees, the damage ratio ξ between the multi-axial correlated load and the uncorrelated load is always equal to 1. In this case, the multi-axial vibration is very similar to the case of sequentially applied uniaxial loads, and the behavior of the load is like two uncorrelated signals, making the damage not change with the coherence coefficient.

[0131] Correlation coefficient γ ij When equal to 1, the damage ratio ξ between the multi-axial correlated load and the uncorrelated load reaches the maximum value (0 < θ ij < 90 degrees) or the minimum value (90 < θ ij < 180 degrees) at the respective phase difference. Among them, the minimum value of ξ appears when θ ij = 180 degrees; the maximum value of ξ appears when θ ij = 0 degrees.

[0132] According to the characteristics of the above damage ratio ξ, the function can be constructed as follows:

[0133] ξ = (1 + a · γ ij · cos θ ij ) b Equation (31),

[0134] In the formula, a and b are parameters determined by the vibration characteristics of the structure, which are related to the natural frequency interval of the structure, and can be fitted by the test or finite element simulation results of multi-axial correlated vibration and uncorrelated vibration.

[0135] Therefore, combined with equation (31), when the multi-axial vibration excitation is correlated, the analytical expression of the damage modification factor λ determined by the narrow-band random process is:

[0136]

[0137] In particular, when the multi-axial vibration excitation is correlated, for the biaxial correlated vibration loading, the analytical expression of the damage modification factor λ determined by the narrow-band random process is:

[0138]

[0139] Among them, can be obtained by vibration test or finite element simulation. a and b are parameters determined by the vibration characteristics of the structure, which are related to the natural frequency interval of the structure, and can be fitted by the test or finite element simulation results of multi-axial correlated vibration and uncorrelated vibration.

[0140] The uniaxial vibration life of each uniaxial direction of the structure can be obtained by sequentially performing uniaxial vibration tests on the structure. Then, the fatigue life of the structure under correlated or uncorrelated multi-axial vibration loads can be obtained by combining the multi-axial vibration damage correction factor λ. The parameters of the correction factor λ can be obtained by performing uniaxial and multi-axial vibration finite element simulations on the structure.

[0141] In another embodiment provided in the application, the damage equivalent method for predicting the structure fatigue life under multi-axial random vibration test by uniaxial random vibration test is further described below in combination with an example of a LY12CZ aluminum alloy notched specimen:

[0142] The specimen material is LY12CZ aluminum alloy. The material mechanical properties of the LY12CZ aluminum alloy at room temperature are shown in Table 1.

[0143] Table 1 Mechanical properties of LY12CZ aluminum alloy

[0144] p E m u ]]> ​ 2700 kg / m3 73 GPa 0.33 545 MPa

[0145] The parameter values of the S-N curve formula of the material are as follows: C = 1.23*10 18 ; K = 5.60. The specimen is designed as a circular groove notched specimen. The specific shape and size of the test device are shown in Table 2. Figure 2 .

[0146] The experiment uses a MAV-6000-5H (140201) three-axis vibration testing machine for vibration loading. The available frequency range is 5 Hz-2000 Hz (random) and 5 Hz-800 Hz (sine). The upper limit of the random vibration load is X direction -20g, Y direction -22g, and Z direction -26.9g. The sine is X direction -32g, Y direction -32g, and Z direction -34.8g. They can excite the specimen along three orthogonal translational degrees of freedom for vibration loading. In the experiment, strain gauges are used to record the dynamic response and dynamic strain of the specimen.

[0147] Four specimens are used as a group, and the test specimen is fixed at one end of the exciter by a clamp, and two counterweights are added at the other end. The modal analysis uses a multi-axis vibration test bench to sweep the frequency, and the strain gauges are connected to the specimen to obtain the natural frequency of each order of vibration. The random vibration fatigue test uses acceleration load base excitation, and the input form is acceleration power spectral density, the size is 0.015g 2 / Hz, and the frequency range is in the range of [20, 200] Hz. In the biaxial random vibration fatigue test, the random acceleration base excitation is applied in the X and Y directions at the same time, and different combinations of the correlation coefficient and phase difference between the two vibration axes are set. The specific load application is shown in Table 2. The measured data are strain time history and fatigue failure time. The fracture time of the notched plate specimen is defined as the experimental fatigue life of the random vibration fatigue test. All experiments are carried out at room temperature.

[0148] Table 2 Input acceleration power spectral density

[0149]

[0150] In the biaxial random vibration fatigue test, different combinations of correlation coefficient and phase difference between two vibration axes are set to study the influence of these factors on the fatigue life of the notched specimen. The fatigue life of the notched specimen under different loading conditions is shown in Table 3.

[0151] Table 3 Vibration fatigue life of the specimen under each condition of uniaxial vibration and multiaxial vibration

[0152]

[0153] The modal analysis and random vibration of the specimen are performed by Abaqus. Since simulation calculation needs to be performed in software (for example, Abaqus), the finite element calculation model of the device needs to be used. The device structure needs to be meshed, and since there is a stress concentration phenomenon, especially for the notched part, the mesh needs to be encrypted. For example, the finite element calculation model of the device used for simulation calculation in the present application is shown in FIG. 1. The unit type is C3D8R, and local encryption is performed at the notch. Figure 3

[0154] Table 4 shows the comparison between the first two vibration modes obtained by finite element and experiment. From Table 4, it can be concluded that the natural frequency of the above specimen obtained by finite element analysis is basically consistent with the experimental result, which indicates that the finite element model can accurately describe the dynamic characteristics of the structure, thereby verifying the effectiveness of the calculation model.

[0155] Table 4 First two order modal frequencies and modal types of the structure

[0156] Mode shape Mode shape Natural frequency - test (Hz) Natural frequency - FEM (Hz) 1 X-direction bending 70.20 71.940 2 Y-direction bending 142.10 149.06

[0157] Next, the random vibration analysis of the structure under uniaxial loading and multiaxial loading is performed. The PSD of the stress component and the strain component of the dangerous point under each vibration condition is output. The code is written using the programming language Python to realize the following functions:

[0158] 1) The equivalent Mises and Lemaitre stress methods are used to respectively equivalent the PSD data of each stress component;

[0159] 2) Calculate the spectral distance m0, m1, m2, m4 and zero crossing rate n0, irregularity coefficient a1, a2 of each uniaxial (X, Y) random vibration +

[0160] ​​3) Write a damage factor calculation program for narrowband random vibration (refer to formula (3)) and a damage factor calculation program for broadband random vibration (refer to formula (4));

[0161] 4) Calculate the multiaxial vibration-uniaxial vibration damage equivalent factors calculated by the two stress equivalence methods and the two bandwidth methods respectively. Table 5 shows the multiaxial vibration-uniaxial vibration damage equivalent factors calculated by the above methods.

[0162] Table 5 Multiaxial vibration-uniaxial vibration damage equivalent factors

[0163]

[0164] Where NB represents a narrowband random process and TB represents a broadband random process. Next, the proposed multiaxial vibration-uniaxial vibration damage equivalence factor is applied to the fatigue life prediction of the notched specimen under multiaxial random vibration loading.

[0165] According to the life of X-axis uniaxial vibration and Y-axis uniaxial vibration obtained from the test, combined with the damage equivalent factor λ given in Table 5, the fatigue life of the notched specimen under multi-axial random vibration load can be calculated as follows: Figure 4 As shown, Figure 4 This is a schematic diagram comparing the predicted fatigue life and the experimental fatigue life of the device according to the embodiment of the present application under the triaxial vibration test, wherein: Figure 4 The vertical axis is the predicted fatigue life (seconds), and the horizontal axis is the fatigue life (seconds) obtained by the test. The predicted fatigue life is the fatigue life obtained by the prediction method provided by the present invention, and the experimental fatigue life is the fatigue life actually determined by the test or simulation. The NB method is a narrowband random process, and the TB method is a broadband random process. y=x indicates that the predicted fatigue life is the same as the experimental fatigue life. Figure 4 It can be seen that the equivalent damage factor calculated by the TB method has a higher accuracy (within 20%) in predicting the fatigue life of multi-axial random vibration specimens. Figure 5 Schematic diagram of the vibration fatigue life of the device of the embodiment of the present application under various multi-axis vibration conditions, Figure 5 The horizontal axis represents the coherence coefficient and phase difference of the XY axis vibration. For example, 0.5-0 represents a coherence coefficient of 0.5 and a phase difference of 0 degrees. The vertical axis represents fatigue life (seconds). Figure 5 This is a box plot. The horizontal line in the box plot reflects the median of the data, and the circle represents the mean. The box plot (interquartile range, IQR) reflects the neutrality of the data set. For example, the box corresponding to the horizontal axis of 0.5-45 is tall, indicating scattered data; the box corresponding to the horizontal axis of 0.95-45 is relatively short, indicating relatively concentrated data.

[0166] Next, the proposed multiaxial vibration-uniaxial vibration damage equivalent factor is applied to the fatigue life prediction of the above-mentioned notched specimen under multiaxial random vibration loading.

[0167] According to the above characteristics of the damage ratio ξ, the structure can be constructed as follows:

[0168] ξ=(1+a·γ ij cosθ ij ) b Formula (34),

[0169] According to the experimental results in Table 3, the coefficients a and b can be fitted as follows:

[0170] a=0.20;b=1.28

[0171] Then there is

[0172] ξ=(1+0.20·γ ij cosθ ij ) 1.28 Formula (35),

[0173] D 3-D，correlated =ξ·D 3-D，uncorrelated =(1+0.20·γ ij cosθ ij ) 1.28 ·D 3-D，uncorrelated Formula (36),

[0174] According to the above formula, the fatigue life and test fatigue life of the case related to biaxial excitation are predicted as follows: Figure 6 As shown, Figure 6 This is a schematic diagram comparing the predicted fatigue life and the experimental fatigue life of the device according to the embodiment of the present application under the biaxial vibration test, wherein: Figure 6 The vertical axis is the predicted fatigue life (seconds), and the horizontal axis is the fatigue life (seconds) obtained by the test. Figure 6 It can be seen that the error between the predicted fatigue life and the experimental fatigue life is within 20%. The following analysis can also be obtained:

[0175] Phase difference θ ij When the angle is equal to 90 degrees, the damage ratio ξ between correlated and uncorrelated multiaxial loads is always equal to 1. In this case, multiaxial vibration closely resembles sequentially applied uniaxial loads. The loads behave like two uncorrelated signals, making the damage independent of the coherence coefficient. In this case, the fatigue life of correlated multiaxial loads is approximately equal to that of uncorrelated multiaxial loads.

[0176] Correlation coefficient γ ij When 0<θ ijIn the range of <90 degrees, the cross power spectrum density of multi-axis related loads is positive, and with the phase angle θ ij This results in the equivalent damage decreasing with the increase of the phase angle θ. ij The lifespan is shortest when the phase angle is 0 degrees.

[0177] In 0<θ ij In the range of <90 degrees, a larger coherence coefficient leads to a larger cross-power spectrum density, which in turn leads to a larger equivalent damage gradient. Therefore, the fatigue life of the specimen when the load coherence coefficient is 0.5 is greater than that when the coherence coefficient is 0.95.

[0178] It should be noted that the method of the embodiment of the present application can be performed by a single device, such as a computer or server. The method of this embodiment can also be applied in a distributed scenario and performed by multiple devices working together. In such a distributed scenario, one of the multiple devices may only perform one or more steps of the method of the embodiment of the present application, and the multiple devices will interact with each other to complete the method.

[0179] It should be noted that the above description is limited to some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in an order different from that described in the above embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0180] Based on the same inventive concept, corresponding to any of the above-mentioned embodiment methods, the present application also provides a fatigue life prediction device under multi-axis vibration testing.

[0181] refer to Figure 7 , the fatigue life prediction device under the multi-axial vibration test comprises:

[0182] The acquisition module 10 is configured to acquire test parameters of the device under a uniaxial vibration test.

[0183] The first determination module 20 is configured to determine a damage correction factor corresponding to the device based on the number of axes in the multi-axis vibration test and the test parameters, and to determine a uniaxial damage intensity corresponding to the device based on the test parameters.

[0184] The second determining module 30 is configured to determine a first multi-axial fatigue life of the device based on the single-axial damage strength and the damage correction factor in response to determining that the multi-axial vibration test has no correlation in vibration load in each axial direction.

[0185] The third determining module 40 is configured to determine a damage ratio of the device based on the test parameters in response to determining that the multi-axial vibration test has correlation in vibration load in each axial direction, and determine a second multi-axial fatigue life of the device based on the damage ratio, the single-axial damage strength and the damage correction factor.

[0186] By the above device, the test parameters of the device under single-axial vibration test are obtained, and the damage correction factor of the device is determined based on the number of axes in the multi-axial vibration test and the test parameters. The single-axial damage strength of the device is determined based on the test parameters, ensuring the accuracy of the determined damage correction factor and single-axial damage strength of the device. In response to determining that the multi-axial vibration test has no correlation in vibration load in each axial direction, a first multi-axial fatigue life of the device is determined based on the single-axial damage strength and the damage correction factor, achieving the purpose of accurately predicting the first multi-axial fatigue life of the device under multi-axial vibration test by single-axial vibration test. In response to determining that the multi-axial vibration test has correlation in vibration load in each axial direction, a damage ratio of the device is determined based on the test parameters, and a second multi-axial fatigue life of the device is determined based on the damage ratio, the single-axial damage strength and the damage correction factor, achieving the purpose of accurately predicting the second multi-axial fatigue life of the device under multi-axial vibration test by single-axial vibration test.

[0187] In some embodiments, the first determining module 20 is further configured to: the damage correction factor includes a first damage correction factor and a second damage correction factor, and the test parameters include a first test parameter and a second test parameter, wherein the number of parameters in the second test parameter is greater than the number of parameters in the first test parameter, and the second test parameter includes the first test parameter; the first damage correction factor is determined based on the first test parameter in response to determining that the number of axes in the multi-axial vibration test is two axes; and the second damage correction factor is determined based on the second test parameter in response to determining that the number of axes in the multi-axial vibration test is three axes.

[0188] In some embodiments, the first determining module 20 is further configured to determine the first damage correction factor by the following formula: wherein λ1 is the first damage correction factor, is a positive zero-crossing rate under multi-axial vibration test conditions, m 0-y is each order spectrum moment of y-axis vibration, m0-x is the spectrum moment of the x-axis vibration, is the positive zero-crossing rate of the x-axis vibration, is the positive zero-crossing rate of the y-axis vibration, k is the material fatigue strength index.

[0189] In some embodiments, the first determining module 20 is further configured to determine the second damage correction factor by the following formula: wherein λ2 is the second damage correction factor, is the positive zero-crossing rate under multi-axis vibration test conditions, m 0-x is the spectrum moment of the x-axis vibration, m 0-y is the spectrum moment of the y-axis vibration, m 0-z is the spectrum moment of the z-axis vibration, is the positive zero-crossing rate of the x-axis vibration, is the positive zero-crossing rate of the y-axis vibration, is the positive zero-crossing rate of the z-axis vibration, k is the material fatigue strength index; or, the second damage correction factor is determined by the following formula:

[0190]

[0191] wherein λ2 is the second damage correction factor, is the positive zero-crossing rate under multi-axis vibration test conditions, m 0-x is the spectrum moment of the x-axis vibration, m 0-y is the spectrum moment of the y-axis vibration, m 0-z is the spectrum moment of the z-axis vibration, b eq is the bandwidth correction coefficient corresponding to multi-axis damage, b1 is the total bandwidth correction coefficient corresponding to single-axis damage, is the irregularity coefficient corresponding to multi-axis damage, is the positive zero-crossing rate of the x-axis vibration, b x is the bandwidth correction coefficient of the x-axis, is the irregularity coefficient of the x-axis, is the positive zero-crossing rate of the y-axis vibration, b y is the bandwidth correction coefficient of the y-axis, is the irregularity coefficient of the y-axis, is the positive zero-crossing rate of the z-axis vibration, b z is the bandwidth correction coefficient of the z-axis, is the irregularity coefficient of the z-axis, k is the material fatigue strength index.

[0192] In some embodiments, the second determining module 30 is further configured to calculate a product of the uniaxial damage strength and the damage correction factor to obtain a first multi-axial damage strength corresponding to the device; and determine the first multi-axial fatigue life based on the first multi-axial damage strength.

[0193] In some embodiments, the third determining module 40 is further configured to determine the damage ratio by the following formula: wherein, ξ is the damage ratio, a is a first fitting parameter, γ ij is a correlation coefficient of vibration of each axis, θ ij is a phase difference of vibration of each axis, and b2 is a second fitting parameter.

[0194] In some embodiments, the third determining module 40 is further configured to correct the damage correction factor based on the damage ratio; calculate a product of the uniaxial damage strength and the corrected damage correction factor to obtain a second damage strength corresponding to the device; and determine the second multi-axial fatigue life based on the second damage strength.

[0195] For the convenience of description, the above apparatus is described in various modules in terms of functions. Of course, the functions of the modules can be implemented in one or more software and / or hardware in the implementation of the present application.

[0196] The apparatuses of the above embodiments are used to implement the fatigue life prediction method under multi-axial vibration test in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be described here.

[0197] Based on the same inventive concept, the present application also provides an electronic device corresponding to any of the above method embodiments, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the fatigue life prediction method under multi-axial vibration test as described in any of the above embodiments when executing the program.

[0198] Figure 8 A more specific hardware structure of an electronic device provided by the present embodiment is shown, which can include a processor 1010, a memory 1020, an input / output interface 1030, a communication interface 1040, and a bus 1050. The processor 1010, the memory 1020, the input / output interface 1030, and the communication interface 1040 are connected to each other through the bus 1050 for communication within the device.

[0199] The processor 1010 can be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits, etc., for executing relevant programs to implement the technical solutions provided by the embodiments of the present specification.

[0200] The memory 1020 can be implemented in the form of a ROM (Read Only Memory), a RAM (Random Access Memory), a static storage device, a dynamic storage device, etc. The memory 1020 can store an operating system and other application programs, and when the technical solutions provided by the embodiments of the present specification are implemented by software or firmware, the relevant program codes are saved in the memory 1020 and called and executed by the processor 1010.

[0201] The input / output interface 1030 is configured to connect input / output modules to implement information input and output. The input / output modules can be configured as components in the device (not shown in the figure) or externally connected to the device to provide corresponding functions. The input devices can include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output devices can include a display, a speaker, a vibrator, an indicator light, etc.

[0202] The communication interface 1040 is configured to connect a communication module (not shown in the figure) to implement the communication interaction between the device and other devices. The communication module can realize communication through a wired manner (such as USB, network cable, etc.) or through a wireless manner (such as mobile network, WIFI, Bluetooth, etc.).

[0203] The bus 1050 includes a channel for transmitting information between various components (such as the processor 1010, the memory 1020, the input / output interface 1030, and the communication interface 1040) of the device.

[0204] It should be noted that although the above device only shows the processor 1010, the memory 1020, the input / output interface 1030, the communication interface 1040, and the bus 1050, in the specific implementation process, the device can also include other components necessary for normal operation. In addition, those skilled in the art can understand that the above device can also only include the components necessary to implement the solutions of the embodiments of the present specification, and does not have to include all the components shown in the figure.

[0205] The electronic device of the above-mentioned embodiments is used to implement the method for predicting fatigue life under multi-axis vibration test in any of the preceding embodiments, and has the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0206] Based on the same inventive concept, the present application also provides a non-transitory computer-readable storage medium storing computer instructions for causing a computer to perform the method for predicting fatigue life under multi-axis vibration test according to any of the preceding embodiments.

[0207] The computer-readable medium of the embodiments can include permanent and non-permanent, removable and non-removable media, which can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic tape disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible by a computing device.

[0208] The computer instructions stored in the storage medium of the above-mentioned embodiments are used to cause the computer to perform the method for predicting fatigue life under multi-axis vibration test according to any of the preceding embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0209] Based on the same concept, the present application also provides a computer program product comprising computer program instructions for causing a computer to perform the method for predicting fatigue life under multi-axis vibration test according to any of the preceding embodiments, having the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0210] It should be noted that the embodiments of the present application can also be further described in the following ways:

[0211] It can be understood that before using the technical solutions of the various embodiments in the present disclosure, the user will be informed of the type, scope of use, use scenario, etc. of the personal information involved in a proper manner, and the user's authorization will be obtained.

[0212] For example, in response to receiving an active request of a user, a prompt information is sent to the user to explicitly prompt the user that the operation requested to be performed will require obtaining and using personal information of the user. Thus, the user can autonomously select whether to provide the personal information to the software or hardware, such as an electronic device, an application program, a server or a storage medium, performing the operation of the technical solution of the present disclosure according to the prompt information.

[0213] As an optional but non-limiting implementation, in response to receiving an active request of a user, the prompt information can be sent to the user in the form of a pop-up window, in which the prompt information can be presented in the form of text. In addition, the pop-up window can also carry selection controls for the user to select "agree" or "disagree" to provide personal information to the electronic device.

[0214] It can be understood that the above notification and obtaining user authorization process is only illustrative, and does not limit the implementation of the present disclosure, and other ways that meet the relevant laws and regulations can also be applied to the implementation of the present disclosure.

[0215] Those skilled in the art will understand that the discussion of any of the above embodiments is merely exemplary and is not intended to suggest that the scope of the application be limited to these examples; the embodiments or technical features among different embodiments can be combined, and the steps can be implemented in any order, and there are many other changes to the aspects of the embodiments of the present application as described above. In order to be brief, they are not provided in detail.

[0216] In addition, in order to simplify the description and discussion, and so as not to make the embodiments of the present application difficult to understand, the known power / ground connections of integrated circuit (IC) chips and other components can or can not be shown in the provided drawings. In addition, the devices can be shown in the form of block diagrams in order to avoid making the embodiments of the present application difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform to be implemented in the embodiments of the present application (i.e. these details should be fully within the understanding of those skilled in the art). Where specific details (e.g. circuits) are set forth in order to describe an exemplary embodiment of the present application, it will be apparent to those skilled in the art that the embodiments of the present application can be practiced without these specific details or with variations on these specific details. Therefore, these descriptions should be considered as illustrative rather than limiting.

[0217] Although the present application has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. For example, other memory architectures (e.g. dynamic RAM (DRAM)) can use the embodiments discussed.

[0218] Embodiments of the present application are intended to cover any and all such substitutions, modifications, and variations. Accordingly, any one of the above-described embodiments of the present application can be replaced by any other disclosed embodiments of the present application, and the entirety of any disclosed series can be substituted for any other disclosed series, and the entirety of any disclosed series can be substituted for any other disclosed series, and the entirety of any disclosed series can be substituted for any other disclosed series, and the entirety of any disclosed series can be substituted for any other disclosed series, and the entirety of any disclosed series can be substituted for any other disclosed series, and the entirety of any disclosed series can be substituted for any other disclosed series, and the entirety of any disclosed series can be substituted for any other disclosed series, and the entirety of

Claims

1. A method for predicting fatigue life under multi-axial vibration testing, characterized in that: include: Obtain test parameters of the device under uniaxial vibration test; Determining a damage correction factor corresponding to the device based on the number of axes in the multi-axial vibration test and the test parameters, and determining a uniaxial damage intensity corresponding to the device based on the test parameters; In response to determining that there is no correlation between the vibration loads in each axial direction of the multi-axial vibration test, determining a first multi-axial fatigue life corresponding to the component based on the uniaxial damage intensity and the damage correction factor; In response to determining that there is a correlation between the vibration loads in each axial direction of the multi-axial vibration test, a damage ratio corresponding to the device is determined based on the test parameters, and a second multi-axial fatigue life corresponding to the device is determined based on the damage ratio, the uniaxial damage intensity and the damage correction factor.

2. The method according to claim 1, characterized in that The damage correction factor includes a first damage correction factor and a second damage correction factor, and the test parameters include a first test parameter and a second test parameter, wherein the number of parameters in the second test parameter is greater than the number of parameters in the first test parameter, and the second test parameter includes the first test parameter; Determining the damage correction factor corresponding to the device based on the number of axes in the multi-axis vibration test and the test parameters includes: In response to determining that the number of axes in the multi-axial vibration test is two, determining the first damage correction factor based on the first test parameter; In response to determining that the number of axes in the multi-axial vibration test is three axes, the second damage correction factor is determined based on the second test parameter.

3. The method according to claim 2, characterized in that The determining the first damage correction factor based on the first test parameter includes: The first damage correction factor is determined by the following formula: Where λ1 is the first damage correction factor, is the positive zero crossing rate under multi-axis vibration test conditions, m 0-y is the spectral moment of each order of y-axis vibration, m 0-x are the spectral moments of each order of x-axis vibration, is the positive zero crossing rate of x-axis vibration, is the positive zero-point crossing rate of y-axis vibration, and k is the material fatigue strength index.

4. The method according to claim 2, characterized in that The determining the second damage correction factor based on the second test parameter includes: The second damage correction factor is determined by the following formula: Where λ2 is the second damage correction factor, is the positive zero crossing rate under multi-axis vibration test conditions, m 0-x is the spectral moment of each order of x-axis vibration, m 0-y is the spectral moment of each order of y-axis vibration, m 0-z are the spectral moments of each order of z-axis vibration, is the positive zero crossing rate of x-axis vibration, is the positive zero crossing rate of y-axis vibration, is the positive zero-point crossing rate of z-axis vibration, k is the material fatigue strength index; or, The second damage correction factor is determined by the following formula: Where λ2 is the second damage correction factor, is the positive zero crossing rate under multi-axis vibration test conditions, m 0-x is the spectral moment of each order of x-axis vibration, m 0-y is the spectral moment of each order of y-axis vibration, m 0-z is the spectral moment of each order of z-axis vibration, b eq is the bandwidth correction coefficient corresponding to multi-axis damage, b1 is the total bandwidth correction coefficient corresponding to uniaxial damage, is the irregularity coefficient corresponding to multiaxial damage, is the positive zero crossing rate of x-axis vibration, b x is the bandwidth correction factor of the x-axis, is the irregularity coefficient of the x-axis, is the positive zero crossing rate of y-axis vibration, b y is the bandwidth correction factor of the y-axis, is the irregularity coefficient of the y-axis, is the positive zero-crossing rate of z-axis vibration, b z is the bandwidth correction factor of the z-axis, is the irregularity coefficient of the z-axis, and k is the material fatigue strength index.

5. The method according to claim 1, wherein The determining, based on the uniaxial damage intensity and the damage correction factor, a first multiaxial fatigue life corresponding to the device includes: Calculating the product of the uniaxial damage strength and the damage correction factor to obtain a first multiaxial damage strength corresponding to the device; The first multiaxial fatigue life is determined based on the first multiaxial damage intensity.

6. The method according to claim 1, characterized in that Determining the damage ratio corresponding to the device based on the test parameters includes: The damage ratio is determined by the following formula: Wherein, ξ is the damage ratio, a is the first fitting parameter, γ ij is the correlation coefficient of each axis vibration, θ ij is the phase difference of each axis vibration, and b2 is the second fitting parameter.

7. The method according to claim 1, characterized in that Determining a second multiaxial fatigue life corresponding to the device based on the damage ratio, the uniaxial damage intensity, and the damage correction factor includes: Based on the damage ratio, modifying the damage correction factor; Calculating the product of the uniaxial damage intensity and the corrected damage correction factor to obtain a second damage intensity corresponding to the device; The second multiaxial fatigue life is determined based on the second damage intensity.

8. A fatigue life prediction device under multi-axis vibration test, characterized in that: include: An acquisition module is configured to acquire test parameters of a device under a uniaxial vibration test; A first determination module is configured to determine a damage correction factor corresponding to the device based on the number of axes in the multi-axis vibration test and the test parameters, and to determine a uniaxial damage intensity corresponding to the device based on the test parameters; a second determination module configured to determine, in response to determining that there is no correlation between the vibration loads in each axial direction of the multi-axial vibration test, a first multi-axial fatigue life corresponding to the component based on the uniaxial damage intensity and the damage correction factor; A third determination module is configured to, in response to determining that there is a correlation between the vibration loads in each axial direction of the multi-axis vibration test, determine a damage ratio corresponding to the device based on the test parameters, and determine a second multi-axis fatigue life corresponding to the device based on the damage ratio, the uniaxial damage intensity and the damage correction factor.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the program, the method according to any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium storing computer instructions, characterized in that: The computer instructions are used to enable a computer to execute the method according to any one of claims 1 to 7.

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