Vibration environment interface crack propagation life prediction method and related equipment

Abstract

The invention provides a vibration environment interface crack propagation life prediction method which comprises the following steps: constructing an initial crack on a test piece to obtain a standard test piece; mounting a strain gauge on the surface of the standard test piece, wherein the strain gauge is vertically crossed with the initial crack; the method comprises the steps that a standard test piece is installed on a multi-axis vibration testing machine, multi-direction vibration excitation is input into the multi-axis vibration testing machine, strain time domain data of the standard test piece in the testing process are collected through a strain gauge, and inherent frequency data of the standard test piece are obtained through the strain time domain data; continuously monitoring inherent frequency data of the standard test piece, and when the inherent frequency data is reduced to a preset threshold value, determining that the standard test piece fails due to crack propagation; and determining the actual time or the actual cyclic load frequency of the multidirectional vibration excitation as the actual crack propagation life. According to the prediction method, complex multi-direction vibration borne by the standard test piece under the actual working condition can be restored, and test result distortion caused by single-axis sequential tests is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crack propagation life test, and particularly relates to a vibration environment interface crack propagation life prediction method and related equipment. BACKGROUND

[0002] The vibration fatigue test is used for studying the damage and fracture behavior of a solid in a multi-directional vibration environment. The prior art uses three orthogonal axial uniaxial vibration tests to simulate the multi-directional vibration environment, but this test method is not reasonable: the uniaxial equivalent test assumes that the dynamic responses of the structure in each axial direction are independent of each other, but for a complex structure with small overall stiffness such as a missile, an aircraft pod, a launch vehicle, etc., a vibration excitation in a certain axial direction may excite other axial vibration modes and generate a large vibration response; therefore, the uniaxial vibration direction is difficult to completely reproduce the real environment failure. Therefore, the conventional uniaxial sequential vibration fatigue test equivalent method cannot meet the increasing test requirements of high precision and high efficiency. SUMMARY

[0003] In view of this, the present application aims to provide a vibration environment interface crack propagation life prediction method and related equipment to solve the problem that the current uniaxial sequential vibration test cannot accurately simulate the vibration damage behavior of a solid.

[0004] To achieve the above purpose, the present application provides a vibration environment interface crack propagation life prediction method, which comprises the following steps:

[0005] An initial crack is constructed on a test piece to obtain a standard test piece;

[0006] A strain gauge is installed on the surface of the standard test piece, and the strain gauge is arranged perpendicularly across the initial crack;

[0007] The standard test piece is installed on a multi-axial vibration testing machine, a multi-directional vibration excitation is input to the multi-axial vibration testing machine, the strain gauge collects strain time domain data of the standard test piece during the test, and the natural frequency data of the standard test piece is obtained through the strain time domain data;

[0008] The natural frequency data of the standard test piece is continuously monitored, and when the natural frequency data drops to a preset threshold value, it is determined that the standard test sample has failed due to crack propagation;

[0009] The actual time or actual cycle load number of the multi-directional vibration excitation is determined as the actual crack propagation life of the standard test piece in a multi-directional vibration environment.

[0010] Optionally, the method further comprises verifying a pre-constructed crack propagation life prediction model through the actual crack propagation life.

[0011] Optionally, the construction step of the crack propagation life prediction model comprises:

[0012] constructing an initial crack on a simulation test piece to obtain a simulation standard test piece, and taking at least one tip of the initial crack as a target sampling point;

[0013] constructing a multi-directional vibration environment, and obtaining a plurality of stress intensity parameters of each target sampling point in a vibration process, wherein each stress intensity parameter has a direction vector;

[0014] determining a stress intensity variation parameter for the target sampling point based on the plurality of stress intensity parameters;

[0015] constructing a crack propagation life prediction model based on a total crack length, material parameters, a cycle load number, and the stress intensity variation parameter of the simulation standard test piece;

[0016] verifying the pre-constructed crack propagation life prediction model through the actual crack propagation life, including determining a simulation cycle load number based on the pre-constructed crack propagation life prediction model;

[0017] verifying the accuracy of the pre-constructed crack propagation life prediction model based on the actual cycle load number and the simulation cycle load number.

[0018] Optionally, the crack propagation life prediction model is constructed based on the total crack length, the material parameters, the cycle load number, and the stress intensity variation parameter of the standard test piece, and the crack propagation life prediction model is:

[0019]

[0020] wherein a is the total crack length, C and m are the material parameters, ΔK is the stress intensity variation parameter, and N is the cycle load number, i.e., the predicted crack propagation life.

[0021] Optionally, in response to determining that the vibration environment interface crack propagation test is a zero-mean stationary random vibration test, the stress intensity factor root mean square value Krms is determined as the stress intensity variation parameter, and the crack propagation life prediction model is modified as:

[0022]

[0023] Optionally, the step of constructing the crack propagation life prediction model includes:

[0024] constructing an initial crack on a simulation test piece to obtain a simulation standard test piece, and taking at least one tip of the initial crack as a target sampling point;

[0025] constructing a multi-directional vibration environment, and decomposing a crack propagation process of the simulation standard specimen in the vibration environment into a plurality of crack propagation stages;

[0026] For each crack propagation stage, the following steps are performed: obtaining a plurality of stress intensity parameters for each target sampling point, wherein each stress intensity parameter has a direction vector; determining a stress intensity change parameter for the target sampling point based on the plurality of stress intensity parameters; and constructing a crack propagation life prediction model for the crack propagation stage based on a crack length increment of the simulation standard specimen at the crack propagation stage, material parameters, a cycle load increment, and the stress intensity change parameter;

[0027] The verification of the pre-constructed crack propagation life prediction model by the actual crack propagation life includes:

[0028] Based on the pre-constructed crack propagation life prediction model of a crack propagation stage, the cycle load increment of the crack propagation stage is determined;

[0029] The actual cycle load increment of the crack propagation stage is compared with the simulated cycle load increment to verify the accuracy of the pre-constructed crack propagation life prediction model at the stage.

[0030] Optionally, the cycle load increment in the crack propagation life prediction model of the crack propagation stage is converted from a cycle load increment to a time increment;

[0031] The conversion step includes:

[0032] The 0-order vibration spectrum moment and the 2-order vibration spectrum moment of the vibration load signal of the crack propagation stage are obtained to obtain a defined mean positive crossing expectation rate;

[0033] Based on the cycle load increment of the crack propagation stage and the defined mean positive crossing expectation rate, the time increment of the crack propagation stage is obtained;

[0034] The verification of the pre-constructed crack propagation life prediction model by the actual crack propagation life includes:

[0035] Based on the pre-constructed crack propagation life prediction model of a crack propagation stage, the cycle load increment of the crack propagation stage is determined;

[0036] The actual time increment of the crack propagation stage is compared with the simulated time increment to verify the accuracy of the pre-constructed crack propagation life prediction model at the stage.

[0037] Optionally, the verification of the actual crack propagation life by the pre-constructed crack propagation life prediction model includes:

[0038] By the interface crack propagation life test under the multi-directional vibration environment and the interface crack propagation life test under the uniaxial vibration environment in turn, the actual crack propagation life under the two test conditions is obtained, the difference between the actual crack propagation life under the two test conditions is compared, and the actual crack propagation life obtained under the multi-directional vibration environment is verified through the pre-constructed crack propagation life prediction model.

[0039] Optionally, the preset threshold is 90% to 95% of the initial natural frequency, and the initial natural frequency is the natural frequency measured at the initial test of the standard sample.

[0040] Optionally, the preset threshold is 93% of the initial natural frequency.

[0041] Optionally, the strain gauge is a resistance strain gauge.

[0042] Based on the same inventive concept, the disclosure also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable by the processor, wherein the processor implements the method as described above when executing the computer program.

[0043] Based on the same inventive concept, the disclosure also provides a non-transitory computer readable storage medium, which stores computer instructions for causing a computer to execute the method as described above.

[0044] As can be seen from the above, the vibration environment interface crack propagation life prediction method provided by the present application applies multi-directional vibration excitation to the standard sample through the multi-axis vibration testing machine, thereby restoring the complex multi-directional vibration received by the standard sample under actual working conditions, avoiding the distortion of test results caused by uniaxial sequential test, and making the test data more consistent with the actual use scenario. In addition, compared with the traditional monitoring method of observing crack length, the strain gauge acquires the natural frequency of the standard sample by collecting strain time domain data, thereby judging the crack propagation failure condition more accurately, and significantly improving the accuracy and reliability of the test data. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the present application or related art, the following will briefly introduce the drawings needed to be used in the embodiments or related art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0046] Figure 1 The flowchart of the crack propagation prediction method is shown in the embodiments of the present application;

[0047] Figure 2 Figure 8 shows a PSD load spectrum diagram for a random excitation according to an embodiment of the present application;

[0048] Figure 3 Figure 9 shows a first and second order natural frequency response peak diagram for a standard sample according to an embodiment of the present application;

[0049] Figure 4 Figure 10 shows a first order natural frequency change curve diagram for a standard sample according to an embodiment of the present application;

[0050] Figure 5 Figure 11 shows an electronic device hardware structure schematic according to an embodiment of the present application. DETAILED DESCRIPTION

[0051] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to specific embodiments and drawings.

[0052] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be understood as the usual meaning understood by a person with ordinary skills in the art to which the present application belongs. The terms "first", "second" and similar terms 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 terms mean that the elements or objects before the terms cover the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "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.

[0053] Based on the background, in the modern engineering field, vibration fatigue test is an important means to explore the damage and fracture behavior of solid materials under multi-directional vibration environment. In the prior art, a uniaxial vibration test is generally carried out in three orthogonal axial directions in turn to simulate the multi-directional vibration environment. This method is based on the simplified thinking, and by completing the individual test of each axial direction in turn, the overall multi-directional vibration effect is expected to be pieced together. This method has a certain application basis in early engineering practice.

[0054] However, this test method has significant irrationality. From the perspective of dynamics, single-axis equivalent test is based on the assumption that the dynamic responses of each axis of the structure are independent of each other. However, for missiles, aircraft pods, launch vehicles and other complex structures with small overall stiffness, this assumption is far from the actual situation. In actual working conditions, vibration excitation in one axis is likely to excite vibration modes in other axes, resulting in much larger vibration response than expected. For example, in the ground test of a certain type of missile, when only the lateral single-axis vibration test was conducted, the longitudinal vibration mode was accidentally excited, resulting in a vibration response of the local structure that was 30% higher than the theoretical value. This coupling effect is difficult to accurately reflect in single-axis equivalent test.

[0055] To make up for the difference between single-axis test and real multi-axis test, engineers often take measures to increase the vibration time or increase the vibration level. However, these operations are mostly based on engineering experience and lack precise theoretical basis. This experience-based adjustment method is likely to cause the product to withstand excessive testing. Excessive testing not only increases the cost of research and development, but also may cause irreversible damage to the product before it is put into actual use, cannot truly reflect the performance of the product in the actual multi-directional vibration environment, and leads to distorted test results.

[0056] In addition, the selection of single-axis vibration direction also has limitations. Since the vibration direction of single-axis sequential test is fixed, it is likely to be inconsistent with the actual failure sensitive direction of the product. In actual application, the failure of the product is often closely related to the vibration stress in a specific direction. If the test cannot accurately simulate the vibration in this sensitive direction, it is difficult to completely reproduce the failure phenomenon in the real environment. Taking an aircraft pod as an example, it may produce multi-directional vibration due to complex airflow during flight, and single-axis test cannot fully capture the impact of these complex vibrations on the weak parts of the pod, so that the test results cannot provide effective guidance for product optimization design.

[0057] With the continuous improvement of modern engineering requirements for product performance, the traditional single-axis sequential vibration fatigue test equivalent method cannot meet the growing demand for high-precision and high-efficiency testing. In the fields of aerospace, automobile manufacturing and other fields with high requirements for product reliability, more scientific and accurate multi-directional vibration fatigue test methods are needed to ensure the safety and stability of products in complex vibration environments.

[0058] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. Figures 1-5 The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0059] A vibration environment interface crack propagation life prediction method, comprising:

[0060] S100: constructing an initial crack on a test piece to obtain a standard test piece;

[0061] Specifically, in the process of vibration environment interface crack propagation life prediction, first, an initial crack needs to be constructed on the test piece to obtain a standard test piece. For example, the test piece can be designed to have a regular geometric shape, and the size is generally in the range of 150-200 mm in length, 80-120 mm in width, and 5-10 mm in thickness, so as to meet the clamping requirements of the multi-axis vibration testing machine while ensuring that the test piece presents typical dynamic response characteristics during vibration. The initial crack is constructed on the test piece, and for example, the length of the initial crack is generally controlled to be 20-40 mm, the height is close to the thickness of the test piece, and the width is about 1-3 mm to simulate the morphology of the crack in actual engineering. The initial crack is usually introduced by mechanical processing, electric spark machining or fatigue precasting. For example, for metal material test pieces, the method of fatigue precasting crack is commonly used. By applying cyclic load on the test piece, local fatigue damage is generated in the material, and a stable initial crack is gradually formed.

[0062] S200: mounting a strain gauge on the surface of the standard test piece, the strain gauge being arranged perpendicularly across the initial crack;

[0063] Specifically, after obtaining the standard test piece, a strain gauge needs to be mounted on its surface, and the strain gauge is arranged perpendicularly across the initial crack. The strain gauge is a key element for measuring the strain change on the surface of the test piece, and its installation position and direction directly affect the accuracy of the measurement data. The strain gauge is arranged perpendicularly across the initial crack, because when the crack propagates, the strain change perpendicular to the crack direction is most significant, and the crack is mainly a type I crack. Through this arrangement, the strain fluctuation caused by crack propagation can be most effectively captured. The strain gauge can be a BE120-3AA type resistance strain gauge, which is a high-precision measurement element that can quickly capture the transient strain signal caused by crack propagation, ensuring that the strain time domain data collected truly reflects the actual mechanical state of the test piece, and laying a reliable foundation for obtaining the natural frequency data through subsequent data processing. The resistance strain gauge is pasted at the center of the initial crack, slightly below the position, and the slightly lower direction is the crack propagation direction, so that the strain gauge can capture the signal as soon as the crack begins to expand downward, which helps to monitor the signs of crack propagation earlier.

[0064] S300: mounting the standard test piece on a multi-axis vibration testing machine, inputting multi-directional vibration excitation to the multi-axis vibration testing machine, the strain gauge collecting strain time domain data of the standard test piece during testing, and obtaining natural frequency data of the standard test piece through the strain time domain data;

[0065] Specifically, the multi-axis vibration testing machine can be a three-axis vibration testing machine, which is provided with a piezoelectric vibration acceleration signal sensor. The three-axis vibration testing machine feeds back the acceleration of three axes of the table surface to the control system through the piezoelectric vibration acceleration signal sensor to realize the control of the vibration environment. The standard test piece is installed on the three-axis vibration testing machine through bolts, and a high-flux test method is adopted to install four groups of test samples on the three-axis vibration testing machine, thereby improving the test efficiency.

[0066] In addition, the strain gauge collects strain time domain data of the surface of the standard test piece in real time during the test, and the data reflects the change of the strain of the test piece with time during the vibration process. Through signal processing technologies such as Fourier transform, the first-order and high-order natural frequencies of the standard test piece can be extracted by analyzing and processing the collected strain time domain data. The natural frequency is an important dynamic characteristic parameter of the test piece, and its change is closely related to crack propagation. Therefore, accurately obtaining the natural frequency data is crucial for subsequent prediction of crack propagation life.

[0067] S400: continuously monitoring the natural frequency data of the standard test piece, and determining that the standard test sample fails due to crack propagation when the natural frequency data drops to a preset threshold value;

[0068] Specifically, since the crack propagation cannot be directly observed when the vibration table vibrates, but the first-order natural frequency of the structure will change when the crack propagates, the change of the first-order natural frequency is monitored to analyze whether the crack propagation of the structure has caused the failure of the structure. The preset threshold value is determined through multiple fatigue loading tests. When the preset threshold value is 90% to 95% of the initial natural frequency, it is determined that the standard test sample fails due to crack propagation. Further, when the preset threshold value is 93% of the initial natural frequency, it is determined that the standard test sample fails due to crack propagation without the need for further testing.

[0069] S500: determining the actual time or the actual number of cyclic loads of the multi-directional vibration excitation as the actual crack propagation life of the standard test piece under the multi-directional vibration environment.

[0070] Specifically, after determining that the standard test piece fails due to crack propagation, the actual time or the actual number of cyclic loads of the multi-directional vibration excitation is determined as the actual crack propagation life of the standard test piece under the multi-directional vibration environment. This data is a key indicator for evaluating the reliability of materials or structures under multi-directional vibration environment. The actual time reflects the life of the test piece under continuous vibration excitation, while the actual number of cyclic loads focuses more on the fatigue life of the test piece under periodic vibration load. By recording this data and combining the test results of multiple groups under different working conditions, a crack propagation life prediction model of materials or structures under multi-directional vibration environment can be established, which provides important theoretical basis and data support for the reliability evaluation and maintenance cycle of the test piece.

[0071] In the embodiment, the multi-axis vibration test can be used to apply vibration excitation to the standard test piece in multiple directions at the same time, so as to truly restore the complex multi-directional vibration of the standard test piece in the actual working condition, avoid the distortion of the test results caused by the single-axis test, and make the test data more suitable for the actual use scene. In addition, compared with the traditional monitoring method of observing the crack length, the strain gauge can obtain the natural frequency of the standard test piece by collecting strain time domain data, so as to more accurately judge the crack propagation failure condition, and significantly improve the accuracy and reliability of the test data.

[0072] In some embodiments, a vibration environment interface crack propagation life prediction method further comprises:

[0073] S600: verifying the pre-constructed crack propagation life prediction model by using the actual crack propagation life.

[0074] In the embodiment, the pre-constructed crack propagation life prediction model can obtain a simulated crack propagation life. By using the actual crack propagation life and the simulated crack propagation life, the accuracy of the crack propagation life prediction model can be verified.

[0075] In some embodiments, the construction step of the crack propagation life prediction model comprises:

[0076] S700a: constructing an initial crack on a simulation test piece to obtain a simulation standard test piece, and taking at least one tip of the initial crack as a target sampling point;

[0077] Specifically, the simulation test piece is constructed by using a finite element analysis software (such as Abaqus), and the initial crack on the simulation test piece is constructed to obtain the simulation standard test piece. The position and size of the initial crack on the simulation test piece are the same as those on the standard test piece, so as to verify the rationality of the crack propagation life prediction model. The initial crack is generally a straight-line crack, and the tip of the straight-line crack is the target sampling point.

[0078] S700b: constructing a multi-directional vibration environment, and obtaining a plurality of stress intensity parameters of each target sampling point in the vibration process, wherein each stress intensity parameter has a direction vector;

[0079] Specifically, the vibration environment of the engine under different working conditions is simulated by using the finite element analysis software (such as Abaqus), and the material parameters such as the elastic modulus and the Poisson's ratio of the standard test piece are input into the Abaqus engineering software. Based on the contour integral method in the Abaqus engineering software, the stress intensity parameters of the target sampling points on the crack tip of the simulation test piece can be calculated, so as to construct the crack propagation life prediction model.

[0080] S700c: determining a stress intensity change parameter for the target sampling point based on the plurality of stress intensity parameters;

[0081] Specifically, the stress intensity parameter is a stress intensity factor, and the stress intensity change parameter is a stress intensity change amplitude. The crack propagation life prediction model is constructed by using the stress intensity change amplitude and other parameters.

[0082] S700d: constructing a crack propagation life prediction model based on the total crack length of the simulation standard specimen, the material parameters, the cycle load number, and the stress intensity change parameter;

[0083] S600 includes the following steps:

[0084] S600a: determining a simulation cycle load number based on the pre-constructed crack propagation life prediction model;

[0085] S600b: verifying the accuracy of the pre-constructed crack propagation life prediction model based on the actual cycle load number and the simulation cycle load number.

[0086] Specifically, the cycle load number is the crack propagation life. The simulation cycle load number is obtained by using the pre-constructed crack propagation life prediction model. The actual cycle load number obtained by using the crack propagation life prediction method is compared with the simulation cycle load number to verify the accuracy of the pre-constructed crack propagation life prediction model.

[0087] In the embodiment, the number of physical vibration tests is reduced by constructing a crack propagation life prediction model, thereby reducing the test cost and the test time. The pre-constructed model inputs the total crack length change amount in the actual crack propagation process, the calculated stress intensity change parameter, and other parameters, reversely deduces the required simulation cycle load number, compares the simulation cycle load number with the actual cycle load number to form "theoretical prediction-experimental verification", and provides data support for model correction.

[0088] In some embodiments, the crack propagation life prediction model is constructed based on the total crack length of the standard specimen, the material parameters, the cycle load number, and the stress intensity change parameter, and the crack propagation life prediction model is as follows:

[0089]

[0090] wherein a is the total crack length, C and m are the material parameters, ΔK is the stress intensity change parameter, and N is the cycle load number, i.e., the predicted crack propagation life.

[0091] Specifically, ΔK is the stress intensity factor amplitude, which is defined as:

[0092]

[0093] where R is the stress ratio, R = K min / K max For a zero-mean stationary random process, the stress ratio R = -1, so ΔK = K max .

[0094] In some embodiments, in response to determining that the vibration environmental interface crack propagation test is a zero-mean stationary random vibration test, the stress intensity factor root mean square value Krms is determined as the stress intensity variation parameter, and the crack propagation life prediction model is modified as:

[0095]

[0096] In this step, since the random vibration excitation is a zero-mean stationary random process, the stress at the crack tip and the variation of the stress intensity factor K are also random processes. From the perspective of probability statistics, the stress intensity factor mean square value represents the energy level of the random variable, and then the corresponding stress intensity factor root mean square value K rms reflects the stress intensity factor amplitude ΔK = K max The average characteristics in the entire frequency domain, considering the energy conservation in the frequency domain and time domain in the random vibration process, and in order to find a stable replacement for K max which is not constant in the time domain, K rms is used instead of K max , and the Paris formula is transformed into: Among them, in order to calculate the stress intensity factor root mean square value at the crack tip, the equivalent displacement of the free end of the structure is first obtained through random vibration analysis, and the equivalent displacement is applied to the calculation process of the stress intensity factor, and then the required cycle load number of crack propagation is calculated.

[0097] In some embodiments, the crack propagation life prediction model construction step includes:

[0098] S701a: constructing an initial crack on a simulation test piece to obtain a simulation standard test piece, and taking at least one tip of the initial crack as a target sampling point;

[0099] S701b: constructing a multi-directional vibration environment, and decomposing the crack propagation process of the simulation standard test piece in the vibration environment into a plurality of crack propagation stages;

[0100] Specifically, the crack propagation stage is a segmentation of the crack growth process. For example, the crack growth stage can be divided according to the crack growth of 1 mm. The crack propagation life prediction model for the 1 mm crack growth stage is built.

[0101] S701c: For each crack propagation stage, the following is performed: obtaining a plurality of stress intensity parameters of each target sampling point, wherein each stress intensity parameter has a direction vector; determining a stress intensity change parameter for the target sampling point based on the plurality of stress intensity parameters; and building a crack propagation life prediction model for the crack propagation stage based on the crack length increment of the simulation standard specimen at the crack propagation stage, the material parameters, the cycle load increment, and the stress intensity change parameter;

[0102] The verification of the pre-built crack propagation life prediction model by the actual crack propagation life in S600 includes:

[0103] S601a: determining the simulation cycle load increment of the crack propagation stage based on the pre-built crack propagation life prediction model of the crack propagation stage.

[0104] S601b: comparing the actual cycle load increment of the crack propagation stage with the simulation cycle load increment to verify the accuracy of the pre-built crack propagation life prediction model at the stage.

[0105] In this step, the crack propagation life prediction model for the crack propagation stage is represented by the following formula:

[0106] a i = a0+∑Δa i ;

[0107] Wherein, ΔN i is the cycle load increment of the i-th crack propagation stage, a0 is the initial length of the crack, ai is the crack length at the beginning of the i-th crack propagation stage, Δai is the crack length increment of the i-th crack propagation stage, Ki is the stress intensity factor root mean square value of the i-th crack propagation stage. i i rmsi

[0108] The cycle load increments of i crack propagation stages are accumulated, and the cycle number N required for crack propagation is obtained, which is represented by the following formula: N = ∑ΔN i .

[0109] ​​​In the embodiment, the crack propagation life prediction model is constructed for each crack propagation stage, so as to accurately describe the crack propagation in each crack propagation stage. The discretized model regards each crack tip as an independent unit node, and respectively tracks the stress state and propagation path of each crack tip, thereby avoiding the limitation of the traditional simplified model which regards the crack as a single whole.

[0110] In some embodiments, the step of constructing the crack propagation life prediction model further comprises:

[0111] S701d: performing load cycle increment-time increment conversion on the cycle load increment in the crack propagation life prediction model of the crack propagation stage;

[0112] The conversion step comprises:

[0113] obtaining the 0-order vibration spectrum moment and the 2-order vibration spectrum moment of the vibration load signal of the crack propagation stage to obtain a defined mean positive crossing expectation rate;

[0114] obtaining the time increment of the crack propagation stage based on the cycle load increment of the crack propagation stage and the defined mean positive crossing expectation rate;

[0115] The step of verifying the pre-constructed crack propagation life prediction model by using the actual crack propagation life in S600 comprises:

[0116] determining the simulation time increment of the crack propagation stage based on the pre-constructed crack propagation life prediction model of the crack propagation stage;

[0117] comparing the actual time increment of the crack propagation stage with the simulation time increment to verify the accuracy of the pre-constructed crack propagation life prediction model in the stage.

[0118] Specifically, the conversion step is expressed by the following formula:

[0119]

[0120] wherein m0 is the 0-order spectrum moment, m2 is the 2-order spectrum moment, η + is the defined mean positive crossing expectation rate, and Δt i is the time increment of the i-th crack propagation stage.

[0121] The time increments of the i crack propagation stages are accumulated to obtain the total vibration time, which is expressed by the following formula: t = ∑Δt i ; wherein t is the total vibration time.

[0122] In the embodiment, by establishing a mapping relationship between the fatigue life model and the actual time, the disconnection between the cycle number and the engineering time management in the traditional fatigue analysis is solved, the abstract cycle number is converted into the intuitive time, and the thinking habit of the engineering personnel is met.

[0123] In some embodiments, the actual crack propagation life obtained is verified by the pre-constructed crack propagation life prediction model, including:

[0124] The actual crack propagation life under the multi-directional vibration environment and the actual crack propagation life under the uniaxial vibration environment are obtained through the interface crack propagation life test under the multi-directional vibration environment and the interface crack propagation life test under the uniaxial vibration environment, the difference between the actual crack propagation life under the two test conditions is compared, and the actual crack propagation life obtained under the multi-directional vibration environment is verified by the pre-constructed crack propagation life prediction model.

[0125] Specifically, the life difference between the standard specimen under the multi-axial simultaneous vibration and the standard specimen under the uniaxial vibration is compared through the interface crack propagation life test under the multi-directional vibration environment and the interface crack propagation life test under the uniaxial vibration environment; further, the simulated crack propagation life under the uniaxial vibration and the simulated crack propagation life under the multi-axial vibration of the standard specimen are obtained through the crack propagation life model, and are compared with the actual test results, so as to verify the accuracy of the crack propagation life model.

[0126] In the embodiment, the actual result difference of the two tests is revealed by comparing the interface crack propagation life test under the multi-directional vibration environment and the interface crack propagation life test under the uniaxial vibration environment, so as to determine that the multi-axial vibration test is more in line with the actual application scene.

[0127] The crack propagation prediction method is described below in combination with specific embodiments:

[0128] Embodiment 1

[0129] The vibration environment interface crack propagation prediction method comprises:

[0130] An initial crack is constructed on the aluminum alloy test piece to obtain an aluminum alloy standard specimen;

[0131] A strain gauge is installed on the surface of the aluminum alloy standard specimen, and the strain gauge is arranged perpendicularly across the initial crack;

[0132] The aluminum alloy standard specimen is installed on a clamp and fixed by a pressing strip to ensure that the specimen remains stable during the vibration process;

[0133] Random vibration excitation is applied to the installed aluminum alloy standard specimen, and the random excitation PSD (Power Spectral Density) load spectrum diagram is as follows:Figure 2 The acceleration power spectral density is 0.015 g 2 Hz, and the vibration conditions include single-axis (Y-axis, Z-axis) and multi-axis (Y+Z-axis combination) vibration conditions, wherein different coherence coefficients (0 / 0.5 / 0.95) and phase angles (0° / 45° / 90°) are set for the multi-axis vibration to simulate the complex load coupling relationship in actual engineering.

[0134] During the vibration process, the strain gauge collects the strain time domain data of the standard specimen during the test, and the collected strain time domain signal is subjected to fast Fourier transform (FFT) by using a Python program to obtain the first-order and second-order inherent frequency response peak values of the aluminum alloy standard specimen (as shown in Figure 3 The first-order inherent frequency is continuously recorded as a function of time (as shown in Figure 4 When the first-order inherent frequency drops to 93% (a drop of 7%) of the undamaged value, the initial crack extends to 6 mm, so the crack extension of 6 mm is taken as the judgment basis for structural failure, and the vibration time when the crack extends to 6 mm under each vibration condition is recorded as the actual crack propagation life of the aluminum alloy standard specimen under each vibration condition. The specific results are referred to Tables 8 and 9.

[0135] At the same time, the crack propagation life prediction model is used to perform a simulation test on the aluminum alloy standard specimen to obtain the simulated crack propagation life of the aluminum alloy standard. The vibration conditions of the simulation test are the same as those of the above-mentioned vibration environment interface crack propagation prediction method, so that the actual crack propagation life can verify the pre-constructed crack propagation life prediction model. The simulation results are referred to Tables 8 and 9. In addition, the stress intensity factor root mean square value Krms under single-axis and multi-axis vibration environments is calculated by using the finite element simulation to verify the rationality of the crack propagation life prediction model under single-axis and multi-axis vibration environments (Tables 1-7), wherein different coherence coefficients (0 / 0.5 / 0.95) and phase angles (0° / 45° / 90°) are set for the multi-axis vibration to simulate the complex load coupling relationship in actual engineering.

[0136] As shown in Tables 1-3, the simulated crack propagation life corresponding to the 6 mm crack under Y+Z-axis (0 coherence coefficient, 0° phase angle) multi-directional vibration is only 51 seconds, which is significantly lower than that under single-axis vibration conditions, indicating that the superposition of multi-directional loads leads to a significant increase in the stress intensity factor, reflecting the synergistic damage effect of multi-axis vibration, thereby verifying the theoretical hypothesis of "multi-axis vibration accelerating crack propagation", i.e., the rationality of the crack propagation life prediction model.

[0137] As shown in Tables 4-7, the simulated crack propagation life corresponding to a 6mm crack is 22 seconds at a coherence coefficient of 0.95 and a phase angle of 0° (Table 4), which is the shortest among all working conditions, indicating that the stress concentration is the most serious when the load correlation is strong and the phases are synchronized. Under the same coherence coefficient, the simulated crack propagation life is extended to 27 seconds as the phase angle increases from 0° to 45° (Table 5), indicating that the load phase difference can alleviate part of the stress concentration; the simulated crack propagation life is further extended as the coherence coefficient decreases from 0.95 to 0.5 (Tables 6-7), indicating that the weakening of load correlation will reduce the damage accumulation rate. The simulation test results verify the regulatory effect of load correlation and phase difference on damage, and further verify the rationality of the crack propagation life prediction model.

[0138] As shown in Tables 8-9, Table 8 records the comparison data of the measured life and the simulated life of the aluminum alloy standard specimen under Z-axis and Y-axis uniaxial vibration conditions, which is used to verify the accuracy of the crack propagation life prediction model under uniaxial vibration environment, and Table 9 covers multi-axis (Y+Z-axis) vibration conditions, including different coherence coefficients (0 / 0.5 / 0.95) and phase angles (0° / 45° / 90°) combinations, to verify the influence of multi-axis load coupling on crack propagation life and the prediction ability of the model. The error between the measured life and the simulated life shown in Tables 8 and 9 is within 30%, which meets the standard of "acceptable within 3 times error band", so it can be considered that the crack propagation life prediction model is effective.

[0139] Table 1 Stress intensity factor and crack propagation life calculated under Y-axis uniaxial vibration (simulation)

[0140]

[0141] Table 2 Stress intensity factor and crack propagation life calculated under Z-axis uniaxial vibration (simulation)

[0142]

[0143] Table 3 Stress intensity factor and crack propagation life calculated under Y+Z-axis multi-axis vibration (simulation)

[0144]

[0145] Table 4 Stress intensity factor and crack propagation life calculated under 0.95 coherence coefficient and 0° phase angle (simulation)

[0146]

[0147] Table 5 Stress intensity factor and crack propagation life calculated under 0.95 coherence coefficient and 45° phase angle (simulation)

[0148]

[0149] Table 6 Stress intensity factors and crack growth life calculated with 0.5 coherence factor and 0° phase angle (simulation)

[0150]

[0151] Table 7 Stress intensity factors and crack growth life calculated with 0.5 coherence factor and 45° phase angle (simulation)

[0152]

[0153] Table 8 Comparison of uniaxial vibration test results and simulation

[0154]

[0155] Table 9 Comparison of multiaxial vibration test results and simulation

[0156]

[0157]

[0158] It should be noted that the method of the embodiments of the present application can be executed by a single device, such as a computer or a server, etc. The method of the embodiments of the present application can also be applied to a distributed scenario, and be completed by multiple devices cooperating with each other. In the distributed scenario, one of the multiple devices can only execute one or more steps in the method of the embodiments of the present application, and the multiple devices can interact with each other to complete the method.

[0159] It should be noted that some embodiments of the present application have been described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in a different order and still achieve desirable results. Additionally, the process depicted in the figures does not necessarily require the particular order shown, or sequential order to achieve the desired results. In certain implementations, multitasking and parallel processing can be advantageous.

[0160] Based on the same inventive concept, the present application also provides an electronic device corresponding to the method of any of the above embodiments, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to realize the crack growth life prediction method of any of the embodiments.

[0161] Figure 5A more specific electronic device hardware structure schematic diagram provided by the embodiment is shown, and the device 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 internal communication.

[0162] 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 related programs to implement the technical solutions provided by the embodiments of the present specification.

[0163] The memory 1020 can be implemented by 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 related program codes are stored in the memory 1020 and called and executed by the processor 1010.

[0164] The input / output interface 1030 is used to connect input / output modules to realize 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 device can include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device can include a display, a speaker, a vibrator, an indicator light, etc.

[0165] The communication interface 1040 is used to connect a communication module (not shown in the figure) to realize 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.).

[0166] 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.

[0167] 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 contain the components necessary to implement the embodiments of the present application, and does not necessarily contain all the components shown in the figure.

[0168] The electronic device of the above embodiment is used to implement the crack propagation life prediction method corresponding to any of the above embodiments, and has the beneficial effects of the corresponding method embodiments, which are not repeated here.

[0169] Based on the same inventive concept, corresponding to any of the above embodiment methods, the present application also provides a non-transitory computer readable storage medium storing computer instructions for causing the computer to perform the crack propagation life prediction method according to any of the above embodiments.

[0170] The computer readable medium of the present embodiment includes permanent and non-permanent, removable and non-removable media, which can be realized 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.

[0171] The computer instructions stored in the storage medium of the above embodiment are used to cause the computer to perform the crack propagation life prediction method according to any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which are not repeated here.

[0172] It can be understood that before using the technical solutions of various embodiments in the present disclosure, the type of personal information involved, the scope of use, the use scenario, etc. will be informed to the user in an appropriate manner, and the authorization of the user will be obtained.

[0173] For example, in response to receiving the active request of the user, the user is sent prompt information 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 choose 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.

[0174] As an optional but non-limiting implementation, in response to receiving the active request of the user, the user is sent prompt information in the form of a pop-up window, for example, 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.

[0175] It can be understood that the above notification and obtaining of 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.

[0176] 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 is limited to these examples; the above embodiments or technical features among different embodiments can also be combined, 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.

[0177] 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 the exemplary embodiments of the present application, it will be apparent to those skilled in the art that the embodiments of the present application can be implemented without these specific details or with variations on these specific details. Therefore, these descriptions should be considered illustrative rather than limiting.

[0178] 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.

[0179] 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 any disclosed series can

Claims

1. A method for predicting the crack propagation life at the interface in a vibration environment, characterized in that, include: Initial cracks were created on the test specimen to obtain a standard specimen; Strain gauges are mounted on the surface of the standard specimen, and the strain gauges are arranged perpendicularly to the initial crack. The standard specimen is mounted on a multi-axis vibration testing machine, and a multi-directional vibration excitation is input to the multi-axis vibration testing machine. The strain gauge collects the strain time-domain data of the standard specimen during the test, and the natural frequency data of the standard specimen is obtained through the strain time-domain data. The natural frequency data of the standard specimen is continuously monitored. When the natural frequency data drops to a preset threshold, it is determined that the standard specimen has failed due to crack propagation. The actual time or actual number of cyclic loads of the multi-directional vibration excitation is determined as the actual crack propagation life of the standard specimen under multi-directional vibration environment.

2. The method for predicting the interface crack propagation life in a vibration environment according to claim 1, characterized in that, Also includes: The pre-constructed crack propagation life prediction model was validated using the actual crack propagation life.

3. The method for predicting the interface crack propagation life in a vibration environment according to claim 2, characterized in that, The steps for constructing the crack propagation life prediction model include: An initial crack is constructed on the simulated test specimen to obtain a simulated standard specimen, and at least one tip of the initial crack is used as a target sampling point; A multi-directional vibration environment is constructed, and multiple stress intensity parameters of each target sampling point during the vibration process are obtained, wherein each stress intensity parameter has a direction vector; The stress intensity variation parameters for the target sampling point are determined based on multiple stress intensity parameters. Based on the total crack length, material parameters, number of cyclic loadings, and stress intensity variation parameters of the simulated standard specimen, a crack propagation life prediction model is constructed. The verification of the pre-constructed crack propagation life prediction model by the actual crack propagation life includes: determining the number of simulated cyclic loads based on the pre-constructed crack propagation life prediction model; The accuracy of the pre-constructed crack propagation life prediction model is verified based on the actual number of cyclic loads and the simulated number of cyclic loads.

4. The method for predicting the interface crack propagation life in a vibration environment according to claim 3, characterized in that, Based on the total crack length, material parameters, number of cyclic loading cycles, and stress intensity variation parameters of the standard specimen, a crack propagation life prediction model is constructed. The crack propagation life prediction model is as follows: Where a is the total crack length; C and m are material parameters; ΔK is the stress intensity variation parameter; and N is the number of cyclic loads, i.e., the predicted crack propagation life.

5. The method for predicting the interface crack propagation life in a vibration environment according to claim 4, characterized in that, In response to determining that the vibration environment interface crack propagation test is a zero-mean stationary random vibration test, the root mean square value of the stress intensity factor Krms is determined as the stress intensity variation parameter, and the crack propagation life prediction model is modified as follows:

6. The method for predicting the interface crack propagation life in a vibration environment according to claim 2, characterized in that, The steps for constructing the crack propagation life prediction model include: An initial crack is constructed on the simulated test specimen to obtain a simulated standard specimen, and at least one tip of the initial crack is used as a target sampling point; A multi-directional vibration environment is constructed, and the crack propagation process of the simulated standard specimen in the vibration environment is decomposed into multiple crack propagation stages; For each crack propagation stage, the following steps are performed: acquiring multiple stress intensity parameters for each target sampling point, wherein each stress intensity parameter has a direction vector; determining stress intensity variation parameters for the target sampling point based on the multiple stress intensity parameters; and constructing a crack propagation life prediction model for the crack propagation stage based on the crack length increment, material parameters, cyclic loading number increment, and stress intensity variation parameters of the simulated standard specimen at the crack propagation stage. The verification of the pre-constructed crack propagation life prediction model using the actual crack propagation life includes: Based on a pre-constructed crack propagation life prediction model for a crack propagation stage, the increment of simulated cyclic loads for this crack propagation stage is determined. The actual increment of the number of cyclic loads during the crack propagation stage is compared with the simulated increment of the number of cyclic loads to verify the accuracy of the pre-constructed crack propagation life prediction model at this stage.

7. The method for predicting the interface crack propagation life in a vibration environment according to claim 6, characterized in that, Also includes: The incremental number of cyclic loads in the crack propagation life prediction model for the crack propagation stage is converted from the incremental number of loads to the incremental time. The conversion steps include: Obtain the 0th and 2nd order vibration spectral moments of the vibration load signal during the crack propagation stage, and then define the mean positive crossover expectation rate. Based on the increment of the number of cyclic loads during the crack propagation stage and the defined mean positive crossover expectation rate, the time increment of the crack propagation stage is obtained. The verification of the pre-constructed crack propagation life prediction model using the actual crack propagation life includes: Based on a pre-constructed crack propagation life prediction model for a crack propagation stage, the simulation time increment for this crack propagation stage is determined. The actual time increment of the crack propagation stage is compared with the simulated time increment to verify the accuracy of the pre-constructed crack propagation life prediction model at this stage.

8. The method for predicting the interface crack propagation life in a vibration environment according to claim 2, characterized in that, The verification of the actual crack propagation life obtained by using a pre-constructed crack propagation life prediction model includes: The actual crack propagation life under the two test conditions was obtained by conducting interface crack propagation life tests under multi-directional vibration environment and uniaxial sequential vibration environment. The difference between the actual crack propagation life under the two test conditions was compared, and the actual crack propagation life obtained under the multi-directional vibration environment was verified by a pre-constructed crack propagation life prediction model.

9. The method for predicting the interface crack propagation life in a vibration environment according to claim 1, characterized in that, The preset threshold is 90% to 95% of the initial natural frequency, and the initial natural frequency is the natural frequency of the standard sample measured at the beginning of the test.

10. The method for predicting the interface crack propagation life in a vibration environment according to claim 9, characterized in that, The preset threshold is 93% of the initial natural frequency.

11. The method for predicting the interface crack propagation life in a vibration environment according to claim 1, characterized in that, The strain gauge is a resistance strain gauge.

12. 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, it implements the method as described in any one of claims 1 to 11.

13. A non-transitory computer-readable storage medium storing computer instructions, characterized in that, The computer instructions are used to cause the computer to perform the method according to any one of claims 1 to 11.

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