A method and device for predicting uniaxial fatigue life with mean stress

Abstract

The present application relates to the field of material mechanics and engineering technology, in particular to a method and device for predicting the uniaxial fatigue life with mean stress. The method comprises splitting the uniaxial fatigue load with mean stress into symmetric tension-compression fatigue load and mean stress load; constructing a damage characterization parameter calculation formula under stress amplitude control based on the symmetric tension-compression fatigue load; constructing an additional damage characterization parameter calculation formula under mean stress control based on the mean stress load; and constructing a uniaxial fatigue damage accumulation equation with mean stress based on the damage characterization parameter under stress amplitude control and the additional damage characterization parameter under mean stress control. The uniaxial fatigue life prediction model constructed by the method is used to predict the uniaxial fatigue life with mean stress, and the prediction value is more accurate and the prediction error is smaller.

Description

Technical Field

[0001] This invention relates to the fields of materials mechanics and engineering technology, specifically to a method and apparatus for predicting uniaxial fatigue life with mean stress. Background Technology

[0002] With the development of science and technology, metallic materials are widely used in high-end equipment such as aerospace, energy equipment, and offshore platforms that withstand complex and variable reciprocating loads. These complex and variable reciprocating loads often cause metallic materials to fail and fracture due to fatigue. Once fatigue fracture occurs, it can easily lead to safety accidents and seriously affect the service safety of equipment. In fact, the fatigue fracture of metallic materials is closely related to their load history, and different load paths significantly affect their service life. Uniaxial fatigue loads containing mean stress, as one of the typical fatigue load paths, affect the fatigue life of metals through the superposition and interaction of stress amplitude and mean stress damage. Based on this, research on uniaxial fatigue life prediction methods containing mean stress has significant engineering application value.

[0003] Existing methods for predicting uniaxial fatigue life with mean stress include the Goodman model and the SWT model, but these methods have relatively high prediction errors. Summary of the Invention

[0004] In order to solve or at least partially solve the defects or deficiencies of the prior art, the present invention proposes a method and apparatus for predicting uniaxial fatigue life with mean stress.

[0005] In a first aspect of the present invention, a method for predicting uniaxial fatigue life with mean stress is provided, comprising:

[0006] S1. Decompose the uniaxial fatigue load containing average stress into a symmetrical tensile-compressive fatigue load and an average stress load;

[0007] S2. Formulas for calculating damage characterization parameters under stress amplitude control based on symmetrical tensile and compressive fatigue loads;

[0008] S3. Construct a calculation formula for additional damage characterization parameters under average stress control based on average stress load;

[0009] S4. Construct a uniaxial fatigue damage accumulation equation with mean stress based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under mean stress control;

[0010] S5. Based on the calculation formula of damage characterization parameters under stress amplitude control, the calculation formula of additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation, obtain the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life.

[0011] S6. Construct a uniaxial fatigue life prediction model based on the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life;

[0012] S7. Based on the uniaxial fatigue life prediction model, predict the fatigue life of a uniaxial structure with mean stress.

[0013] As a preferred embodiment of the present invention, in step S2, the formula for calculating the damage characterization parameters under stress amplitude control based on symmetrical tensile and compressive fatigue loads specifically includes:

[0014] S21. Constructing a calculation model for cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loading:

[0015]

[0016] in, For the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loading, For material parameter one, The symmetrical tensile and compressive fatigue loads obtained by splitting the load are... It is the elastic modulus;

[0017] S22. Constructing a second calculation model for cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loads with equivalent fatigue life:

[0018]

[0019] in, This refers to the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loads with equivalent fatigue life. For material parameter one, For symmetrical tensile and compressive fatigue loads with equivalent fatigue life, It is the elastic modulus;

[0020] S23. Based on the calculation models 1 and 2 of cumulative intrinsic damage dissipation, construct the calculation formula for damage characterization parameters under stress amplitude control:

[0021]

[0022] in, For damage characterization parameters under stress amplitude control, For the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loading, This refers to the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loads with equivalent fatigue life. The symmetrical tensile and compressive fatigue loads obtained by splitting the load are... For symmetrical tensile and compressive fatigue loads with equivalent fatigue life.

[0023] As a preferred embodiment of the present invention, in step S3, the calculation formula for the additional damage characterization parameters under average stress control based on the average stress load specifically includes:

[0024] S31. Constructing a calculation model for cumulative intrinsic damage dissipation under mean stress load:

[0025]

[0026] in, This represents the cumulative intrinsic damage dissipation under average stress load. For material parameter two, The average stress load obtained by splitting, It is the elastic modulus;

[0027] S32. Constructing a calculation model for cumulative intrinsic damage dissipation under tensile strength: (Model 4)

[0028]

[0029] in, For cumulative intrinsic damage dissipation under tensile strength, For material parameter two, For the tensile strength of the material, It is the elastic modulus;

[0030] S33. Based on the calculation models three and four for cumulative intrinsic damage dissipation, construct the calculation formula for additional damage characterization parameters under mean stress control:

[0031]

[0032] in, Additional damage characterization parameters under mean stress control. This represents the cumulative intrinsic damage dissipation under average stress load. For cumulative intrinsic damage dissipation under tensile strength, The average stress load obtained by splitting, This refers to the tensile strength of the material.

[0033] As a preferred embodiment of the present invention, in step S4, the construction of the uniaxial fatigue damage accumulation equation containing average stress based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under average stress control is specifically as follows:

[0034]

[0035] in, For damage characterization parameters under stress amplitude control, Additional damage characterization parameters under mean stress control. This is the damage interaction coefficient;

[0036] The formula for the damage interaction coefficient is as follows:

[0037]

[0038] in, This is the damage interaction coefficient. For symmetrical tensile and compressive fatigue limits, This represents the yield strength of the material.

[0039] As a preferred embodiment of the present invention, in step S5, the calculation formula for symmetrical tensile-compressive fatigue loads with equivalent fatigue life obtained based on the calculation formula for damage characterization parameters under stress amplitude control, the calculation formula for additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation specifically includes:

[0040] S51. Substitute the calculation formulas for damage characterization parameters and additional damage characterization parameters under average stress control into the uniaxial fatigue damage accumulation equation to obtain the equal life equation.

[0041] S52. Transform the equal-life equation to obtain the calculation formula for symmetrical tensile-compressive fatigue loads with equivalent fatigue life:

[0042]

[0043] in, For symmetrical tensile and compressive fatigue loads with equivalent fatigue life, The symmetrical tensile and compressive fatigue loads obtained by splitting the load are... This is the damage interaction coefficient. The average stress load obtained by splitting, This refers to the tensile strength of the material.

[0044] As a preferred embodiment of the present invention, in step S6, constructing a uniaxial fatigue life prediction model with average stress based on the symmetrical tensile-compressive fatigue load calculation formula with equivalent fatigue life specifically includes:

[0045] S61. Substitute the symmetrical tensile-compressive fatigue load calculation formula into the SN curve equation to obtain the uniaxial fatigue life prediction model:

[0046]

[0047] in, This is the predicted value for uniaxial fatigue life. The symmetrical tensile and compressive fatigue loads obtained by splitting the load are... This is the fatigue strength coefficient of the metal. This is the damage interaction coefficient. The average stress load obtained by splitting, For the tensile strength of the material, This is the fatigue strength index of metals.

[0048] As a preferred embodiment of the present invention, it further includes:

[0049] S7. The prediction error of the uniaxial fatigue life prediction value is obtained based on the following formula:

[0050]

[0051] in, For the prediction error value, These are experimental values ​​for uniaxial fatigue life. This is the predicted value for uniaxial fatigue life.

[0052] In a second aspect of the present invention, a uniaxial fatigue life prediction device with mean stress is provided, comprising:

[0053] The load splitting module is configured to split a uniaxial fatigue load containing average stress into a symmetrical tensile-compressive fatigue load and an average stress load.

[0054] The module for constructing damage characterization parameter calculation formulas is configured to construct damage characterization parameter calculation formulas under stress amplitude control based on symmetrical tensile and compressive fatigue loads.

[0055] The module for constructing additional damage characterization parameter calculation formulas is configured to construct additional damage characterization parameter calculation formulas under average stress control based on average stress loads.

[0056] The uniaxial fatigue damage accumulation equation construction module is configured to construct a uniaxial fatigue damage accumulation equation with mean stress based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under mean stress control.

[0057] The module for obtaining the symmetrical tensile and compressive fatigue load calculation formula is configured to obtain the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life based on the calculation formula of damage characterization parameters under stress amplitude control, the calculation formula of additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation.

[0058] The uniaxial fatigue life prediction model construction module is configured to construct a uniaxial fatigue life prediction model based on the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life.

[0059] The fatigue life prediction module is configured to predict the fatigue life of a single axis containing average stress based on a uniaxial fatigue life prediction model.

[0060] In a third aspect of the present invention, a computer program product is provided, including a computer program that, when executed by a processor, implements the method provided according to the first aspect.

[0061] In a fourth aspect of the present invention, an electronic device is provided, including one or more processors and a memory associated with the one or more processors, the memory being used to store program instructions that, when read and executed by the one or more processors, perform the method provided in the first aspect.

[0062] In summary, the present invention has the following beneficial effects:

[0063] The uniaxial fatigue life prediction method of this invention first constructs a calculation formula for damage characterization parameters under stress amplitude control based on symmetrical tensile and compressive fatigue loads, and then constructs a calculation formula for additional damage characterization parameters under average stress control based on average stress loads. Next, based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under average stress control, a uniaxial fatigue damage accumulation equation containing average stress is constructed. Then, based on the calculation formulas for damage characterization parameters under stress amplitude control, the calculation formulas for additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation, a symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life is obtained. Finally, based on the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life, a uniaxial fatigue life prediction model is constructed, and the uniaxial fatigue life prediction model is used to predict the fatigue life of a uniaxial load containing average stress. This method obtains uniaxial fatigue life prediction values ​​with higher accuracy and smaller prediction errors.

[0064] Further or more detailed beneficial effects will be described in conjunction with specific embodiments in the detailed implementation. Attached Figure Description

[0065] Figure 1 A flowchart of a uniaxial fatigue life prediction method with mean stress according to an embodiment of the present invention is shown;

[0066] Figure 2 A block diagram of a uniaxial fatigue life prediction device with mean stress according to an embodiment of the present invention is shown.

[0067] Figure 3 A block diagram of an electronic device according to an embodiment of the present invention is shown;

[0068] Figure 4 A schematic diagram of uniaxial fatigue load decomposition with mean stress according to an embodiment of the present invention is shown;

[0069] Figure 5 A schematic diagram illustrating the error analysis of the prediction results for ZK60-T5 magnesium alloy material according to an embodiment of the present invention is shown.

[0070] Figure 6 A schematic diagram illustrating the error analysis of the prediction results for CK45 steel material according to an embodiment of the present invention is shown;

[0071] Figure 7 A schematic diagram of the error analysis of the prediction results for 2017A-T4 aluminum alloy material according to an embodiment of the present invention is shown. Detailed Implementation

[0072] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the invention. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention.

[0073] In the description of embodiments of the present invention, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0074] This invention proposes a method for predicting uniaxial fatigue life with mean stress, such as... Figure 1 As shown, the method includes:

[0075] S1. Decompose the uniaxial fatigue load containing average stress into a symmetrical tensile-compressive fatigue load and an average stress load.

[0076] As described in the background section, uniaxial fatigue loads containing mean stress are complex, and the fatigue life of metals under such loads is difficult to predict. Therefore, this embodiment decomposes the original load into a symmetrical tensile-compressive fatigue load and a mean stress load. Figure 4 As shown, this embodiment decomposes a uniaxial fatigue load containing average stress into a symmetrical tensile-compressive fatigue load and an average stress load. The specific method for decomposing a uniaxial fatigue load containing average stress into a symmetrical tensile-compressive fatigue load and an average stress load is existing technology.

[0077] S2. Formula for calculating damage characterization parameters under stress amplitude control based on symmetrical tensile and compressive fatigue loads.

[0078] In S2 of this embodiment, the formula for calculating the damage characterization parameters under stress amplitude control based on symmetrical tensile and compressive fatigue loads specifically includes:

[0079] S21. Constructing a calculation model for cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loading:

[0080]

[0081] in, For the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loading, For material parameter one, The symmetrical tensile and compressive fatigue loads obtained by splitting the load are... It is the elastic modulus.

[0082] S22. Constructing a second calculation model for cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loads with equivalent fatigue life:

[0083]

[0084] in, This refers to the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loads with equivalent fatigue life. For material parameter one, For symmetrical tensile and compressive fatigue loads with equivalent fatigue life, It is the elastic modulus;

[0085] The cyclic life under a uniaxial fatigue load containing average stress necessarily corresponds to the equivalent fatigue life under a certain symmetrical tensile-compressive fatigue load stress amplitude. This "symmetrical tensile-compressive fatigue load stress amplitude" is called the "symmetrical tensile-compressive fatigue load with equivalent fatigue life," denoted as . .

[0086] S23. Based on the calculation models 1 and 2 of cumulative intrinsic damage dissipation, construct the calculation formula for damage characterization parameters under stress amplitude control:

[0087]

[0088] in, For damage characterization parameters under stress amplitude control, For the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loading, This refers to the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loads with equivalent fatigue life. The symmetrical tensile and compressive fatigue loads obtained by splitting the load are... For symmetrical tensile and compressive fatigue loads with equivalent fatigue life.

[0089] S3. Construct a formula for calculating additional damage characterization parameters under average stress control based on average stress load.

[0090] In S3 of this embodiment, the formula for calculating the additional damage characterization parameters under average stress control based on the average stress load specifically includes:

[0091] S31. Constructing a calculation model for cumulative intrinsic damage dissipation under mean stress load:

[0092]

[0093] in, This represents the cumulative intrinsic damage dissipation under average stress load. For material parameter two, The average stress load obtained by splitting, It is the elastic modulus.

[0094] The average stress after splitting can be regarded as quasi-static tension to And remain unchanged. Quasi-static tensile failure can be considered a special form of average stress load, where the cyclic maximum stress is equal to the material's tensile strength. .

[0095] S32. Constructing a calculation model for cumulative intrinsic damage dissipation under tensile strength: (Model 4)

[0096]

[0097] in, For cumulative intrinsic damage dissipation under tensile strength, For material parameter two, For the tensile strength of the material, It is the elastic modulus;

[0098] S33. Based on the calculation models three and four for cumulative intrinsic damage dissipation, construct the calculation formula for additional damage characterization parameters under mean stress control:

[0099]

[0100] in, Additional damage characterization parameters under mean stress control. This represents the cumulative intrinsic damage dissipation under average stress load. For cumulative intrinsic damage dissipation under tensile strength, The average stress load obtained by splitting, This refers to the tensile strength of the material.

[0101] S4. Construct a uniaxial fatigue damage accumulation equation with mean stress based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under mean stress control.

[0102] In S4 of this embodiment, the uniaxial fatigue damage accumulation equation containing mean stress is constructed based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under mean stress control as follows:

[0103]

[0104] in, For damage characterization parameters under stress amplitude control, Additional damage characterization parameters under mean stress control. This is the damage interaction coefficient;

[0105] Considering the differences in damage interaction between ductile and brittle materials, the formula for the damage interaction coefficient is as follows:

[0106]

[0107] in, This is the damage interaction coefficient. For symmetrical tensile and compressive fatigue limits, This represents the yield strength of the material.

[0108] S5. Based on the calculation formulas for damage characterization parameters under stress amplitude control, the calculation formulas for additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation, a symmetrical tensile-compressive fatigue load calculation formula with equivalent fatigue life is obtained.

[0109] In S5 of this embodiment, the calculation formula for symmetrical tensile-compressive fatigue load with equivalent fatigue life based on the calculation formula for damage characterization parameters under stress amplitude control, the calculation formula for additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation specifically includes:

[0110] S51. Substitute the calculation formulas for damage characterization parameters and additional damage characterization parameters under mean stress control into the uniaxial fatigue damage accumulation equation to obtain the equal life equation.

[0111] Will and Substituting the calculation formula into the uniaxial fatigue damage accumulation equation, we obtain the equal life equation:

[0112]

[0113] in, .

[0114] S52. Transform the equal-life equation to obtain the calculation formula for symmetrical tensile-compressive fatigue loads with equivalent fatigue life:

[0115]

[0116] in, For symmetrical tensile and compressive fatigue loads with equivalent fatigue life, The symmetrical tensile and compressive fatigue loads obtained by splitting the load are... This is the damage interaction coefficient. The average stress load obtained by splitting, This refers to the tensile strength of the material.

[0117] S6. Construct a uniaxial fatigue life prediction model based on the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life.

[0118] In S6 of this embodiment, the construction of a uniaxial fatigue life prediction model with average stress based on the symmetrical tensile-compressive fatigue load calculation formula with equivalent fatigue life specifically includes:

[0119] S61. Substitute the symmetrical tensile-compressive fatigue load calculation formula into the SN curve equation to obtain the uniaxial fatigue life prediction model:

[0120]

[0121] in, This is the predicted value for uniaxial fatigue life. The symmetrical tensile and compressive fatigue loads obtained by splitting the load are... This is the fatigue strength coefficient of the metal. This is the damage interaction coefficient. The average stress load obtained by splitting, For the tensile strength of the material, This is the fatigue strength index of metals.

[0122] In this embodiment, the SN curve equation itself is existing technology.

[0123] S7. Based on the uniaxial fatigue life prediction model, predict the fatigue life of a uniaxial structure with mean stress.

[0124] In this embodiment, S1-S6 are mainly for constructing a uniaxial fatigue life prediction model. Once the uniaxial fatigue life prediction model is constructed, when predicting the fatigue life of a uniaxial axis containing average stress, it is only necessary to substitute the relevant parameters of the uniaxial axis (such as symmetrical tensile and compressive fatigue load, metal fatigue strength coefficient, average stress load, material tensile strength, etc.) into the uniaxial fatigue life prediction model to obtain the predicted value of the uniaxial fatigue life of the uniaxial axis.

[0125] Furthermore, the method in this embodiment also includes:

[0126] S7. The prediction error of the uniaxial fatigue life prediction value is obtained based on the following formula:

[0127]

[0128] in, For the prediction error value, These are experimental values ​​for uniaxial fatigue life. This is the predicted value for uniaxial fatigue life.

[0129] In this embodiment, the prediction error of the uniaxial fatigue life prediction model for a single axis can be obtained through S7. The prediction error can be used to determine whether the uniaxial fatigue life prediction model is good or bad and whether it meets the usage requirements.

[0130] Furthermore, this embodiment of the invention uses three typical metallic materials—ZK60-T5 magnesium alloy, CK45 steel, and 2017A-T4 aluminum alloy—as examples to determine the prediction effect of the uniaxial fatigue life prediction model in this embodiment. Table 1 below shows the mechanical property parameters and fatigue performance parameters of the three materials:

[0131] Table 1

[0132]

[0133] Table 2 below shows the experimental data and prediction data of various models for ZK60-T5 magnesium alloy, along with the index errors:

[0134] Table 2

[0135]

[0136] Table 3 below shows the experimental data and prediction data of various models for CK45 steel, as well as the index errors:

[0137] Table 3

[0138]

[0139] Table 4 below shows the experimental data and prediction data of various models for 2017A-T4 aluminum alloy steel, as well as the index errors:

[0140] Table 4

[0141]

[0142] The prediction results and error analysis for three lifetime prediction methods—Goodman, SWT, and the method proposed in this invention—for the three materials are shown in Tables 2, 3, and 4. Figure 5 , Figure 6 , Figure 7 As shown in the figure, the red line represents the predicted lifetime being equal to the experimental lifetime, and the two blue dashed lines represent the 3x error boundary. A comparison of the data points in the figure reveals that the lifetime prediction method proposed in this invention shows good consistency between the predicted lifetime and experimental data for the three metallic materials, with the vast majority of data points falling within the 3x error zone. In contrast, other lifetime prediction methods for ZK60-T5 magnesium alloy, CK45 steel, and 2017A-T4 aluminum alloy have a significant number of data points falling outside the 3x error zone.

[0143] The prediction results show that, compared with the existing life prediction methods for three typical materials, ZK60-T5 magnesium alloy, CK45 steel and 2017A-T4 aluminum alloy, the fatigue life prediction method proposed in this invention has a more accurate prediction advantage, achieving a basic match between the predicted life and the experimental life. It also has higher accuracy and smaller prediction error for uniaxial fatigue life with mean stress.

[0144] This invention also provides a uniaxial fatigue life prediction device with mean stress, such as... Figure 2 As shown, the device includes:

[0145] The load splitting module is configured to split a uniaxial fatigue load containing average stress into a symmetrical tensile-compressive fatigue load and an average stress load.

[0146] The module for constructing damage characterization parameter calculation formulas is configured to construct damage characterization parameter calculation formulas under stress amplitude control based on symmetrical tensile and compressive fatigue loads.

[0147] The module for constructing additional damage characterization parameter calculation formulas is configured to construct additional damage characterization parameter calculation formulas under average stress control based on average stress loads.

[0148] The uniaxial fatigue damage accumulation equation construction module is configured to construct a uniaxial fatigue damage accumulation equation with mean stress based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under mean stress control.

[0149] The module for obtaining the symmetrical tensile and compressive fatigue load calculation formula is configured to obtain the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life based on the calculation formula of damage characterization parameters under stress amplitude control, the calculation formula of additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation.

[0150] The uniaxial fatigue life prediction model construction module is configured to construct a uniaxial fatigue life prediction model based on the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life.

[0151] The fatigue life prediction module is configured to predict the fatigue life of a uniaxial axis containing mean stress based on a uniaxial fatigue life prediction model.

[0152] Figure 3A block diagram of an electronic device 300 according to some embodiments of the present invention is shown. The device 300 includes a processor 301, which performs various appropriate actions and processes based on computer program instructions loaded into random access memory (RAM) 303 according to computer program instructions stored in read-only memory (ROM) 302. Various programs and data required for the operation of the device 300 may also be stored in RAM 303. The processor 301, ROM 302, and RAM 303 are interconnected via a bus 304. An input / output (I / O) interface 305 is also connected to the bus 304.

[0153] The various processes and procedures described above, such as method 100, can be executed by processor 301. For example, in some embodiments, method 100 may be implemented as a software program tangibly contained in a machine-readable medium. In some embodiments, part or all of the software program may be loaded and / or installed on device 300 via ROM 302. When the software program is loaded into RAM 303 and executed by processor 301, one or more actions of method 100 described above may be performed.

[0154] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload programmable logic devices (CPLDs), and so on.

[0155] The program code used to implement the methods of the present invention can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a standalone software package partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0156] This invention can be a method, apparatus, system, and / or program product. The program product may include a machine-readable storage medium on which machine-readable program instructions for performing various aspects of the invention are loaded. The machine-readable program instructions described herein can be downloaded from the machine-readable storage medium to various computing / processing devices, or downloaded via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the machine-readable program instructions from the network and forwards them for storage in the machine-readable storage medium of the respective computing / processing device.

[0157] Machine program instructions used to perform the operations of this invention may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The machine-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing state information from the machine-readable program instructions. This electronic circuitry can execute the machine-readable program instructions to implement various aspects of the invention.

[0158] In the context of this invention, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media can include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. Furthermore, although the operations are depicted in a specific order, this should be understood as requiring that such operations be performed in the specific order shown or in sequential order, or requiring that all illustrated operations be performed to achieve the desired result. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the invention. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0159] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A method for predicting uniaxial fatigue life with mean stress, characterized in that, include: S1. Decompose the uniaxial fatigue load containing average stress into a symmetrical tensile-compressive fatigue load and an average stress load; S2. Formulas for calculating damage characterization parameters under stress amplitude control based on symmetrical tensile and compressive fatigue loads; S3. Construct a calculation formula for additional damage characterization parameters under average stress control based on average stress load; S4. Construct a uniaxial fatigue damage accumulation equation with mean stress based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under mean stress control; S5. Based on the calculation formula of damage characterization parameters under stress amplitude control, the calculation formula of additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation, obtain the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life. S6. Construct a uniaxial fatigue life prediction model based on the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life; S7. Based on the uniaxial fatigue life prediction model, predict the fatigue life of a uniaxial structure with mean stress.

2. The method according to claim 1, characterized in that, In S2, the formula for calculating the damage characterization parameters under stress amplitude control based on symmetrical tensile and compressive fatigue loads specifically includes: S21. Constructing a calculation model for cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loading: ； in, For the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loading, For material parameter one, The symmetrical tensile and compressive fatigue loads obtained by splitting the loads are as follows: It is the elastic modulus; S22. Constructing a second calculation model for cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loads with equivalent fatigue life: ； in, This refers to the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loads with equivalent fatigue life. For material parameter one, For symmetrical tensile and compressive fatigue loads with equivalent fatigue life, It is the elastic modulus; S23. Based on the calculation models 1 and 2 of cumulative intrinsic damage dissipation, construct the calculation formula for damage characterization parameters under stress amplitude control: ； in, For damage characterization parameters under stress amplitude control, For the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loading, This refers to the cumulative intrinsic damage dissipation under symmetrical tensile and compressive fatigue loads with equivalent fatigue life. The symmetrical tensile and compressive fatigue loads obtained by splitting the loads are as follows: The symmetrical tensile and compressive fatigue loads have the same fatigue life.

3. The method according to claim 1, characterized in that, In S3, the formula for calculating the additional damage characterization parameters under average stress control based on average stress load specifically includes: S31. Constructing a calculation model for cumulative intrinsic damage dissipation under mean stress load: ； in, This represents the cumulative intrinsic damage dissipation under average stress load. For material parameter two, The average stress load obtained by splitting, It is the elastic modulus; S32. Constructing a calculation model for cumulative intrinsic damage dissipation under tensile strength: (Model 4) ； in, For the cumulative intrinsic damage dissipation under tensile strength, For material parameter two, For the tensile strength of the material, It is the elastic modulus; S33. Based on the calculation models three and four for cumulative intrinsic damage dissipation, construct the calculation formula for additional damage characterization parameters under mean stress control: ； in, Additional damage characterization parameters under mean stress control. This represents the cumulative intrinsic damage dissipation under average stress load. For the cumulative intrinsic damage dissipation under tensile strength, The average stress load obtained by splitting, This refers to the tensile strength of the material.

4. The method according to claim 1, characterized in that, In S4, the uniaxial fatigue damage accumulation equation containing mean stress is constructed based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under mean stress control as follows: ； in, For damage characterization parameters under stress amplitude control, Additional damage characterization parameters under mean stress control. This is the damage interaction coefficient; The formula for the damage interaction coefficient is as follows: ； in, This is the damage interaction coefficient. For symmetrical tensile and compressive fatigue limits, This represents the yield strength of the material.

5. The method according to claim 1, characterized in that, In S5, the calculation formula for symmetrical tensile-compressive fatigue loads with equivalent fatigue life obtained based on the calculation formula for damage characterization parameters under stress amplitude control, the calculation formula for additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation specifically includes: S51. Substitute the calculation formulas for damage characterization parameters and additional damage characterization parameters under average stress control into the uniaxial fatigue damage accumulation equation to obtain the equal life equation. S52. Transform the equal-life equation to obtain the calculation formula for symmetrical tensile-compressive fatigue loads with equivalent fatigue life: ； in, For symmetrical tensile and compressive fatigue loads with equivalent fatigue life, The symmetrical tensile and compressive fatigue loads obtained by splitting the loads are as follows: This is the damage interaction coefficient. The average stress load obtained by splitting, This refers to the tensile strength of the material.

6. The method according to claim 1, characterized in that, In step S6, the construction of a uniaxial fatigue life prediction model with mean stress based on the symmetrical tensile-compressive fatigue load calculation formula with equivalent fatigue life specifically includes: S61. Substitute the symmetrical tensile-compressive fatigue load calculation formula into the SN curve equation to obtain the uniaxial fatigue life prediction model: ； in, This is the predicted value for uniaxial fatigue life. The symmetrical tensile and compressive fatigue loads obtained by splitting the loads are as follows: This is the fatigue strength coefficient of the metal. This is the damage interaction coefficient. The average stress load obtained by splitting, For the tensile strength of the material, This is the fatigue strength index of metals.

7. The method according to claim 1, characterized in that, Also includes: S7. The prediction error of the uniaxial fatigue life prediction value is obtained based on the following formula: ； in, For the prediction error value, These are experimental values ​​for uniaxial fatigue life. This is the predicted value for uniaxial fatigue life.

8. A uniaxial fatigue life prediction device with mean stress, characterized in that, include: The load splitting module is configured to split a uniaxial fatigue load containing average stress into a symmetrical tensile-compressive fatigue load and an average stress load. The module for constructing damage characterization parameter calculation formulas is configured to construct damage characterization parameter calculation formulas under stress amplitude control based on symmetrical tensile and compressive fatigue loads. The module for constructing additional damage characterization parameter calculation formulas is configured to construct additional damage characterization parameter calculation formulas under average stress control based on average stress loads. The uniaxial fatigue damage accumulation equation construction module is configured to construct a uniaxial fatigue damage accumulation equation with mean stress based on the damage characterization parameters under stress amplitude control and the additional damage characterization parameters under mean stress control. The module for obtaining the symmetrical tensile and compressive fatigue load calculation formula is configured to obtain the symmetrical tensile and compressive fatigue load calculation formula with equivalent fatigue life based on the calculation formula of damage characterization parameters under stress amplitude control, the calculation formula of additional damage characterization parameters under average stress control, and the uniaxial fatigue damage accumulation equation. The uniaxial fatigue life prediction model construction module is configured to construct a uniaxial fatigue life prediction model based on the calculation formula of symmetrical tensile and compressive fatigue loads with equivalent fatigue life. The fatigue life prediction module is configured to predict the fatigue life of a single axis containing average stress based on a uniaxial fatigue life prediction model.

9. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, implements the steps of the method according to any one of claims 1-7.

10. An electronic device, characterized in that, It includes one or more processors and memory associated with the one or more processors, the memory being used to store program instructions that, when read and executed by the one or more processors, perform the steps of the method according to any one of claims 1-7.

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