CN-121997481-A - Fatigue safety coefficient prediction method and device

CN121997481ACN 121997481 ACN121997481 ACN 121997481ACN-121997481-A

Abstract

The method and the device for predicting the fatigue safety coefficient comprise the steps of obtaining physical parameters, structural characteristic information, nonlinear factors and material fatigue properties of a mechanical system to be predicted, constructing a dimensionless nonlinear multi-body dynamics model based on the physical parameters, the structural characteristic information and the nonlinear factors, simulating the dimensionless nonlinear multi-body dynamics model through a harmonic balancing method to obtain system dynamics response, calculating stress strain response data of a preset position in the mechanical system to be predicted based on the system dynamics response, and calculating a life prediction value of the preset position by using a preset life calculation expression and combining the stress strain response data and the material fatigue properties. The nonlinear characteristics in the nonlinear multi-body dynamics model of the mechanical system to be predicted are accurately captured by utilizing a harmonic balance method, the solving process is simplified, the computational complexity and the resource consumption are reduced, and the accuracy of fatigue life estimation is improved.

Inventors

QIAO ZHIZHONG
CAO YANJUN
QIN BO
Ji Rigele
XIAO WANGQIANG
CAI ZHIQIN
WU HAOHAO

Assignees

神华准格尔能源有限责任公司

Dates

Publication Date: 20260508
Application Date: 20251216

Claims (10)

1. A method for predicting a fatigue safety factor, comprising: Step S1, obtaining physical parameters, structural characteristic information, nonlinear factors and material fatigue properties of a mechanical system to be predicted; S2, constructing a dimensionless nonlinear multi-body dynamics model based on the physical parameters, the structural characteristic information and the nonlinear factors; S3, simulating the nondimensionalized nonlinear multi-body dynamics model by a harmonic balance method to obtain a system dynamics response; Step S4, stress-strain response data of a preset part in the mechanical system to be predicted are calculated based on the system dynamics response; And S5, calculating a life prediction value of the preset part by utilizing a preset life calculation expression and combining the stress-strain response data and the material fatigue attribute.
2. The method for predicting a fatigue safety factor according to claim 1, wherein the step S2 includes: Based on the physical parameters, the structural characteristic information and the nonlinear factors, establishing a nonlinear multi-body dynamics differential equation of the mechanical system to be predicted by a Newton-Euler method or a Lagrangian method; And carrying out dimensionless treatment on the nonlinear multi-body dynamics differential equation to obtain the dimensionless nonlinear multi-body dynamics model.
3. The method for predicting a fatigue safety factor according to claim 1, wherein the step S3 includes: Assuming a solution of the non-dimensionalized nonlinear multi-body dynamics model as a harmonic form; substituting the solution of the harmonic form into the non-dimensionalized nonlinear multi-body dynamics model, and converting a differential equation into a nonlinear algebraic equation set about harmonic coefficients through the harmonic balancing method; and solving the nonlinear algebraic equation set to obtain harmonic coefficients, and further obtaining the dynamic response of the system.
4. The method for predicting fatigue safety factor according to claim 1, wherein the structural characteristic information includes a geometric parameter and a sectional area, and step S4 includes: determining a damping force and a stiffness force based on the system dynamics response; and calculating the stress-strain response data of the preset part by combining the sectional area based on the damping force, the rigidity force and the geometric parameters of the preset part.
5. The method for predicting a fatigue safety coefficient according to claim 1, wherein the material fatigue property comprises a material fatigue limit, an effective stress concentration coefficient, a size coefficient, a surface state coefficient and an average stress conversion coefficient, and the life calculation expression is: ; Wherein, the In order to achieve a fatigue life, the base plate, In order to be a material fatigue limit, In order to be an effective stress concentration factor, As a result of the dimensional coefficients of the dimensions, Is the coefficient of the surface state of the wafer, For an equivalent alternating stress, the stress is, As a coefficient of the conversion of the average stress, Is equivalent mean stress.
6. The method for predicting a fatigue safety factor according to claim 1, further comprising, after the step S5: And (3) carrying out design optimization on the mechanical system to be predicted according to the life prediction value, and if the fatigue life does not meet a preset target, adjusting the physical parameters and/or the structural characteristic information and/or the nonlinear factor system, and repeating the steps S1 to S5 until the fatigue life meets the preset target.
7. A fatigue safety factor prediction apparatus, comprising: the acquisition module is used for acquiring physical parameters, structural characteristic information, nonlinear factors and material fatigue properties of the mechanical system to be predicted; the model construction module is used for constructing a dimensionless nonlinear multi-body dynamics model based on the physical parameters, the structural characteristic information and the nonlinear factors; The simulation module is used for simulating the nondimensionalized nonlinear multi-body dynamics model through a harmonic balance method to obtain a system dynamics response; the response data calculation module is used for calculating stress-strain response data of a preset part in the mechanical system to be predicted based on the system dynamics response; And the prediction module is used for calculating a life prediction value of the preset part by utilizing a preset life calculation expression and combining the stress-strain response data and the material fatigue attribute.
8. An electronic device comprising a processor and a memory storing computer readable instructions that, when executed by the processor, perform the method of any of claims 1-6.
9. A storage medium having stored thereon a computer program which, when executed by a processor, performs the method of any of claims 1-6.
10. A computer program product comprising a computer program, characterized in that the computer program, when executed by a processor, implements the method of any of claims 1-6.

Description

Fatigue safety coefficient prediction method and device Technical Field The invention relates to the technical field of structural fatigue reliability, in particular to a method and a device for predicting fatigue safety coefficients. Background Calculating the fatigue life of nonlinear dynamics is an important topic in the engineering field, and especially in complex systems, the influence of nonlinear characteristics on the fatigue life is significant. In order to solve the problem, the existing research mainly surrounds three directions of combining a finite element simulation with a fatigue damage model, directly solving a nonlinear dynamics equation and an estimation method based on experimental data, and aims to capture nonlinear dynamic characteristics through different technical paths and evaluate fatigue life. The finite element simulation combined fatigue damage model has high precision, can process nonlinear characteristics of a complex system, but has the defects of high consumption of computational resources, complex solving process, strong grid division dependence and the like, the nonlinear dynamic characteristics can be directly captured by directly solving a nonlinear dynamic equation, the result is unstable due to high solving difficulty and sensitivity to initial/boundary conditions, the solving complexity is aggravated by nonlinear interaction in a multi-body system, and the actual working condition characteristics are directly reflected by an estimation method based on experimental data, but the cost is high, the application range of the result is limited, and estimation deviation is easily caused by the difference between the experimental conditions and the actual working conditions. In addition, the linear assumption method is simple but low in precision, and the algorithm is applicable to a periodic system but has a truncation error. Disclosure of Invention The invention provides a fatigue safety coefficient prediction method and a device, which estimate the fatigue life of a multi-body dynamics system by a harmonic balance method so as to rapidly predict the fatigue failure process of a mechanical system. In a first aspect, the present invention provides a method for predicting a fatigue safety factor, comprising: Step S1, obtaining physical parameters, structural characteristic information, nonlinear factors and material fatigue properties of a mechanical system to be predicted; S2, constructing a dimensionless nonlinear multi-body dynamics model based on the physical parameters, the structural characteristic information and the nonlinear factors; S3, simulating the nondimensionalized nonlinear multi-body dynamics model by a harmonic balance method to obtain a system dynamics response; Step S4, stress-strain response data of a preset part in the mechanical system to be predicted are calculated based on the system dynamics response; And S5, calculating a life prediction value of the preset part by utilizing a preset life calculation expression and combining the stress-strain response data and the material fatigue attribute. Optionally, the step S2 includes: Based on the physical parameters, the structural characteristic information and the nonlinear factors, establishing a nonlinear multi-body dynamics differential equation of the mechanical system to be predicted by a Newton-Euler method or a Lagrangian method; And carrying out dimensionless treatment on the nonlinear multi-body dynamics differential equation to obtain the dimensionless nonlinear multi-body dynamics model. Optionally, the step S3 includes: Assuming a solution of the non-dimensionalized nonlinear multi-body dynamics model as a harmonic form; substituting the solution of the harmonic form into the non-dimensionalized nonlinear multi-body dynamics model, and converting a differential equation into a nonlinear algebraic equation set about harmonic coefficients through the harmonic balancing method; and solving the nonlinear algebraic equation set to obtain harmonic coefficients, and further obtaining the dynamic response of the system. Optionally, the structural characteristic information comprises geometric parameters and sectional areas, and the step S4 comprises the following steps: determining a damping force and a stiffness force based on the system dynamics response; and calculating the stress-strain response data of the preset part by combining the sectional area based on the damping force, the rigidity force and the geometric parameters of the preset part. Optionally, the material fatigue property comprises a material fatigue limit, an effective stress concentration coefficient, a size coefficient, a surface state coefficient and an average stress conversion coefficient, and the life calculation expression is as follows: ; Wherein, the In order to achieve a fatigue life, the base plate,In order to be a material fatigue limit,In order to be an effective stress concentration factor,As a result of the dimensional