Fatigue life assessment method of components based on nonlinear fatigue damage accumulation theory

Abstract

The invention discloses a fatigue life evaluation method of a component based on a nonlinear fatigue damage accumulation theory, which comprises the following steps of: adopting a finite element analysis model to carry out stress analysis on the component under at least one working condition, and selecting a region with a stress value greater than a set stress as a hazard analysis region under theworking condition; obtaining the maximum and minimum of stress and strain in the hazard analysis area by simulating the load on the finite element analysis model of the component in one mission. According to the maximum and minimum value of stress in the hazard analysis area, the equivalent stress of each working condition is calculated. According to the maximum and minimum value of strain in thehazard analysis area, the fatigue life prediction value of the component under each working condition is predicted. According to the equivalent stress and fatigue life predicted under each working condition, the fatigue cumulative damage of the member under stress spectrum is calculated. According to the accumulated fatigue damage, the fatigue life of the component is calculated.

Description

technical field [0001] The invention relates to an evaluation method of equipment life, in particular to a component fatigue life evaluation method based on nonlinear fatigue damage accumulation theory. Background technique [0002] In engineering practice, most of the loads borne by mechanical components are variable amplitude loads, that is, the peak and valley values ​​of the load change with time. From an economic point of view, it is obviously unrealistic to directly use test methods to determine the fatigue life under such service loads. In contrast, the fatigue test under constant amplitude loading is simple and easy, and a large amount of test data has been accumulated so far. In this way, the life data under constant amplitude loading can be converted equivalently through the fatigue cumulative damage criterion, and then the structure under variable amplitude can be estimated. Fatigue life under load. [0003] Many scholars have proposed a variety of cumulative da...

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Problems solved by technology

(2) The damage has nothing to do with the course of the load

(3) There is no relationship between damage and the interaction between loads

[0006] The nonlinear fatigue cumulative damage model makes up for the lack of the linear cumulative model that fails to consider the impact of the load sequence on the fatigue life, and considers the impact of the load sequence on the fatigue life, but with the deepening of the research, more problems to be solved are gradually exposed

First of all, the parameters in some models are difficult to determine and require a large amount of experimental data to fit, which makes the model unable to be applied to engineering practice

At the same time, most nonlinear models are proposed in the form of semi-empirical formulas, which lack physical meaning, or cannot find the theoretical basis for the parameters in the model

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