Fatigue damage analysis method considering loading lower than fatigue limit

Abstract

The invention relates to a fatigue damage analysis method considering loading lower than fatigue limit. Since the structure generates initial damage under the action of high amplitude load when the magnitude of the loaded fatigue load is high-low two-stage loading or high-low alternating loading, and the fatigue performance of the material will continue to deteriorate under the effect lower than the fatigue limit load to affect accumulation of the fatigue damage, an improved nonlinear continuous damage accumulation model is proposed based on the fuzzy mathematics theory for considering the damage caused by being lower than the fatigue limit load by using a membership function. Based on the continuous damage mechanics, the model relates load parameters to damage parameters, which reflects the influence of load sequence changes on fatigue damage. At the same time, the damage parameters caused by the small load lower than the fatigue limit is described by using the reinforcement functionsand membership functions. A multi-stage loading fatigue damage accumulation model comprehensively considering the characteristics of load parameters is established by step-by-step derivation, which ensures the reliability of mechanical structure life prediction and damage assessment.

Description

technical field [0001] The present invention belongs to the field of structural strength. Specifically, it relates to a structural fatigue damage prediction method under the loading condition below the fatigue limit load in the loading process, which is used for high cycle fatigue damage analysis of materials, components and structures in aviation, marine and other engineering. Background technique [0002] Fatigue fracture is one of the main modes of structural failure under alternating loading. Research on fatigue life prediction and damage assessment can not only effectively avoid failure accidents, but also guide structural design, safety assessment, and optimization of materials and structures. However, the service environment of aviation and marine engineering structures is harsh and the loading conditions are complex. Fatigue tests cannot accurately restore the load spectrum of the structure during the working process, and the load parameters considered by the fatigu...

AI Technical Summary

Problems solved by technology

[0011] In order to solve the problem of insufficient accuracy of the existing fatigue damage prediction methods under the loading conditions below the fatigue limit, an improved nonlinear continuous damage accumulation model is proposed based on fuzzy mathematics theory, and the membership function is used to consider the damage caused by the load below the fatigue limit. damage

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