Fatigue crack initiation prediction method considering surface integrity

Abstract

The invention discloses a fatigue crack initiation prediction method considering surface integrity, and belongs to the field of engineering material fatigue failure. According to the method, a fatigue crack initiation micro-nano model is provided based on the crystal plasticity constitutive structure and in combination with dislocation strain energy, the fatigue crack initiation position, direction and cycle can be accurately predicted by establishing the fatigue crack initiation prediction model and in combination with crystal plasticity finite element simulation, the influence of the integrity of the machined surface, including the surface roughness, residual stress and surface layer texture, can be considered at the same time, and the method plays an important role in anti-fatigue manufacturing and failure analysis of important parts; a multilevel microstructure modeling method is adopted, martensite microstructure modeling is achieved, meanwhile, the relation between martensite block and martensite beam crystal orientation is combined, the martensite crystal orientation is accurately established, and compared with a Thiessen polygon modeling method, the method has the advantage of being high in precision, and the method plays an important role in mechanical property analysis and failure analysis of martensite materials.

Description

technical field [0001] The invention relates to a fatigue crack initiation prediction method considering surface integrity, and belongs to the field of fatigue failure of engineering materials. Background technique [0002] Fatigue failure, as the main form of engineering material failure, accounts for more than 80% of all mechanical component failures, which has caused us huge property losses and casualties every year. Therefore, improving the fatigue resistance of engineering materials has become a Key points and difficulties of existing research. The fatigue failure process can be clearly divided into three stages, the fatigue crack initiation stage, the fatigue crack growth stage and the transient fracture stage. Among them, the fatigue crack initiation stage occupies the main part of the fatigue life. In high cycle fatigue and ultra-high cycle fatigue, It can even account for more than 90% of the total fatigue life, and fatigue crack initiation can be divided into two ...

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Problems solved by technology

[0005] Traditional fatigue failure prediction models, such as SWT model, critical plane method, Basquin formula, Coffin-Manson formula, etc., fail to take into account the influence of surface integrity, while the failure prediction models developed in recent years often only consider surface roughness and residual stress, the microstructure of the surface layer is not considered, so these models are difficult to accurately predict the fatigue resistance of the surface layer material after the surface strengthening process

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