Fatigue short crack propagation life prediction method under multi-axis variable amplitude loading

Abstract

The invention discloses a fatigue short crack propagation life prediction method under multi-axis variable amplitude loading, and relates to the multi-axis fatigue strength theory field. The algorithmincludes the following steps: (1) using the Wang-Brown multi-axis cycle counting under stress loading to obtain a plurality of half cycles, and realizing multi-axis constant amplitude loading of eachhalf cycle; (2) using the weighted average maximum shear stress method to determine a weight critical surface for the characteristic that the critical surface is not fixed; (3) obtaining the crack propagation amount of a single variable amplitude load block by using a multi-axis fatigue short crack propagation model on the weight critical surface; and (4), performing plastic zone size correctionon crack tips, and calculating the short crack propagation life by the fracture mechanics method. The method can well describe the influence of multi-axis variable amplitude loading on crack propagation. The results show that the method can predict the short crack propagation life under multi-axis variable amplitude loading.

Description

technical field [0001] The invention relates to the field of multiaxial fatigue strength theory, in particular to a method for predicting the life of fatigue short crack growth under multiaxial variable amplitude loading. Background technique [0002] In many engineering fields, such as nuclear power plants, automobiles, aircraft and pressure vessels, structural components are subjected to complex multi-axial variable-amplitude loads, and multi-axial fatigue research has become an important research content in various countries. Compared with uniaxial loading, damage accumulation, crack initiation and growth, and life prediction methods under multiaxial variable amplitude loading need to consider more factors. Therefore, it is of great engineering significance to study the life prediction method of fatigue short crack growth under multiaxial variable amplitude loading. [0003] Studying the problem of short cracks is conducive to understanding fatigue from the microcosmic a...

AI Technical Summary

Problems solved by technology

For multiaxial short crack growth, due to the lack of an accurate solution of the stress intensity factor and the difficulty in obtaining test data for multiaxial fatigue short cracks, the research progress of the multiaxial fatigue short crack growth model is slow.

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