Multiaxial short crack propagation life prediction method based on critical surface method

Abstract

The present invention provides a multiaxial short crack propagation life prediction method based on a critical surface method, and relates to the field of multiaxial fatigue strength theory. The algorithm comprises the steps of: (1) selecting a plane, which contains the maximum shearing strain range, as a critical surface, and using the damage parameters on the critical surface to characterize a short crack propagation driving force; (2) based on the shear-type multiaxial fatigue damage parameters, establishing an equivalent crack stress intensity factor applicable to the multiaxial stress state; (3) fitting the short crack propagation rate data under uniaxial loading to obtain an uniaxial short crack propagation curve; and (4) carrying out plastic zone size correction on the crack tip, and calculating the short crack propagation life by a fracture mechanics method. The method can well descript the influence of non-proportional loading on crack propagation. The results show that the method can well predict the short crack propagation life under multiaxial proportional and non-proportional 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 multiaxial short crack propagation based on the critical surface method. Background technique [0002] In many engineering fields such as nuclear power plants, automobiles, aircraft, and pressure vessels, structural components are subjected to complex multiaxial loads, and multiaxial 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 loading need to consider more factors. Therefore, it is of great engineering significance to study the short crack growth model and life prediction method under multiaxial loading. [0003] Studying the problem of short cracks is conducive to understanding fatigue from the microcosmic and submicrocosmic levels, so as to understand the whole pro...

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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