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

A crack growth life and prediction method technology, which is applied in the field of multiaxial short crack growth life prediction based on the critical surface method, can solve the lack of stress intensity factor, multiaxial fatigue short crack test data difficulty, multiaxial fatigue short crack growth model Problems such as slow research progress, to achieve the effect of clear physical meaning and easy engineering application

Active Publication Date: 2016-04-06
BEIJING UNIV OF TECH
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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 ob...

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

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Embodiment Construction

[0032] The present invention is illustrated in conjunction with the accompanying drawings.

[0033] The present invention further illustrates the present invention through the fatigue test, the test is divided into two parts, one part is the short crack test under uniaxial constant amplitude loading, the stress ratio is -1, and the short crack growth data is observed. In the range of high cycle fatigue life, there is mainly a single dominant crack, which is convenient for measuring and calculating the crack growth curve. The other part is the multiaxial proportional and non-proportional loading test, which calculates the range of equivalent stress intensity factors under multiaxial loading conditions.

[0034] A multi-axial short crack growth life prediction method based on the critical surface method, the specific calculation method is as follows:

[0035] Step 1): If figure 2 As shown in , the cracks of thin-walled pipes mainly originate in the plane where the maximum she...

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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...

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Application Information

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IPC IPC(8): G01N3/08G01N3/22
CPCG01N3/08G01N3/22
Inventor 尚德广赵相锋宋明亮张嘉梁王晓玮程焕
Owner BEIJING UNIV OF TECH
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