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

A technology of crack growth life and crack growth, applied in the field of fatigue short-crack growth life prediction under multi-axial variable amplitude loading, which can solve the problem of slow progress in multi-axial fatigue short-crack growth model research, lack of stress intensity factor, multi-axial fatigue short-crack Problems such as difficult test data

Active Publication Date: 2018-11-27
BEIJING UNIV OF TECH
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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.

Method used

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

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Embodiment Construction

[0031] The present invention is illustrated in conjunction with the accompanying drawings.

[0032] 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 variable amplitude loading test, which calculates the range of the equivalent stress intensity factor under the condition of multiaxial variable amplitude loading.

[0033] A method for predicting the life of fatigue short crack growth under multi-axial variable amplitude loading, the specific calculation method is as follows:

[0034] Step 1): Multi-axis variable amplitude load processing and multi-axis cycle counting; in the...

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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...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/50
CPCG06F30/20Y02E30/30
Inventor 尚德广赵杰李磊董恩军李罗金
Owner BEIJING UNIV OF TECH
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