Method for determining specific fatigue strength rated value under multi-axial loading condition

A multi-axial load and fatigue strength technology, applied in the field of fatigue strength, can solve the problem of less research on DFR theory

Active Publication Date: 2014-07-23
BEIJING UNIV OF TECH
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Problems solved by technology

[0003] Although the DFR method is simple and practical, the method is based on the uniaxial fatigue theory, so the DFR theory related to multiaxial is rarely studied

Method used

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  • Method for determining specific fatigue strength rated value under multi-axial loading condition
  • Method for determining specific fatigue strength rated value under multi-axial loading condition
  • Method for determining specific fatigue strength rated value under multi-axial loading condition

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Embodiment Construction

[0026] The present invention is illustrated in conjunction with the accompanying drawings.

[0027] The present invention further illustrates the present invention through the fatigue test, the test is divided into two parts, one part is a uniaxial DFR test, the stress ratio is 0.06, and the test is for calculating the DFR value. According to the method of calculating the DFR value by the two-point method, two stress levels are selected, and a group of experiments are done under each stress level, and the life of the specimen is within a certain range. The other part is the multiaxial proportional and non-proportional test, which is to calculate the DFR value under multiaxial loading conditions.

[0028] A method for determining the fatigue strength rating of details under multiaxial loading conditions, the specific calculation method is as follows:

[0029] Step 1): Using the existing high-cycle multiaxial fatigue model to convert the multiaxial load into the equivalent stre...

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Abstract

The invention provides a method for determining the specific fatigue strength rated value under the multi-axial loading condition, and relates to the field of fatigue strength. The method comprises the first step of converting a multi-axial load into equivalent stress through an existing high-cycle multi-axial fatigue model, the second step of converting the equivalent shearing stress amplitude into the equivalent axial stress amplitude if the converted equivalent stress is a shearing type model, the third step of converting the equivalent axial stress amplitude sigma eq,a into the maximum stress sigma eq,0.06 when the stress ratio is 0.06 based on the Goodman equation, and the fourth step of calculating the DFR value based on the double-point method. The method is used for calculating the DFR value under the multi-axial loading condition, and the predicting result shows that the DFR value under the multi-axial loading condition can be calculated with the method.

Description

technical field [0001] The invention relates to the field of fatigue strength, in particular to a method for determining the rated value of fatigue strength of details under multiaxial load conditions. Background technique [0002] Fatigue failure is the main form of aircraft component failure, so fatigue strength design has become an indispensable part of modern aircraft design. Detail Fatigue Rating (DFR), that is, the detail fatigue rating, is an inherent characteristic of the structure itself, and its magnitude is not affected by the magnitude of the loading stress. The DFR method uses the inherent fatigue performance quality of structural details as the fatigue performance parameter to estimate the fatigue life of structural details. It is simple and reliable, so it has been widely used in the field of aeronautical design. [0003] Although the DFR method is simple and practical, it is based on the uniaxial fatigue theory, so the DFR theory related to multiaxial is rar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F19/00G01N3/00
Inventor 尚德广王晓玮熊健王聪刘小冬郭振坤
Owner BEIJING UNIV OF TECH
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