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Method for measuring expansion rate of intrinsic fatigue crack of welded plate vertical to weld direction

A fatigue crack propagation, plate technology, used in measuring devices, using stable tension/pressure testing materials strength, instruments, etc., can solve the problem of the accuracy of the method needs to be studied, the structure cannot be completely released, the method is complicated, etc. Simple implementation, simple measurement process, and high prediction accuracy

Inactive Publication Date: 2017-04-26
BEIHANG UNIV
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Problems solved by technology

But this method also has the following disadvantages: stretching 2% plastic strain can not completely release the residual stress in the structure (in fact, about 90%), and the plastic zone formed during the stretching process will have an impact on the crack propagation tip plastic zone
This method is relatively complicated, and the calculation based on empirical formulas makes the accuracy of the method need to be studied

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  • Method for measuring expansion rate of intrinsic fatigue crack of welded plate vertical to weld direction
  • Method for measuring expansion rate of intrinsic fatigue crack of welded plate vertical to weld direction
  • Method for measuring expansion rate of intrinsic fatigue crack of welded plate vertical to weld direction

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Embodiment Construction

[0020] The present invention will be further described below in conjunction with the accompanying drawings and specific examples.

[0021] The invention provides a method for measuring the intrinsic fatigue crack growth rate of a welded plate perpendicular to the direction of the weld. The test equipment required by the test method includes an X-ray stress tester, a hydraulic servo fatigue testing machine, crack observation and length measurement Apparatus, test piece, method step process such as figure 1 As shown, the details are as follows:

[0022] The first step, residual stress measurement;

[0023] Use an X-ray stress tester to measure the residual stress distribution in the longitudinal direction (parallel to the weld direction) of the welded plate;

[0024] The second step is to process the test piece;

[0025] According to the requirements of the crack growth test, the welded plate is processed as figure 2 A compact tensile test piece 1 containing a weld 2, the w...

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Abstract

The invention discloses a method for measuring the expansion rate of an intrinsic fatigue crack of a welded plate vertical to the weld direction, and belongs to the technical field of solid mechanics. The method comprises the following steps: at first, measuring residual stress horizontal to the weld direction; making a welded plate into a weld containing compact stretch sample, wherein the crack expansion direction is vertical to the weld direction; calculating the stress strength factor of residual stress corresponding to different crack lengths; through a residual stress superposition model, by combining a given constant stress factor range and a constant effective stress ratio, calculating the applied external loads under different crack lengths; carrying out fatigue crack expansion experiments under the calculated external loads, and determining the expansion rate of an intrinsic fatigue crack in a welded member under a given constant stress factor range and constant effective stress ratio. The provided method can directly obtain the expansion rate of an intrinsic fatigue crack in a welded member under a given stress state through fatigue experiments, is simple, and has a high accuracy.

Description

technical field [0001] The invention belongs to the field of solid mechanics, and relates to a method for measuring the influence of the change of the material microstructure caused by the welding process on the growth rate of the fatigue crack, specifically refers to the measurement of the weldment under the constant stress intensity factor range and constant effective stress ratio Methods for Fatigue Crack Growth Rates. Background technique [0002] Advanced welding technology has been widely used in the aviation industry due to its light weight, high processing efficiency, and good economic benefits, but it also brings new challenges to the damage tolerance assessment of structures. Fatigue crack growth life prediction is an important part of damage tolerance assessment, so it is of great significance to study the fatigue crack growth rate of welded structures. [0003] The influence of the welding process on the crack growth rate of the structure is mainly reflected in ...

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Application Information

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IPC IPC(8): G01N3/08
CPCG01N3/08G01N2203/0066G01N2203/0282
Inventor 鲍蕊许耀午刘浩
Owner BEIHANG UNIV
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