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Method for predicting variable-amplitude fatigue life of friction stir welding component

A technology of friction stir welding and components, which is applied in the direction of measuring devices, testing material strength by applying repetitive force/pulsation force, instruments, etc., and can solve problems such as crack propagation hysteresis

Pending Publication Date: 2021-12-07
BEIJING UNIV OF TECH
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Problems solved by technology

The Wheeler model believes that a large overload cycle will lead to an overloaded plastic region, and the range of the cyclic plastic region generated in the cycle will not exceed the range of the overloaded plastic region, which will lead to hysteresis in crack growth

Method used

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  • Method for predicting variable-amplitude fatigue life of friction stir welding component
  • Method for predicting variable-amplitude fatigue life of friction stir welding component
  • Method for predicting variable-amplitude fatigue life of friction stir welding component

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Embodiment Construction

[0058] Such as figure 1 As shown, the specific implementation of the fatigue life prediction method for friction stir welded components based on the load sequence and the performance of each zone of the joint is as follows:

[0059] Step 1): Use finite element software (for example: ABAQUS) to simulate the change of the weak area of ​​the friction stir welded member under different load levels, and model the model according to the characteristics of different material properties in different regions of the friction stir welded member, It is mainly divided into four areas: weld nugget (NZ), heat engine (TMAZ), heat effect (HAZ), and base metal (BM). The material properties of each area are obtained through micro-tensile test data, including stress-strain data and elastic modulus of each area of ​​the joint. , apply different loads, and take the area of ​​maximum stress under different loading levels as the weak area under this loading level;

[0060] Step 2): According to the ...

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Abstract

The invention discloses a method for predicting variable-amplitude fatigue life of a friction stir welding component, and belongs to the technical field of fatigue diagnosis and analysis of mechanical components. The method includes: prefabricating micro-cracks in the weak area according to the loading sequence under the simulated variable-amplitude load, determining the change of the weak area through the variable-amplitude load, and simulating the crack propagation rule of the component under variable amplitude; carrying out different load fatigue small crack propagation interruption fatigue experiments, calculating the small crack propagation rate, and obtaining a crack propagation rule under variable amplitude; calculating corresponding correction factors MK and f, adding the correction factors MK and f on the basis of an effective stress intensity factor in an Elber crack closing method to obtain delta Keff-da / dN crack growth rate base lines of different areas under different stress ratios, and fitting material constants C and m; determining an initial crack size a0 and a critical crack size ac; and determining a weak area under the current load level, and selecting a correction factor MK, f and an initial crack size a0 according to the weak area. Through cyclic calculation, fatigue life under different loading levels is obtained.

Description

technical field [0001] The invention relates to a method for predicting fatigue life, in particular to a method for predicting fatigue life of variable-amplitude fatigue life of a friction stir welded component based on the load sequence and the performance of each zone of a joint, and belongs to the technical field of diagnosis and analysis of mechanical components. Background technique [0002] In engineering applications, the main components in construction machinery, light industry, ships, railways and other fields are mostly subject to periodic alternating loads. According to literature statistics, the failure of welded components caused by fatigue load can reach 80% to 90% of the failed components. Therefore, it is very necessary to carry out research on the failure position and life prediction of high cycle fatigue of metal structural parts under the condition of variable amplitude for friction stir welded members. [0003] When predicting the life of friction stir w...

Claims

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Application Information

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IPC IPC(8): G01N3/32
CPCG01N3/32G01N2203/0066G01N2203/0073
Inventor 孙国芹刘鹤刘金峰
Owner BEIJING UNIV OF TECH
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