Welded joint fatigue limit rapid prediction method based on fatigue damage entropy production rate

Abstract

The invention discloses a welded joint fatigue limit rapid prediction method based on a fatigue damage entropy production rate. A butt joint test piece is used for carrying out a fatigue test on a PLG-200 high-frequency fatigue testing machine; the temperature rise of the butt joint in the fatigue test process is measured; a butt joint cumulative fatigue damage entropy model is established, a welding joint fatigue limit rapid prediction mathematical model based on a cumulative damage entropy production rate is preliminarily established, an intersection point between two linear fitting functions is obtained, and a welding joint is predicted by using a lifting method to obtain a fatigue limit test value; and the fatigue limit prediction value is compared with the fatigue limit test value toobtain an error value. According to the method, the function relationship between the cumulative fatigue damage entropy production rate and the fatigue limit is established, the turning point of the cumulative fatigue damage entropy production rate along with the change degree of the load level is found, and the turning point is used as the prediction value of the fatigue limit, so that the fatigue limit can be rapidly predicted from the perspective of the fatigue damage entropy production rate.

Description

technical field [0001] The invention relates to the technical field of model building, in particular to a rapid prediction method for the fatigue limit of welded joints based on fatigue damage entropy entropy production rate. Background technique [0002] Fatigue fracture is the main form of structural failure, and many catastrophic accidents in engineering are caused by structural fatigue failure. The fatigue problem of welded structure has certain particularity because of the geometrical discontinuity of the weld. [0003] Traditional welding fatigue evaluation methods based on S-N curves include nominal stress method, hot spot stress method and structural stress method, etc. The nominal stress method is the earliest evaluation method used. However, due to the sensitivity of the finite element software to the grid, the calculation results of the peak stress at the weld toe also vary from person to person. Professor Dong Pingsha, a Chinese American scientist, invented a g...

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Problems solved by technology

[0003] Traditional welding fatigue evaluation methods based on S-N curves include nominal stress method, hot spot stress method and structural stress method, etc. The nominal stress method is the earliest evaluation method used. The problem of stress concentration at the weld toe, but due to the sensitivity of the finite element software to the mesh, the calculation results of the peak stress at the weld toe are also different from person to person

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