A notch part low-cycle fatigue prediction method for total strain energy density correction

Abstract

The invention relates to a notch piece low-cycle fatigue prediction method based on total strain energy density correction, which mainly comprises the following steps: (1) carrying out a tensile property test on a material to obtain the most basic mechanical property of the material; (2) carrying out a fatigue performance test on the standard part to obtain a cyclic stress-strain curve, and establishing an equation of the total strain energy density and the fatigue life of the material, (3) obtaining the stress distribution of the notched piece at different moments through finite element analysis, (4) selecting a notch root as a fatigue danger point, extracting stress data according to the load action direction to obtain a stress change range at the danger point, (5) respectively calculating the elastic-plastic strain energy density of the dangerous point, correcting the total strain energy density of the dangerous point according to the correction coefficient, and (6) substituting thecorrected total strain energy density into the total strain energy density and fatigue life equation of the material to obtain a prediction result. The method solves the problem that the total strainenergy density is too conservative when evaluating the low-cycle fatigue life, and is high in prediction precision and good in stability.

Description

Technical field [0001] The present invention relates to the problem of low-cycle fatigue prediction for structures containing notches, and in particular to a fatigue assessment method based on total strain energy density. Background technique [0002] Fatigue failure is a phenomenon in which the material is damaged after several cycles of cyclic loading when the strength is lower than normal. In today's many industries, such as vehicles, aviation, navigation, bridges, metallurgy, electric power, etc., the main structures will be subjected to various complex cyclic loadings, and fatigue failure is one of the most important failure modes of these mechanical parts. Due to the long initiation period of fatigue failure cracks, it is difficult to find before rapid expansion. Major accidents occur every year and cause huge economic losses. This makes people pay high attention to the research of material fatigue failure. In the structural design, it is inevitable that there will be step...

AI Technical Summary

Problems solved by technology

However, initially, this method only considers the energy at the root of the notch and does not consider the stress distribution around the notch, so it has a good application in the prediction of high cycle fatigue, but when the local large plastic deformation occurs, the prediction effect will be too large. Conservative, poor predictor of low-cycle fatigue problems

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