Monotonic tensile parameter-based metal material fatigue crack growth model construction method

Abstract

The invention discloses a monotonic tensile parameter-based metal material fatigue crack growth model construction method. The method includes the following steps that: step 1, a linear cumulative damage-based crack growth rate model is obtained; step 2, low-cycle fatigue parameters are characterized with monotonic tensile parameters; and step 3, results obtained in the step 2 are introduced intothe linear cumulative damage-based crack growth rate model in the step 1, so that a required crack growth rate model is obtained. According to the monotonic tensile parameter-based metal material fatigue crack growth model construction method of the invention, relationships between the monotonic tensile parameters and the low-cycle fatigue parameters are established; and the model is characterizedwith the monotonic tensile parameters, high test costs and cumbersome calculation processes in a low-cycle fatigue test can be avoided, and the prediction of a crack growth rate is more accurate.

Description

technical field [0001] The invention relates to a method for building a metal material fatigue crack growth model, in particular to a method for building a metal material fatigue crack growth model based on monotone tensile parameters. Background technique [0002] In engineering, the relevant test data are generally obtained through the crack growth rate test and fitted according to the Paris formula to obtain the relationship between the crack growth rate and the stress intensity factor ΔK: [0003] [0004] In the formula: C and m are constants related to the material, which can be obtained by fitting the test data, and the crack length a and the number of cycles N are the half-length of the crack and the corresponding number of cycles, respectively, which can be measured in the test; but the scheme The test value of the crack growth rate is needed, and the measured crack growth rate will have a large dispersion due to some objective factors (such as measurement errors...

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Problems solved by technology

[0004] In the formula: C and m are constants related to the material, which can be obtained by fitting the test data, and the crack length a and the number of cycles N are the half-length of the crack and the corresponding number of cycles, respectively, which can be measured in the test; but the scheme The test value of the crack growth rate is needed, and the measured crack growth rate will have a large dispersion due to some objective factors (such as measurement errors, changes in environmental conditions in the test, etc.), which will affect the simulation of the Paris formula. Accuracy

[0005] Considering the insufficiency of the Paris formula, scholars at home and abroad have established crack growth rate models based on material properties, for example, based on the relationship between low-cycle fatigue parameters and crack growth rates; However, due to the instability of the low-cycle fatigue parameter test, the parameter values ​​obtained in the test may have deviated from the real value, resulting in a large difference between the crack growth rate prediction model and the real value. far; it cannot meet the needs of engineering applications, and the determination of low cycle fatigue parameters requires a cumbersome test and solution process, which will consume a lot of manpower and material resources

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