Method for predicting low-cycle fatigue life of metallic material under multi-step loading conditions

Abstract

The invention discloses a method for predicting the low-cycle fatigue life of a metallic material under multi-step loading conditions. The method comprises the following steps of: (1) obtaining the low-cycle fatigue life of the metallic material through one-step and multi-step loaded asymmetric cyclic stress control fatigue experiments; (2) according to the working conditions of the fatigue experiments and the fatigue property of the material, determining a fatigue parameter (FP) calculation equation of the material during one-step loading, and establishing a fatigue life prediction model of the material under one-step loading conditions; (3) proposing a fatigue parameter (FP') calculation equation of the material during multi-step loading according to the nonlinear damage accumulation characteristics of the material in a multi-step loading process; and (4) establishing a low-cycle fatigue life prediction model of the metallic material under multi-step loaded asymmetric cyclic stress control conditions, and predicting the fatigue life of the metallic material. According to the method disclosed by the invention, the low-cycle fatigue life of the metallic material under the multi-step loaded asymmetric cyclic stress control conditions can be quickly predicted, thereby providing a theoretical reference for the reliable design and evaluation of parts.

Description

technical field [0001] The invention relates to a method for predicting the life of low-cycle fatigue failure of metal materials under the condition of multi-step loading and asymmetrical stress cycle control. Background technique [0002] Materials / parts are often subjected to cyclic loads during actual service, making fatigue failure one of the main causes of part damage. Especially when the average stress of the metal material / part under cyclic load is not equal to zero, and the load amplitude is constantly changing and large enough (to make the material yield), the plastic strain will continue to accumulate, which seriously reduces the fatigue performance of the material / part . Therefore, to ensure the reliability, durability and safety of such materials / parts during use, the nonlinear fatigue damage accumulation characteristics of materials / parts must be considered in fatigue design and safety assessment. In the actual service process, most of the loads on materials / p...

AI Technical Summary

Problems solved by technology

Therefore, if the characteristics of material nonlinear fatigue damage accumulation are not fully considered, as well as the impact of the previous loading step on the subsequent loading step, there will be a large error between the predicted results and the actual situation, which directly leads to unreliable life evaluation results.

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