含缺口试件疲劳全寿命预测一种建议的方法

传统的研究含缺口构件的疲劳的方法是将疲劳启裂和疲劳裂纹扩展两个过程完全独立起来,用不同的方法来模拟,相互间并没有定量的关系。本文是基于最新发展的多轴疲劳损伤理论,建立了一种适用于各种载荷条件下的疲劳启裂和裂纹扩展的普适方法。根据从弹塑性分析中得到的应力应变,确定疲劳损伤模型,建立能够预测疲劳启裂、裂纹扩展速率和扩展方向的新方法。整个模拟可以分为两步:弹-塑性应力分析得到材料的应力应变分布;再运用一个通用的疲劳准则预测疲劳裂纹启裂和裂纹扩展。通过对1070号钢含缺口试件的疲劳全寿命预测,得到了与实验非常吻合的模拟结果。

A Suggested Method for Fatigue Total Life Prediction of Notched Specimen

Traditional methods for fatigue total life prediction of notched specimen model fatigue process with completely different methods for two stages of crack nucleation and growth of cracks to final failure with no quantitative relationships between them.Based on the new developing multiaxial fatigue damage theory,current work was aimed at a robust approach to predicting fatigue life from crack initiation to final fracture.Elasticplastic stress analysis was conducted to obtain the detailed stress strain responses and get the fatigue model,and predict the crack initiation and crack propagation and the direction of crack propagation.The approach consists of two steps.Elastic-plastic stress analysis was conducted to obtain the detailed stress strain responses.A general fatigue criterion was used to predict both fatigue crack nucleation and growth.Notched specimens made of 1070 steel were experimentally tested from crack initiation till fracture.The predicted fatigue lives are in excellent agreement with the experimental observations.