变幅载荷作用下疲劳裂纹扩展研究综述

机械结构主要承受疲劳载荷,工程上尤其承受变幅载荷。本文对目前国内外比较常用的变幅载荷作用下疲劳裂纹扩展的模型理论进行了详细地综合分析,大致包括了塑性诱导闭合理论、裂纹尖端钝化理论和残余压应力理论。目前常用的模型单峰或多峰超载疲劳裂纹扩展寿命的预测结果比较理想,但在高载比以及考虑构件厚度效应时误差往往比较大。所有模型均有其依据的理论、成立的前提条件和适用范围,在实际工程应用中应根据不同的条件选择相应的模型。高载比,裂尖大范围屈服时模型寿命预测的准确度问题是今后重点。本文对读者了解模型的使用范围和简化模型以提高其寿命预测的适用性、方便性和准确度,可以提供借鉴。

Review of Fatigue Crack Propagation under Variable Amplitude Loading

Mechanical structures mainly bear fatigue loading, especially variable amplitude loading in the engineering. In this article, the current frequently-used crack propagation models and theories under variable amplitude loading were analyzed in detail, including induced plastic closure theory, crack tip passivation theory and residual compressive stress theory. The current frequently-used models can obtain relatively accurate results in predicting single or multimodal overload fatigue crack propagation life. But in high load ration and taking the component thickness effects into account, there tend to be big errors. Every model has its own basis of theory, premise condition and application area. In the practical engineering application, proper models should be chosen according to different conditions. The prediction accuracy of the models under high load ration or large scale yielding of crack tip will be emphasized in the future. Based on this paper, the readers can know about the application area of the prediction models and their simplified versions so that proper models can be used to obtain relatively accurate results.