结构金属材料超高周疲劳破坏行为

受传统试验方法的限制,结构材料的疲劳研究范围常限于107周次以内.然而,过去十年出现了一系列意料之外的破坏事件,尤其是对于认为具有明显疲劳极限的钢铁结构部件.因此,对于不同材料达到1010周次的超高周疲劳行为的研究引起了广泛关注,尤其是近年来成为了热点.本文综述了结构金属材料超高周疲劳的研究现状并介绍了其基本方面.主要内容包括:加速疲劳试验方法的发展与应用、超高周疲劳引起的内部断裂的裂纹萌生机制与扩展特征、S-N曲线的形状特点、疲劳极限存在性及其预测、加载频率和环境及表面状况的影响等.在此基础上提出值得进一步研究的一些方向.

UNDERSTANDING FATIGUE FAILURE IN STRUCTURAL METALS IN ULTRA-HIGH CYCLE REGIME

Most experimental studies on fatigue of structural materials are usually limited by conventional testing to lifetimes of 107 cycles or less. However, during the last decade, several unexpected failures have been recorded even for structural components made of ferrous metals, which were assumed to have a distinct fatigue limit. Consequently, there has been a growing interest especially in the recent years in studying ultra-high cycle fatigue up to 1010 cycles in various materials. This paper reviews the state of the art and presents some fundamental aspects on ultra-high cycle fatigue in structural metals. The main contents covered by the paper included: Development of accelerated fatigue testing method and its application, crack initiation and growth mechanisms of internal fracture due to very high cycle fatigue, S-N diagram, fatigue limit and life prediction, frequency and environmental effects, and surface treatments, etc. Future research topics have also been identified.