Formalisation and experimental validation of a novel design methodology to estimate finite lifetime under fretting fatigue loading

微动疲劳是指在两种材料之间的接触区域发生的损伤，并且与小的振荡运动和远程循环力的同时作用有关。在服役时变载荷作用下的金属材料中，考虑到名义载荷历史的特点，与无微动时相比，微动会导致疲劳损伤的增加。微动疲劳一直是结构工程师关注的问题，因为它可以显着降低重要结构部件的使用寿命，例如，螺纹管连接，燃气/蒸汽涡轮机中的叶片盘附件，以及航空发动机花键联轴器。通过利用“缺口模拟”的概念，本研究的目的是正式和验证一种新的方法，专门设计来估计变幅（VA）微动疲劳下的寿命，直接评估当地的线弹性多轴应力场损坏的材料alin附近的接触区域。

Fretting fatigue refers to the damage occurring at contact area between two materials and is associated with the simultaneous action of a small oscillatory motion and a remote cyclic force. In metallic materials undergoing in-service time-variable loading, given the features of the nominal load history, fretting leads to an increase of fatigue damage as compared with that in the absence of fretting. Fretting fatigue is always a matter of concern to structural engineers since it can remarkably reduce the in-service lifetime of important structural parts such as, for instance, threaded pipe connections, bladedisk attachments in gas/steam turbines, and aero-engine splined couplings. By making use of the "notch analogue" concept, the aim of this research is to formalise and validate a novel methodology specifically devised to estimate lifetime under variable amplitude (VA) fretting fatigue by directly assessing the local linear-elastic multiaxial stress fields damaging the materialin the vicinity of the contact region.