On the determination of stress intensity factors in ultrasonic fatigue loading

In this paper, stress and modal analysis of an ultrasonic vibration system has been performed by using 3D finite element calculation The stress intensity factors in ultrasonic fatigue crack propagation are evaluated by means of displacement and energy approaches. The particular advantages as well as limitations of the two approaches are discussed. Two types of ultrasonic fatigue loading with different stress ratio are exerted on the specimen. For better comprehension, the operating principle of the ultrasonic fatigue machine and experimental procedures are briefly presented. First the experimental results are given. From comparison the conclusion is formed that the energy approach developed in this study is more accurate, and it merits a particular recommendation. Copyright (C) 1996 Elsevier Science Limited