A tribute to Claude Bathias - Highlights of his pioneering work in Gigacycle Fatigue

Current fundamental academic research in the field of Gigacycle Fatigue, now frequently referred to as Very High Cycle Fatigue (VHCF), is strongly related to the pioneering work of Professor Claude Bathias during the last two decades. Claude Bathias passed away in April 2015. In the present paper, dedicated to his memory, his most important contributions in conducting and initiating fatigue studies in the area of Gigacycle Fatigue are highlighted. In light of what is known today about the details of fatigue behaviour in the range of up to 1010 cycles and more, the pivotal role of Claude Bathias cannot be overestimated. He was among the first to demonstrate, in painstaking ultrasonic fatigue studies, that a fatigue limit in the traditional sense does not exist in the Gigacycle regime. In his subsequent work on different materials, he substantiated his earlier findings experimentally and, in close collaboration with Paul Paris, quantitatively described the mechanisms of subsurface and surface VHCF failures, originating from inclusions. Together they showed that, in the VHCF range, most of the fatigue life is spent in crack initiation and not in propagation. Claude Bathias' work stimulated worldwide research and was instrumental in the emergence and development of the current new field of Very High Cycle Fatigue.