ABSTRACT
In the middle of the nineteenth century failures were observed in bridges and railway components that were subjected to repeated loading. Because the loading was such that statically it would pose no problem, it was accepted very soon that the failures were a consequence of the cyclic nature of the loading. A complicating factor was that most failures occurred without any obvious warning. The problem was defined as metal fatigue, which was considered as a fracture phenomenon caused by repeated or cyclic loading. A rigorous definition of metal fatigue is difficult. In reference 1 it is defined as: “Failure of a metal under a repeated or otherwise varying load which never reaches a level sufficient to cause failure in a single application”.
