Section I—Introduction

Although it is nearly a century since August Wöhler started his classic fatigue tests, we see about us more fatigue testing than ever before. This is, of course, a consequence of the Machine Age in which we are living. New forms of transportation, new automatic production machinery, advances in prime movers such as the gas turbine, all demand better knowledge of materials. In this connection, fatigue of materials is of prime importance because it is a direct mechanism of failure. It has been estimated that over 80 per cent of machine failures are due to fatigue. In fact it was Wöhler's appointment to a commission for studying causes of railway wrecks which led to a study of failures of railway axles and in turn to fatigue testing. As we see it, the most important objective of fatigue testing is to build up basic knowledge which will contribute to the design, construction and maintenance of mechanisms and structures in such a way that they are as free from failures as possible and at the same time are efficient and economical.