Constant life diagrams — a historical review

A historical review of the early development of constant life diagrams (variously referred to as Goodman, Smith, Haigh, etc. diagrams) is presented. It is shown that there were two distinct approaches to the formulation of constant life diagrams for fatigue design purposes. The first one was based on Wöhlerʹs fatigue experiments and involved engineering curve fits of the fatigue endurance data. The Launhardt–Weyrauch, Gerber and Johnson formulae are the main representatives of this approach. The second approach is based on the dynamic theory used for bridge design. The Fidler–Goodman formula is an example of this approach. The early proponents of the second approach questioned Wöhlerʹs test results and did not believe that they could be used for design purposes. Finally, the first books on fatigue of metals introduced citation inaccuracies, which were propagated by subsequent authors.