Practical Fatigue Strength Diagrams for Compression Springs Based on the FKM-Guideline “Analytic Strength Assessment for Springs“

Abstract

Today’s helical compression springs are designed according to DIN EN 13906-1. The fatigue diagrams contained there are outdated and essential influences on fatigue strength are not taken into account. In order to resolve these circumstances, endurable stresses were calculated with the FKM guideline “Analytic Strength Assessment for Springs and Spring Elements”, which was published in 2020. The application of the included safety concept results in characteristic curves for permissible stresses that are conservative with regard to real test data. Therefore, the new fatigue strength diagrams can be used directly for standard applications. This article gives an overview of the method and accompanying experiments. The presented results enable spring designers to design competitive springs in a shorter time and with less testing effort according to the current state of research.