Analytical models of the S-N curve based on the hardness of the material

To calculate fatigue life in high-cycle region, the S-N characteristics for the material or construction element (depending on the calculation model employed) must be obtained. Due to this, analytical models are used for estimating the S-N fatigue curve. Since these methods bear significant error, hybrid models based on experimental data from hardness measurements were developed. Such evaluation is easy to perform, quick, and, most importantly, is a non-destructive examination. The paper presents two models for evaluating high-cycle fatigue characteristics, one of which is an own model. Both of these approaches are based on hardness measurement, and employ the relationship between hardness and tensile strength & fatigue limit. The described models were verified on experimental data for several construction materials. Tests were performed on smooth samples, and - for two materials - on notched samples. Moreover, literature data were also used for expanding the verification performed. The characteristics obtained indicate that the estimation of fatigue life for construction steel may be deemed as satisfactory. For the aluminum alloys and stainless steel, on the other hand, the estimation error is significant. (C) 2017 The Authors. Published by Elsevier B.V.