Effect of the Pre-strain on the Fatigue Strength of a Bolt Steel

Fatigue strength of a pre-strained bolt steel, SCM 3, has been investigated in relation to the effects of the amount of pre-strain and the additional straining of the pre-strained specimen in the course of the fatigue process and the influence of the time when the secondary strain was applied. This simulated re-fastening the relaxed bolts commonly encountered in service. Furthermore, differing from the current investigations, where average diametral strain is used, actual surface strain which was obtained by FEM analysis was employed considering the fact that the fatigue damage is concentrated on the specimen surface