On the Fatigue Life of Single Spot-Welded Joint under 2-Steps Repeating Load

Comparison of Results for Mild Steel with Ones for High Strengh Steel

Abstract

This paper deals with an effect of the load hysteresis on the fatigue life of single spot-welded joint specimen of tensile-shear type for mild steel (SPCC) and high strength steel (HT50) of 0.8 mm in thickness under 2-steps repeating load. Main results obtained are summarized as follows:
(1) The fatigue life for SPCC is generally longer than one for HT50 under usual constant amplitude repeating load, but it is possible that the fatigue life for HT50 is very longer than one for SPCC under the specific repeating load condition.
(2) It becomes clear that fatigue life is considerably influenced according to mechanical properties of spot welds, and fatigue damage due to each load of 2-steps repeating load is not independent each other and can not be discussed without considerations on the hysteresis effect of each load.