Cumulative damage of welded high-strength steels under uniaxial constant and variable amplitude loading

The paper presents the calculation of cumulative damage for two types of welded joints (butt weld and transverse stiffeners) of four steels (medium to high): S355N, S355M, S690Q and S960Q. This calculation is based on experimental data obtained under axial and bending loading with constant and variable amplitudes (Gauss and Gauss with overload spectrum). The experiments were performed under fully reversed (R = -1) and under pulsating (R = 0) loading. The fatigue life is calculated using the modifications of the Palmgren-Miner-Original rule, according to the Palmgren-Miner-Elementary as well as Haibach. The fatigue life doesn´t depend on the materials strength. For the investigated welded specimens, mean stresses didn´t influence the fatigue life due to already existing high tensile residual stresses. For fatigue life calculations the real damage sum Dreal = 0,3 is suggested.