Effects of welding residual stresses on the vibration fatigue life of a ship's shock absorption support.

Abstract The shock absorption support of a ship is a type of welding structure for reducing vibrations. In this paper, the vibration modal and frequency responses are first analysed using the finite element method, which is helpful to obtain exciting loads and the high stress areas of the support. Then, the vibration fatigue life of the support is analysed according to the power spectral density method and Miner linear cumulative damage theory. Based on the experimentally measured welding residual stresses of the support, the S – N curves are modified. The vibration fatigue life of the support is then calculated considering the welding residual stresses, and the key areas prone to cause vibration-fatigue damage are obtained. Finally, by improving the local structure of these key areas, the vibration fatigue strength of the support is increased. The results show that the vibration fatigue failure of the ship's shock absorption support usually occurs at the places where the structure suffers from larger stresses, defects, or stress concentrations. The welding residual stresses greatly influence the vibration fatigue of the support. Consequently, the welding residual stresses must be minimized or eliminated at the key areas of the support. [ABSTRACT FROM AUTHOR]