Fatigue long term deck structural assessment based on dynamic stress response, of a 100000 CBM LPG carrier

Abstract

The purpose of this work is to analyse the fatigue damage at the joint between the main deck structure and the transversal web frame (near x/L=0.6) composed of butt weld plate joints, in order to estimate the initial design ship service life period. The analysis adopts the hot spot approach based on three dimensional finite elements. The stress concentration factor is estimated using a linearization of the calculated longitudinal normal stress and equivalent von Mises stress around the hot spot. Fatigue damage is calculated by Palmgreen – Miner method for the initial ship hull structure, based on the long-term prediction ship dynamic response, using the cumulative damage ratio criterion, for the North Atlantic and World Wide Trade wave significant height histogram. The numerical analyses are carried out for a large double hull LPG Carrier with 230.4 m length between perpendiculars.