A Study on the Design Guidance for Low Cycle Fatigue in Ship Structure

초록

Fatigue tests in high stress and low cycle regime were carried out with the base metal as well as welded joints to unveil the fatigue performances in this new region. Cyclic and monotonic stress-strain curves on the base metal and weld metal were obtained through lab test. Base materials ranging from mild steel to high tensile steel and weld metal out of welded joint where conven-tional welding procedure was used according to the shipyard practice was employed in the test. Efforts were also made to accurately estimate the notch stress-strain state since the elasto-plastic stress-strain state at the notch root of the welded joint is important in low cycle fatigue problems. Well-known Neuber’s rule was used to calculate the elasto-plastic notch stress-strain state of partially penetrated fillet welded joint loaded in trans-verse direction. Also, nonlinear elasto-plastic finite element analysis was carried out to find detail stress-strain behavior at notch root taking into account the effect of material inhomogeneity.