Low Cycle Fatigue Analysis of Marine Structures

Abstract

There are situations where a marine structure is subjected to stress cycles of such large magnitude that small, but significant, parts of the structural component in question experiences cyclic plasticity. Welded joints are particularly vulnerable because of high local stress concentrations. Fatigue caused by oscillating strain in the plastic range is called “low cycle fatigue”. Cycles to failure are typically below 104. Traditional welded joint S-N curves do not describe the fatigue strength in the low cycle region (< 104 number of cycles). Typical Class Society Rules do not directly address the low cycle fatigue problem. It is therefore the objective of this paper to present a credible fatigue damage prediction method of welded joints in the low cycle fatigue regime.

Effect of fatigue strain range on properties of high-strength structural steel

“…Therefore, fatigue damage accumulates over the service life of the ship. Dexter and Pilarski [5], Gu and Moan [9], Huther et al [11], Kim et al [13], and Wang et al [17] have acknowledged the occurrence of fatigue damage in welded connections and have described it to be the main failure mode in current ship structures.…”

“…Many researchers have expressed concerns regarding the damage caused by fatigue loads and its influence on the ultimate load carrying capacity and ductility of steel; especially for aged ship structures [5,7,16,17]. It is important to understand that examples as that shown in Fig.…”

Technologies and Materials Issues Related to Naval and Ocean Engineering

“…Reference [27] presents a suitable reasoning to address this low cycle condition. The strain indicator takes the elastic and plastic regimes together, by summing up each contribution.…”