Fatigue Strength Assessment of a Ship Structures using the Influence Coefficient Concept and Spectral Analysis Technique

영향계수법과 스펙트럼 해석법을 이용한 선체의 피로강도평가

The up-to-date fatigue strength assessment system for ship structures was developed based on the spectral analysis method and numerical calculation for a membrane type LNG carrier was carried out to verify the effectiveness of the developed system. The wave induced loads acting on the ship's hull were calculated based on strip theory. And introducing the concept of influence factor and 3-D fine mesh structural analysis, direct calculation of long-term distribution of wave induced stress components was realized. Using the derived long term distribution of stress components and Miner-Parmgren's linear damage accumulation rule, fatigue strength of structural components were investigated.

본 연구에서는 스펙트럼 해석법에 기초한 새로운 개념의 정밀한 선체구조 피로강도평가 시스템을 개발하였으며 membrane 방식 LNG 운반선을 대상으로 하여 수치계산을 수행함으로써 그 효용성을 검증하였다. 선체에 작용하는 파랑하중을 스트립 이론으로 직접계산하고 3차원 정밀 구조해석과 영향계수 개념을 바탕으로 Miner 법칙에 의한 누적손상도를 계산하여 설계기준과 비교, 검토하였다.