ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 4 October 2004
Page Count: 15

Study on Fatigue Design Loads for Ships Based on Crack Growth Analysis

Tomita, Y
Professor, Research Assistant, Associate Professor, and Graduate Students, Graduate School of Engineering, Osaka University, Suita, Osaka,

Hashimoto, K
Professor, Research Assistant, Associate Professor, and Graduate Students, Graduate School of Engineering, Osaka University, Suita, Osaka,

Osawa, N
Professor, Research Assistant, Associate Professor, and Graduate Students, Graduate School of Engineering, Osaka University, Suita, Osaka,

Terai, K
Professor, Research Assistant, Associate Professor, and Graduate Students, Graduate School of Engineering, Osaka University, Suita, Osaka,

Wang, Y
Professor, Research Assistant, Associate Professor, and Graduate Students, Graduate School of Engineering, Osaka University, Suita, Osaka,

(Received 19 April 2002; accepted 17 July 2003)

Abstract

Although ship structural members are designed to survive 20 years, fatigue crack damage still occurs, often starting very early in the ship's life, with some cracks growing quickly to considerable size. The primary factor causing variability is the sequence of the variable amplitude load cycle, and the others are welding irregularities on the weld toe and variations in mechanical properties in the material. In this paper, the load sequence effect on fatigue life variability is examined by the use of a fatigue design procedure proposed by the authors. It is found that the fatigue lives of ship structural members vary from several months to 20 years, strongly dependent on the sequence of sea state which ships encounter during ocean-going service. The worst possible loading sequence is elucidated for the fatigue life of the ship's hull. Sensitivity study of fatigue life is discussed.

Keywords:
fatigue design, crack growth analysis, storm model

Paper ID: JAI19046
DOI: 10.1520/JAI19046
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