engleski

REVIEW OF GAMMA FUNCTIONS IN ACCUMULATED FATIGUE DAMAGE ASSESSMENT OF SHIP STRUCTURES

Palmgren-Miner (P-M) approach is the oldest, simplest and the most frequently applied method for cumulative fatigue damage assessment of ship structures. By assuming Weibull distribution as probability distribution of stress ranges, closed-form P-M expressions for accumulated damage calculation are adopted by Ship Classification Societies. There are several versions of such expressions currently in use and all of them implement various kinds of Gamma functions. Accurate evaluation of Gamma functions is therefore of crucial importance for reliable accumulated damage calculation. However, it is noticed that fatigue rules provides insufficient attention to the precise definition of Gamma functions, causing unnecessary wasting of time and possible mistakes. The present paper gives review of expressions for accumulated damage assessment proposed by major Classification Societies aiming to clarify which kind of Gamma functions are used and how to calculate them efficiently.

fatigue damage; gamma functions; classification societies

nije evidentirano