Analysis on Fatigue Life under Random Overloads with Ductile Fracture Mode Using Computer Simulations

Abstract

Probabilistic properties associated with residual life against fatigue failure under random overloads with retardation phenomenon are investigated through computer simulations, where ductile fracture mode is simultaneously taken into analysis. First, based upon a fatigue crack growth model under plural overloads proposed by one of the authors, a system of random differential equations is formulated under random overloads. Next, the so-called reset function, which describes a size of a newly created yielding zone near crack tip by an overload, is newly proposed for steel materials. Based upon the bi-modal approach for failure occurrence against random overloads, in which both a fatigue failure mode and a ductile failure mode are taken into account, the residual life distribution for each failure mode is numerically estimated through computer simulations. Finally, residual life probability distribution function of a cracked component is numerically shown under two failure modes.