Experimental investigation of overload effects on fatigue crack growth behaviour of 7050‐T7451 aluminium alloy

Abstract

AbstractFatigue damage and fracture of metals are the major failure modes of mechanical structures. Studying the fatigue crack growth (FCG) behaviour under overload effects can better explain the loading interactions and develop more accurate FCG prediction models. This research innovatively designed and established the experimental system that is suitable for FCG test under variable amplitude loading (VAL). Systematically, FCG experiments were carried out by introducing single tensile overload, single compressive overload and tensile/compressive sequential overload in constant amplitude loading (CAL). The effects of overload ratio, stress intensity factor (SIF) range ∆K and tensile/compressive overload sequence on the FCG behaviour of 7050‐T7451 aluminium alloy were comparatively analysed. The retardation or acceleration effects on the macro FCG and the micro crack deflection, crack bifurcation and particle falling effects of different overloads as well as their interactions were revealed.