An overview on experimental investigation on variable amplitude fatigue crack growth rule

An overview of the present state of the art is carried out for the experimental study of the variable amplitude fatigue problem in the last 10 years.The summary is divided into six categories: overload(underload) effects on fatigue crack growth;the combination effects of overloads and underloads;the role of baseline load;the effects of magnitude and length of block loads;the influence pattern specimen and the behavior of small stress,etc.Through this overview,some former conclusions were further confirmed while some previous conclusions about fatigue crack growth rule were found incomplete.The general idea for developing a new model of fatigue crack growth is proposed.