Surface Fatigue Crack Propagation Behavior in a Residual Stress Field : (Fatigue Crack Growth Law and Evaluation of Fatigue Crack Propagation Rate)

概要

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The fatigue life of plain carbon steel with residual stress was studied with special reference to the initiation and the propagation of surface fatigue cracks. Tensile residual stresses have no significant influence on crack initiation lives, but increased the fatigue crack propagation rate for surface fatigue cracks. The propagation rate of a surface fatigue crack was controlled by the parameter {(ΔK)^<0.5>(K_<max>)^<0.5>} in which ΔK and K_<max> were, respectively, the stress intensity factor range and stress intensity factor calculated from the maximum stress distribution containing residual stress measured at the stress cycles of the initiation of surface cracks. This parameter also served to help understand surface fatigue crack shape in a residual stress field. Finally, the equation of (ΔK)^p(K_<max>)^q=K_<max>-p・K_<min> was derived under the condition of both p+q=1 and the minimum stress intensity factor |K_<min>|<K_<max>, which enabled us to discuss the effects of K_<min> (<0) on fatigue crack propagation from the mechanical behavior of the plastically deformed layer left in the wake of the advancing crack.
一般社団法人日本機械学会の論文
1989-07-15