Cycle-dependent creep under random loading

An important aspect of the response of a metal subjected to cyclic loading and a superimposed mean load is its capacity for progressive strain accumulation. In the present investigation, random loading with tensile mean loads is applied to carbon-steel specimens. The cycle-dependent creep properties are described and a phenomenological approach to predict the number of cycles to ductile failure is proposed. At lower stress values, the fatigue-type brittle failure occurs. To predict the failure lives, the familiar fatigue-damage theory is modified for the case of random loading, and the effect of mean stress is included.