A unified equation for creep-fatigue

"Pure fatigue" is a special case of creep-fatigue; and the Coffin-Manson equation, Delta epsilon(p) = C-o(N-beta o), is a special case of the general creep-fatigue equation, which is proposed to take the form: Delta epsilon(p) = C(o)s(sigma)c(T,f)N--beta ob(T,N-f). The functions, s(sigma), c(T,f) and b(T, f), embody the stress-time-temperature characteristic of creep. At the reference condition when creep is dormant, s(sigma) = c(T,f)= b(T,f) = 1, the Coffin-Manson equation is recovered. At the extreme condition when c(T,f) = 0, creep-rupture occurs without fatigue. In between these two extreme conditions whence 0 <= c(T,f) <= 1, creep-fatigue prevails. (C) 2014 Elsevier Ltd. All rights reserved.