The determination of creep constants from stress-relaxation measurements in bending and torsion

The problem of determining creep constants from stress-relaxation measurements, performed either in torsion or bending, when the material creeps according to the law d(epsilon)/dt = K(sigma-sigmasub(i))sup(n)f(t) is considered. The general equations that describe the stress relaxation behaviour are discussed and a procedure is given to extract the creep parameters from the stress-relaxation data. Finally, the results are applied to some in-pile stress-relaxation measurements reported in the literature. (Auth.)