Stress relaxation and hysteresis at various strain rates

Abstract

SynopsisApplying the Boltzmann superposition principle on a generalized Maxwell model, an analysis of the relations between extension, relaxation, and hysteresis is presented, which shows that any one of these three can be calculated from the other two. It is shown that the relaxation modulus does not vary with strain rate when time is measured from the start of extension, except in the early period of relaxation. It is demonstrated that the first derivative of the ratio of extension stress-strain rate with respect to time is the limiting value of the relaxatjon modulus. The short-time end of relaxation modulustime curve can be readily extended for several decades of logarithm of time without resorting to the temperature effect. The results obtained from the treatment of experimental data on polyisobutylene verify the theoretical deductions, which may also be considered as an additional explicit proof of the Boltemann superposition principle.