A Comparative Study of Two State-Variable Constitutive Theories

Direct quantitative comparisons are drawn between the predictions of two state-variable constitutive theories, that of Hart and a recently-proposed theory due to Robinson, for a number of simple uniaxial load histories. The predictions of the two theories agree well in relaxation, constant strain-rate, and constant stress creep simulations. However, substantial differences may be noted in simulations involving more complex loading histories. These differences are discussed within the context of the structure of the theories and comparisons are drawn with real material behavior.