Thermomechanical constitutive model of shape memory polymer

A nonlinear thermomechanical constitutive model of shape memory polymer (SMP) is developed by modifying a linear model. The coefficients in the model are expressed by the single exponential functions of temperature in order to describe the variation in mechanical properties of the material due to the glass transition. The proposed theory expresses well the thermomechanical properties of polyurethane-shape memory polymer, such as shape fixity, shape recovery and recovery stress. The proposed model is useful for design of shape-memory polymer elements. (C) 2001 Elsevier Science Ltd. All rights reserved.