A constitutive equation for nonlinear viscoelasticity is used to model the mechanical response of solid polymers such as polycarbonate. The nonlinearity arises from a reduced time variable which causes stress relaxation to occur faster as strain increases. This constitutive equation is used to study the consequences of the interaction of the acceleration of stress relaxation with strain and the spatial variation of strain within the context of the structural theory of beams undergoing small displacements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41706/1/707_2005_Article_BF01182510.pd