Methods of representing the properties of viscoelastic materials
Introduction. In a recent paper1 it has been shown that the solution of the first and second boundary value problem for linear viscoelastic media can be obtained in two steps requiring (a) the solution of an equivalent problem for a perfectly elastic medium, and (b) the determination of the response of the viscoelastic material to an applied shearing stress (or shearing strain) which is a given function of time. The study of the behaviour of viscoelastic materials in pure shear is accordingly seen to be of particular importance. To coordinate various manners of describing this behaviour is the purpose of the present paper. From the mathematical point of view the behaviour of a viscoelastic material in pure shear is represented by a differential relation between the shear stress 5 and the shearing strain e. We may write this relation in the form