On the behaviour of viscoelastic solids under multiaxial loads

On the basis of modified Hooke's law for multiaxial stress in viscoelastic solids, threedimensional constitutive equations for strains have been derived. It is shown that after application or removal of triaxial static load, normal and shear strain components vary in course of time proportionally to each other and that in-phase stress components produce in-phase strain components. Harmonic out-of-phase stress as well as multiaxial periodic and stationary random stresses are also considered. The matrix of dynamical flexibility of viscoelastic materials is determined which depends on three material constants (Young modulus, Poisson's ratio and coefficient of viscous damping of normal strain) and load circular frequency.