Modelling of Viscoelastic Behaviour of Plates

The behaviour of viscoelastic plates can be described by several engineering theories, based on different assumptions and theoretical conceptions. One of them — the direct approach — is used in this paper to modelize the viscoelastic behaviour of plates. This theory is physically and mathematically correct, but there are other problems, especially the identification of the effective properties in the constitutive equations. The paper deals with a Timoshenko-Reissner-Mindlin type theory, so the main problem is the determination of the classical-plate-properties for stretching, plane shear, bending and torsion and the properties for transverse shear. It is shown by a simple analytical method, that all properties can be found out for viscoelastic plates without any restrictions for the distribution of the material properties in the thickness (symmetric, unsymmetric) and the linear-viscoelastic behaviour (differential or integral relations, complex moduli). The proposed theory is suitable for homogeneous and inhomogeneous (e.g. laminated) plates. For some special cases there are given examples.