Modelling of perfectly and weakly bonded laminated plates and shallow shells

An model suitable for the accurate stress analysis of laminated plates and shallow shells with perfectly or weakly bonded layers is developed within the framework of the theory of elasticity. A six-degrees-of-freedom displacement field is employed and both the transverse deformation and the interfacial bonding conditions are accounted for by means of a set of three shape functions of the transverse co-ordinate parameter. These are determined on the basis of three-dimensional elasticity considerations and account for the weak interfacial bonding conditions. The model makes use of only six equations of equilibrium which are obtained variationally. Upon assuming that linearized interfacial constitutive relations describe quite adequately the initial stages of delamination, closed-form solutions are obtained for simply supported rectangular plates and shell panels made of specially orthotropic layers. The effects of opening delamination and shear slip are discussed and some interesting observatons are made through the numerical results obtained.