THE NONLINEAR RESPONSE OF UNSYMMETRIC MULTILAYERED PLATES USING SMEARED LAMINATE AND LAYERWISE MODELS

A continually growing interest in the response of unsymmetric multilay ered plates is apparent. Analyses were recently completed addressing t he load-deflection behaviour of these plate geometries. The characteri stic feature of the analyses is the use of nonlinear strain-displaceme nt relations. even at low loading levels, in reaction to the large-def lection effect enhanced by the bending-extension and twisting-shearing coupling. Approaches where use is made of Higher Order Shear Deformat ion Theories (HSDT) for predicting global quantities, such as deflecti ons and critical loads, are not found in the open literature. Such mod elling approaches, in particular those of the layerwise type, are rese rved to predict distributions across the thickness. Thus, a further as sessment of the influence of the transverse shear effect on global qua ntities should be required. To give some preliminary contributions on this subject, the load-deflection behaviour of a [90(4)/0(4)] cross-pl y plate with pinned edges, subjected to cylindrical bending under unif orm transverse pressure, is investigated. Use is made of the Layerwise Higher Order Shear Deformation Layerwise Theory (RHSD) to serve this purpose. From the numerical results presented, the influence of modell ing is enhanced or reduced, depending on the sign of loading. It is co ncluded that, depending on the loading, boundary conditions and lay-up , higher-order approaches can be used for predicting global quantities in unsymmetric multilayered plates. In order to investigate stability , nonlinear equations are developed where critical points are located under boundary and combined loading conditions which vary during pertu rbation.