A MULTILAYERED COMPOSITE PLATES FORMULATION

This paper deals with free vibrations analysis of multilayered plates. A set of equations for modelling laminated composite plates has been derived. These dynamic equations of the plate are derived using a higher order shear deformation theory with a displacement field that includes five unknown parameters. Equivalent single layer theories, which are adequate in predicting global characteristics of laminates and have the ability to change a three- dimensional problem to a two-dimensional one will be used. Material properties in the thickness direction for all layers are combined to an equivalent single layer property. The employed theory is based on the same assumptions as the classical and first order shear deformation plate theories, except that the assumption on the straightness and normality of the transverse normal is relaxed. This generalized formulation covers symmetric as well as antisymmetric layer combinations. It is also a general case for classical, first order and previous higher order shear deformation theories. Finally, the governing equations are solved by Ritz method. Geometric factors, stacking pattern, transverse shear effect, in-plane strain and lamination stacking sequence will be compared to classical, first and higher order shear deformation theories.