The purpose of the present book is to study the theoretical investigation the non-linear dynamic behaviour of a Glare 3 hybrid composite panel and elastic rectangular isotropic plates with fully clamped boundary conditions at large deflections. The part II of this book is the study the non-linear free vibration of hybrid composite plates made of a new aircraft structural material called Glare 3 using a new improved approach.This approach is based on a model which has been applied to the non-linear free vibrations of beams and to non-linear free and forced vibrations of rectangular plates. The part III is to study the geometrically nonlinear dynamic behaviour of thin elastic rectangular isotropic plates with fully clamped boundary conditions at large deflections. The geometrical nonlinearity is expressed by the nonlinear strain-displacement relationships of Von Kármán. The model has been obtained using the multi-mode theory based on Hamilton’s principle and spectral analysis. The model is used to determine the effect of the excitation frequency and the applied level of forces on the dynamic response at large vibration amplitudes.