| A general framework has been developed to investigate dynamic stability of composite plates, including delamination, subject to dynamic and static compressive loads.; A variationally consistent, higher-order shear deformation theory has been used to model the displacement field. The in-plane displacements are modeled using cubic variations through the thickness, and the out-of-plane displacement is assumed independent of plate thickness. The linear strain-displacement relationship corresponding to the small deformation assumption is used first. Both transverse shear and rotary inertia effects are taken into account.; The mathematical model is implemented using the finite element approach. Delamination is modeled using two multi-point constraint techniques. The principal and secondary instability regions are determined using both first and second order approximations. The developed procedure is validated by comparisons of natural frequencies and critical buckling load with the available analytical and experimental data. The natural frequencies are also compared with results obtained using a three-dimensional, commercial finite element code. Good correlation is observed. The natural frequencies, the critical buckling load, and the instability regions, obtained using the higher-order theory, are also compared with those obtained using the classical laminate plate theory and the first-order shear deformation theory. Significant deviations are observed for thick configurations due to increase in shear deformation.; The impact of delamination on the natural frequencies, critical buckling load, and instability regions is investigated by varying the placement and size of the delamination. As expected, the presence of delamination lowers the natural frequencies and critical buckling load. The instability regions are also shifted to lower parametric resonance frequencies. The extent of the instability regions is also affected by delamination.; Parametric studies are also conducted to investigate the influence of boundary conditions, plate thickness, static pre-stress, and stacking sequence on the instability regions.; Finally, the importance of geometric nonlinearity is studied by introducing von Kármán nonlinearity. Natural frequency results are obtained for square isotropic and cross-ply laminates and compared with available analytical data. The effect of geometric nonlinearity on the principal instability region is also investigated for cross-ply laminates. |
