High-order nonlinear contact effects in the dynamic behavior of delaminated sandwich panels with a flexible core

The nonlinear dynamic behavior of delaminated sandwich panels with a flexible core is studied. A general analytical model that accounts for the real contact characteristics of the delaminated interface is developed. The analysis characterizes the influence of the contact phenomenon on the dynamic behavior of the sandwich structure and compares them to simplified models in which the contact conditions at the delaminated interface are assumed a priori. The dynamic model uses the high-order sandwich panel theory (HSAPT) that takes into account the flexibility of the core and considers the geometrically nonlinear effects of the face-sheets as well as the nonlinearity associated with the real contact characteristics of the delaminated surfaces. The dynamic governing equations, boundary conditions, and continuity requirements are derived through the Hamilton principle. The formulation yields a set of coupled nonlinear partial differential equations. The solution in time is based on the Newmark method of integration, and the solution in space uses the Multiple Shooting method combined with a Newton–Raphson iterative scheme. Numerical results that reveal the influence of the contact characteristics on the dynamic response of a sandwich panel are presented. In addition, the results are compared with finite element analysis, and with the simplified models. The study reveals the influence of the real contact phenomenon on the linear and nonlinear response and highlights its role in the dynamic response of the sandwich panel.