Dynamic interfacial debonding in sandwich panels

A nonlinear dynamic analytical approach is formulated aiming to investigate the dynamic interfacial debonding mechanism in sandwich panels. The approach is derived using the variational principle of virtual work and it incorporates the Extended High-Order Sandwich Panel Theory with a cohesive interface modeling for the interfaces between the face sheets and the core. The model adopts the first-order shear deformation theory kinematic assumptions for the face sheets along with a geometrically nonlinear behavior. The high-order small deformations kinematic assumptions that account for out-of-plane compressibility are considered for the core layer. The two interfaces link the three components of the panel together and the nonlinear traction-displacement laws introduce the interfacial nonlinearity into the model. The model considers dynamic effects in order to assess the influence of the inertial terms on the interfacial debonding mechanism and to examine the coupling between the two. The results of the dynamic analysis are compared with results of a static analysis for two cases: a sandwich panel with a pre-existing delamination subjected to an end-shortening loading and an intact sandwich panel subjected to three-point-bending. In the second case, the interfacial debonding triggers a dynamic response that substantially affects the structural behavior. The dynamic results, the assessment of the time scales of the process, and the comparison with the static results shed light on the significance of the dynamic nature of the interfacial debonding failure mechanism.