Modeling of interfacial crack propagation and kinking in sandwich panels

Abstract The paper presents an analytical model for the nucleation, propagation, and kinking of cracks in sandwich panels. The analytical approach adopts the variational principle of minimum of the total potential energy and it is based on cohesive interface modeling. The mathematical modeling considers two face sheets, a core layer, and an interfacial core-face sheet crack that can kink into the core and form a diagonal shear crack. This phenomenon, which has been observed in experiments, divides the core into two bodies. The core is therefore modeled using such two body approach. Three interfaces are introduced between the four components and appropriate interfacial laws are used to describe the interfacial phenomenon. The First-Order Shear Deformation Theory with geometrically nonlinear kinematic relations is adopted for the face sheets. The two core layers use linear geometrical relations and assume the high order polynomial displacement fields of the Extended High-Order Sandwich Panel Theory. Linear elastic laws are considered for the two face sheets and the core. The model is validated through a comparison with experimental observations of pre-cracked Double Cantilever Beam sandwich specimens that show a diversity of crack paths. The comparison and the quantitative investigation explore the capabilities and the limitations of the approach and shed light on the nucleation, debonding, and kinking phenomena in soft-core sandwich panels.