Delamination behavior of spliced Fiber Metal Laminates. Part 2. Numerical investigation

Abstract

A strategy is presented for the simulation of delamination in Fiber Metal Laminates. These composite materials are made of aluminum layers which are connected by either aramid or glass fiber reinforced prepreg layers. They are modeled using solid-like shell elements in the three-dimensional case and plane stress elements for the two-dimensional calculations. Plasticity in the aluminum is modeled with the von Mises yield criterion. Delamination is modeled by interface elements which are inserted into the FE-mesh at the interface between material layers. For the description of the delamination in the interface a plasticity based material model is considered. It is derived from a Hoffman-like yield function which bounds all states of stress in the interface. When the state of stress in a material point of the interface reaches the yield surface softening occurs. Then, the stresses are reduced to zero while the inelastic deformations grow significantly. To describe the initialization of mixed-mode delamination the strengths of the interface for tension, compression and the two shear components are utilized. The growth of the delamination is controlled by the fracture toughness of the interface. In the limiting case when the energy dissipated by the inelastic deformations equals the fracture toughness delamination is completed. For a peel specimen the performance of the model is assessed. However, the focus of the paper lies in the comparison of the numerical results with the experimental finding described in Part 1. Hereby, the impact of the fiber orientation in the prepreg and the geometry of the structure on the delamination behavior are of special interest.