C0 plate element for delamination damage analysis, based on a zig-zag model and strain energy updating

Abstract

In this paper, a C 0 eight-node plate element for analysis of global/local effects in sandwich and composite laminates is developed, based on a piecewise cubic zig-zag model. Characteristic feature, it is developed upon the kinematics and nodal degrees of freedom of a first-order, shear deformation parent plate element wherein strain energy is updated to incorporate the energy contributions brought by the zig-zag model. This allows to overcome the C 1 continuity requirement resulting from enforcement of the transverse shear stress continuity at the interfaces. The element is implemented in a finite element code for damage simulation and used for investigating low velocity impact-induced damage in laminated composite panels with I and Ω stiffeners. The impact load is computed by the Hertz's contact law, where the dynamic equations are integrated by the Newmark's algorithm. Local damage extent and position across the thickness are predicted using several classical semi-empirical strength-based criteria, while degradation is simulated by reducing the stiffness of damaged plies. The damage extent and thickness position by present finite element simulation appears rather accurate when confronted with ultrasonic inspection and cost effective.