A discontinuous shell-interface element for delamination analysis of laminated composite structures

This contribution focuses on the delamination phenomenon in a thin structural composite, which represents a major source of degradation during deformation in a composite material. The problem is resolved at a "meso-level", where separate plies are explicitly modelled and connected via interfaces to form a laminate. A recently proposed formulation of the interface, cf. [Int. J. Numer. Methods Engrg. 54 (2002) 473], based on the regularized strong discontinuity concept, is used to model delamination considered as a damage process accompanied by regularized displacement discontinuity development. As to kinematics, since structural composites often can be considered as shells, shell kinematics is adopted for both the continuous and the discontinuous parts of the deformation. The discontinuous mid-surface and director are considered as independent fields from the corresponding continuous ones, whereby incompatible discontinuous modes within the finite element can be avoided. As compared to the other formulations in the literature, where a structural coupling of the layers of plies are normally emphasized, the present shell formulation focus on the consistent incorporation of a discontinuum with a regularized strong discontinuity in the context of shell kinematics. The paper is concluded by a numerical example involving delamination growth in a composite laminate. (C) 2004 Elsevier B.V. All rights reserved.