Regular and singular metis finite element models for delamination in composite laminates

The modeling and the experimental characterization of the delamination phenomenon become an important field of design and analysis of advanced composite materials and structures. It is one of the most frequently encountered types of fracture in composite laminates due to high stress concentration at the tip of delamination crack.The present paper uses the regular and singular “metis” finite element models to solve the delamination problem in composite laminate structures. A special class of hybrid finite element named “metis element” (mongrel element) which assures the monotone convergence was proposed by Nguyen Dang Hung [On the monotony and the convergence of a special class of hybrid finite element: the mongrel element, in: S. Nemat-Nasser (Ed.), Variational Methods in Mechanics of Solids, Pergamon, Oxford, 1978; Sur un class particulière d’éléments finis hybrides: les éléments métis, in: Proceeding of International Congress on Numerical Methods for Engineering—GAMNI, Dunod, Paris, 1979, pp. 53–63]. The three stress intensity factors (KI,KII,KIII)(KI,KII,KIII) that characterize the toughness of the structure are calculated. A solution is also considered by the calculation of the energy release rates for delamination crack. Results for delamination problem in composite laminates under axial extension are presented and compared to other studies.