Finite Element Analysis of Free-Edge Delamination in Laminated CompositeSpecimens

摘要

A mixed-type finite element formulation based on minimization of potential energy, and censuring continuity of displacements as well as tractions, is developed to analyze the free-edge delamination problem in composite laminate coupons under uniform longitudinal strain. In this model, compatible cubic interpolation functions, originally proposed by Felippa for plate bending analysis, were used for defining the displacement field within each element. To ensure traction continuity, the nodal displacement components and their gradients normal to element boundary were transformed to a mixed set of degrees of freedom through appropriate displacement-traction relationships. Thus, for global assembly, the nodal degrees of freedom include interlaminar traction components at the corner nodes, as well as traction components at the mid-side nodes of each element. This ensures continuity of displacement and traction along interelement boundaries as well as across laminate interfaces.