Delamination Analysis for Laminated Composites. I: Fundamentals

Analytical models for the delamination of a class of composite laminates are developed. Two approaches are used in deriving the governing equations. The first approach follows a refined engineering bending theory that stems from the premise that the statically equivalent stresses obtained from classical theory can be used to estimate the strains ignored in the classical theory. The second follows a modified Donnell approach in which the stresses obtained from the classical engineering theory are improved by adding a series of corrections. These corrections are determined by satisfying the stress equilibrium and compatibility conditions of two‐dimensional elasticity theory. A comparison of the derived governing equations is provided in order to assess the consistency and accuracy of the engineering approach. The deformation modes associated with each model are identified. Interlaminar stresses predicted by the developed models for a quasi‐isotropic double cracked‐lap‐shear laminate are compared with finite‐element results.