Interaction Between Interlaminar and Intralaminar Damage in Fiber-Reinforced Composite Laminates

The interaction between interlaminar and intralaminar damage mechanisms, which may notably affect the structural behavior of fiber reinforced polymeric composites, is investigated. The theoretical model is consistent with an approach based on a thermodynamic framework and the internal variable method, in which specific variables are introduced to predict both in-plane and out-of-plane damage mechanisms. In particular, the damage formulation refers to both Continuum Damage Mechanics and Fracture Mechanics approaches to predict homogenized distributed microcraks and interfacial delamination processes, respectively. The laminate description is based on the use of the first-order shear deformable laminate plate theory and the interface methodology, leading to a satisfactory accuracy in the energy release rate mode mix calculation and low computational costs. The numerical modeling is based on a finite element approach, in which proper integration procedures have been considered to solve nonlinearities involved by the interlaminar and intralaminar damage modes. Numerical examples devoted to multidirectional laminate have been proposed to evaluate the interactions between intralaminar and interlaminar damage mechanisms with respect to both energy release rate prediction and crack growth behavior, by calculating energy release rate distribution along the crack front.