Abstract

The parameters concerning the interface debonding between fiber and matrix have been of great scientific interest in the field of composite materials. The study of this phenomenon has applications on both the determination of the failure conditions of a composite in microscale, as well as offering the possibility of exploring the reusability of fiber reinforced polymers through the reclamation of the individual materials that consist the composite. The focus of the present study is the effect of combined local heating and axial, pull-out load application, on the fiber/matrix debonding. As a result of these conditions, the adhesion of the fiber onto the thermoplastic matrix is degraded, resulting in controllable fiber/matrix separation which facilitates the above mentioned recycling purposes. The separation mechanism is studied numerically at different temperatures, utilizing the Virtual Crack Closure Technique (VCCT) to derive the energy release rates (ERR) that characterize the crack propagation, as well as the Benzeggagh ? Kennane fracture criterion to define the critical ERR values depending on the thermomechanical properties of the materials involved. Those properties? values are exploited to discuss optimal material design in an effort to enhance interface debonding performance. The numerical model is solved with finite element method in a three-dimensional geometry concept, as a means to investigate the effect of the presence of neighboring fibers, in the separation mechanism. Crack initiation is approached with a pre-meshed crack, in accordance with a suggested failure criterion, after relevant failure criteria evaluation for this specific application. Crack propagation is studied with the aid of interface cohesive elements, whose behavior ultimately determines the debonding. The simulation results contribute in the evaluation of physical parameters like initial crack length, strain rate, loading conditions as well as model parameters like the order of finite elements used and the appropriateness of the debonding theory applied, for the determination of useful post-processed quantities.