Damage mechanisms of matrix cracking and interfacial debonding in random fiber composites under dynamic loadings.

摘要

By considering the wide applications of composite materials, it is necessary to have a proper knowledge of dynamic behavior as well as static behavior reflecting the damage in composite materials. Strain rates have significant effects on dynamic behavior in composite materials when they are under dynamic loadings.;In this thesis, a multiscale numerical approach with finite element code ABAQUS is developed to characterize failure criteria to express static and dynamic damage mechanisms of matrix cracking and interfacial debonding under uniaxial tensile loadings for composite materials. The random epoxy/glass composite material is investigated under three strain rates: quasi-static, intermediate and high, corresponding to 10-4, 1 and 200 s-1, respectively. A representative volume element (RVE) of a random glass fiber composite is employed to analyze microscale damage mechanisms of matrix cracking and interfacial debonding, while the associated damage variables are defined and applied in a mesoscale stiffness reduction law. The macroscopic response of the homogenized damage model is investigated using finite element analysis and validated through experiments. The random epoxy/glass composite specimens fail at a smaller strain; there is less matrix cracking but more interfacial debonding accumulated as the strain rate increases. The dynamic simulation results of stress strain response are compared with experimental tests carried out on composite specimens, and a respectable agreement between them under the low strain rate is observed. Finally, a case study of a random glass fiber composite plate containing a central hole subjected to tensile loading is performed to illustrate the applicability of the multiscale damage model.