Evaluating the Accumulated Interfacial Damage in Carbon Fiber/Epoxy Composite Laminates

Abstract

Abstract The objective of this study was to analytically and experimentally evaluate the effects of interfacial damage in the forms of voids and interfacial cracking on the overall dynamic mechanical response of composites. A micro–mechanics model incorporating a nonuniform interphase and a finite element model with a damaged interphase were employed. Four-point-bending fatigue tests and torsion fatigue tests were conducted on carbon fiber/epoxy laminates to initiate interfacial damage. The fatigue tests were periodically stopped and dynamic mechanical measurements were made after each segment of fatigue loading. The results indicated that the interfacial damage caused stiffness degradation and damping increase in the interphase and thus the composite materials.