Damage Mechanics Analysis of Matrix Effects in Notched Laminates

Abstract

The main objective of this study was to investigate the matrix influence on the fracture behavior of carbon/epoxy three-point bend specimens. The matrices investigated were a brittle Fiberite 1034 and a more ductile Fiberdux 914C epoxy matrix. For the analysis of strength and load versus displacement behavior of the specimens, a damage zone model (DZM) was used. The damage is represented by a Dugdale/Barenblatt cohesive zone, where the cohesive stresses are assumed to decrease linearly with an increased crack opening. Excellent agreement is obtained between predicted and measured fracture loads of the specimens. Also the nonlinear load versus displacement curves are accurately reproduced by the analysis. The present model is compared with previous models, such as the inherent flaw and the point stress criteria. The damage zone extension in the brittle and ductile matrix specimens was studied and compared with the DZM calculations, as an attempt to explain the difference in fracture behavior between the brittle and ductile matrix specimens.