Nonlinear Mechanical Behavior and Fracture Criterion of Unidirectional Fiber Reinfored Plastics

Abstract

The mechanical behavior of the unidirectional fiber reinforced plastics in the nonlinear viscoelastic region was studied on the basis of the nonlinear behaviors of fiber and matrix and the progress of debonding between these components. The fracture criterion of this composite was also determined using the following two conditions, (1) the normal stress in the fiber direction reaches a critical value, (2) the maximum resultant stress of normal stress and shear stress on a plane parallel to the fiber reaches a critical value.Experimental works for uniaxial and biaxial tensile tests were conducted by using the copper fiber-epoxy resin composites having various fiber volume fractions and fiber directions. The good agreements between the calculated and the experimental results were observed for both the stress-strain relations in the nonlinear viscoelastic region and the fracture criterion.