Assessment of the influence of interfacial properties on stress transfer in composites by a numerical approach

Abstract

To investigate the effect of interfacial properties on stress transfer by a numerical approach, a finite element model has been used where the fiber, the matrix and the interphase were treated separately. When the interphase was assumed to be orthotropic, an influence of the interfacial shear stiffness on stress transfer was evaluated from the axial tensile stress transferred from the matrix to the fiber by passing through the interphase. The influence of fiber breakage and interfacial debonding or matrix cracking on the stress distribution has also been studied. When the shear stiffness of the interphase is greater than that of the matrix, a high stress concentration appears near the fiber break point. However this stress concentration disappears when the fiber breakage occurs together with interfacial debonding or matrix cracking. It was therefore suggested that the fiber fracture propagation mode might be changed by altering the shear stiffness of the interphase and by the existence of interfacial debonding or matrix cracking. Thus it was obvious that the proposed FE numerical approach and the concept of material constants of the composite interphase might be appropriate for investigating the influence of the interfacial properties on stress transfer.