POTENTIAL EFFECTS OF MICROMECHANICAL STRESSES ON THE FAILURE INITIATION IN COMPOSITE LAMINATES

In this work, we consider the effect of modeling details on the potential initiation of failure within a laminated composite in the classical free edge problem. The work follows the demonstration by Pagano and Rybicki (1974) that the artificial singularities introduced by the effective modulus (EM) approach may lead to inconsistencies in the physical/mechanical behavior, such as failure, of the body. The present authors (1998) have recently revisited this issue by solving the same boundary value problem using modern finite element technology (ANSYS) in a micromechanical model (MM) and have shown stresses that were in very good agreement with the earlier work. Unfortunately, the transverse stresses developed in the composite studied were very small, so that experimental confirmation based on failure initiation is not feasible. Therefore, we now consider a similar laminate under a transverse loading (loading normal to the fiber direction) to accentuate these stresses, as well as the fiber-matrix interfacial stresses.