Interply Behavior Exhibited in Compliant Filamentary Composite Laminates

Abstract

Abstract Cord-rubber composite systems allow a visualization of interply shear strain effects because of the compliant nature of the matrix material. A technique termed the pin test was developed to aid this visualization of interply shear strain. The pin test performed on both flat pads and radial tires shows that interlaminar shear strain behavior in both types of specimens is similar, most of the shear strain being confined to a region approximately 10 interly rubber thicknesses from the edge. The observed shear strain is approximately an order of magnitude greater than the applied extensional strain. A simplified mathematical model, called the Kelsey strip, for describing such behavior for a two-ply (±θ) cord-rubber strip has been formulated and demonstrated to be qualitatively correct. Furthermore, this model is capable of predicting trends in both compliant and rigid matrix composites and allows for simplified idealizations. A finite-element code for dealing with such interply effects in a simple but efficient manner predicts qualitatively correct results.