On the Relationship between Engineering Properties and Delamination of Composite Materials

Abstract

The influence of the coefficient of mutual influence, poisson's ratio and coefficients of thermal and moisture expansion on delamination is studied. Engineering theories are compared to finite element and experimental results. It is shown that the mismatch in coefficient of mutual influence can have a strong influence on delamination with fiber angles in the 10°—15° range being critical for adjacent (±θ) layer combinations. The mismatch in coefficient of mutual influence is reduced by a factor of two and the interlaminar shear stress τ zx is reduced significantly when the ±θ layers are interspersed between 0° and 90° layers. It is shown how the results can be used for design of composite laminates.