The Two Isotropic Asymptotes of Fiber Composites,

Abstract : In conventional laminate analysis of fiber reinforced materials, the in-plane directional stiffness of constituent plies is summed to determine the entire laminate's characteristics. Conventional laminate analysis indicates that in-plane elastic isotropy accompanies certain ply pattern combinations and in general all laminates with three or more plies and orientation uniformly distributed from 0 to 180 deg. A corresponding analog for this quasi isotropic stiffness also exists for in-plane compliance in which compliance values are serial, and overall in-plane material property is determined by compliance summation. The two isotropic asymptotes are analogous to the Voigt and Reuss models of summed stiffness and compliance. The compliance quasi isotropic asymptote, which has evidently not been discussed in the literature, is presented here with some useful applications. The compliance computation is cast in the compact multiple-angle form, in analogy with the form used by many authors for laminate stiffness. Keywords: Compliance isotropic limits, Composites, Fiber composites, Isotropic properties, Quasi isotropic asymptotes, Quasi isotropic limits.