Micro- and mesomechanics of 8-harness satin woven fabric composites: I - evaluation of elastic behavior

In part I of this two-part paper, simplified two-dimensional micromechanics and mesomechanics models have been introduced to predict the elastic behav ior of 8-harness satin (8HS) woven fabric composites. The woven warp and fi ll tows were independently treated as unidirectional composites and composi te cylinder assemblage (CCA) theory was adopted to predict tow elastic prop erties from constituent fiber and matrix properties, Since evaluation of wo ven lamina stiffness requires an accurate description of tow geometry, a me thod was also developed to describe arbitrary tow geometries by mathematica lly fitting cubic splines and/or polynomials to micrographs of composite cr oss-sections. Finally, classical lamination theory was introduced to determ ine the overall elastic behavior of an n-layered composite laminate, assumi ng the woven lamina was a modified, two-layer laminate. The simplified mechanics model was evaluated using results from numerical s train energy and equivalent force approaches and results from a series of e xperimental Iosipescu shear tests and off-axis tensile tests on T650-35(3k) , 8HS woven graphite-PMR 15 composites. Issues regarding exclusion of a mat rix layer in the simplified, 2-layer laminate analysis were addressed in th e strain energy analysis of an idealized 3-D, representative volume element (RVE). The mechanics model was found adequate in estimating the lower boun ds of 8HS woven fabric, composite elastic properties. The model also provid ed a reasonable estimation of symmetric cross-ply composite properties. (C) 2001 Elsevier Science Ltd. All rights reserved.