MODELING WEAVE AND STACKING CONFIGURATION EFFECTS ON INTERLAMINAR SHEAR STRESSES IN FABRIC LAMINATES

In an effort to improve out-of-plane properties, such as shear delamin ation strength, laminated composites have often incorporated laminae i n which the fibres have been woven into a cloth. There are, however, m any possible weave geometries for the cloth reinforcement, and many po ssible ply stacking configurations with these laminae. It is not well understood which combinations of weave and stacking can significantly improve, or inadvertently degrade, properties. This paper models the l aminate geometry for woven-reinforced composites. Commonly available w eave types, such as twills and five-harness satins, are considered. St acking configurations include effects of weave pattern offset, folded vs. unfolded, and alternate stacking of different weaves. A rudimentar y model is used to estimate the shear stress distribution within these various laminates. These distributions suggest the effectiveness of t he various geometries. It is found that there may be significant effec ts due to weave offsets, that a folded configuration is undesirable, a nd that mixed weave types are unlikely to provide much improvement. A new quantity is defined-the lacing number-that has potential for quant ifying the waviness of weave types.