Layup optimization of ramie fabric reinforced composite: Woven fabric and lamination parameters

Composites reinforced with plant-based fabrics are gaining attention as promising, low cost and environmentally friendly alternatives to those reinforced with traditional synthetic fabrics. The present article studies the resin permeability and resulting mechanical properties of ramie fabric reinforced unsaturated polyester composites. First, the effects of the fabric areal density on the properties of composites were investigated and optimized. Then, composites were prepared with the fabric with the optimum areal density and varying lamination parameters including the number of fabric layers and the orientation of the fabric layers relative to the resin flow direction. The results showed that composites prepared with a fabric with an areal density of 135 g/cm2 had the highest resin permeability, tensile strength, tensile modulus, flexural strength, flexural modulus, and storage modulus due to high apparent porosity of the fabric reinforcement and efficient load-bearing structure of the composite. The optimal number of layers was determined to be 8, and because of the lower crimping in the weft compared with the warp of the fabric, layering the weft of the fabric at 90 degrees relative to the resin flow direction increased the mechanical properties of the composites. Meanwhile, the composite with 8 layers of 135 g/cm2 fabric that were orientated 45 degrees relative to the resin flow direction absorbed the most energy and had the highest impact resistance. In summary, the results presented here provide new selection guidelines to optimize the structure of laminated composites for various applications.