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A multi-objective optimization methodology is proposed which simultaneously considers the mechanical performance and the manufacturing cost from the early stage of design of composite laminated plates. Resin transfer molding process is chosen as the manufacturing process for its wide acceptance among industries. Interrelations between the structural parameters and the process parameters are identified. With proper assumptions, the multi-objective problem is formulated into a problem with a single objective function. As design variables, the stacking sequence of layers is investigated which minimizes the maximum displacement and the mold filling time. Injection gate location is also considered in order to minimize the mold filling time for a given structure geometry, material properties and loading condition. The genetic algorithm is adopted as the optimization scheme. The results from the sample problems illustrate usefulness of the developed methodology. [Copyright &y& Elsevier]

Abstract: The thermoforming of continuous fiber reinforced thermoplastic (CFRTP) composite panels generally involves significant in-plane shear deformation. In the present work, the in-plane shear behavior of woven thermoplastic composites (Carbon/Polyphenylene Sulfide) over a range of processing temperatures is studied by bias-test experiments at different velocities. The experimental data of force versus displacement and force versus shear strain are presented for different extension velocities and temperatures. A thermo-visco-elastic model for numerical simulations of woven thermoplastic composite forming is proposed considering the influences of temperature and of strain rate. We applied a large displacement three-dimensional cohesive element with eight nodes which has been used for crack analysis in fracture mechanics by other authors, to investigate the inter-ply shear mechanism of woven thermoplastic composites. Applying three-dimensional cohesive elements, multi-plies forming simulations are performed to show inter-ply slip behaviors at different temperatures. The proposed models can be useful to predict from the properties of reinforcement and resin the intra/inter-ply shear behaviors of woven thermoplastic composites at high temperatures if experimental characterization of composite laminate behaviors is difficult to conduct. [Copyright &y& Elsevier]