| Liquid molding (LM) processes, most notably resin transfer molding (RTM), have recently become popular methods for the production of polymer composite pans. These techniques have gained notoriety because of their ability to form large, complex shapes with varying levels, types, and orientations of reinforcing fibers that integrate several components into a single molding. These features differentiate LM from all other composites manufacturing techniques and afford the opportunity for a "materials-by-design" approach for the development of a part.;In this study, we concentrate on RTM and investigate the importance of two issues related to the development of a preform's fiber architecture, namely preform compressibility and preform joining. An analytical model is presented that estimates the force required to compact the fabric/preform considering both fiber type and architecture. Comparisons are then made between the model predictions and fabric/preform compaction experiments. The influence of compressibility on fiber volume fraction, which in turn affects both resin flow, primarily through the permeability, and mechanical performance, is presented.;The microstructure of RTM composites that contain preform joints is examined, and analytical and numerical models are developed that describe how load is transferred in these parts. The predictions of these models are compared with experimental results. Due to the two-step nature of RTM, the influence of preform joints on processing is also considered since local perturbations in the fiber architecture affect resin flow. Comparisons are made between preform joint flow experiments and numerical predictions using the LIMS finite element flow code.;In order to illustrate the integrated demands of material, tooling, processing, and performance on the design and the development of an actual RTM structure, a demonstration project is presented This project is described from the initial stages of selecting an I-beam, to the preliminary and detailed design of the preform/part and the tool, through the manufacturing and testing of the actual parts, and finally, to the investigation of the effects of preform joints on processing and performance. Based on this study, a concurrent engineering approach to preform/part design is presented. |
