Resin transfer molding (RTM) is an attractive, versatile and cost-effective alternative to autoclave processing for manufacturing geometrically complex, structural polymer matrix composites (PMC). However, process induced defects such as microvoids or unwetted, dry spots often limit wider usage of RTM parts in high performance, mission critical applications. Understanding morphology of these defects, in addition to their formation mechanisms and removal techniques is an important step towards developing improved RTM processes. In this work, process induced defects in RTM parts are presented and contrasted to other defects encountered in PMCs. Defects in PMCs, which are classified as design induced and process induced, are both reviewed. Thereafter, more attention is drawn on voids and dry spots since they are known to be the most significant defects in RTM PMCs. Hence, dry spot formation mechanisms in RTM and available prevention techniques are summarized. In addition to adverse effects, formation mechanisms, and characterization methods of voids as well as their removal techniques are presented.

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Composite materials can offer wide range of thermo-mechanical properties when designing load bearing components using them. The wide range of properties can be obtained by varying fiber-matrix volumetric ratio. Another advantage of using composite materials in design is that the directional properties of laminated composite materials can be easily manipulated by varying the angle of orientation with respect to the direction of the load. Theoretically it is possible to design composite laminates with any fiber-matrix ratio, and in any orientation. But in practice, only a selective number of laminates with given fiber volume fraction are produced and sold by the companies depending on their market demands. So, it is necessary for a designer to perform the selection of laminates from a list of available composite laminates to make it commercially viable. The manual selection process of composite laminates can be very cumbersome for the designers when multiple design goals need to be satisfied in the load bearing component that is being designed. This paper presents a new customization approach for design of load bearing components where appropriate unidirectional laminated composites can be selected to satisfy multiple property requirements. In this approach, a laminate customization technique is incorporated with a grammatical method that deals with a shape design technique, and loading analysis for the designed shape. A hip-replacement joint is designed using commercially available composite laminates to illustrate the approach.