A design procedure for textile composite materials that is able to satisfy a set of target mechanical and thermal properties is presented. First the search space, within which a feasible solution may exist, is divided into discrete sections. These sections are sufficiently small so that material properties show little variation. In each section, the composite is defined as a set of yarn segments that possess certain relative volume fractions, initial elliptical cross-section shape, and spatial direction cosines. A unique solution is calculated using a stiffness averaging routine. Solutions are then compared and ranked based on a chosen selection criterion.

The nature of the textile forming process is considered in the design approach. Proposed textile preforms are graphically constructed in 3-D space. The feasibility of changing the elliptical cross-section shape of yarns at different locations to fit within a high fiber-volume-fraction composite is investigated. A distortion factor is introduced to characterize the departure of the yarn cross-section from an initial elliptical shape. Two shapes for yarns cross-section, race track and boat-shape, are parametrically defined and used in the model.