Effect of Preform Architecture on Modulus and Strength of Two-Dimensional, Triaxially Braided, Textile Composite Materials

This paper investigates the mechanical response of two-dimensional, triaxially braided, textile composites from an experimental viewpoint. The specific objective of this study was to empirically define the role of the braid architecture in determining laminate mechanical properties. Three primary braiding parameters, that is, braid angle, 0° yarn content, and yarn size, were identified. A number of reinforcing fiber architectures were designed to provide a direct comparison of the effects of these parameters on mechanical performance. These parameters were varied over a wide range to establish data that reflect the full spectrum of viable braid architectures. Braid angle varied from 45° to 70°, 0° yarn content ranged from 12 to 46%, and yarn bundle size ranged from 6 thousand fibers per bundle to 75 thousand fibers per bundle. The laminates studied featured AS4 graphite fibers in Shell's 1895 epoxy matrix.

In addition, two secondary braiding parameters, 0° yarn spacing and yarn crimp, were also investigated. A set of laminates was designed to isolate the effects of these two parameters.

The effects of fiber architecture on the mechanical performance are thus further defined in the investigation. Experimental results will include measures of the materials' longitudinal and transverse tensile moduli, their Poisson's ratios, and their shear moduli. In addition, the effects of the textile preforms' architecture on laminate tensile strength will also be reviewed.