PORE GEOMETRY IN WOVEN FIBER STRUCTURES - 0-DEGREES 90-DEGREES PLAIN-WEAVE CLOTH LAYUP PREFORM/

Composite preform fiber architectures range from the very simple to th e complex, and the extremes are typified by parallel continuous fibers and complicated three-dimensional woven structures. Subsequent proces sing of these preforms to produce dense composites may depend critical ly on the geometry of the interfiber porosity. The goal of this study is to fully characterize the structure of a 0 degrees/90 degrees cloth layup preform using x-ray tomographic microscopy (XTM). This characte rization includes the measurement of intercloth channel widths and the ir variability, the transverse distribution of through-cloth holes, an d the distribution of preform porosity. The structure of the interclot h porosity depends critically on the magnitude and direction of the of fset between adjacent cloth layers. The structures observed include tw o-dimensional networks of open pipes linking adjacent holes, arrays of parallel one-dimensional pipes linking holes, and relatively closed c hannels exhibiting little structure, and these different structures wo uld appear to offer very different resistances togas flow through the preform. These measurements, and future measurements for different fib er architectures, will yield improved understanding of the role of pre form structure on processing.