Fiber Alignment in Directed Carbon Fiber Preforms — A Feasibility Study

Abstract

The directed carbon fiber preforming (DCFP) process has the potential to create discontinuous fiber architectures with significant levels of fiber alignment. This article investigates the achievable levels of alignment and identifies the compromises inherent in the production of aligned preforms. The tensile properties of laminates produced from 6 and 24 K filament counts are compared at three different fiber lengths (28, 58, and 115mm). Experimental characterization indicates that up to 94% of fiber bundles can be aligned within ±10° using the current DCFP alignment method. Consequently, tensile stiffness and strength can be increased by 206 and 234%, respectively, over the random fiber case, as a result of the high concentration of aligned fibers in the loading direction. These alignment properties equate to maximum stiffness and strength retention values of 83 and 31% compared to continuous unidirectional material.