Z-FIBER REINFORCEMENT OF LAMINATED COMPOSITIES

Increasing the interlaminar strength of advanced composite materials will improve damage tolerance and permit use of thin gage facesheets for ultralightweight structural materials. This project will investigate novel means of implanting individual fibers through the thickness of laminated composites. Such reinforcement with separate fibers extending through multiple plies is expected to offer the preferred combination of mechanical properties, in which interlaminar strength is improved without degrading the in-plane strength. The fiber implantation method, which does not involve stitching or weaving, appears to be suitable for large scale processing. It may be used also with non-weavable fibers and whiskers. Phase I effort will focus on experimentation with the process variables. Diverse fiber materials, fiber diameters, fiber lengths, and laminate forms (unidirectional and woven) will be tested. An objective is control over fiber orientation and areal density as required for interlaminar reinforcement purposes. Reinforced composite samples will be fabricated and inspected. The most promising process will be used to fabricate samples for short beam mechanical testing. Potential improvements in the damage tolerance of composite facesheets and the potential for aircraft weight reduction will be assessed. Phase 2 would develop further the leading process and scale up to fabricate and test prototype composite panels.