The assessment of novel materials and processes for the impact tolerant design of stiffened composite aerospace structures

This paper reviews the most promising material concepts (tougher matrix systems, 2D and 3D woven materials, stitching and Z-pinning, selective interlayers, protective surface layers and hybrid laminates) for improving the damage tolerance of aerospace stringer-stiffened structures. Although all of these concepts can impart improvements, all also have disadvantages including reduced undamaged performance, weight penalties and the need for requalification. Recommendations have been made as to which show the most promise for improving the impact tolerance of current and future structures. For current structures, Z-pinning shows the most promise, although the cost associated with this concept is currently high. For future structures, 3D woven materials show significant promise for impact tolerant design. (C) 2003 Elsevier Science Ltd. All rights reserved.