Design, Manufacturing, and Performance of Stitched Stiffened Composite Panels With and Without Impact Damage

摘要

The goal of this project was to develop the knowledge base required for certification of composite structures in air transportation systems in the form of a design-manufacturing-performance relationship. Specifically, this project contributes to an improved definition of certification requirements for substantiating damage tolerance and durability of structural elements based on textile composites. Fundamental questions concerning analytical certification procedure, spectrum versus constant-amplitude fatigue, effect of low-velocity impact on strength, and effect of manufacturing defects were addressed. Unstitched and stitched blade-stiffened panels applicable to airframe construction were investigated during Phases I and II of this project. The specific areas addressed were as follows: Analytical models to predict properties of unidirectional, fabric, and stitched fabric laminates; Manufacturing processes; Inspection methods; Predictions of buckling and postbuckling loads; Static compression properties; Constant-amplitude fatigue properties; Spectrum fatigue properties; and Effect of impact damage on static and fatigue properties.