Characterization of Composites for the Purpose of Reliability Evaluation

A philosophy of design based on the prevention of failure is defensible and workable. One such philosophy is reliability based design and is the target of our work. The reliability of a structure depends upon a description of the material system (for example, strength) and the attendant uncertainties in this description (for example, scatter in strengths), along with a description of the structural complexity, expected structural loads, and expected operating environment and their attendant uncertainties. We will discuss, develop, and experimentally verify, wherever possible, models for composite material behavior. These models include a description of static failure resistance by lamination theory combined with energy based fracture mechanics criterion for failure, and a description of wearout via kinetic fracture mechanics. The relationships between the material's capability, as defined by these models, and the anticipated use and misuse reflected by the expected loads and environments will be defined and implemented. Our goal is to define critical technical areas for the development of structural composites; progress can be made only by examining these critical areas and confirming, extending, or redeveloping the tools described here.