United States industry and the Air Force have a critical need for materials that are light, strong, and capable of performing at elevated temperatures for applications in energy and industrial technologies. One of the specific needs to achieve the objectives is composite design. The initial focus of this program is to predict the matrix initiation of the brittle matrix composites at high temperatures. The asymptotic solutions of the stress fields near the crack tip of the matrix cracking will be investigated in detail. The continuing research addresses structural integrity in reactor pressure vessels using advanced fracture mechanics technology.
Thin shells are often susceptible to instability prior to material failure.
Therefore buckling strength has been considered to be indicative of load-carrying capacity of the structures and has become a crucial design criterion. For composite shells, it is well recognized that the actual load-carrying behavior strongly depends on their geometries, material anisotropy, stacking sequence, and boundary conditions. However the mechanical coupling of the structural response may alter its buckling characteristics and lead to a smaller buckling strength. The use of composite shells has posed many new analytical challenges and has spurred the development of prediction techniques for evaluating the buckling behavior under various loading conditions. The research is to investigate the bucking strength of thin composite cylindrical shells under axial compression using Koiter's energy criterion for stability.