Fatigue Life of Composite Structures in Extreme Environments

The phase II objective is to develop a general design/analysis methodology as a design tool to predict the dynamic responses and fatigue life of composite structures in high thermal gradient and under high acoustic loading for new generation hypersonicflight vehicles and propulsion system integration. This task is particularly challenging as the structural response exhibits both randomness and strong nonlinear features. To achieve the objective, ZONA proposes four major tasks. The ZONA team will (1)Extend the capabilities of nonlinear MSC/NASTRAN to include two new elements specifically designed for this application and exhibiting improved shear and temperature distribution modeling; (2) Develop reduced order modeling approaches and equivalentlinearization schemes to reduce the computational cost associated with the prediction of the random structural response using the full nonlinear MSC/NASTRAN; (3) Extend the fatigue life prediction technique with the reduced order models; and (4) Establishexpedient design guidelines that can be used in the preliminary design phase. This effort is endorsed by Boeing, Lockheed-Martin and Pratt-Whitney whose support will ensure the success of the proposed project.