Thermostructural Behavior of Polymer and Ceramic Matrix Composites Under Extreme Short Term Thermal Loads

Future supersonic missiles can be improved through the use of PMCs and CMCs for structural airframes. However the severe aerodynamic heating conditions that the missiles undergo will expose the structure to short term temperatures and stresses that are beyond those typically seen by these materials. Nevertheless because the airframes are required to survive these conditions for very short times, it may be possible to employ PMCs and CMCs as primary structural materials. Designs using these materials are presently limited by the lack of a consistent database that reflects the property degradation caused by se-vere short term thermal exposure. Materials Research & Design, Inc. (MR&D) proposes to determine the appropriate material properties through the development of a degraded micromechanical property model coupled with a focused material characterization plan. This approach couples the economy of a composite property model with the reality of critical measured data. The program will be performed by a team of MR&D, Raytheon Missile Systems, and Southern Research Institute. The MR&D team is uniquely suited to perform the proposed effort because of previ-ous experience on the SM-3 Gr/BMI nosecone, development of high temperature CMC components, and in-depth knowledge of the thermal degradation of PMCs under severe aerothermal loads. BENEFITS: The successful completion of the Phase I program will provide a theoretical model and preliminary experimental data that address the thermostructural degradation of PMCs and CMCs under severe short term thermal environments. This information is of direct interest to the DOD and NASA in the design of high speed airframes for missiles and hypersonic vehicles. Additional commercial applications include petrochemical machinery and gas turbine engines.