High Strain-Rate Characterization Methods for Carbon-Carbon Composites at Elevated Temperature

Thermal Protection Systems (TPS) exhibit a damage mechanism known as “shear-plugging” when impacted by a hypervelocity projectile. Test methods to extract strain-rate dependent strength data relevant to shear-plugging of composite materials do not exist. Therefore, Materials Research & Design, Inc. (MR&D) and Southwest Research Institute (SwRI) propose to develop innovative test methods for the characterization of TPS materials subjected to hypervelocity impact at elevated temperature. In the Phase I effort, SwRI conducted split Hopkinson pressure bar (SHPB) testing on ACC-6, a well characterized 2D carbon-carbon manufactured by Carbon Carbon Advanced Technologies. In parallel MR&D developed a hydrodynamic constitutive model for 2D carbon-carbon implemented as a hydrocode user-material (UMAT). MR&D successfully correlated their hydrocode material model to the experimental data generated by SwRI. The Phase II program will build upon the results of the Phase I effort. MR&D and SwRI propose to audition novel specimen designs and innovative test fixtures not currently employed by state-of-the-art split Hopkinson pressure bar test methods. These new testing approaches will be performed at room and elevated temperatures. MR&D’s dynamic material model will be exercised and correlated to the experimental results to help guide specimen and fixture designs to ensure the test methods are extracting the intended strength properties of interest. At the conclusion of the Phase II, the team will have developed high temperature test methods to measure dynamic properties relevant to shear-plugging for input to hydrocode material models used by various DoD agencies. Approved for Public Release |21-MDA-10789 (21 Apr 21)