Development of a High Frequency Material Test Machine

Development of high temperature materials (which can withstand temperatures of 2500 to 4000 Degrees F) will require new test techniques and new test machines which can measure their mechanical behavior under extreme environments. The new test machines should be capable of measuring mechanical and physical behavior under cyclic stresses at high frequencies of up to several kilohertz (2,000-5,000 Hz) at high temperatures. The damage tolerance factors to be tested include failure modes, crack and void growth, oxidation, etc. Existing materials test machines cannot test beyond 1,000 Hz; hence we propose to develop a new test machine with 5,000 Hz capability. Its central feature is examining the feasibility of the resonance principle to amplify the cyclic stress applied to the specimen. Another key feature is the use of a two-level vibration isolation system that permits the specimen to resonate, but prevents resonances in the machine frame. A third key feature is the employment of a closed-loop controller which will maintain constant cyclic stresses throughout the tests. In the Phase I, we proposed to address critical issues relating to incorporation of these key features and develop a layout of a conceptual configuration of the test machine. OPTION: None submitted.