Material Damping Measurements of 2D Carbon-Carbon Composite Beams.
Abstract
Current work in thermal protective materials for space systems and advanced jet engines are investigating the use of an advanced carbon-carbon composite material (ACCM) to build critical components that must operate in very high temperature regimes. The potential use of ACCM in these applications must address the problems of vibration that might occur during system operations. Vibrations can cause severe performance degradations, if not controlled. One method of control, called passive damping, relies on the material's inherent damping characteristics. This study evaluates ACCM's damping characteristics, important to passive damping understanding. Modal analysis techniques using an impact hammer to excite sinuseidal free vibration were used to find the damping natural frequencies for 2-D ACCM beams. The logarithmic decrement technique was applied to the fundamental modes to verify the frequency and damping data derived by the modal analysis. Additionally, the logarithmic decrement technique was used to evaluate atmopheric drag influences on damping. It was shown that for small amplitudes, less than the beam's thickness, the damping effects of atmospheric drag were minimized and considered negligible. Cantilevered beam specimens were studied for the first three modes in test conditions at room temperature and atmospheric pressure. Keywords: material damping, carbon-carbon composites, modal analysis, vibration analysis.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1986
- Accession Number
- ADA179109
Entities
People
- Ernest S. Muller
Organizations
- Air Force Institute of Technology