Material Damping of Aliminum by a Resonant-Dwell Technique
Abstract
At intermediate and high stress levels, material damping has been considered stress-amplitude-dependent and contributions from frequency-dependent anelastic mechanisms have been considered negligible. These considerations are contradicted by the findings of this investigation for Aluminum 2024-T4. The relations between material damping, stress amplitude, and frequency were experimentally examined for this material by means of a resonant-dwell technique employing "identical" double cantilever reeds. Tests were run in air (760 mm, 700F), and in vacuum (0.2 mm, 700 F), at stress amplitudes up to 20,000 psi and at frequencies from 15 to 1500 cps. Results showed that: damping as measured in air was largely aerodynamic drag and was displacement-amplitude and frequency dependent; damping as measured in vacuum was wholly material damping, independent of stress amplitudes up to 20,000 psi, and dependent on frequency; and there was agreement with the Zener theory of thermal relaxation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1965
- Accession Number
- ADA396991
Entities
People
- Jesse E. Stern
- Neal Granick
Organizations
- National Aeronautics and Space Administration