Investigation of Air Damping of Cicular and Rectangular Plates, a Cylinder, and a Sphere
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
Pagination or Media Count:
An investigation was conducted to determine the mechanism of air damping exhibited by rigid bodies of different shapes oscillating in a pressure environment. Circular and rectangular plates, as well as a sphere and cylinder, were attached to cantilever springs and the free decay of an induced oscillation was measured at pressure levels from atmospheric to k x 10-2 torr. Data are presented to show the effect of pressure, vibratory amplitude, frequency, shape, and surface area on the air damping of the models. Results indicate that the magnitude of the air damping may greatly exceed the structural damping of the system. The air damping associated with the plates is directly proportional to the pressure and amplitude and is indicative of dissipative loads proportional to the dynamic pressure. Furthermore, the plate damping was found to be independent of shape and is a nonlinear function of the surface area. The sphere and cylinder exhibit viscous damping characteristics which are in good agreement with available theory.
- Theoretical Mathematics
- Structural Engineering and Building Technology