On the prediction of oil layer damping on plates
Abstract
High damping of machinery panels can be achieved using a sandwich construction consisting of an attached plate sandwiching a layer of fluid filled porous material. The vibration of the plate pumps the fluid laterally at high velocities, resulting in energy loss due to the fluid viscosity. Loss factors greater than 0.1 can be achieved with this layered configuration. However, if the gap is filled with the high viscosity fluid alone, the losses are very low. The ratio of the fluid dynamic viscosity and its density is the controlling parameter on the level of the losses. High loss factors are possible only if the fluid viscosity can be increased by many orders of magnitude for liquids. The damping over the whole frequency range above and below the excited plate critical frequency is measured and compared with prediction. The agreement in results is good. The layered configurations are so strongly coupled that the loss factor measured on both the excited and the attached plates are the same.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- May 1986
- Bibcode:
- 1986STIN...8632590C
- Keywords:
-
- Panels;
- Perforated Plates;
- Sandwich Structures;
- Vibration Damping;
- Glass;
- Impedance;
- Oils;
- Porous Materials;
- Stiffness;
- Viscosity;
- Engineering (General)