A Study of Damping Effects Arising from External Coating of Visco-Elastic Materials on Metal Bars

摘要

In a previous report (AD-657 136), a short study was made to determine the extent to which internal damping of metals could be relied upon to reduce vibration. It was found that for ordinary temperatures this effect is almost negligible. In this report a study is made of the damping effectiveness of external coatings on bars, the coatings being made of some visco-elastic material such as tar or plastic tape. It is possible that the motions induced in the coatings by the corresponding motions in the rod or beam may, by virtue of the viscosity of the coating material, reduce undesired vibrational energy to an acceptable level. There is the additional problem, however, that too much coating material may be needed to provide sufficient damping. In such cases, undesirability large increases in weight may result. In the following brief study coated metal bars are studied theoretically over a rather wide range of assumed values of coating viscosity and coating thickness, and wave length of vibrational disturbance. (Author)