## 3aSAb1. Specific damping capacity for high-loss materials.

### Session: Wednesday Morning, May 15

### Time: 10:45

**Author: Gilbert F. Lee**

**Author: Bruce Hartmann**

**Location: Naval Surface Warfare Ctr., Silver Spring, MD 20903**

**Abstract:**

The purpose of this presentation is to establish the relation between
specific damping capacity and loss factor for high-loss materials. The
motivation for this work is that the commonly used relationship between these
variables is only valid for low-loss materials and leads to significant errors
as the loss increases. The relationship cited in numerous references between
specific damping capacity is (Delta)W/W=2(pi) tan(delta). This equation is only
valid for very small values of (delta). Another difficulty with the above
relationship is that the specific damping capacity is generally assumed to
represent the fraction of energy converted to heat. For large values of tan
(delta), (Delta)W/W can be greater than one, which seems to be a contradiction.
In this presentation, a relationship between specific damping capacity and loss
factor is derived, which is valid for all values of tan (delta). In the limit as
the loss factor approaches infinity, the specific damping capacity approaches
unity. A comparison of our relationship with others found in the literature will
be presented. [Work supported by Naval Surface Warfare Center's In-house
Laboratory Independent Research Program sponsored by the Office of Naval
Research.]

from ASA 131st Meeting, Indianapolis, May 1996