A method for determining material damping from driving point measurements

Abstract

<p>An experimental method for determining material damping from the forced vibration of beam specimens has been developed. In this method, the damping was determined from measurements of the driving force and driving point acceleration. The governing equations of the test system were developed and analyzed so that near optimal system parameters could be selected. Based on the analysis, limiting cases of system parameter selection were considered;Tests using the new method were performed on 2024-T351 aluminum and an aluminum particle filled epoxy. The tests were conducted in atmospheric air and in a reduced pressure environment to observe the effect of air damping. The material damping loss factor was extracted from the test results and compared with results obtained from a different test method for the same materials. The loss factor determined for the aluminum specimen was also compared with the loss factor predicted by the Zener Thermal Relaxation Theory.</p>