Measurement of Large Damping

Abstract

Damping is an elementary factor to be considered in designing vibration isolators. So measurement of damping coefficient or damping ratio is of great importance. Usually, these values are calculated by logarithmic decrement or resonance method. These are convenient methods, if a system possesses light damping. The accuracy of these methods, however, is not satisfactory in a large damping system. In this paper, two new methods to calculate large damping with high accuracies are proposed. One is a method utilizing a phase angle between input and output, called "phase method", and the other is one utilizing the gravitational acceleration, called "gravity method". Damping coefficients of the oil damper were measured by the methods mentioned above. As the results, it is made clear that the measured values obtained by the phase method and the gravity method show higher degree of accuracy than the ones obtained by the resonance method.