Abstract
We pay attention to the fact that free vibration amplitude of rigid body decrease rapidly without dampers or damping materials. We consider rocking of rigid body is very attractive as a low cost dynamic vibration absorber. In the previous paper we propose new type rigid bodies which base shape are not flat in order to design damping characteristics of rocking of rigid body in wide range without fall. However, natural frequency of the rocking of the rigid bodies has strong amplitude dependency. In this paper, in order to apply rocking of rigid body to dynamic vibration absorber, amplitude dependency of natural frequency of rocking rigid body is examined, and approximate equations to calculate natural frequency and damping ratio of several types of rigid bodies are derived to discuss how to improve amplitude dependency of natural frequency. Effects of the base shape on amplitude dependency of natural frequency and damping ratio are discussed using the derived equations. From the discussion it can be seen that rigid bodies which vase shape is near circular arc can improve amplitude dependency of natural frequency.
