Clearance Adjustable Impact Damper for Flexure Mechanism
Nobuhiko Henmi and Yuta Sumi
Department of Mechanical Systems Engineering, Faculty of Engineering, 4-17-1 Wakasato, Nagano 380-8553, Japan
An impact damper dissipates energy from mechanical vibration by making use of collision energy rather than viscous and frictional forces. It works successfully without scarifying the merits given by a frictionless flexure guide or mechanism. In the past, the authors investigated the dynamic vibrational behaviors of a displacement amplification mechanism by using two types of impact damper, namely, loading- and external-type impact damper, for showing the effectiveness of employing impact dampers for the vibration control of a flexure mechanism. In conclusions, the initial setting for the clearance between an impactor and object is very dominant and very sensitive to the damping performance. In this study, the authors have developed an impact damper which can adjust the clearance between the impactor and object by means of a piezoelectric bimorph actuator. With the ability to adjust the clearance, we have accurately examined the influential results from various contributing factors, for example, the natural frequency ratio between the damper and displacement amplification mechanism, better than the results for a normal impact damper. It is clarified that a large impactor mass gives a short settling time under the same frequency ratio and that a slightly smaller value than 0.5 is the best value for the frequency ratio. Finally, we have also studied not only the open-loop performance but also the closed-loop performance of the system. The damper can work in both open-loop and closed-loop system, but is more remarkable for an open-loop system.
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