Development of the Ball Bearing Isolator for Precision Machinery Systems

Abstract

This report deals with a base isolation system for the protection of precision machinery systems from seismic excitation. This base isolation system is called the Ball Bearing Isolator (BB Isolator), and consists of a bowl-shaped base and ball bearings. When an earthquake occurs, the isolator can reduce acceleration by the movement of the ball bearing rolling on the base. In order to examine the dynamic properties and isolation effects of the isolator, shaking tests and theoretical analysis were conducted. From the experimental results, it was confirmed that the response acceleration of the isolator would almost always be less than about 40 Gal even if it was subjected to big earthquakes such as E1 Centro and Taft. From the analytical investigations, it was shown that the proposed equation is effective for estimating the dynamic response of the isolator.