The Development of Economy Mechanism for Low Frequency Vibration Isolation: The Characteristic of Stiffness and Natural Frequency

Abstract

This research describes the design and the construction of a low cost mechanism for low vibration isolation used to study and develop the method to reduce seismic vibration disturbed the scanning tunneling microscope. The prototype mechanism is designed based on principle of mass-spring-damper system in which it consists of 3 pillars and a top plate. Inside each pillar, a low cost motorcycle’s inner tube and tire are employed as the air spring and internal enclosure, respectively.  Evaluation of the characteristic of the developed mechanism using tested mass from 35 to 105 kg when applied air pressure of 0.20, 0.25 and 0.30 bar into the inner tubes over a period of 10 minute illustrates that the employed inner tubes have satisfied lift up level. The maximum relative displacements of the top plate for a tested mass of 105 kg while applying air pressure of 0.20, 0.25 and 0.30 bar into the inner tubes are measured of 0, 12.45 and 25.89 mm, respectively.  The displacements are used to calculate the stiffness then the natural frequency of the mechanism. The results show that the average natural frequency for the mass starting from 35 to 105 kg when applied air pressure of 0.25 and 0.30 bar are of 4.14 and 3.00 Hz, respectively, are achieved.