ABSTRACT A vibration isolation system using spring units and visco ...

2.2 Composition of the system
2.2.1 Helical steel spring elements
Several helical steel springs are used as a spring unit. Usually a spring unit, consisting of the
springs and a top and bottom plate, can resist only compression forces. But in this special system,
springs can resist compression and tension force because both ends of the springs are fixed to the
end plates (see Fig. 3).
Fig. 3 Spring unit Fig. 4 Damper
2.2.2 Visco-elastic dampers
Visco-elastic dampers consist of three parts as shown in Fig. 4.
(1) Lower cylindrical vessel
(2) Visco-elastic liquid in the vessel
(3) Cylindrical piston submerged in the visco-elastic liquid.
The cylindrical piston can move in the visco-elastic liquid three-dimensionally relative to the
movement of the lower vessel transferring vibration energy in this way into heat.
3. DYNAMIC TEST OF THE DEVICES
Several dynamic tests of the spring units and the visco-elastic dampers were done.
3.1 Dynamic test of the characteristics of the spring unit
3.1.1 Outline of the test
The spring unit contains seven helical steel springs fixed to the end plates. The natural frequency
in the vertical direction of the spring supported system is 2.5 Hz.
The test pattern is
(1) Horizontal loading test at different displacements in vertical direction.
(2) Vertical loading test at some displacements in horizontal direction.