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

(3) Results
Fig. 7 shows the relation between vertical load and displacement.
Fig. 8 shows the relation between vertical stiffness and horizontal displacement.
According to Fig. 8 vertical stiffness increases at increasing horizontal displacements.
Fig. 7 Vertical load displacement line Fig. 8 Vertical stiffness versus horizontal displacement
3.2 Test of the characteristics of the visco-elastic damper
3.2.1 Outline of the test
The vertical and horizontal characteristics of the visco-elastic damper were found in a test with
random noise excitation and tests with sinusoidal force excitation at several frequencies.
3.2.2 Vibration test in vertical and horizontal direction
(1) Vibration
Vibrations were excited by random noise or sinusoidal loads. The frequency range of the random
noise was 0 to 5 Hz and 3 to 50 Hz. The amplitude range was very small. The amplitude range of
the vertical sinusoidal excitation was 5 ~ 45 mm at 1 Hz, 5 ~ 15 mm at 2 Hz and 2 ~ 12 mm at
5 Hz. The amplitude range of the horizontal sinusoidal excitation was 5 ~ 30 mm at 1 Hz,
5 ~ 15 mm at 1,5 Hz and 2 ~ 15 mm at 3 Hz.
�� Results of random noise excitation
Fig. 9 Displacement dependency
of damping resistance