3.4.5 Hydraulic actuator

A hydraulic shaking system has recently been widely applied which obtains the energy for vibration from a hydraulic piston and has the capability to provide a nominally programmable input motion. This type of system has been adopted on a number of academic centrifuges in the world. In general, the system consists of a shaking table, an actuator, an oil supply unit and a system controller. The controller has a sequence circuit to control all servo, control and shut off valves. The photo 1 shows the shaker for Nishimatsu Centrifuge, whose major capacities are the size of shaking table of 100 cm and 70 cm, the horizontal acceleration of 40 G, the maximum horizontal displacement of 5 mm and frequency range of 10-300 Hz. A similar but larger shaker is employed by PWRI centrifuge III. Another hydraulic shaker (Photo 2), serving for PHRI centrifuge, has the following specifications; maximum acceleration of 18 G, the maximum frequency of 250 Hz and the maximum displacement of 6 mm.

Imamura, S., Hagiwara, T. and Nomoto, T. (1998) : Nishimatsu dynamic geotechnical centrifuge facility, Proc. of CENTRIFUGE 98 (in print).

Inatomi, T., Kazama, M., Kitazume, M. and Terashi, M. (1988) : Development of an earthquake simulator for the PHRI centrifuge, Proc. of CENTRIFUGE 88, pp.111-114.