Installation of Shake Table Facility
| Seismic
Table: |
| The
Seismic Table has a linear hydraulic actuator with a fatigue rating of
110 kip (500 kN). The actuator is attached to a 3 M x 3 M table which
is guided by linear bearings. The stroke capability of the unit is ±
300 mm (± 12 inch) with a nominal peak velocity of 1 meter/sec (40
inches/sec) and average velocity of ½ meter/sec (20 in/sec). The
linear guide bearing are sized to test a 20 MT payload with a CG 3 M
off the table surface, with 60 MT-M over turning moment at one g. The
entire table assembly is attached to the mass via the post tensioned
steel plates on the mass top surface. The actuator is attached to the
moving table via a coupling flexure which is guided by linear
bearings.
The
table surface includes a mounting grid pattern to simplify specimen
attachment. The assembly has a complete with a servo valve 900 lpm (240 gpm)
and position transducer to allow displacement to be used as the feedback for
loop closure. An accelerometer is used to control or monitor the table motion
in an external loop as well. The control system accepts a signal from the
control system. The hydraulic power is provided via a 156 gpm, 3000 psi HPS. The
Siesmic Table Assembly is attached to a reaction mass in order to develop full
force performance. A mass to maximum load ratio is 20:1. The
systems include control software which all standard features. The System has
four (4), 32 bit input A/D channels with 16 bit programmable attenuators, one,
64-bit output D/A channel with 16-bit D/A, one, high speed signal processing
module, classical shock vibration and a 2.93 GHz PC based computer. Hydraulic Linear Actuator, 500 kN (110 kip), is a double ended fatigue rated, with hydrostatic and replaceable non-metallic back up bearings, one-piece 133.4 mm (5.25 inch) heat treated alloy piston rod, and internal, concentrically mounted LVDT. Hydrostatic bearing provide a low friction high side load bearing to assure low harmonic distortion during high velocity tests. |
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