FACTORY VISIT AND PERFORMANCE TEST 1. Compression stiffness test 2. Shear stiffness test PROCEDURES COMPRESSION STIFFNESS TEST One unit of laminated rubber bearing had been chosen randomly for the testing. The bearing tested at 28th December 2010 morning was bearing no 7 with size 600mm X 400mm X 66mm (Type Slide Guide).
Located the bearing at the central of the tester machine.
Setups for the four dial gauge are used to measure the deflection f or the bearing during compression. Measurements of displacement are made at each corner of the laminated bearing as shown.
One pressure gauge will be fixed in the hydraulic system to measure the hydraulic pressure
A vertical test load (3477kN) applied to the bearing with the serviceability limit during the first cycle for hold time 2 minutes then released For second cycle, the vertical load applied in increment to the maximum design load.
Load vs. deflection measurements should be taken at each increment after any obvious short-term creep has ceased. The vertical deflection of the bearing, between one-third and full test load, for the second loading cycle should be plotted and determined for the compression stiffness for the bearing. Compression stiffness = gradient of graph, k = =1629.8 kN/mm
(Displacement, mm )
SHEAR STIFFNESS TEST Placed the robust plate in between pair of rubber bearing opposite each other on both sides as shown below:
Assembly the compression testing machine horizontally in order to apply load to the intermediate steel plate while a vertical load is applied simultaneously to the assembly.
All surfaces in contact with the bearing should be plane and prepared so as to prevent slippage between the contacts surfaced with causing any damage to the bearing.
Apply the horizontal load to the intermediate plate to achieve the maximum horizontal deflection then released.
Reapply the horizontal load in increment of deflection until a horizontal load equal to the design displacement. Record the horizontal load for each displacement. From the recordings, shear stiffness can be obtained from horizontal load/ deflection graph as the slope, K of the chord between displacement point 0.05 and 0.25 time total thickness of elastomeric in the bearing
Compression stiffness = gradient of graph, k =3.989 kN/mm
(Load, kN) 60
y = 3.9898x + 9.0881 50 40
30 20 10 0 0
(Displacement, mm )
HERCULES ENGINEERING SDN.BHD.
DATE : 29TH DECEMBER 2010 COMPRESSION STIFFNESS TEST The pot bearing type (HPT C-FX 3000) located at the centre of the compression machine. Setups for the four dial gauge are used to measure the displacement f or the bearing during compression. Measurements of displacement are made at each corner of the top steel plate as shown.
The vertical test loads in SLS shall be applied gradually in each increment and load deflection measurement shall be recorded for each increment. The rate of loading should be slow enough to prevent any adverse shock effect.
Hold time at maximum loading is 10 minutes or until the deflection gauges ceased movement whichever first. It is to ensure any obvious short term creep has ceased. HORIZONTAL LOAD CAPACITY Assemble the fixed type bearing in the compression test machine. Then set up a inverted sliding guide bearing on the top of the fixed bearing
All surfaces in contact with the bearing should be plane and prepared so as to prevent slippage. Apply the horizontal load to the intermediate plate to achieve the maximum horizontal deflection then released.
For compliance requirement, the visual check should be carried out after testing. The condition of the inner seal, elastomeric pad should show no sign of visible damage or permanent deformation due to the loading cycle subsequent to the initial bedding in cycle.
Take out the pot bearing using forklift
Carefully dismantle the pot bearing
Visually check on the elastomeric any damaged or deformation