Elastomer for Heavy Engineering Applications

(a)Laminated Bearing

• Sandwich structure between elastomer and steel plate

• Widely used because it is able to prevent & reduce the movement of the bridge due to few factors (earthquake, creep, etc)

• The number of steel plate, will increase the amount of load that can be sustain by the bridge

(b) Plain Pad Bearing

• Consist of rubber, without the steel plate

( c ) Strip bearing

“Strip bearing” similar with “plain pad bearing” but the length of the bearing is longer than its width.

( d ) Pot Bearing

“Pot bearing” – bearing which consists of solid rubber block and it is located in between metal piston and metal cylinder.

Pot Bearing

Plain Pad Bearing

Laminated Bearing

Example the needs of good bridge bearings

Benicia-Martinez Bridge

The bearing for this bridgeIncreased to 53 inch whenever sustained

5 mil. Lbs loads.

Main materials used as bridge bearing:

ELASTOMER

Function of Elastomer

• absorb the vibration

• allow the changes in the length of bridge

• ease of installation

• used to cover the metal plate (for laminated bearing)

Types of Elastomer used as bridge bearings

• Natural Rubber

• HDRB ( High Damping Rubber )

• Neoprene

• SBR

• EPDM

• NBR

Why Elastomer?

• Long lasting• Good in impact absorption• Good bonding with metal • Good resistance to ageing • Good tearing properties• Good physical properties • sesuai untuk panas dan sejuk• Good resistance to oil and chemicals

Disadvantages

• Expensive (especially for rubber with high resistance to ageing)

• Can be attack by: ester ketone hydrocarbon with nitrogen aromatic

Physical PropertiesNaturalRubber

SBR EPDM Neoprene Nitrile Urethane Silicone Fluorocarbon

Specific Gravity 0.93 0.94 0.86 1.23 1.001.05 to 1.25

0.95 to 1.20 1.4 to1.95

Durometer, Range 30-100 40-100 30-90 40-95 30-90 55-100 25-90 55-90

Tensile Strength E F-G VG VG VG E F-G VG

Elongation VG-E G G G G G-VG VG-E F-G

Compression Set G G G F-G G G-E G-E G-E

Heat Resistance F F-G VG-E F-G G F-G E E

Resilience or Rebound E F-G G VG F-G F-E G F

Impact Resistance E E G G F G-E P-G E

Abrasion Resistance E G-E G-E G-E G-E E P-F F-G

Tear Resistance E F F-G F-G F-G E P-F F

Cut Growth E G G G G G-E P-F P-F

Flame Resistance P P P G P P-F F-G VG-E

Impermeability, Gas F F F-G F-G G P-F F-G E

Weathering Resistance P-F F E VG F-G G-E E E

Low Temperature Limit*

-10° TO -50°F

0° TO -50°F-20° TO -

60°F-10° TO -

50°F-30° TO -

40°F-10° TO -

50°F-65° TO -

150°F+10° TO -40°F

High Temperature Limit*

158° TO 225°F

158° TO 225°F

300° TO 350°F

225°F 275°F 250°F400° TO 550°F

400° TO 450°F

Comparison of physical properties of polymer

P = Poor F = Fair G = GoodVG = Very Good

E = Excellent

Neoprene = polychloroprene

First Choice

Polychloroprene before vulcanization

Polychloroprene after vulcanization

Natsyn 2200 100.0 Zink oxide 3.0 stearic acid 2.0 Wingstay 100 – AZ 1.0 VANOS 3C 2.0 VANWAX H 2.0 HAF (N-330) carbon black 50.0 aromatic oil 10.0 Sulphur 0.5 MOFAX 1.9 TOTAL 172.4

NEOPRENE PADS: FORMULATION

NEOPRENE PADS: FORMULATION

Properties, cured 17 minutes @ 143C Hardness, shore A 62

Tensile, MPa(psi) 26(3750) Elongation,% 650

Density, Mg/m3 1.10

Tear strength, Die C, kN/m (pli) 68(390)

Compression set after 22 Hours@70C (158F)Method B, % Set 13

Methodology in preparing the

laminated bearing

Preparation of rubber compound- according to the right composition

Prepare the metal plate

Apply the bonding agent to the metal plate

Prepare the rubber compound and metal plate

Compression Moulding

Testing ( to test the quality and the properties)