Laminated Rubber Bearings, Heavy Duty Composites for Aerospace and Undersea
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Laminated Rubber Bearings, Heavy Duty Composites for Aerospace and Undersea

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Developed the concept of high-load rubber laminate bearings and the first application for helicopter blade retention in place of ball or roller bearings. LAMIFLEX Bearing-Seals for underwater hermetic ...

Developed the concept of high-load rubber laminate bearings and the first application for helicopter blade retention in place of ball or roller bearings. LAMIFLEX Bearing-Seals for underwater hermetic shaft seals are a more recent innovation.

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    Laminated Rubber Bearings, Heavy Duty Composites for Aerospace and Undersea Laminated Rubber Bearings, Heavy Duty Composites for Aerospace and Undersea Presentation Transcript

    • Laminated Rubber BearingsHeavy Duty Composites for Aerospace andUndersea
    • Laminated Rubber Bearings (Elastomeric Bearings)• Composite of elastomer and metal layers• Support massive structures -Permit thermal expansion -Isolate bulidings from earthquakes -Big, maybe 1/2 inch thin• Small & dynamic -Helicopters -Undersea
    • (Seen from above,moving up on picture)
    • Heavy Duty for a Thrust Bearing • Tons of CF while oscillating +/- a few degrees • Early failure of ball / roller bearings -spalling, fretting corrosion A New Idea was needed --- Laminated Rubber Bearings
    • (Seen from above,moving up on picture)
    • Laminated Rubber / Elastomeric Bearings•Easily handle tons of CF•Oscillate at high frequency•No lubrication•NR for high resilienceUsed on most helicopters now
    • Enstrom – First with Elastomeric Bearings
    • Enstrom Bearing Design • 2-1/4" in diameter • More than100 rubber & brass layers each • All layers 0.002” thick • 18,000 lbs. CF
    • Small Wind Turbines • Blade pitch angle variable with wind • Increase efficiency
    • Compression Very Slight• At 10,000 psi pressure on bearing - thinner by a few sheets of paper - about .010 of an inch• Rubber layers can’t squeeze out - because rubber layers are very thin -only .002 of an inch thick• Compression due to volume decrease
    • One-inch Square Laminate Pads • 40 layers .002’ brass • 39 layers .002” NR • Bendable • RIGID
    • • RRC specializes in laminates with very thin layers• Small helicopters• Chemical bond of NR to hi-tensilebrass• Lack of adhesive reduces thickness• Larger helicopters use thicker, fewer layers
    • Planar & Chevron• Planar - angular oscillation & lateral movement - easier to make – no metal forming• Chevron - precludes lateral shifting - permits taller bearing for given load
    • Conical• Combined radial & thrust loads• Angular motion about axis
    • Cylindrical (Radial) Bearing • Circular & axial motion • Wrapped around shaft • Axial thermal expansion of shaft • Silicone rubber for heat
    • Spherical Bearings• 3D angular motion about center - rotation about longitudinal axis - tilting L/R and in/out of screen
    • Helicopter Spherical Bearing • Many large helicopters • Ordinary pitch oscillation • Also lead-lag & flapping
    • Design Factors• Diametral dimensions• Height• Load forces• Torsional stiffness• Oscillatory torsional shear strain• Fatigue life• Angular range.
    • Some Relationships• Torsional Stiffness - prop. to 4th power of diameter - inverse with height• Torsional Shear Strain for given angle - prop. to diameter - inverse with height• Fatigue Life - Max oscillatory torsional shear strain - internal pressure - other factors
    • Bearing-Seals• A more recent development by RRC• New design opportunities for undersea craft
    • Undersea Bearing-Seal It’s the same thing!-An ordinary laminated rubber bearing - Top and bottom enclosed•Circular body makes a hermetic seal - Seawater outside cant penetrate - Solid barrier around central hole
    • Undersea Bearing-Seal It’s the same thing!• Seals against immense pressure -tested to 17,000 psi• No flimsy sliding surfaces like lip or face• Immune to sand and grit• Torque remains constant with depth
    • What can we do with a bearing-seal?• Suppose we have a pressure vessel - like a submarine• And suppose we want to have a sealed shaft that extends from the inside of it to the outside - like a diving plane shaft• We can do that with a bearing-seal.
    • AUV• Small autonomous robotic submarine• Looks like a torpedo, but leisurely• Loaded with sensors - pressure, temps, sonar, guidance• Pre-programmed for a mission over area• Military, Scientific, Offshore Oil & Gas - mine-hunting for the Navy - sensing ocean variables - inspect underwater oil & gas pipelines.
    • Application of Bearing-Seals• Mount & seal external hydrofoils that can control AUV: - direction by rudder - climb/descent by diving planes• Even “fishtail” propulsion - swivelling tail fin back & forth• Advantage of actuation in air environment - low cost, off shelf actuators - no worries about seawater corrosion
    • Typical Bearing-Seal • OD = 2.06", ID = 1", ht. = 1/2“ • 80 hi-tensile brass + 78 natural rubber layers, both .002" thick • 10,000 psi water pressure outside • +/- 15 degrees for 1,000,000 cycles • Also cycled at max sea depth, 17,000 psi
    • Bearing-Seal application similar to helicopter use• Bearing - as well as hermetic seal• Angular movement/oscillation +/-15 degrees• High force -intense hydrostatic pressure instead of centrifugal force• Millions of cycles
    • Laminated Rubber Bearing Technology• Simplicity• Low cost• No lubrication• Reliability• Long life For vehicles thatProbe the sky and depths of the sea