Transcript Desjardins.pptx

FINITE ELEMENT MODELING OF THE EFFECT
OF WEAR ON THE LOAD-CARRYING
CAPACITY AND MAXIMUM OIL PRESSURE OF
A PLAIN JOURNAL BEARING
Marc Desjardins and
Ernesto Gutierrez-Miravete
Rensselaer at Hartford
Wear in Journal Bearings
Steady Laminar Flow of a Newtonian
Fluid: Governing Equations
∂vx/∂x + ∂vy/∂y + ∂vz/∂z = 0
v · ∇vx = − ∂p/∂x + µ∇2 vx + ρgx
v · ∇vy = − ∂p/∂y + µ∇2 vy + ρgy
v · ∇vz = − ∂p/∂z + µ∇2 vz + ρgz
Sommerfeld Hydrodynamic Lubrication
Journal Bearing Model
p – p0 =
W/L =
6 𝑉 𝑟 ε sin θ (2+ε cos θ)
𝑐2 (2+ε2 )(1+ ε cos θ)2
12 π μ 𝑉 𝑟2
ε
𝑐2
(2+ε2 )√(1−ε2)
=0
=0
Characteristics of Journal Bearings Studied
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Sleeve radius rs (mm)
= 100
Journal (shaft) radius r (mm) = 98
Offset in the x-direction (mm) = 1.0
Eccentricity e (mm)
= 1.0
Radial clearance c (mm) = 2.0
Eccentricity ratio ε = e/c = 0.5
Rotation Speed N (rpm) = 60 - 130
Temperature (oF) = 50 – 150
Viscosity μ (Pa s) = 0.3
Density ρ (kg/m3) = 900
Finite element Model Validation:
Baseline Journal Bearing
p – p0 (Sommerfeld Solution) = 6473 Pa
p – p0 (Finite Element Solution) = 6500 Pa
Modeling Journal Bearing Wear
Smearing and Flaking Scars
Computed Pressure versus Smearing
Wear Scar Location (90 o vs 150 o)
Peak Pressure Locations
Second Pressure Peak
First Pressure Peak
Maximum Pressure vs Smearing Wear Scar
Location
Load Carrying Capacity vs Smearing Wear
Scar Location
Conclusions
• The amount of influence a single wear site can have
on a plain journal bearing depends on its location
relative to the maximum pressure location of the
same journal bearing without wear.
• The wear location site relative to the maximum
pressure location of the bearing without wear (φ =
132°) seems to be an important parameter affecting
the bearing’s performance.
• Wear sites downstream of this maximum pressure
location cause an abrupt and severe decrease in
load-carrying capacity.