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 · v∇ x = − ∂p/∂x + µ∇2 vx + ρgx

v · v∇ y = − ∂p/∂y + µ∇2 vy + ρgy

v · v∇ z = − ∂p/∂z + µ∇2 vz + ρgz

Sommerfeld Hydrodynamic Lubrication Journal Bearing Model

p – p0 =

W/L =

Characteristics of Journal Bearings Studied

• 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 Pap – 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

First Pressure Peak

Second 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.