1. 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

2. Wear in Journal Bearings

3. Steady Laminar Flow of a Newtonian Fluid: Governing Equations ∂v x /∂x + ∂v y /∂y + ∂v z /∂z = 0 v · ∇ v x = − ∂p/∂x + µ ∇ 2 v x + ρg x v · ∇ v y = − ∂p/∂y + µ ∇ 2 v y + ρg y v · ∇ v z = − ∂p/∂z + µ ∇ 2 v z + ρg z

4. Sommerfeld Hydrodynamic Lubrication Journal Bearing Model

5. Characteristics of Journal Bearings Studied Sleeve radius r s (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 ( o F) = 50 – 150 Viscosity μ (Pa s) = 0.3 Density ρ (kg/m 3 ) = 900

6. Finite element Model Validation: Baseline Journal Bearing p – p0 (Sommerfeld Solution) = 6473 Pa p – p0 (Finite Element Solution) = 6500 Pa

7. Modeling Journal Bearing Wear Smearing and Flaking Scars

8. Computed Pressure versus Smearing Wear Scar Location (90 o vs 150 o )

9. Peak Pressure Locations First Pressure Peak Second Pressure Peak

10. Maximum Pressure vs Smearing Wear Scar Location

11. Load Carrying Capacity vs Smearing Wear Scar Location

12. 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.