SEMESTER PROJECT OF FEA

ANALYSIS OF BUSH BEARING USING ANSYS

SUBMITTED BY: MUHAMMAD ABDULLAH BEG

SUBMITTED TO: DR IRFANULLAH

Introduction:

Bush bearings are used to support long shaft. They are used in industries for bearing loads in any radial

direction.

Assumptions:

Thick film lubrication is considered in which a minimum film thickness ho is at an offset from the bottom

of the bearing. This occurs either at left or right side of the bottom depending upon the direction of

rotation of shaft. We here assume that the shaft is rotating in clockwise direction. In order to use

realistic loads examples from chapter “lubrication and journal bearing”, from Mechanical Engineering

Design by Shigley, are referred.

Loads considered:

Bearing load=W=1500lbf

Viscosity=µ=6µreyn

Shaft speed=N=40rev/sec

Radial clearance=0.0015in

Shaft radius=1-15/16=1.93in

Given data:

Model dimensions mentioned in the isometric view of drawing.

Calculations:

BUSH BEARING

Using the formulas and charts given in Mechanical Engineering Design by Shigley following values are

assumed for analysis

Nominal bearing pressure=P=w/2rl=129psi=0.89MPa

Sommerfeld number=S=(r/c)2(µN/P)=3

l/d=1.5

From figure 12-21,

P/pmax=0.6

pmax=215psi=1.48MPa

From figure 12-17 and 12-22,

Position of minimum film thickness=ø=800

Terminating position of film θp0=1350

Position of maximum film pressure θpmax=300

Analysis:

In order to simplify the analysis and minimize the analysis time the problem is solve using a plane. The

plane is copied from the model in such a way that only required details are included in it.

Element type:

Plane42 is the element type used for analysis. It’s a 2D plane element. The element can be used either

as a plane element (plane stress or plane strain) or as an axisymmetric element. The element is defined

by four nodes having two degrees of freedom at each node: translations in the nodal x and y directions.

Real constant:

The only real constant required in the analysis is the depth of plane which is equal to the depth of

bushed bearing.

Material properties:

The material of the bush is taken as gun metal whose properties are as follow:

E=103.42MPa ; Poisson ratio=0.37

Loading:

Since the bush is press fit into the bearing casing, in order to represent this constrain the circular surface

of the bearing casing is constraint in x and y direction. The pressure loads are applied on the nodes that

are on the periphery of bearing surface and within the positions determined by the calculations. The

pressure loads are shown as red line in the following figure.

1

12

X

Y

Z

JUN 29 2009

09:20:04

NODES

U

PRES-NORM

1.18

Solution:

After applying loads the problem was solved in the solution section.

Results:

After solving the problem the nodal elongations and von mises stresses are checked in general

postprocessper. Maximum stress is 1.398MPa. Maximum elongation is 0.27mm. The graphical results

obtained from Ansys® are shown on next page.

BEARING LOADING

VON MISES STRESS

BEARING ELONGATION

1

MN MX

12

X

Y

Z

0

.030101.060201

.090302.120403

.150504.180604

.210705.240806

.270907

JUN 29 2009

09:18:47

NODAL SOLUTION

STEP=1

SUB =1

TIME=1

USUM (AVG)

RSYS=0

DMX =.270907

SMX =.270907

1

MN

MX

12

X

Y

Z

.160E-04

.155309.310603

.465896.621189

.776483.931776

1.0871.242

1.398

JUN 29 2009

09:18:08

NODAL SOLUTION

STEP=1

SUB =1

TIME=1

SEQV (AVG)

DMX =.270907

SMN =.160E-04

SMX =1.398