AUTOMOTIVE

TRANSMISSION

SYSTEMS PROJECT

TITLE Stress analysis of a rear

axle.

By: Akshay Singhvi 10BMA0059 Kartik Kabra 10BMA0026 Sagar Bhatt 10BMA0061 Siddharth Negandhi 10BMA0043

ABSTRACT: An axle is central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be

fixed to the wheels, rotating with them, or fixed to its surroundings, with the wheels

rotating around the axle. In any case, axle is one of the most important parts of a vehicle. [2,

3]

Simulation is carried out in 3 stages. First stage of the analysis is a forming simulation i.e. the

CAD, followed by service load simulation in second stage. The third stage is for fatigue

simulation.

Stress analysis was done on a given rear axle using ANSYS software. The modelling was done

in SolidWorks software.

Simulation results are validated by comparing them with the reference work.

The axle used in this report is a Ford 9 inch rear axle.

INTRODUCTION:

Axle is a very important load carrying component of the vehicle. It experiences many types of loads

during its operation. It must be able to endure such load and operate under such conditions. There

are two types of axles:

Fixed axle: axle that does not rotate with the wheel.

Rotating axle: axle that rotates with the wheel.

Now, the main load acts on the axle housing. It is vital that the housing resist against failure for

the predicted service life.

The forces acting on the rear axle are:

Longitudinal forces: It acts vertically downwards on either side of the differential case. It is a

result of the weight of the car and the additional load that the vehicle maybe carrying

(including passengers)

Lateral forces: It is the result of the reaction force from the drive shaft when the brakes are

applied or a pull force when the vehicle starts.

Torque reaction: It is the torsional reaction generated through the drive shaft and the

torque generated through the braking action on wheels.

CAD:

The CAD was made in SolidWorks 2012-2013.

The material was chosen as grey cast iron during CAD modelling.

MATERIAL PROPERTIES:

Gray Cast Iron

Density 7200 kg m^-3

Coefficient of Thermal Expansion 1.1e-005 C^-1

Specific Heat 447 J kg^-1 C^-1

Thermal Conductivity 52 W m^-1 C^-1

Resistivity 9.6e-008 ohm m

Gray Cast Iron > Compressive Ultimate Strength

Compressive Ultimate Strength Pa

8.2e+008

Gray Cast Iron > Compressive Yield Strength

Compressive Yield Strength Pa

0

Gray Cast Iron > Tensile Yield Strength

Tensile Yield Strength Pa

0

Gray Cast Iron > Tensile Ultimate Strength

Tensile Ultimate Strength Pa

2.4e+008

Gray Cast Iron > Isotropic Secant Coefficient of Thermal Expansion

Reference Temperature C

22

Gray Cast Iron > Isotropic Elasticity

Temperature C Young's Modulus Pa Poisson's Ratio Bulk Modulus Pa Shear Modulus Pa

1.1e+011 0.28 8.3333e+010 4.2969e+010

Gray Cast Iron > Isotropic Relative Permeability

Relative Permeability

10000

STRESS ANALYSIS:

The stress analysis on the axle was done in ANSYS 13 software. The loads on the axle were: the

normal stress due to the weight of the vehicle and a reaction force from the propeller shaft due to

sudden stopping of the vehicle.

The Ford 9 inch axle is an axle for small cars, hence we assumed the load to be 1000 Kg evenly

distributed as 5000N on each side of the differential case.

Then the stopping force was calculated assuming the velocity of the car to be 60 Km/h and stopping

distance to be 15 m. This force came out to be 9269 N which stopped the car in 1.78 s.

The CAD after being imported into ANSYS:

Meshed rear axle:

The loads described above were applied as follows:

A and B: equal forces of 5000 N evenly distributed on the surface.

C: Reaction force of 9269 N

D: Fixed support on both sides. (Assuming wheels as fixed support)

DETAILS OF THE GEOMETRY:

RESULTS:

The results of the analysis were:

Object Name

Maximum Principal Stress

Equivalent Stress

Total Deformation

Strain Energy

Structural Error

Results

Minimum -4.0392e+006 Pa 0. Pa 0. m 0. J

Maximum 1.3602e+007 Pa 1.148e+007 Pa 1.0944e-004 m 1.2004e-003

J 3.3276e-004

J

Bounding Box

Length X 0.28765 m

Length Y 0.28448 m

Length Z 1.0846 m

Properties

Volume 1.1626e-002 m³

Mass 83.706 kg

Scale Factor Value 1.

Statistics

Nodes 26077

Elements 13599

Mesh Metric None

Following were the contours generated:

Maximum principle stress:

Von-misses stress:

Total deformation:

Structural error:

Strain Energy:

Now, let us examine the critical points of the model, i.e. at the corners where structural failure might

occur due to high stress:

Max. Principle Stress Von misses stress

Now, following result was obtained for Mean Stress Theory for Googman, Soderberg and Gerber

equations:

CONCLUSION: Maximum deformation was found out in the analysis

Stress concentrated regions were predicted

Critical regions with high possibility of damage were determined

Increasing the thickness of crumples zones can be one of the solution

Reinforcement rings can be used in order to enhance the strength