Seminar Presentationon

Stress Analysis of a heavy duty vehicle chassis by using FEA

Prepared by

SUNIL RATHOD (MM15M12)

• Contents

1. Introduction

2. Different types of automobile chassis

3. Typical heavy duty vehicle chassis

4. Methodology

5. Stress analysis of chassis

6. Results and Discussions

7. Conclusion

8. References

• Introduction

• Importance of chassis in vehicle

The chassis frame forms the backbone of a heavy vehicle, its principle function

is to safely carry the maximum load for all designed operating conditions.

• Design constraints for chassis

Stresses and Deflections are the design constraints for chassis.

• Different types of automobile chassis

• Ladder Chassis: This is considered to be one of the oldest forms of automotive

chassis and used by most of the SUVs till today. As its name ladder chassis resembles

a shape of a ladder having two longitudinal rails inter linked by several lateral and

cross braces.

 

• Monocoque Chassis: This is a one-piece structure that prescribes the overall shape of

a vehicle. This type of chassis is manufactured by welding floor pan and other pieces

together. Since this is cost effective and suitable for robotized production, most of the

vehicles today make use of steel plated monocoque chassis.

 

• Backbone Chassis: It has a rectangular tube like backbone, usually made up of glass

fibre that is used for joining front and rear axle together. This type of chassis is strong

and powerful enough to provide support smaller sports car. This is easy to make and

cost effective.

Typical heavy duty vehicle chassis

• Methodology

• Stress analysis of chassis

• Modeling

Full scale model of heavy vehicle chassis in CATIA

• Finite element analysis

The safety and the strength of chassis are important issues for the chassis structure. To meet these requirements, it is essential to perform a static analysis on the chassis. Static analysis was done using finite element method as it is an effective and efficient approach. The analysis was performed based on following assumptions:-

1. The maximum design of payload for the chassis structure during application is

approximately 350kN.

2. The total load is distributed over the contact surface on chassis structure.

• Material Selection

The material for the chassis structure is ASTM Low Alloy Steel A 710 C (Class

3).Modulus of

elasticity E (Gpa)Poissons Ratio Yielding strength, (MPa) Ultimate tensile strength, (MPa)

210 0.3 550 620

• Meshing

When the material properties are given the geometry of wheel is imported from

CATIA software to ANSYS 12.1. After importing the model the meshing of the chassis is

carried out the meshing consist of 31559 elements and 32194 nodes.

• Loading

The force that has been imposed downward to the structure model. The load

is distributed uniformly along contact surface area. The total load of 350KN is applied

on the whole body of chassis uniformly as shown in fig.

Loading distribution on chassis

• Results & DiscussionsAs the analysis is carried out from the ANASYS 12.1 the results are generated.

There is some critical regions and areas where the stresses and deflections are maximum.

It is observed that the maximum deflection is pointed in situated in between BC1 and

BC2.

Stress distributions on chassis

As shown in above fig the value of equivalent von moises stresses variation the

maximum von moises stress acting on the chassis is 200.67 MPa

Deformations of Chassis

As the fig shows the deformation variations, the maximum deformation shown in

fig is 8.15mm and it is in the middle of the chassis between BC1 and BC2.

As the stresses and deformations are maximum there is some modifications

required for the structure of the chassis so that these stresses and deformations should be

minimized. As we increase in web height, thickness of frame can be reduced with this

relation we can decrease the stresses and deformations in chassis. Modification of cross

section of chassis frame member is made in three different cases. The inside fillet radius is

also increased by 2 times than the thickness of the cross section. Also the stresses on the

side member can be reduced by increasing the side member thickness locally. If the

thickness change is not possible, increasing the connection plate length may be a good

alternative. By using this technique we can reduce the value of stresses and deformation of

chassis.

• Conclusion

Hence in this seminar work I have studied the importance of chassis in

vehicle, various design constraints of chassis. The methodology that how to carry out

the finite element analysis of chassis and complete stress analysis procedure. The

complete chassis analysis is carried out by using ANSYS 12.1 and hence results

generated from this analysis shows the areas or regions of chassis which are critical

where maximum stresses acting, and regions where deformations are maximum are

find out and to reduce the stresses and deformations of chassis at critical point and to

increase the life of the chassis of heavy duty vehicle various design enhancement

solutions will be applied.

• References

1. A. Rahman, R., Tamin, M. N., Kurdi, O., 2008, “Stress Analysis of Heavy Duty Truck Chassis using Finite Element Method,” Jurnal Mekanikal, No 26, 76-85.

2. Ingole, N. K., Bhope, D. V., 2011, “Stress analysis of tractor trailer chassis for self weight reduction,” International Journal Of Engineering Science and Technology (IJEST), Vol.3 No. 9.

3. Mohd Azizi Muhammad Nora, Helmi Rashida, Wan Mohd Faizul Wan Mahyuddin, Mohd Azuan Mohd Azlanc, Jamaluddin Mahmud “Stress Analysis of a Low Loader Chassis” International Symposium on Robotics and Intelligent Sensors 2012 (IRIS 2012).

4. Sane, S. S., Jadhav, G., Anandraj, H., 1955, ” Stress Analysis of Light Commercial Vehicle Chassis by FEM”,Piaggio Vehicle Pte.Ltd pune.Stress Analysis of Heavy Duty Truck Chassis using Finite Element Method,” Phil. Trans. Roy. Soc. London, vol. A247, pp. 529–551.

5. Roslan Abd Rahman, Mohd Nasir Tamin, Ojo Kurdi “Stress analysis of heavy duty truck chassis as a preliminary data for its fatigue life prediction using FEM” Jurnal Mekanikal December 2008, No. 26, 76 - 85

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