International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 11, November 2017)
244
Design and Analysis of Multi Utility Vehicle Chassis
B Bhaskar
1, S Bala Subramanyam
2, G Kedarnath
31,2,3Assistant Professor in Mechanical Engineering & Gurunanak Institute of Technical Campus, Khanapur, Ibrahimpatnam,
Hyderabad, Telangana-501506, India
Abstract— Chassis of a vehicle usually refers to lower body
which consists of tires, frame, engine and suspension. Among these, Frame provides support to the components of vehicle. The frame of chassis consists of side members with a series connection of cross members. To locate critical regions that have higher stresses, finite element method is used. Improvements and changes in the design of the multi utility vehicle chassis were made to improve load carrying capacity of structure. As a part of improvement, thickness has been modified. Torsional, Bending and normal mode analysis were performed on the structure to find out stress and displacement by using OPTISTRUCT. SOFTWARES used CATIA, HYPERMESH and OPTISTRUCT. ACCEPTANCE CRITERIA for the first flexible mode of natural frequency is > 30HZ. Acceptance criteria for the bending stiffness is >3KN/mm. Acceptance criteria for torsional stiffness is > 4KN-m/DEG.
Keywords— Chassis, Catia, Hypermesh, Optistruct, Stiffness.
I. INTRODUCTION
Chassis refers to lower part of the vehicle body. Chassis consists of tires, frames, engine and suspension system attached to it. Among these frame provides support to the
components of the vehicle. Chassis consists of an internal
frame work that supports a manmade object in its construction and use.
Conventional chassis is a type of chassis in which the
body is made as a separate unit and then joined with ladder frame. It supports all the systems in a vehicle such as engine, transmission system, steering system, suspension system. Advantage of this type is higher load capacity and
strength. Disadvantage is the body tends to vibrate easily
and the overall vehicle handling and refinement is lower. Non conventional or frameless chassis type of chassis the ladder frame is absent and the body itself acts as the frame. It supports all the systems in a vehicle such as engine, transmission system, steering system and suspension system. Advantage of this type is less rattles and squeaks are developed and handling is better due to the higher body rigidity and weight. Disadvantage is the load carrying capacity is less and It is not safe in accidental condition.
Ojo Kurdi, Roslan Abdul Rahman studies the roughness of road and stress distribution effects of heavier body chassis. static and dynamic conditions were analysed using FEM software to lower or less cost and required design. load was expected as uniform pressure achieved from highest load weight divided by contact area. to achieve best result fine meshing applies in region allowed to have more stress.
[image:1.612.330.556.323.524.2]II. MATERIAL AND PROPERTIES
Figure 1 Original Finite Element Model & Material Data
[image:1.612.326.562.532.701.2]International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 11, November 2017)
245
After clicking on optistruct green button as shown above, based on the analysis methods it will solve the problem using finite element method. After getting job is completed successfully then we should click on hyper view for Post processing. There we can see the results like stress, strains and displacement by applied Force of 1500 N.The above description is about the inputs and procedure to solve the problem using RADIOSS.
Based on the torsional deflection, torsional
stiffness is determined as
Where M=F.W is the moment applied at the front suspension, resulting from two oppositely oriented forces F
Similarly, the bending stiffness is determined from
Where f is vertical force applied at the frontal suspension location
The stiffness properties of the Chassis are estimated for both the models the torsional and bending stiffness indicators are listed, as well as the approximation involved by the simplified model with respect to the original model. The results show that the bending stiffness of the original
Vehicle model is accurately Predicted by the model with the replaced simplified with new concept, while a significant discrepancy between the original and the simplified models is obtained for torsion. In the latter case, the stiffness of the full vehicle body is over estimated by 10.15%, which suggests that the definition of correction factors is indeed required.
Figure 3 Original FE model of the Chassis
The figure 3 shows the original finite element model of the Chassis component and also Appling force 4304N.
Base Model Torsion stiffness Analysis
[image:2.612.324.575.246.394.2]Two vertical forces, one on each spring tower, are acting in opposite direction. The forces act on rigid components which are corresponding to the upper connection of the wheel suspension. The rigid components are then bolted to the spring towers.
Figure 4 Force Applying the Chassis Vehicle
Front portion torsional load on spring towers to find torsion stiffness of the Chassis component applying the force is 4304N the back clamp is fixed and the force applied to the spring towers.
III. METHODOLOGY
Following Paragraphs describes the different
optimization objectives on different systems.
Second Modified Design has changed to meet the acceptance criteria
[image:2.612.53.284.558.691.2]For gauge optimization of chassis steps are mention below
Figure 5 Modified Chassis
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 11, November 2017)
246
For the same loading conditions torsion and bending stiffness analysis is carried out. The modified results are shown below for achieving the acceptance criteria. [image:3.612.69.271.198.312.2]Second Modified Model Torsion Stiffness Analysis Results
Figure 6 Deflection on chassis in torsion after modification
[image:3.612.328.565.326.465.2]Second Modified Model Bending Stiffness Analysis Results
Figure 7 Deflection on chassis in bending after modification
As per above formulas the torsion and the bending stiffness values are calculated for modified design of chassis.
The calculations are shown below for modified model.
Table 1
Comparison of results with acceptance criteria after modification
Acceptance Criteria
FEA Results
1st flexible mode natural frequency
> 30 Hz 30.16 Hz
Bending Stiffness
> 3 kN/mm 3.26 kN/mm
Torsion Stiffness > 4 kN-m/deg 5.9 kN-m/deg
IV. RESULTS
First Design Chassis Torsional Stiffness Results
Figure 8 Base Model Torsion Stiffness Analysis
[image:3.612.60.272.353.525.2]The figure 8 shows maximum displacement 12mm is the base model torsion stiffness analysis results .Base Model Torsion stiffness analysis is done using optistruct software.
[image:3.612.324.583.523.673.2]International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 11, November 2017)
[image:4.612.337.551.156.675.2]247
The figure 9 shows the maximum stress 305MPA for the base model torsion stiffness analysis.Figure 10 Base Model Torsion Stiffness Analysis
The figure 10 shows the maximum strain 0.001MPA is for the base model torsion stiffness analysis results using optistruct software. Torsional stiffness is calculated and compared with base model.
[image:4.612.49.300.168.315.2]First Design Bending Stiffness Analysis Results
Figure 11 Base Model Bending Stiffness Analysis Results
The figure 11 shows the maximum Displacement= 2.82mm of base model bending stiffness analysis results using by optistruct software.
First Design Free Modal Analysis Results
[image:4.612.54.275.404.543.2]International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 11, November 2017)
[image:5.612.325.563.138.291.2]248
Table 2 [image:5.612.65.282.157.352.2]Mode shape values
Table 3
Comparison of Stiffness values between First Design
The design does not meet the required acceptance criteria hence redesign the model.
Redesign Of Chassis
[image:5.612.58.288.370.515.2]Design Changes has been done for Chassis to match with given acceptance criteria:
Figure 13 Design changes have been done at two locations which are shown in above image
Following Paragraphs describes the different
optimization objectives on different systems.
Second Modified Design has changed to meet the acceptance criteria:
For gauge optimization of chassis steps are mention below
Figure 14 Modified Chassis
For the same loading conditions torsion and bending stiffness analysis is carried out. The modified results are shown below for achieving the acceptance criteria.
Mode Number Frequencies(Hz)
7 29.84
8 36.46
9 37.56
10 40.69
11 54.38
12 72.24
13 85.43
14 97.25
S.No Description Base
1 Torsional Stiffness
(KN-m/deg) 2.419
2 Bending Stiffness
(KN/mm) 2.75
3 Modal 29.84
Extra Cross member bracket is added
[image:5.612.328.517.414.522.2]International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 11, November 2017)
249
Second Modified Model Torsion Stiffness Analysis Results:
Figure 15 Deflection on chassis in torsion after modification
[image:6.612.64.273.158.363.2]Second Modified Model Bending Stiffness Analysis Results:
Figure 16 Deflection on chassis in bending after modification
As per above formulas the torsion and the bending stiffness values are calculated for modified design of chassis.
The calculations are shown below for modified model.
Table 4
Comparison of results with acceptance criteria after modification
Acceptance Criteria
FEA Results
1st flexible mode natural frequency
> 30 Hz 30.16 Hz
Bending Stiffness
> 3 kN/mm 3.26 kN/mm
Torsion Stiffness > 4 kN-m/deg 5.9 kN-m/deg
V. CONCLUSION
The objective of the analysis had successfully achieved in the area of improvement of torsion stiffness based on the result gained from the finite element analysis, further enhancement of the current chassis had been done through the chassis FE model in order to improve its torsional stiffness as well as reduce the vibration level. Series of modifications and tests were conducted by adding the stiffener in order to strengthen and improved the chassis stiffness as well as the overall chassis performances.
Table 5
Comparison of weight before and after modification
Before Modification
After Modification
Weight 124 kg 128 kg
1st flexible mode natural frequency
30.08 Hz 30.16 Hz
Bending Stiffness 2.2 kN/mm 3.26 kN/mm
[image:6.612.63.271.409.554.2]International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 7, Issue 11, November 2017)
250
REFERENCES[1] V. Veloso, H.S.Magalhaes, G.I. Bicalho , E.S. Palma. ―Failure investigation and stress analysis of a longitudinal stringer of an automobile chassis‖, Engineering Failure Analysis, Vol.16, PP 1696–1702, 2009.
[2] Ojo Kurdi, Roslan Abdul Rahman, ―Finite Element Analysis of Road Roughness Effect on Stress Distribution of Heavy Duty Truck Chassis‖, International Journal of Technology, Vol.1, PP 57-64, 2010.
[3] M.Ravi Chandra, S. Sreenivasulu, Syed Altaf Hussain, ― Modeling and structural analysis of Heavy vehicle chassis made of Polymeric composite material by three different cross sections‖, International Journal of Modern Engineering Research(IJMER), Vol.2, PP 2594-2600, 2012.
[4] K. Chinnaraj, M. Sathya Prasad, C. Lakshmana Rao, ―Experimental Analysis and Quasi-Static Numerical Idealization of Dynamic Stresses on a Heavy Truck Chassis Frame Assembly‖, Applied Mechanics and Materials, Vol.13-14, PP 271–280, 2008.
[5] Teo Han Fui, Roslan Abd. Rahman, ―Statics and Dynamics structural analysis of a 4.5 ton Truck chassis‖, Jurnal Mekanikal, Vol.24, PP 56-67, 2007.
[6] Vijaykumar V. Patel, R. I. Patel, ―Structural analysis of a ladder chassis frame‖, World Journal of Science and Technology, Vol.2, PP 05-08, 2012.
[7] N.K.Ingole, D.V. Bhope, ―Stress analysis of Tractor Trailer Chassis for self weight reduction‖, International Journal of Engineering Science and Technology (IJEST), Vol.3, No 9, 2011.
[8] Yongjie Lu, Shaopu Yang, Shaohua Li, Liqun Chen, ―Numerical and experimental investigation on stochastic dynamic load of a heavy duty vehicle‖, Applied Mathematical Modelling, Vol.34, PP 2698– 2710, 2010.