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FINAL DESIGN REPORT

SD EMINENTS

TEAM NO. 93

ABSTRACT

S.D Eminents BAJA SAE team was

tasked to design, build and test a final

prototype of a single seat, off-road vehicle.

The design objectives emphasized a more

compact and durable vehicle and high

performance design. The vehicle features

includes the following:

A continuously variable transmission with 2

speed gearbox

Smaller rear track width for better

manoeuvrability

Tilt wheel steering

The final prototype has shown an excellent off

road performance and will be a attractive

purchase for consumers.

INTRODUCTION

According to the common objective of

BAJASAE-2013, TEAM SD EMINENTS, the

SAE collegiate club team from SD Bansal

College of technology had to initially

formulate a virtual design of an All Terrain

Vehicle aimed at the weekend off-road

enthusiast at areasonable price point and alsofactor in themanufacturability and marketingaspects. We approached our design by

considering all possible alternatives for a

system and modelling them in CAD softwarelike Catia and PRO-E, to obtain a model with

maximum geometric details. The models were

than subjected to analysis using ANSYS FEA

Software. Based on analysis results the models

were modified and retested and a final design

was frozen. Theoretical calculations of

performance characteristics were also done.

As weight is critical in a vehicle powered by a

small engine, a balance must be foundbetween the strength and weight in the design.

To optimize this balance the use of solid

modelling and finite element analysis (FEA)

software is extremely useful in addition to

conventional analysis.

DESIGN OF VEHICLE

ROLL CAGE

Objective

The rollcage is designed to meet the technical

requirements of Baja SAE 2013 rules. Careful

design consideration included the frames

structural integrity, manufacture ability,

ergonomics and aesthetics.

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Figure 1 : Catia drawing of 2013 frame

Design Calculations

The material used for Rollcage is IS 1239 MS

was chosen for its well established properties

including weldability, favourable weight to

strength ratio. All joints/weldments were

fabricated by MIG (Metal Inert Gas) welding

process. All main rollcage structural members

including secondary members are having a

cross section with OD of 26.4mm with a wall

thickness of 3.2mm All bracing members are

of same specifications. In order to comply

with the requirement specified in Baja SAE

rules, a comparison is made with the

suggested material (AISI 1018).

Calculation for Bending Strength (IS 1239)

OD = 26.4 mm, Thickness = 3.2 mm

ID = 20 mm

(b) = SyI/c

5.381588

2.13

4^38.15990315

315

mm

mmMPa

c

IS

MPaS

y

y

Which is greater than the suggested materials

strength (As per formula provided in rulebook

2013 in section 3.6.2)

By comparison of the values we find that the

material used for rollcage has greater bending

stiffness and strength than then the minimum

requirement relating to size and properties of

1018 steel tubing. MIG welding is used to

fabricate the rollcage. The strength of weld

will be demonstrate by submission of test

sample as required by BAJA rules.

ANALYSIS

Aside from exceeding the minimum material

requirements set by rules, structural integrity

of the rollcage was verified by comparingrollcage analysis. Analysis was conducted by

using ANSYS FEA. Stresses were calculated

by simulating different induced load cases that

are frontal, side impact and rear.

Figure 2 : Deflection while frontal impact

PROPERTIES IS 1239 AISI 1018

Ultimate tensile

strength

480N/mm 418.8N/mm

Yield Strength 412.8 N/mm 375 N/mm

Elongation 18.5% 15%

Modulous of

Elasticity

2.9GPa 2.9GPa

Cost per 20 ft 740 760

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Figure 3 : Stresses during Frontal impact

The front impact simulation results for stressand displacement were 209 MPa and 4.5 mm

respectively.

Figure 4 : Deflection during rear impact

Figure 5 : Stresses during rear impact.

The rear impact simulation results for stress

and displacement were 205 MPa and 1.9 mm

respectively.

Figure 6: Deflection during Side Impact

Figure 7: Stresses during Side Impact

The side impact simulation results for stress

and displacement were 207 MPa and 4.3 mm

respectively.

Manufacturability

The design for manufacturability, ergonomics

and aesthetics for the rollcage are favourable

for its reproduction, serviceability and

comfort. The material selected IS 1239 is

readily available and malleable enough for

easy forming. The favourable formingcapabilities of the material used allows for

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more bends in the rollcage members thereby

reducing the amount of welding needed.

However, the use of proper techniques, the

frame is easily welded by 2 experienced

welders. The MIG Welding is widely used ineconomic welding of large volumes of weld

metal.

The roll cage, all bracing members and all

mounting members are designed to ensure all

components are easily accessible and

serviceable. The rollcage was also designed

with the drivers comfort and safety in mind.

As for safety in structural design, the frame

encloses the driver in a crush resistant pocketthat is protected from various loading

directions. For eg. Frame members are

designed to sustain considerable impact that

dissipate the force first then transfer the force

throughout the frame.

Aesthetics

Aesthetically, the rollcage design is

improved by the use of more roundedcorners. The unique use of rounded corners

allows for a more pleasing look to the

vehicles body. The lack of sharp edges on

the lower rollcage allows for the design of

more streamlined body panels which not

only look smoother, but may also have a

positive effect on the overall aerodynamic

drag forces.

DRIVE TRAIN

Objective

To create a two speed gearbox that would

flow seamlessly with the operation of our

CVT and 10 HP engine. This gearbox was

designed to be easily manufacture able,

rebuild able and maintainable for the average

consumer.

ENGINE

The gasoline IC engine with which we were

graciously provided by Briggs and Stratton 10

HP Intek engine. This engine has a horizontal

output shaft with a keyway which is used

to couple the transmission system.

CVT (Continuous Variable

Transmission)