International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-3, Issue-2, December 2013

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Abstract— This study aims to design of an All-Terrain Vehicle

(ATV) in accordance with the SAE BAJA 2014 rule book. A detailed designing of components is carried out like Roll cage, Suspensions & Braking mechanism. The main focus of our was on Safety of driver & Stability of vehicle. Roll cage of our vehicle is designed in such a way that in case of rolling of vehicle (mostly occurs in high speed turns & off roading) that it will provide double the strength to the roll cage with also considering the Aesthetic of the cage. International standards are followed by us where ever possible and an extensive market survey is also done. Finite Element Analysis is carried out on roll cage & braking mechanism for optimum safety & reliability of the vehicle. Engine the heart of an automobile is installed in such a way that it can perform well for an extensive time on any terrain.

Index Terms—Cooling duct, Ergonomics, Finite element Analysis & Von misses stress.

I. INTRODUCTION

The objective of the study is to design a safest vehicle for driver. The roll cage is being strictly designed in accordance with SAE BAJA 2014 rule book. 3D Assembly of whole vehicle & Line model of the roll cage is modelled in PTC Creo 2.0. Finite element analysis (FEA) is carried out on line model of roll cage in cases of front collision, rear collision, rolling, front bump & Rear bump analysis in Ansys. FEA of suspension arms was carried out in Catia & FEA of Braking mechanism in Solidworks. Based on the result obtained from above tests the design is modified accordingly.

The Centre of Gravity was tried to keep in middle of the vehicle & closest to the ground for optimum stability. The length of the vehicle was kept small so as to reduce weight and maintain a desired center of gravity, while the width of the vehicle was keep the most to maintain stability in turns.

II. ROLL CAGE DESIGN & ANALYSIS

Design of a roll cage consists of numerous factors like material selection, pipe size selection, frame design and finite element analysis. These each steps are elaborated further.

A. Material Selection

As per the rule book constraint there should be at least 0.18% of carbon content in metal. Our initial step was to conduct a market survey to have an idea of the availability of the material.

Based on market survey we have chosen following material namely:-

Manuscript received December 2013

Harsh Raghuvanshi, Mechanical department, Echelon Institute of Technology, Faridabad (Haryana), India.

N.S. Ramnaveen, Mechanical department, Echelon Institute of Technology, Faridabad (Haryana), India.

Puneet Malhotra, Mechanical department, Echelon Institute of Technology, Faridabad (Haryana), India.

Rakshit, Mechanical department, Echelon Institute of Technology, Faridabad (Haryana), India.

Anurag Khatri, Mechanical department, Echelon Institute of Technology, Faridabad (Haryana), India.

• AISI 1020 • ASTM A 106 Grade B • IS 2062

A comparative study of the chosen material was done for our use. The methodology for material selection followed by us are as follows.

Consideration Priority

Availability Necessary

Carbon Content Necessary

Strength High

Cost High

Weight Necessary

On above factors these three material where compared the final selection of the material are as follows on basis of carbon content, tensile strength, yield strength & density.

Name Carbon Content

Tensile Strength (MPa)

Yield Strength (MPa)

AISI 1020 0.20% 394.7 294.8

ASTM A 106 Grade B

0.30% 415 240

IS 2062 0.22% 410 240

On the above comparison ASTM A 106 Grade B was

selected. The properties of this material are Density (x 1000 kg/m3) 7.7-8.03

Poisson’s ratio 0.27-0.30

Elastic Modulus (GPa) 190-210

Tensile Strength (MPa) 415

Yield Strength (MPa) 240

Elongation (%) 20

Reduction in Area (%) 48

Hardness (HRB) 100

B. Pipe Size Selection

We were having a constraint in selection of size for secondary members of the frame that the minimum wall thickness should be 0.89 mm (0.035 in) and min outside diameter should be 25.4 mm (25.4 in).

To select a standard pipe size we followed ASME B36.10M which is an international standard for welded and seamless wrought steel pipes.

Identification [Standard (STD), Extra-Strong (XS), Strong (XXS)]

Outside Diameter (mm)

Wall Thickness

(mm)

XS 26.7 (Secondary

Member) 3.91

XS 21.3 (A-arms) 3.73

C. Frame design

The crucial objective of the frame is to provide a safe driving environment to the driver keeping in mind the weight,

Innovative Design of an All-Terrain Vehicle (ATV)

Harsh Raghuvanshi, N.S. Ramnaveen, Puneet Malhotra, Rakshit, Anurag Khatri

Design & Analysis of an All-Terrain Vehicle (ATV)

152

space & cost. Roll cage was designed in such a way that it should withstand driver weight, bump loads, engine and transmission load. It was also required to keep a minimum clearance of 3 in between driver & roll cage members. Pedals of brake & accelerator were installed at the extreme front position so as to reduce the length of the roll cage from front and give that extra length to rear which results in sustaining the center of gravity in the middle of the vehicle. Our main focus was also to provide a better viewing angle to the driver so we opt for a curved front members of the roll cage. This curved member also provide support to the roll cage in case of rolling.

After fulfilling the all the given constraints in the rule book a 3D model was designed.

Fig 1. Modelled frame

Our design methodology in designing a roll cage were

some parameters on which certain priorities were listed. A table representing such parameters with priority & reason is shown

S.NO CONSIDERATI

ON

PRIORITY

REASON

1 Light Weight

Necessary

A light weight Buggy is fast

2 Meet

Requirements

Essential

Must not deform during rugged

driving

4 Simple Frame

Essential

Majority of frame fabrication done in

College

5 Attractive Design

Desired

Easier to sell an aesthetically

pleasing vehicle

6 Cost

Low

Car needs to be within budget

7 Manufacturability

High

Manufacturing is

done in the College

D. Analysis results

After completion of design of the roll cage we need to find that our roll cage will perform well in field so we performed analysis in Ansys.

Fig 2. Roll over analysis (Von misses stress= 97.93 MPa)

Fig 3. Front impact Analysis (Von misses stress= 42.9 MPa)

Fig 4. Rear impact Analysis (Von Mises stress= 53.79 MPa)

International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-3, Issue-2, December 2013

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Fig 4. Front bump Analysis (Von Mises stress= 14 MPa)

Fig 6. Front impact Analysis (Von misses stress= 37.9 MPa)

In Ansys maximum Von mises stress is calculated and is

represented by colour coding. These stresses are evaluated to find the factor of safety &

certain remarks were given.

E. Conclusion

� Hence for design purposes force is taken to be 7000N. � Also, design output is for no plastic deformations. The

vehicle should remain in the elastic region. � The Safety of the driver in case of crash is taken care of

by safety equipment which includes special helmets, foam padding on bars and seat belts.

� The Design Factor of Safety, FS d is taken as 2. This

relatively high value is taken to account for the

uncertainty in the nature of forces.

III. SAFETY CONSIDERATION

Fig 7. Similar Curvatures

• Curved FBM (Front Bracing Members) & RRH(Rear Roll Hoop)

• A five point racing harness

• Two Kill switches are used in supporting rod of steering column and behind the firewall

• Other important safety equipments such as brake light, Reverse light, reverse alarm and fire extinguisher

• Dual Pipe Front bumper • Under Seat Member (USM) • Wide exit • Casings are done between steering and FAB (Fore/Aft

Bracing) • A minimum of 6 inch vertical distance from driver’s

head to the bottom of RHO(Roll Hoop Overhead members) and a 3inch clearance between body and roll-cage.

• Better stability due to less distance b/w roll center and C.G

IV. ERGONOMICS

� Outward bend of FBM gives large front vision to Driver � Firewall at 12 degree gives good seating posture to

Driver � SIM are made low for the ease of egress � Auto centrifugal clutch � Gear shifter on left side � Dashboard inclination � Rotor coil starter above the shoulder � Side mirrors

V. COOLING DUCT

Due to position of the Air cooled engine (Behind firewall) there was no means of air striking the engine. We decided to place an Air deflecting duct at side of our roll cage.

S.NO

TEST Force Applied

Factor of Safety

Result Remark

1 Roll over Analysis

7000N

2.14 No Yielding

Slight tilt in RHO and effect on FBM

2 Rear Impact Analysis

7000N

3.9 No Yielding

Safe and impact is taken by LSM

3 Front Impact Analysis

7000N

4.89 No Yielding

Safe and impact is taken by LSM

4 Front wheel Bump Analysis

1500N

15 No Yielding

Bump is taken by FAB

5 Rear wheel Bump Analysis

1500N

6 No Yielding

Bump is taken by rear bracing

Design & Analysis of an All-Terrain Vehicle (ATV)

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Fig 8. Cooling duct

This duct was having bigger inlet section (A1) & smaller outlet section (A2) to accelerate the air.

Area of input section (A1) =11542.75 mm2 Area of output section (A2) =7310.11 mm2 Input velocity (max. air velocity) (V1) = 50 km/hr

A1 * V 1 = A2* V 2, 11542.75 *50 =7310.11 * V2

V2 =78.95 km/hr Output Velocities at different speeds

Sr. No V1

(km/hr)

A1/ A2 V2

(km/hr)

1 15 1.579 23.69

2 25 1.579 39.48

3 40 1.579 63.16

4 50 1.579 78.95

VI. SUSPENSION

Due to functioning of vehicle in all terrains, the suspension should be robust. The methodology followed by us is.

A. Design Selection

Fig 9. Suspension system

• We have selected Double Wishbone suspension for the front and rear to reduce the unsprung weight and get a maximum camber gain during cornering.

• Design Arms controls the motion of the wheels throughout the suspension travel and controls the wheel alignment parameters, like Caster angle camber angle, toe, roll center height and scrub radius.

Fig 10. Caster angle Determination: 5.12 degree

Fig 11. SAI angle Determination: 8 degree

Front Suspension Double Wishbone Suspension (Unequal arms)

Rear Suspension Double Wishbone Suspension (Unequal arms)

Camber 1-2 degree (NEGATIVE) Caster 5 degree (POSITIVE)

Steering Axis Inclination Angle 8 degree

Scrub Radius 90 mm

Length of A-arm (Front) 14 inch

Length of A-arm (Rear) 9 inch

Roll center Height (Front) 111mm(from ground)

Roll Center Height (Rear) 240mm (from ground)

Shock Absorber Hydraulic Remote Reservoir

Center of gravity (FROM REAR LEFT CORNER)

X axis- 667mm Y Axis-300mm Z Axis-217mm

International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-3, Issue-2, December 2013

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Fig 12. Front A-arms Analysis (Von Mises stress= 3.47*106

N/m2)

Fig 13. Knuckle Analysis (Von Mises stress= 5.13* 106 N/m2)

VII. BRAKING SYSTEM

The methodology followed by us in designing of braking system is as follows.

On the above factors we decided to install a hydraulic disc

brake for all four tires. .

A. Specification

PEDAL RATIO : 6:1 PEDAL EFFORT : 75lbs MASTER CYLINDER BORE : ¾” CALLIPER BORE SIZE : 0.12’’ TIRE SIZE : 21’’ ROTOR SIZE : 9.5’’

B. Calculation

Braking torque (front) : 8278.76N Braking torque (rear) : 17857.83N Stopping distance : 11.19M Frictional force (front) : 31.04N Frictional force (rear) : 66.95N Vertical forces : 280N

C. Braking layout

Fig 14. Braking layout

D. Analysis

Fig 15. Braket (Von mises stress= 38.8 MPa)

CONSIDERATION

PRIORITY REASON

Simplicity Essential This is a main goal of the team

Light Weight

Essential To minimize the sprung weight

Shock Absorbing

Essential Frontal impacts cause a heavy amount of damage to the car

Side Impact Desired Must be able to handle uneven

impacts from all directions

Compatibility with

Steering

High The suspension geometry determines the geometry of

the steering Wheel

Alignment Parameters

High Reduce tire wear and ensure that vehicle travel is straight

and true

S.NO CONSIDERATION PRIORITY 1 WEIGHT OF THE

VEHICLE MINIMUM

2 COST OF THE VECHICLE

MINIMUM

3 BRAKING TORQUE HIGH 4 CLAMPING FORCE HIGH 5 THERMAL

CAPACITY HIGH

6 AVAILABILITY EASILY AVAILABLE

Design & Analysis of an All-Terrain Vehicle (ATV)

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Fig 16. Pedal (Von mises stress= 78.19 MPa)

VIII. STEERING

Consideration Priority Reason Simple design High Easy to repair

Light Weight Essential Minimize weight to

maximize power to weight ratio

Low Steering Ratio

Essential Quick Steering

response Ackerman

Geometry High

Reduction in tread wear of wheel

Less turning radius

High Consumes less time

& take lesser space On above criterion we selected Manual Rack & pinion

system. Design Specification

Terminologies Approximate Values Turning Radius 11 Feet

Steering Axis Inclination 8’’ Front Steering ratio 17:1

Scrub radius 76 mm

IX. TRANSMISSION

Engine mounting : Tranverse Engine coupling : Key coupling

Fig 17. Drive Train Specification

Gear Ratio

Torque (N-m)

R.P.M Vehicle Speed (km/hr)

Tractive

Effort(N) 4.6 86.25 825.944 12.1638 2208.226

2.733 51.1875 1391.702 20.4959 1311.9744 1.67 31.3125 2275.057 33.5052 808.6821 1.115 20.906 3407.526 50.1827 535.2548 8.05

(Reverse) 151.125 471.383 3.9671 6779.2227

There are number of forces acting on the body of the vehicle that have to be overcome: • FRo = Rolling resistance= fmg = 38.4552 N

• FCl = Climbing resistance = mg sin β = 1765.609 N (β =

40 maximum)

• FAe = Aerodynamics = 0.5 ρcA (v)2 = 403.48 N

Ftot = Total Resistance = FRo + FAe + FCl = 2017.4252 N

X. CONCLUSION

The chosen design was the safest & the most reliable car for any long terrain. All the parameters like Safety, Cost, Reliability, Performance, Durability, aesthetics, Standard dimensions & material were also taken in consideration on the same time. Where ever possible finite element analysis was done on the regularly loaded parts & modifications were done accordingly to avoid any type of design failure. In case of rolling front curved members and rear curved members (Behind the driver’s seat) take the side load equally not like in other designs where only the rear curved members were made to bear the side rolling loads.

International Journal of Engineering and Advanced Technology (IJEAT) ISSN: 2249 – 8958, Volume-3, Issue-2, December 2013

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APPENDIX

Fig18. Whole assembly of an ATV

Fig 19. Sitting arrangement of driver with optimum viewing

angle

REFERENCES

[1] Fundamentals Of Vehicle Dynamics – Thomas D. Gillespie [2] Race Car Vehicle Dynamics – Millikan [3] Dr.N.K.Giri “Automobile Mechanics” By Printed On 2004. [4] Heinz Heisler “Advanced Vehicle Technology 2nd Edition” [5] Srinivasan, “Automotive Mechanics” “Tata Mcgraw-Hill

Publications-New Delhi” Year 2006 [6] Richard Stone And Jeffrey.K.Ball “Automotive Engineering

Fundamentals” Sae International. [7] Ellis.J.R, Vehicle Dynamics, Business Books Ltd., London, 1991 [8] Www.Carbible.Com