ORIENTAL INSTITUTE OF SCIENCE & TECHNOLOGY

BHOPAL

SAE BAJA 2013TEAM - ENIGMA 4T

Design Report 2013DESIGNED BY

AKASH SAXENAHead of the Design Team

Team: ENIGMA-4T

SAE BAJA INDIA 2013 PRELIMINARY DESIGN REPORT

AKASH SAXENAHead of the Design Team

ROHIT DESHPANDETeam Captain

1.0 ABSTRACTThe objectives of the Baja SAEINDIA 2013 competition are to design and manufacture a fun, versatile, safe, durable, and high performance off road vehicle. Team members must ensure that the vehicle satisfies the limits of set rules, while also generating financial support for the project, and managing their educational responsibilities. This vehicle must be capable of negotiating the most extreme terrain with ease.

2.0 INTRODUCTION Baja SAEINDIA is a collegiate design competition sponsored by the Society of Automotive Engineers (SAE) that attracts engineering student teams from all over India.

Each team’s goal is to design, build, test, promote, and race a prototype of a single seat off-road vehicle hypothetically intended for production and eventual sale to the weekend off-road enthusiast.

Team ENIGMA-4T comprises of 25 students of Automobile & Mechanical Engineering from the ORIENTAL INSTITUTE OF SCIENCE & TECHNOLOGY, BHOPAL. Team ENIGMA-4T main design objective was to ensure its vehicle design is able to complete all tasks without any break-downs, whilst being an appealing vehicle to potential customers.

Team ENIGMA-4T met its design objectives by dividing the vehicle into major component subsystems. The teamwas divided into groups, with each group being responsible for a specific subsystem that was designed according to the team objectives and within set rules.

An open source approach was adopted for all the designing and analyzing work. Hence, contributions from other members of the collegiate club were also encouraged.

3.0 INNOVATION

1. RACE ERGONOMICS – A wide field of vision will be incorporated by increasing distance between A-pillars. This will allow ease of maneuverability and cornering ability.

2. DRIVER ERGONOMICS – A spacious driver cabin will allow easy ingress and egress from the vehicle and a riding position designed for maximum driver comfort.

3. FRAME - A light and rigid chassis will ensure good vehicle handling while increasing driver safety in a race.

4. SUSPENSION – An independent double wishbone suspension at front and rear intended to give a comfortable ride whilst not compromising on shock absorption in an off-road terrain.

5. STEERING – Rack & pinion steering assembly to minimize force feedback from track conditions. Disc brakes installed in front will enable quick braking.

6. POWERTRAIN – Spacious engine bay for easy serviceability and repairs under intense track conditions. Directly coupled (4+1 reverse) transmission.

4.0 MAIN SECTION

4.0.1 FRAME DESIGN

Initially the general shape of the frame was sketched using sketcher software (Google Sketch Up). Different shapes and sizes were considered. Finally a frame shape was chosen with form and function in mind. (Fig 1) Before the chassis design was finalized, a 1:1 mock up of the frame was built out of bamboo. The mock up allowed the team to visualize the frame in 3D, as well as mock up the power train, steering, and brake systems to ensure that there is adequate space.

(Fig. 1)

(Fig. 2)

Basic geometrical calculations were done to obtain vehicle dimensions. All main chassis members were scrutinized to ensure compliance with set competition rules. An optimum riding position and driver leg room was finalized. Position of steering wheel, control pedals, side impact members, and seat were considered with a view to maximize cabin room and driver comfort. Horizontal spacing between A-pillars was maximized at the base to improve the driver’s field of vision. Engine bay area was enlarged to fit power train members and leave space for easy servicing. Different hard points for location of suspension, springs, steering, etc were considered. (Fig 3)

(Fig. 3)

After studying the mock-up and making necessary changes to the frame, a CAD model of the frame was made with a view to perform finite element analysis and testing. (Fig 4, 5, 6)

(Fig. 4)

(Fig. 5)

(Fig. 6)

In the CAD model, the final geometrical specifications of the vehicle were implemented. Adequate bracing was given to reduce stresses in main chassis members and ensure proper transmitting of forces to chassis. All corners of the roll cage were braced as shown. The CAD model was analyzed using ANSYS FEA software for static analysis under self-weight, frontal impact, side impact, and roll-over impact as well as natural frequency and torsion analysis. FEA model used beam elements. Under self-weight, the frame was deforming very little. Stress was maximum in the front of the roll hoops and firewall members. The firewall itself will act as additional bracing here.

(Fig. 7)

In the frontal impact analysis, a 5KN force was used as it was assumed impact would be with a stationary object. The deformation was minimal and proved the frame was rigid enough to withstand a crash.

(Fig. 8)

In side impact, hypothetically with another Baja vehicle, a 3KN force was applied to the side impact member. Deformation was again in the roll cage.

(Fig. 9)

The natural frequency was analyzed using model analysis in 3 sub-steps. Maximum vibrations and consequently displacements were occurring again in the roll cage members. Deformation was within limits, but power train etc will be well isolated using rubber bushings to cancel vibrations. (Fig 10, 11, 12)

(Fig.10)

(Fig. 11)(Fig. 12)

(Fig. 13)

In rollover analysis, a 2KN force was applied at an angle to the top front of the roll hoop. The Maximum deflection was observed in the roll hoop as shown in (Fig. 13).

(Fig. 14)

The design was also tested for torsional loading and was found to be stable enough to withstand a load of 10KN.This was applied as a couple on the extreme ends( in side view perpendicular to the plane of the paper) . As shown in (Fig. 14).

For analyzing the wishbones, the A-arms that support the shock absorbers were chosen. These were the lower arm in front and the upper arm at the back. A force of 800N in Y direction and a force of 400N in Z direction were applied. As shown in (Fig 15, 16a, &, 16b).

(Fig. 15)

(Fig. 16a)

(Fig. 16b)

4.0.2 STEERING & BRAKES

Steering used on the vehicle will be a rack and piniontype. Brakes will be single rotor disc brakes with single/multi callipers, depending on the braking force required the no. of callipers will be decided later.

4.0.3 SUSPENSION

TENTATIVE DIMENSIONS FOR THE WISHBONES:

Upper wishbone length: 405.11 mm Upper wishbone angle: 30.23 degrees Lower wishbone length: 438.72 mm Lower wishbone angle: 15.87 degrees Distance between mounting points on hub:

141 mm

Distance between mounting points on chassis: 236 mm

SAL (distance between the intersection of the hubs and the wishbones): 514 mm

4.0.4 POWERTRAIN

The Differential gearbox is a 4 forward 1 reverse type from a Mahindra Alfa. It will be directly coupled onto the final driveshaft. This can be done by using universal couplings.

4.0.5 GEARTRAIN

The Gear train will be a synchro-mesh type.

5.0 SAFETY & ACCESSORIES

The front part of the vehicle has provisions to incorporate a crumple zone before eventual manufacture and sale to the consumer. This is apart from the fire extinguisher and the firewall already provided. A 4/5 point seatbelt, an adjustable bucket seat setup, Specification tail lamp and headlights. Foam padding on the roll cage.

6.0 MATERIAL USED

All the analysis has been done using SAE 1020 carbon steel as the frame material. We have chosen this steel because it is a general purpose mild steel, low-carbon machinery steel, having good over-all mechanical properties. Easily machinable and weld able. It has a nominal carbon content of 0.20% with approximately 0.50% manganese.

7.0 CONCLUSION

The final design of the vehicle is as shown above. The figures provided in the analyses and the dimension lists have been approximated to the least extent possible. These have been made keeping into account the fact that there might be changes to the design in later stages of the competition. A sincere effort has been made to keep the report simple and extensive.

8.0 TEAM CONTACT DETAILS

1. AKASH SAXENAHead of the Design Team

&PDR Designer

Automobile Engineering StudentOriental Institute of Science & Technology,Bhopal

Contact No: 08871413157Email Address:akash.auto.engineer@gmail.com

2. ROHIT DESHPANDE

Team CaptainAutomobile Engineering Student

Oriental Institute of Science & Technology,BhopalContact No:

Email Address:

9.0 FINAL VIEWS OF THE VEHICLE WITH DIMENSIONS