Design Report - ESI 2017
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The document describes the design of an all-terrain vehicle created by Team Juggernaut Racing for the Baja Student India competition. Key aspects of the design include the roll cage, which was analyzed for strength and safety. The suspension and steering systems were optimized for off-road performance. Components like the brakes, drivetrain, and chassis were selected and analyzed using modeling software. The goal was to create a vehicle that can easily handle rugged terrain at high speeds while keeping the driver safe.
Design Report - ESI 2017
- 1. 1 | P a g e Copyright © 2017 BAJA STUDENT INDIA ABSTRACT "BAJA STUDENT INDIA" is a competition organized by Delta Inc. which gathers students from different universities of India. BAJA STUDENT INDIA 2017 Competition's objective is to design and fabricate an all- terrain vehicle that could be manufactured for consumer sale. Team JUGGERNAUT RACING has accepted the challenge to participate in the event and manufacture a vehicle with optimum performance in rugged terrains. An aspect of this event to compose a design documentation report that creates an overview of the vehicles’ construction element. The team focused on improving every single system on the car to enhance performance and handling. As a result of the design and construction process, the members learned the challenges and rewards of real world engineering projects. Introduction Designing an off-road vehicle intended for the non-professional weekend off-road enthusiast is the general mission of the Baja competition that is achieved throughout the production year. The overall objective is to have a vehicle that will maneuver through rugged terrain with ease. The team focused on increasing the quality and optimizing the vehicle weight. We also focused on maximizing strength and optimizing effectiveness under limited resources. Creating an off road vehicle that is faster, more maneuverable, and easier to manufacture required improvements in every aspect of the car Frame Design Objective: The roll cage is the sub-system responsible for supporting all other vehicles’ subsystems with the addition of taking care of the driver safety at all time. The chassis design need to be prepared for impacts created in any crash or rollover. It must be strong and durable taking always in account the weight distribution for a better performance Design Methodology The Roll cage design complies with all the rules mentioned in the Rule Book. During the design and implementation of the chassis the principal aspects focused on were: “Driver safety, Suspension and drive train integration, Structural Rigidity, optimization of weight, Ergonomics and Aesthetics.” Table 1:- Dimensions of roll cage member Member Dimension Primary 31.75mm OD, 1.65mmthickness Secondary 25.4mm OD, 1.65 mm thickness 2017 BAJA STUDENT INDIA TEAM JUGGERNAUT RACING DESIGN REPORT Adarsh Singh, Abhilash Mohanty, Rajat Panday , Niladri Sanyal, Varun Asthna, Aswini Kr Shah, Achyut Srivastava, Shivnath Karmakar, V.Yashvant Material Selection To choose the optimal material an extensive study was done on the property of different carbon steel. AISI 1018, AISI 4130 were under consideration. Property AISI 1018 AISI 4130 Yield strength (MPa) 370 721.40 Tensile strength (MPa) 440 760 Elongation (%) 15.0 20.50 Density(gm./ cm^3) 7.87 7.85 Bending moment (N-m) 387.3 804.77 Bending stiffness (N-m^2) 2763.12 3632.6 Table 2:-Comparison of different grade roll cage material The above Material Matrix shows AISI 4130 just better and henceforth it was chosen. Welding MIG welding was chosen for its uniform weld bead, reduces a slag- free weld bead. It allows welding in all position .It allows long welds to be made without starts or stops. Since MIG uses a shielding gas to protect the arc, there is very little loss of alloying elements as the metal transfers across the arc. The continuously fed wire keeps both hands free for MIG welding, which improves the welding speed, quality of the weld and overall control. Finite Element Analysis Analysis of the roll cage was performed in Ansys 13.5 using the co-ordinates obtained from CATIA V5 and SolidWorks 2015. Table:-3 Different analysis with maximum deformation and factor of safety Analysis Force Maximum Deformation FOS Front Impact 4G 4.314 mm 2.42 Rear Impact 4G 3.22 mm 2.58 Side Impact 4G 6.84 mm 2.44 Torsional 4G 2.84 mm 4.86 Roll Over 3G 2.49 mm 8.81
- 2. 2 | P a g e Steering True Ackerman steering geometry was chosen due to its benficial effects at lower speeds. This geometry allows the tires to roll freely without any slip angles because the wheels are steered to track a common centre, also reducing tire wear. It is seen that less slip angle is required at lighter loads to reach the peak of cornering force curve. Hence, using the geometry ensures that maximum grip can be extracted from the front inside tire as well. Another advantage is that this geometry gives a small turning radius, ideal for tight turns. With such a geometry, steering torques tend to increase with steer angle, thus providing the driver with a natural feel in the feedback through the steering wheel. Analysis of Tie Rod Several forces will act on tie rod 1) Axial Compressive force (which is reaction of steering force) of magnitude 544.88 N 2) Bump force (which will act perpendicular to axial force) of magnitude 1.5G (4267.35 N) Alloy steel is selected as material of tie rod having yield strength 250MPa. Tie rod analysis by using ANSYS software shows that the maximum deformation is 1.92 mm and equivalent stress (Von-misses stress) is 63.83MPa which is less than tensile and compressive yield strength i.e. 250MPa. Table 4:- Steering parameters Particulars Values Turning radius 3.13 m Max. Turning Angle(degrees) 40 Ackerman Angle(degrees) 20.44 Steering ratio 6.83:1 Suspension The suspension is responsible for dissipating the energy obtained from the impacts absorbed by the shocks. These impacts are caused by the uneven terrain. It is also responsible for maintaining the vehicle's stability and ride height when managing obstacles. Another point is to reduce vibration for the vehicle's durability and driver's comfort. With its high capability of shock absorbing suspension system helps to run on any type of terrain with full comfort and efficiently. Design Methodology The main objective of this year’s design was to make the vehicle dynamically more agile around corners, while maintaining a certain level of comfort for the driver as well. The ultimate goal is to formulate a system that can run over any terrain efficiently and comfortably. Tire scrub across the track surface through compression or droop in either cornering or bump travel can cause loss in traction, we completed this obobjective by doing extensive research on the front suspension arm’s gegeometry to help reduce as much body roll as possible. Proper camber and caster angles were provided to the front wheels. Thorough analysis was done on Lotus Suspension Analysis. Particulars Values Static Camber -2.2 ˚ Static Caster +2 ˚ Static Toe -1.5 ˚(front), +2˚( rear) KPI Angle 7˚ Front Suspension For our front suspension we chose one with a double arm wishbone type suspension (unequal and non-parallel arms). ∑ It provides a spacious mounting position, load bearing capacity besides better camber recovery. ∑ By inclining the link pivot axes with respect to each other we can place the roll center wherever we please to. ∑ Front roll center will always be higher than the rear, for best acceleration out of a corner, as well as for better turn entry. This also makes the front understeer, since more of the roll couple will be resisted on the front. FLOAT R shocks feature an Infinite adjustable air spring, velocity- sensitive damping control, external rebound damping adjustment and an ultra-light weight of 2 to 2.25lbs depending on size. Rear Suspension In the rear we have chosen semi trailing link/arm suspension system with camber links. ∑ Trailing arm suspension consists of an arm connecting the frame and the wheel, with the arm in front of the wheel so that it is “trailing”. ∑ Semi trailing arm was used due to its ease of installation and proper damper mounting points, while maintaining a good installation ratio. The camber links help in modifying the camber characteristics in the corners. It is also light weight and compact.
- 3. 3 | P a g e FLOAT X EVOL shocks feature a main air chamber with an infinite adjustable air spring, velocity-sensitive damping control, additional air volume chamber (EVOL) for bottom-out adjustment, external rebound adjustment, external low & high speed compression damping adjustment, and an ultra-light weight of 4 to 4.5lbs depending on size. Brakes Objective: The objective of the braking system is to provide a reliable and prompt deceleration for the vehicle. More importantly the brakes must be capable of locking up all four wheels while on the pavement and on an unpaved surface which is one of the requirements stated by the SAE Rules. Design In order to achieve “Optimum Brake Balance” or to achieve 100% brake efficiency, the ratio of the front to rear dynamic braking forces should be equal to the ratio of the front to rear vertical forces (axial weight). The braking system which we are implementing on our ATV this year consists of a four individual circuit master cylinder brake pedal assembly. The dual master cylinder setup completely isolates the two hydraulic systems. The primary reason which is under our consideration for using a dual master cylinder assembly is to ensure that the braking system would still be able to perform even if one were to fail. The master cylinder that we are using consists of a 40 mm diameter piston. The front disc diameter is 190.5mm and the rear brakes disc diameter 165.1 mm and a brake pad of area 1848.71mm sq. Each wheel has a separate brake disc to have better braking efficiency. A brake pedal of pedal ratio of 5:1 was chosen. The analysis of the brake disc and the brake pedal were done in ANSYS13.0. Drive-Train Objective: Our goal is to design a power transmission system that efficiently and effectively transfers power from a 10hp Briggs & Stratton engine to the wheel. An effective design will provide the vehicle with a high amount of wheel torque while allowing us to reach speeds in excess of 60 km/hr. For this year’s vehicle it is desired to be able to climb a 30 degree slope while carrying the heaviest of the teams’ driver. Design Several different automatic transmissions were compared to find the one that would best fit for our vehicle. The prime objective was to have a wide range of reduction ratio. A continuously variable transmission (CVT) was choose along with a tuning kit, with the help of this we can able to change its performance as per the event demand. To enhance the performance a 2 stage speed reduction customized gearbox was coupled, which would meet the traction demand for off-roading. CONCLUSION:- The process of designing a vehicle is not a simple task; as a matter of fact it takes a lot of effort from all members of the team to achieve a successful design. The final prototype was the product of a collaborative multidisciplinary team design. The goal of the project was to create an off road recreational vehicle that met the SAE regulations for safety, durability and maintenance, as well as to achieve a vehicle performance, aesthetics and comfort that would have mass market appeal for the off-road enthusiast. All of the design decisions were made keeping these goals in mind. The selection of components were made using engineering knowledge achieved through with off-road enthusiast and engineering advisors, taking as parameters first of all safety, performance, weight, reliability and last of all cost. Being part of a project of this nature is an experience as it allows the engineering student to exploit all of his/her knowledge while gaining knowledge in project management, team work, accounting and even marketing sales. ACKNOWLEDGEMENTS:- For our project for the event BAJA STUDENT INDIA by SAE INDIA., we would like to thank The School of Mechanical Engineering, Kalinga Institute of Industrial Technology for their enormous support. We would also like to thank our Faculty Advisor for his constant support and help without which this would not be possible. We would like to extend our thanks and appreciation to our vendors AUDI Bhubaneswar Flameproof Equipment Pvt.Ltd, CVTech, Scholarian Racing, and KIIT UNIVERSITY. Lastly we would like to thank Briggs & Stratton for their help and all of the people without whom the project would not have started. References 1. Milliken, William F. and Douglas L., “Race Car Vehicle dynamics”, SAE Warren dale, PA 1995 2. Smith, Carol, "Tune to win”, Aero Publisher, Inc. Fallbrook, CA 1978. 3. Automobile Mechanics - Dr. N.K. Giri. Particulars Values Tractive Effort 2255.25 N Total Forward Reduction Ratio 44.88:1 Max. Gradability 39% @ 30° Top Speed 60 km/hr Max. acceleration 3.72 m/sec 2
- 4. 4 | P a g e Front view of vehicle Side view of vehicle
- 5. 5 | P a g e Kingpin vs. Wheel Travel Castor vs. Wheel Travel Camber vs. Wheel Travel Toe VS Bump Travel Castor vs. Wheel Travel Toe VS Bump Travel Top view of vehicle
- 6. 6 | P a g e Ansys Reports:- Customized Hub, Upright and Rotors
- 7. 7 | P a g e A R N O 3-D View of Vehicle