baja buggy technical details
TRANSCRIPT
BAJA SAE INDIA 2014VIRTUAL ROUND
TEAM VIKRAMBabu Banarasi Das National Institute of
Technology & ManagementLucknow , Uttar Pradesh
Northern Section
TEAM LEADER
DESIGN & ANALYSIS TEAM
SteeringRoll cage
Suspension
MANUFACTURING TEAM FINANCE
Fabrication
Parts Procurement
Jigs & Fixtures Brakes
Budgeting & Cost Estimations
Market Survey
Marketing and PR
Transmission Engine & Electricals
Modeling & Simulation
SPONSORSHIP
Ergonomics & Aesthetics
TEAM FORMULATION
TEAM SIZE :- 25 MEMBERSDesign Input by: BAJASAE 2014 Rulebook
Modelling on: PRO-E WILDFIRE 5.0FEA Constraints formulation on : ANSYS 14.5 & ALTAIR HYPERWORKS
Technical Specifications Parameter Value
Vehicle length 2500 mm
Vehicle width 1556.4 +00+50 mm
Ground clearance 254 mm
Vehicle height 1534.25 mm
Roll cage material Carbon Steel(AISI 1018)
Tube dimension 25.4 mm outer dia.3mm inner dia.
Roll cage mass 22 kg
Total mass 350 kg approx.
Parameter ValueBattery 12V/44 Ah
SuspensionFront Rear
DoubleWishbone
DoubleWishbone
Damper mounting Lower arm
Upper arm
Max speed 58 km/h
BrakeFront Rear
Disc Disc
Steering Rack and pinion
Tyres 22 X 8 - 10
Roll CageDesign Methodolgy:• Driver oriented rollcage design.• Light weight, compact and simple.• Ease of egress during accident.• Members are kept short by optimum triangulation to have a good load transfer path.• Frame is designed to be stiff for loads like bending and torsional.• Material is kept farther from rotating axis to increase stiffness.• Polar moment of inertia is maximised.
Total number of weld joints: 48
Width of Rollcage: 750 mmLength of Rollcage: 2500 mmHeight of Rollcage: 1280.25 mm
Material Used: Carbon Steel (AISI 1018)• UTS: 365 Mpa• Carbon content: 0.18%• Outer Diameter: 25.4mm• Wall Thickness: 3mm (primary members) 0.89mm(secondary members)
Devised Plan for Finite Element Analysis
INITIAL DESIGN FINAL DESIGN
CONSTRAINTSREAR CORNERS(ALL DOF=0);SUSPENSIONMOUNTINGS(Uy,Uz=0)
OPPOSITE SIM MEMBERS(ALL DOF=0)
LFS MEMBERS (ALL DOF=0)
FRONT CORNERS(ALL DOF=0); SUSPENSIONMOUNTINGS(Uy,Uz=0)
LOADS 5G 3G 2.5G 4G
TESTS FRONT IMPACT SIDE IMPACT ROLL OVER REAR IMPACT
FACTOR OF SAFETY: ALWAYS CONSIDERED FOR THIS DESIGN BETWEEN 1.5 - 4
CONSIDERATION FOR MESHING: Tria elements are considered below 5% for meshing.Warpage below 7O . Jacobian ratio kept around 1. Aspect ratio is kept less than 7.
SteeringThe steering system allows the driver to control the direction of vehicle travel. This is made possible by linkage that connects the steering wheel to the steerable wheels and tires.
Types of steering:1.Recirculating ball steering gear2.Rack and pinion gear3.Worm and Sector We are using the Rack and Pinion gear system.
Design selection criteria:We are using the rack and pinion gear system just because due to its low cost, its better compatibility with our compact design and its simple construction. We are using the manual steering system, so it will help us for immediate response.CALCULATIONS :Wheel base - 1800mmTrack width - 1250mmLock to lock ratio - 3Steering ratio - 16:1Ideal Ackerman angle - 19.15Actual Ackerman angle- 7.660
Inner angle(i) – 37.590
Outer angle(o)- 29.93o
Turning Radius- 2963mm Caster- 5o negativeCamber- 2o positive
Braking System
• The brake system consists of four wheel disc brakes actuated by two independent master cylinders. The brake pedal uses a 6.2:1 pedal ratio .
• The brake callipers chosen are single piston floating type callipers of Honda Aviator and Bajaj Pulsar220 .
• DOT 4 brake fluid will be used for braking purpose
SpecificationsPedal ratio = 6.2:1Pedal size = 7.75”Braking percentage = 62:38Master cylinder type: Two random master cylinders of Maruti 800 and a balance bar.Brake lines: maruti 800 brake lines and hosesCalliper type: single piston floating-type callipers of Honda Aviator and Bajaj Pulsar 220Calliper cup size = 1.5”Rotor type: ventilatedRotor size = 7.48”(190 mm )Rotor thickness = 4mm
f = 7.84m/s2Rf = 2121.45N and Rr = 1308.54N. this will be the front wheel and rear wheel reactions.
after a hard braking on level track, producing a deceleration of 6.87 m/s2
• STOPING DISTANCE
SPEED (Km/Hr)
Stopping Distance(m)
Braking Time(s)
30 4.42 1.06
40 7.87 1.42
50 12.30 1.78
58 16.55 2.05
Ergonomics & Safety Features Ergonomics refers to the relationship between people and their working environment, so in our vehicle the perspective of ergonomics has been considered over 4 points:1. Vision 2. Ease of egress3. Additional Controls
POWER TRAIN TRANSMISSIONManual transmission needed gear shift which would require some area near driver seat and thus increases the dimension of buggy. So we decided to go for cvt transmission.Pulley based CVT is the most affordable and simple one. It consist of two pulleys.primary pulley connected to engine and secondary pulley connected to axle.These two pulleys are connected by a rubber V belt. Variation in the pitch radii of these pulleys lead to the change in the gear ratio.
CVT Transmission option available :1.Mahindra alfa cvt.2.Polaris p90 cvt.
We are opting Mahindra ALFA because of its well known coupling with B&S Engine and its low cost.
Power train refers to the group of components that generate power and deliver it to the wheels of vehicle.
ENGINE SPECIFICATIONSTorque 14.50 ft-lbsDisplacement 305
No. of cylinder Single
Configuration Horizontal
Technology OHV
Length 12.3 in
Width 15.4 in
Height 16.4 in
Weight 50.4 lbs
Bore 3.12 in
Stroke 2.4 in
Engine Fuel Gasoline
Spark Plug RC12YC
SuspensionDesign Criteria:Both the front and rear suspension system are independent double wishbone(A-arm) suspension having unequal control arms. It is chosen because 1: Wishbone suspension give more movement of the tires and hence the vehicle.2: In double A-arm suspension, force is distributed at five points on the roll cage unlike at only one point in macpherson strut.3: It can be slightly adjusted for different parameters of suspension tuning like chamber angle, ground clearance etc.
The A-arms at the front are pinned to the roll cage while at the knuckle end the arms are attached using boll and socket joints. While at the rear as there is no cornering requirement the A-arms are pinned both to the roll cage as well as the knuckle.
FRONT LOWER CONTROL ARMSLENGTH: 280 mm
REAR UPPER CONTROL ARMS
LENGTH: 190 mm
Design Validation Plan
DESIGN MODE AND FAILURE EFFECT ANALYSIS
COLLEGE FACILITIES
Centre latheMillingPipe bendingElectric arc weldingOxy-Acetylene WeldingDrilling machineShaper machinePower hack sawPortable drilling machinePlaner Machine
35%
11%
2%
8%7%
6%
2%
13%
17%
PIE CHARTENGINE & DRIVE TRANSMISSION STEERING SUSPENSIONFRAME & BODY BRAKES ELECTRICAL SAFETYMISCELLANEOUS
SUBSYSTEM MATERIALS EXTRAS TOTAL
ENGINE & DRIVE 70,000 - Rs. 70,000
TRANSMISSION 22,700 150 Rs. 22,850
STEERING 2,500 1,000 Rs. 3,500
SUSPENSION 11,000 4,500 Rs. 15,500
FRAME & BODY 9,000 5,000 Rs. 14,000
BRAKES 10,000 1,580 Rs. 11,580
ELECTRICAL 4,370 - Rs. 4,370
SAFETY EQUIPMENT 25,890 - Rs. 25,890
MISCELLANEOUS - - Rs. 33,500
TOTAL Rs. 2,01,190
Cost Estimation
Processes in sequence of: Pipe Cutting Bending Welding Inspection Undercoating Drawing Baking Painting
Then the roll cage is assembled with: 1.TYRES, DAMPERS AND SUSPENSION 2.ENGINE SYSTEM 3.STEERING AND BRAKES 4.DRIVER SEATPADDING5.TRANSMISSION SYSTEM
MANUFACTURING PROCESSES REQUIRED
THANK YOU!