30469_SPCE Racing

Report
Team Members
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Sameer Kolte (C)
Parshva Shah
Amol Alsundkar
Chaitanya Joshi
Prashant Ramteke
Tushar Karande
Shweta Patil
Gaurav Munot
Pratik Baldota
Jaykishan Choksi
Akshay Jain
Priyank Gajiwala
Aniket Ghatvisave
Dhruv Phadke
Omkar Deshpande
Mukund Lahoti
Sanskar Panse
Nikhil Kotasthane
Sagar Dalvi
Siddhant Shah
Sumant Kherudkar
Presented By
Sameer Kolte, Aniket Ghatvisave,
Pratik Baldota, Parshva Shah, Priyank Gajiwala
Project Plan
Roll cage Design: Material and Cross Section Selection
• Material Used: AISI 1018 Structural Steel
Property
Value
Ultimate Tensile Strength
460 MPa
Yield Strength
365 MPa
Density
7850 kg/m3
Young’s Modulus
2 x e11 N/m2
Poisson’s Ratio
0.26 - 0.3
Cross Section
Moment of
Inertia
(mm4)
Distance of
extreme fibre
(mm)
Section Modulus
(mm3)
Area
(mm2)
Circular
OD 1”
3mm Thick
12771
12.5
1022
207
Circular
OD 1.25”
2mm thick
20774
15.875
1308.5
187
• Bracing: Circular cross section, OD =1”, pipe thickness= 2mm
Roll cage Design: Design Methodology
• Objective: To provide minimal 3-D space surrounding the driver and ensure safety.
• Driver’s measurements:
• RRH design:
Roll cage Design: Design Methodology
• RHO, SIM, FBM design :
Roll cage Design: Finite Element Analysis
Torsional Rigidity
Torsional rigidity:
2500Nm/deg
Stress Induced:
288MPa
Flexural Rigidity
Stress Induced:
107 MPa
Roll cage Design: Finite Element Analysis
Front Impact
Front Impact:
Force=7G=24034N
Stress Induced= 319MPa
Rear Impact
Side Impact
Rear Impact
Force=5G=17167N
Stress Induced= 123MPa
Side Impact
Force=3G=10300N
Stress Induced= 334MPa
Roll cage Design: Human Ergonomics
• Side Impact Member Height: 9”; Kept close to minimum for less driver exit time.
• Steering Wheel Position: Fixed according to driver comfort.
• Driver Head Clearance: 7.5”; Kept greater than 6” as specified in rulebook.
• RRH Inclination: 8 deg, fixed according to driver back leaning.
• Width of chassis: Fixed such that there is clearance of 3” between any chassis member and
driver body part.
Suspension, Steering and Brakes: Chosen Configuration
Brakes:
• Type: Hydraulic disc brakes
• Honda Aviator disc
• Pulsar 220 calipers
•Maruti 800 Master cylinder
Suspension:
• Type: Double Wishbone unequal arm suspension (Front )
Double Wishbone, Twin outer ball joint suspension (Rear)
• Coil Spring and Hydraulic damping
Steering:
• Type: Ackerman Steering
• Maruti 800 rack and pinion assembly
Brake System
• Human Foot force = 40kgf+ 20kgf(emergency)
• Pedal Ratio = 4
• Use of proportionate valve to achieve front: rear brake biasing.
• Calculated stopping distance: 3.6metres
Suspension Design: Kinematics
• Bump/Rebound travel: Front 200/-100, rear 200/-80 (mm) ; Roll angle: 5 degrees
Front0.6 deg/deg Rear
• Camber variation: Front: Static
0.85 Data
deg/inch bump,
roll
Rear:Camber
1.34 deg/inch
bump,
0.42 deg/deg0 roll
angle
0 deg
deg
Caster angle
7 deg
0 deg
Toe angle
0 deg
0 deg
Kingpin angle
8 deg
6 deg
Scrub Radius
90mm
120mm
Caster Trail
23mm
0 mm
Roll centre height
400mm
396mm
• Toe Variation: ZERO bump steer and Roll steer
Suspension design: Spring selection
Objective:
• To achieve desired ground clearance of 12”
• To achieve ‘oversteer’ while cornering.
Spring selection:
• Rear springs: Maruti Zen Front struts
Measured spring stiffness ‘k’ = 21N/mm
Precompressive force= 140kgf
• Front Springs: Inhouse designed springs
Target spring stiffness ‘k’ = 21N/mm
Wheel assembly components
Hubs:
• Front hub: Designed hubs
Torsion and Bending
Braking Torque= 235Nm
Bending force= 1800N
Max Induced stress= 71MPa
Factor of safety= 6.5
• Rear hub: Maruti 800 front hubs
Steering sub system
• Ackerman geometry
• C-factor = 37 mm/rev
• Rack travel = 45mm
• Wheel angles:
Inner= 43deg, Outer= 35deg
• Minimum Turning radius= 4 metres
Powertrain: Engine
Specifications:
• Briggs and stratton 10bhp OHV engine
• Torque: approx 18.75Nm at 2600 rpm
• Power: 10bhp at 3600 rpm
Briggs and Stratton Intek 20 Torque and Power
16
14
12
10
Torque (ft-lb)
8
Power (hp)
6
4
2
0
2000
2200
2400
2600
2800
3000
3200
3400
3600
3800
Engine Speed (RPM)
Engine mounts:
• Operating frequency range: 25 Hz to 70 Hz
Engine Mounts
Natural frequency= 460Hz
Maximum stress induced= 23 Mpa
Powertrain: Transmission
Schematic:
• Engine-> CVT-> Reduction gearbox
• Continuously Variable Transmission
1. CVTech CVT Ratio= 3.6:1 to 0.59:1
2. Comet 780 series= 3.75:1 to 0.6:1
• Reduction gearbox
Constant reduction = 10:1
• Final ratio= 36:1 to 5.9:1
Powertrain: Reduction
Differential
Input from
CVT
Output to
driveshafts
Total reduction:
11.45
Design Failure Modes And Effects Analysis (DFMEA)
Items
Potential Failure
Mode
Potential Cause of Failure
Potential Effect Of Failure
Remedies to avert
Failure
Chassis
Structural
Front/Rear/Side
Collision
Driver Injury, Chassis
deformation, Damage to
engine/suspension.
Incorporate bracing
members, Nodal
Structure, Use of
Bumpers.
Fatigue
Resonance of engine
frequency with chassis
natural frequency.
Failure of welded joints
Use of rubber pad
below engine,
Incorporate bracing to
increase natural
frequency
Suspension
(A-Arms, Springs,
Shock absorbers)
Structural
Bending, compression,
Force due to anti dive;
Torsional shear failure of
spring, Buckling
Permanent buckling of
spring affects ground
clearance;
Wishbone failure
Rear twin Ball joint
suspension , High
Factor of safety
Transmission
Mechanical
Cyclic loading, Radial loads
due to CVT, Torsional shear
stress in shafts
Gear failure, Shaft failure,
Misalignment of shafts in
gearbox
Use of standard shafts
and gears, Bearings
capable of taking high
radial loads
Brakes
Structural
Brake fluid contamination,
Bending of brake pedal,
Bending of master cylinder
rod
Brake system failure
Master cylinder cap,
Brake Bleeding, High
FOS for pedal, proper
Master cylinder
mounting
Safety
• 5 point harness.
• Battery placement: Away from rotating parts, Covered to prevent fuel spill on battery.
• Front and rear bumpers to protect tie rod and toe link.
• Master cylinder mount at height from base of chassis to prevent brake failure.
• Resilient foam material on all pipes of cockpit.
• Use of fire extinguisher.
Summary
Data
Value
Overall Length
90 inches
Overall height
58 inches
Track Width
Front: 52 inches
Rear : 50 inches
Wheelbase
66 inches
Gear Ratio
36:1 to 5.9:1
Estimated Weight of vehicle
Gross Weight : 350 kg
Kerb Weight : 290kg
Estimated Weight of chassis
55 kg with all mounts and welds
3-D view of car

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