M.E. 462 Capstone Design
I.U.P.U.I. Spring 2007
Bishop Steering:
1970 Lotus Europa
Front Axle Re-design
Aaron Emmons
Phil Palmer
Brad Holtsclaw
Adam Spindler
Adam Douglas
Agenda
• Introduction
• Design
–
–
–
–
Specifications Development
Benchmarks
Concept Development
Evaluation
• Conclusions
• Closing Comments
• Questions
Planning: Weekly Progress
Introduction
Fixed Parameters
• Budget $3600
• 5” Ride Height
• 15” Wheels
Design Specifications Development
• Customer
Requirement (right)
• Top Three
Requirements:
1. Safety
2. Minimizing Weight
3. Braking from
200mph
Engineering Specifications
• Ground Clearance of 5
inches
• Weight Minimization
(parts made of
aluminum)
• New Wheel (15” Audi
Wheel)
• Overall width (outside
wheel to outside wheel)
to remain the same
• Overall width – Distance
from frame to remain
the same
• Braking Force to
compensate for 1600lbs
at 200+mph (Wilwood)
• Rotor size increased
(surface area increase
for larger braking
friction)
Engineering Specifications Cont.
• Hub size increased to compensate for 5-bolt Audi
Wheel
• Deflection of bearings minimized
• Machining time increased due to no production line
• Factor of Safety increased (keep Jason safe at 200
mph)
Competitive Benchmarks
• Minimization of
Weight
• Maintain Safe
Operation Conditions
• Stopping Vehicle going
200 M.P.H.+
Competitive Benchmarks
Ranking
Customer Req’s.
Benchmark
15
Min. Weight
Fail
15
Maintain Safe Cond's.
Fail
14
Stop Veh. 200 M.P.H+
Fail
Literature / Patents
• Original car, the benchmark, was the set
standard.
Performance Handling
• Sub-Functions
– Create
– Order
– Refine
Function-Concept Mapping
• Team brainstormed methods for each function.
Ball bearings
Function Concept Mapping
Performance handling
Provide rotation of wheels
along x-axis
Provide rotation of wheels along
y-axis
Stop wheels from rotating along xaxis
Absorb energy from stopping
Tapered roller bearings
Cylindrical roller and thrust
bearings
Mechanical linkage system
Pressurized fluid
Cable system
Parachute
Brake fluid and piston
Parachute
Rotor
Drum
Dissipate energy from
stopping
Transfer horizontal wheel force to
suspension
Knuckle w/ pin joints
Air
Sound
Motion through viscoelastic medium
Heat exchanger
Knuckle w/ ball joints
Transfer vertical wheel force to
suspension
Secure 15’’
Bolt
wheel
Spot Welds
Stud w/ lug nuts
Concept Evaluation
Create
• Overall concepts
Analyze
• Using Concept Outline
Evaluate
• Decision Matrix
Morphology
• Two Phases
– Develop concepts for functions, throughout
conceptual phase.
– Combining the Concepts.
Morphology
Overall Concepts
•
•
Concept 1
– Tapered roller
bearings
– Mechanical linkage
– Brake Fluid w/ piston
– Rotor
– Atmospheric air
– Knuckle w/ ball joints
– Bolts
Concept 2
– Cylindrical roller and
thrust bearings
– Pressurized Fluid
– Mechanical linkage
– Drum
– Heat exchanger
– Knuckle w/ pin joints
– Stud w/ lug nuts
Concept Outline
Brainstorming
Go/No-Go
Failure Modes
•
Concept 1
–
–
–
–
•
Rotor
• heat warping
Mechanical linkage for turning
• Stress/fatigue in linkages and ball joints
Tapered bearings
• Degradation due to heat and friction
Brake fluid w/ piston for stopping
• Leaks/ air pockets in brake lines
Concept 2
–
–
–
–
–
–
Drums
• Heat warping the drum
• Foreign debris can enter the drum easily
Heat Exchanger
• Fluid lines leaking
• Corrosion
Mechanical linkage system for stopping
• Stress/fatigue in linkages and pin joints
Knuckle w/ pin joints
• Limited number of degrees of freedom
Cylindrical roller and thrust bearings
• Degradation due to heat and friction
Pressurized fluid for turning
• Fluid line leaks
Critical Parameters
• Following are our design parameters:
–
–
–
–
–
–
–
–
–
–
Ground Clearance of 5”
Minimum Weight
Width from wheel to wheel of 59.5”
Wheel size of 15”
Stop vehicle for speeds of 200 mph
Budget of $3600
Width from frame to hub of 8.35”
Wheel being hub centric.
Minimum body chassis mod’s
Parts made of Aluminum (6061)
Decision Matrix
Load Distribution
• Lexus V8 mounted in the rear
• 60% rear 40% front
• 1600 lb force on each front wheel with a
factor of safety = 5
FEA: Spindle (Aluminum 6061)
• 10 node tetrahedral
elements
• 6801 Nodes
• 4068 Elements
• Constrained both
ends fixed
• Pressure of 210 psi
• Maximum Von Mises
Stress is 197 psi
• Yield strength of
Aluminum alloy is
73 ksi
FEA: Spindle (Deflection)
• Total deflection
is 1.09x10-5 in.
• Very minimal,
and within our
limits of safety.
FEA: Spindle (Shearing Stress)
• Maximum shear
stress occurs in
the center of the
spindle.
• Value is 98 psi
FEA: Knuckle (Aluminum 6061)
• 10 node tetrahedral
elements
• 6169 Nodes
• 3164 Elements
• Maximum Von Mises
Stress was found to
be 74ksi
• Compared to the
maximum yield
stress of 39ksi
• Does not meet the
design requirements
with a factor of
safety of 5
FEA: Knuckle (Deflection)
• Maxim deformation
occurs at the lower
control arm mount
• Maximum value is
0.06 in.
FEA: Knuckle (Design Improvements)
• Vertical support
thicker, give the
support more
strength!!
• 6568 Nodes
• 3429 Elements
• Maximum Von Mises
stress is 25ksi, a
percent reduction of
65% from the original.
• Notice, maximum
stress moved from
below the control arm
attachment to the top
of the knuckle.
FEA: Knuckle (Maximum Shear Stress)
• Maximum stress of
14ksi was found.
• Percent difference of
65% from the
original.
• Prototype meets the
engineering
requirements.
FEA: Knuckle (Deflection)
• Maximum
deflection value
of 0.02 in. was
determined for
the prototype.
Impact Statements
• There is a definite safety risk when traveling at
200 m.p.h.
• Knowing this, we have designed our parts with a
safety factor of 5 to minimize risk.
• Our design will have minimal impact on society
or the environment
Conclusion
• Aluminum is a viable material for our design
• By using F.E.A. structural design of parts will
withstand all applied forces with a safety
factor greater than 5.
• At this time, 9 out of 12 Engineering
Specifications have been met.
Recommendations
• Upon receiving brake components, complete
dimensional analysis and collaborate with
control arm group to complete assemble.
• Complete the final three engineering
specifications.
Acknowledgements
• Dr. Hazim El-Mounayri
• Bishop Steering
• IUPUI Dept. of Mechanical Engineering
Questions??