M.E. 462 Capstone DesignI.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
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
Function Concept Mapping
Performance handling Provide rotation of wheels along x-axis
Stop wheels from rotating along x-axis
Absorb energy from stopping
Dissipate energy from stopping
Provide rotation of wheels along y-axis
Transfer horizontal wheel force to suspension
Transfer vertical wheel force to suspension
Secure 15’’ wheel
Bolt
Tapered roller bearings
Mechanical linkage system
Pressurized fluid
Cable system
Ball bearings
Brake fluid and piston
Knuckle w/ ball joints
Spot Welds
Stud w/ lug nuts
Parachute
Drum
Air
Heat exchanger
Parachute
Rotor
Motion through viscoelastic medium
Sound
Cylindrical roller and thrust bearings
Knuckle w/ pin joints
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.
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
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)
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.
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.