Unit 91 Week 7 Jon Gutierrez, Chris Sauer, Simon Radomski, Chat Huynh, Jeff Burton, & Robert Platt October 1, 2008 Final Presentation

Outline Project Goal Problem Statement Design and Analysis Prototype Design and Construction Lessons Learned from Testing

Project Goal To Create a long travel downhill mountain bike Must be able to withstand forces from large jumps Needs to work reliably

Problem Statement Begin Impact End Impact Characteristics Low Initial force Goal: allow the rider additional reaction time Characteristics High Final Force Production Downhill Bikes Our Bike Force To Rider

Ma= Pos1 Pos2 Orig. Pos3 Ma = Mechanical Advantage

Part List Axle Mount

Forces Designed for a 180 lb rider and 70 pound bike to fall 9.4 ft to flat with a safety factor of 2.5

Top Tube Yield Strength = 70,000 psi Factor of Safety = 2.5 Max Stress = 28,000 psi

Top Tube Link Yield Strength = 85,000 psi Factor of Safety = 2.7 Max Stress = 32,000 psi

Shock Connect Yield Strength = 85,000 psi Factor of Safety = 2.5 Max Stress = 34,000 psi

Arm Link Max Stress = 20,000 psi Yield Strength = 85,000 psi Factor of Safety = 4.3

Lower Arm Yield Strength = 85,000 psi Factor of Safety = 2.5 Max Stress = 34,000 psi

Axle Mount Max Stress = 8,760 psi Yield Strength = 85,000 psi Factor of Safety = 9.7

Upper Arm Top Max Stress = 32,000 psi Yield Strength = 85,000 psi Factor of Safety = 2.7

Upper Arm Bottom Max Stress = 32,000 psi Yield Strength = 85,000 psi Factor of Safety = 2.7

Seat Tube - Original Max Stress = 66,000 psi Yield Strength = 70,000 psi Factor of Safety = 1.1

Seat Tube - Revised Max Stress = 26,000 psi Yield Strength = 70,000 psi Factor of Safety = 2.7

Bottom Bracket Max Stress =14,000 psi Yield Strength = 70,000 psi Factor of Safety = 5

Bottom Tube Max Stress =20,000 psi Yield Strength = 70,000 psi Factor of Safety = 3.5

Safety Factors PartPart TypeMaterial Yield Strength (ksi)Max Stress (ksi)Factor of Safety Top TubeTube Top Tube LinkMilled Shock ConnectMilled Arm LinkMilled Lower ArmMilled Axle MountMilled Upper ArmMilled Seat TubeTube Bottom BracketTube Bottom TubeTube MATERIALS: Milled:1045 Steel, Tube: ASTM A513 Type 5

Life Cycles for Members

Weight Analysis Prototype Weight: 58 lbs

Result of Engineering Analysis Bolt Analysis  Lowest bolt factor of safety is 2.7 Part Analysis  All other parts have safety factors of 2.5 and above Weight Analysis  The bike including all parts will weigh about 70 lbs  Prototype weight is 58 lbs Fatigue Analysis  All parts have Fatigue cycles greater than 3 x 10 6

Bill of Materials MaterialsMilled: 1045 Cold Drawn Steel Tube: ASTM A513 Type 5 tubes with 1/16” max wall thickness

Bill of Materials Tensile Strength: 144 ksi

Bolts Arm Link Shocks Shock Connect Shock Link Top Shock Link Bottom Upper Arm Lower Arm Axle Mount Bolt Size: 3/8 Bolt Size: 1/4 Bolt Size: 3/8 Bolt Size: 1/4 Bolt Size: 5/16 Bolt Size: 1/4

Prototype

Lower Arm Repair

Lessons Learned Crumpled Lower Arm Difference between Lower arm design / prototype Thicker Tube, Heat Treated, Re-enforcement Confident in current design. Prototype was not built exactly as designed due to cost and manufacturing ability. Successful proof of concept

Video

Questions?