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

0

100

200

300

400

500

600

700

800

900

1000

0 2 4 6 8 10 12 14

Travel (in)

Sp

rin

g F

orc

e (

N)

Problem Statement

Begin Impact End Impact

Characteristics•Low Initial force

Goal: allow the rider additional reaction time

Characteristics•High Final Force

ProductionDownhill Bikes

Our Bike

Force To Rider

0

0.5

1

1.5

2

2.5

0 4 8 12 16Wheel Travel (in)

Sho

ck T

rave

l (in

)

Position 1

Position 2

Original Position

Position 3

Ma= 5 5.5 5.8 6.3

Pos1

Pos2

Orig

.P

os3

Ma = 5 5.5 5.8 6.3

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 psiFactor of Safety = 2.5

Max Stress = 28,000 psi

Top Tube Link

Yield Strength = 85,000 psiFactor of Safety = 2.7

Max Stress = 32,000 psi

Shock Connect

Yield Strength = 85,000 psiFactor of Safety = 2.5

Max Stress = 34,000 psi

Arm LinkMax Stress = 20,000 psi

Yield Strength = 85,000 psiFactor of Safety = 4.3

Lower Arm

Yield Strength = 85,000 psiFactor of Safety = 2.5

Max Stress = 34,000 psi

Axle MountMax Stress = 8,760 psi

Yield Strength = 85,000 psiFactor of Safety = 9.7

Upper Arm Top

Max Stress = 32,000 psi

Yield Strength = 85,000 psiFactor of Safety = 2.7

Upper Arm Bottom

Max Stress = 32,000 psi

Yield Strength = 85,000 psiFactor of Safety = 2.7

Seat Tube - Original

Max Stress = 66,000 psi

Yield Strength = 70,000 psiFactor of Safety = 1.1

Seat Tube - Revised

Max Stress = 26,000 psi

Yield Strength = 70,000 psiFactor of Safety = 2.7

Bottom Bracket

Max Stress =14,000 psi

Yield Strength = 70,000 psiFactor of Safety = 5

Bottom Tube

Max Stress =20,000 psi

Yield Strength = 70,000 psiFactor of Safety = 3.5

Safety Factors

Part Part Type Material Yield Strength (ksi) Max Stress (ksi) Factor of Safety

Top Tube Tube 70 28 2.5

Top Tube Link Milled 85 32 2.7

Shock Connect Milled 85 34 2.5

Arm Link Milled 85 20 4.3

Lower Arm Milled 85 34 2.5

Axle Mount Milled 85 8.8 9.7

Upper Arm Milled 85 32 2.7

Seat Tube Tube 70 26 2.7

Bottom Bracket Tube 70 14 5.0

Bottom Tube Tube 70 20 3.5

MATERIALS: Milled:1045 Steel, Tube: ASTM A513 Type 5

Life Cycles for MembersUsing 1045 Steel

Members Life CyclesTop Tube 1.90E+08Top Tube Link 1.90E+08Shock Connect 9.30E+07Arm Link 4.70E+10Lower Arm 5.90E+06Axle Mount 5.60E+14Upper Arm 1.90E+08Seat Tube 3.30E+06

Weight AnalysisWeight (LBS)

Rear Suspension Subtotal 25.00

Additional Components2 x Shocks 10.00

Front Wheel 6.40 Rear Wheel 6.40

Front Fork 10.00 Handlebars 1.00

Seat 1.00 Drive train and Braking 10.00

Subtotal 44.80

Total Bike Weight 69.80 lbs

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 106

Bill of Materials

Materials Milled: 1045 Cold Drawn SteelTube: ASTM A513 Type 5 tubes with 1/16” max wall thickness

Description Part Type Thumbnail Quantity Description Part Type Thumbnail Quantity

Bottom Bracket Tube 1 Top Tube Tube 1

Arm Link Milled 2 Top Tube Link Milled 2

Lower Arm Milled 1 Seat Tube Tube 1

Axle Mount Milled 2 Shock Connect Milled 1

Upper Arm Milled 2 Bottom Tube Tube 1

Bill of Materials

Quantity Diameter Length6 1/4 1/22 3/8 22 1/4 7/82 1/4 3/42 1/4 5/81 5/16 2

Bolt Bill of Materials

Plain Steel Shoulder BoltSocket Head Style#10-24 thread

Tensile Strength: 144 ksi

Bolts

Arm Link

ShocksShock Connect

Shock Link Top

Shock Link Bottom Upper Arm

Lower Arm

Axle MountBolt Size: 3/8

Bolt Size: 1/4

Bolt Size: 3/8

Bolt Size: 1/4

Bolt Size: 5/16

Bolt Size: 1/4

Bolt Size: 1/4

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?