DSES6070Statistical Methods forReliability Engineering

Reliability of a Bicycle as a Commuter Vehicle

By Adam Brown

Methods

• FMECA

• Quantitative event tree

• Calculate R and z for the system

• Calculate MTTF for the system

• Calculate importance measures

• Make recommendations to improve the system

FMECA

Event Tree

Power applied to pedal

Pedal rotates

Bottom bracket rotates

Chain transmits power

Hub rotates

Wheel is true

Tire is inflated

Outcomes Frequency(per year)

True

On time

Late

Late, and tired

On time, but tired

Extremely late

True

False

0.05

0.95True

False

0.05

0.95

True

False

0.05

0.95

False

0.001

0.999

True

0.98

False

True

False

0.05

0.95True

False

0.05

0.95

True

False

0.05

0.95

False

0.001

0.999

True

True

0.999

0.02

False

0.001

Late

Very late

Late, and tired

Very late, and tired

Extremely late

Extremely late

True

0.999

0.001

False Extremely late

0.8818

0.0464

0.0464

0.0024

0.0010

0.0180

0.0009

0.0009

0.0000

0.0000

0.001

0.001

Summary

• RS(t) = e-0.1258t

• MTTF = 8 days

• Birnbaum’s measure shows that the wheel and tire are the most important components to the system as expected [IB(wheel)=0.9282 and IB(tire)=0.9282].

Supplementary:

Component Importance