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COMPONENT FAILURE MUSEUM

The main sections of the museum are listed below;

Metal Fatigue
Manufacturing Faults
Bicycle Components
Corrosion
Polymers
Composite Materials

Tools of the trade, some ways to investigate problems;
Photoelasticity
Dye penetrant testing

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Bicycle components failure

Fatigue cracks in steel cycle frame

Click on pictures below for larger image.
Click on linked text for explanation of term or see glossary.

 Although steel has a fatigue endurance limit certain parts of the frame are stressed above this limit and are prone to fatigue cracking. The rear triangle, comprising the chainstays and seatstays are particularly vulnerable.

On the opposite side, the associated cracked point had caused surface corrosion. Notice that the cracks had occurred close to the brazed-on cross member. The heat affected zone associated with brazing and welding usually reduces the endurance limit and raises the chance of fatigue crack initiation.

A metallurgical investigation of the extent of the heat affected zone is in progress. The manufacturers did not fulfil their "lifetime" guarantee in this instance by suggesting that damaged paintwork caused corrosion, which in turn initiated fatigue.

Return to Metal fatigue cases
Return to Bicycle components

31/01/02 ed:AG

 
 
© 2005 Materials Engineering - Page last modified 18-Dec-2007