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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

Glossary
of materials engineering terms


Dye-penetrant testing

The crank spider arm of this chainset fractured and unseated the cyclist in heavy city traffic.
It was old but well looked after and cleaned regularly The growing fatigue crack was undetected until the dangerous failure.
The cyclist was concerned if a similar crack had been nucleated in the matching plain crank arm shown alongside.

The equivalent area was sprayed with red penetrating dye which was then left to soak into any cracks or fissures in the component.
After several minutes of soaking the dye was cleaned off the components surface.

The pre-soaked and cleaned area was then sprayed with developer spray which is basically chalk powder in a volatile carrier. Any defects present show up as the red dye is pulled out of any cracks or fissures in the component.
It was concluded that none were present . The only red marks were from dye that had been retained in the stamped product identification marks.

 

 

Ed; AG 9/4/03

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