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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

Another example of dye penetrant testing used on bicycle components.
Select images below for larger picture.

This cycle crank arm was returned to the supplier after a very short time in use. The owner had seen a crack coming from the square taper axle attachment ( see image) and suspected a smaller crack close to the pedal thread (see image).

The suspect areas were sprayed with red penetrant dye and left to soak. The square hole location was clearly cracked but the minor region may be a surface scratch.
Such distinctions are very important in the performance of engineering components.

After the dye was cleaned off the component was sprayed with chalk developer. The crack running from the square axle drive hole gave a very distinct red indication at its precise location, indicating it was clearly cracked. The other feature showed no red line on development indicating a surface scratch not an embyronic crack.

ED; AG 9/4/03

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