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Engineering the Future |
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| MATERIALS ENGINEERING | |||
COMPONENT
FAILURE MUSEUM |
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The main sections of the museum are listed below; Metal Fatigue Tools of the trade, some ways to investigate problems; Glossary |
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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). |
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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. |
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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. |
First example of dye penetrant testing
ED; AG 9/4/03