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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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of materials engineering terms


Reversed torsional fatigue failure

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 Reversed torsional fatigue failure of splined shaft from a differential drive gear

The mating halves of the fracture reveal how two separate cracks initiated in a circumferential recess adjacent to the end of the splines and began to propagate into the cross section following helical paths. Because the cycles of twisting forces acted in opposite directions, each crack follows opposing helices which progressively reduced the effective cross sectional area and, consequently, increased the levels of cyclic stresses from the same applied loads.

Shortly before the shaft finally broke bending forces initiated a third crack at the opposite side of the shaft and this had begun to propagate as a plane fracture at 90° to the shaft axis until the splined end finally broke away.

Return to metal fatigue section

ed:KR 17/12/01

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