The main sections of the museum are listed below;
Tools of the trade, some ways to investigate problems;
Dye penetrant testing
of materials engineering terms
Bending fatigue fracture
on picture below for full size image in new window.
Reversed bending fatigue fracture
starting from keyway
This 100 mm diameter steel shaft failed
after a long period of service on a large dumper truck. The
keyway terminated in a circumferential groove approximately
half the depth of the keyway. Fatigue cracks initiated at both
corners of the keyway had propagated into the cross section
at 900 to the shaft axis, following the sharp corner of a circumferential
groove. The crack arrest fronts are close together and the
surface fairly smooth, showing that the propagation was slow
at first but progressively increasing as the effective cross
sectional area decreased.
Eventually, so little cross
section remained that the final separation took place under a
normal torsional load. This appears as the rougher, pear shaped
area near the centre.
This is the kind of failure expected
when keyways and recesses in shafts are machined with inadequate
radiuses at their roots, thus leading to high stress concentrations
under the applied loads.
to metal fatigue section