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Chevron Marks
Chevron marks
are often left on a fracture surface. Most usually,
they occur as a result of running fractures, i.e., fractures
which progress through the structure. Chevron marks
are extremely helpful to the failure analyst.
Chevrons point to where the crack came from, i.e.,
where the crack ultimately originated.
A clear set of
chevron marks is shown in Photograph A. The chevrons
in Photograph A point from right to left indicating
the fracture origins for the portion of the crack is
locating to the left of Photograph A
Photograph
A
Chevrons, in the
hardened zone (lower smooth fracture) of a turntable
slewing
bearing fracture are shown in Photograph B. The chevrons in
the hardened bearing case clearly indicate (point) to the right.
Therefore, this particular crack originated to the
right in Photograph B.
Photograph B
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Dr.
R. Craig Jerner, Ph.D., PE specializes in accident
investigation and metallurgical failure analysis,
with over 30 years experience as a metallurgical
consultant and accident investigator. He has
testified as a metallurgical expert in over 250
depositions and more than 70 court appearances. If you or someone you know should need the services of Dr. Jerner and J.E.I. Metallurgical, please visit our web site at the buttons below, or e-mail Dr. Jerner --- 