Forensic Engineering Testing of A Chain that Failed

Article Author(s): Edward S. George, P.E. (NAFE 621M)

Volume: 28
Volume #: 2
Month: December
Year: 2011

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Abstract

An attempt to extricate a tractor stuck in a sandy field using a steel tow chain in combination with
a nylon strap was unsuccessful when the steel tow chain failed. The broken chain recoiled back hitting
the plaintiff in the face causing extensive injuries. The plaintiff sued the distributor of the chain for
damages. The Forensic Engineer assessed the specific allegations that included failure to properly
design, manufacture, assemble, test, inspect, label and package subject chain, to ensure that it would not
fail in ordinary foreseeable use. The Forensic Engineer reviewed Factors of Safety and performed load
tests on both the subject chain, an exemplar chain and an exemplar nylon strap. The Forensic Engineer’s
investigation resulted in an informed conclusion as to the cause of this failure.

Keywords
Utility chain, webbing sling, dimple rupture, Scanning Electron Microscopy, Factor of Safety
(safety factor)