Non-intuitive fracture pattern of a failed crane-hanger: A fracture mechanics-based explanation

摘要

A crane hanger in a paper factory failed during service, causing the crash of the transported paper spool weighing 10 tons. Fatigue cracking over 1/3 of the cross section was visible, surprisingly starting at the contact point with the crane hook, where the lifted load produces compressive stresses. This counter-intuitive crack origin could be explained by the manufacturing residual stresses, but still not the final fracture of the hanger.