Failure Analysis of Lift Pad Studs for the Recovery of Objects from the Ocean

摘要

The report describes the application of failure analysis to a Naval Problem regarding the recovery of underwater objects. A lifting pad is attached to the object to be recovered by four studs which are explosively driven through undersized pad eyes into the submerged structure. Experimental trials by the Naval Ordnance Laboratory using a shock resistant tool steel for the studs resulted in breaking stresses of the order of 30,000 psi, far short of the tensile strength of 290,000 psi. NRL was asked to examine the stud failures. KIc and KIscc measurements were made on several unfailed studs. Recommendations include the use of another more suitable, non-ferrous alloy or as a minimum requirement lowering the tensile strength of the steel now used. (Author)