SHIP STRUTURE COMMITTEE to the Behavior of Riveted and Welded Crack Arrestors

摘要

This report describes the laboratory work undertaken 1) to investigate the feasibility of developing a welded crack arrestor and 2) to observe the be¬havior of various crack arresting devices. The study was accomplished by propagating a brittle crack, initiated by driving a wedge into a notch at the edge of the specimen, into 2-ft and 6-ft wide steel plates containing either (a) welded inserts of T-l steel (b) riveted doubler plates or (c) welded inserts of ABS Class C normalized steel, which were located at various distances from the edge of the plate. Most of the tests were conducted at nominal stresses between 20 and 30 ksiand at temperatures between -25 and 40 F. Some of the specimens were instrumented with strain gages to provide information on crack speed and strain pattern.nThe progress of the crack and the extent of its penetration in the T-l steel insert depended primarily on the severity of the resulting eccentric load and the width of the arrestor material. Strain gage measurements indicated that the average speed of brittle crack propagation was generally between 2800 and 3800 fps and that little change occurred in the strain across the uncracked portion of the plate beyond the localized influence of the crack front.