PLASTIC COLLAPSE STRENGTH OF CIRCUMFERENTIALLY MULTIPLE NOTCHED STAINLESS PIPING SUBJECTED TO COMBINED AXIAL TENSION AND BENDING

The present study examines the effects of the number of cracks and the crack interval on the plastic collapse strength of austenitic stainless steel (SUS304) piping with multiple cracks subjected to combined axial tension and bending. The goal of the present study is to simplify the structural integrity assessment of the stainless steel piping. Notches were cut in circumferential direction of the SUS304 pipes. The notch interval was 5 to 32 mm in the double-notched specimens. In the triple-notched specimens, the notches of the specimen were equally spaced. The notches at both ends of the triple-notched specimens were cut at the same interval as the double-notched specimens. The notched specimens were subjected to combined axial tension and bending. The plastic collapse strength of the notched specimens was dependent on the load history, and the plastic collapse strengths of the double- or triple-notched specimens was approximately equal to that of the single-notched specimens. These strengths were higher than the theoretical plastic collapse strength of the single-notched specimen based on an elastic-perfectly plastic material. Therefore, double or triple circumferential notches arranged in intervals of from 5 to 32 mm in SUS304 piping can be considered to be a single circumferential crack by applying the plastic collapse theory for an elastic-perfectly plastic material.