Integrity evaluation of stainless steel piping with multiple flaws under combined load is difficult when one flaw is located near other flaw. This is because that the stress state in the piping becomes complicated as a result of the mutual interference of the stress fields occurred by flaws. If the stress-displacement curve of stainless steel piping with two flaws can be estimated by using the curves of single notched stainless steel piping before and after flaw coalescence, the integrity evaluation of stainless steel piping with two flaws becomes easy and simple. In this study, the stress-displacement curves of the single notched pipes with notch angle 37° or 90° subjected to combined tensile and bending loads are obtained experimentally. In addition, the stress-displacement curve of the pipe which has two notches in the same cross section area and both notch angles are 37° and notch interval 16° (total notch angle is 90°) is also obtained experimentally. The stress-displacement curve of the 37°+37° multiple notched pipe is compared with the curves of the 37° single notched pipe and the 90° single notched pipe. In the tensile principal tests, the stress-displacement curve of the 37°+37° notched pipe shows good agreement with the curve of the 37° notched pipe until notch coalescence. In the bending principal test, the error of the stress-displacement curves between the 37° +37° notched pipe and the 37° notched pipe is higher than that of the tensile principal test. The stress-displacement curve of the 37° +37° notched pipe after notch coalescence shows relatively good agreement with the curve of the 90° notched pipe in the bending principal test. After notch coalescence, the error of the stress- displacement curves of the 37° +37° notched pipe and 90° notched pipe for tensile principal test is higher than that for the bending principal test.
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