J-Integral Tearing Instability Analysis for 8-Inch Diameter ASTM A106 Steel Pipe

摘要

An experimental investigation was performed to evaluate the applicability of using J-Integral tearing instability analysis to describe the fracture behavior of 8-inch diameter, nuclear grade, ASTM A106 steel pipe. Pipe sections measuring 48-inches in length and 8.60 inches in diameter with circumferential fatigue precracks were loaded in four point bending using a variable compliance test arrangement. Variations in crack length, moment arm length, and machine stiffness were used to control the ductile fracture behavior of the pipes resulting in either stable or unstable crack extension. J-Integral tests were performed on plan compact specimens machined from the pipe. These J-Integral resistance curves (J sub I curves) were compared to the J sub I-R curves from the pipe bend behavior. In one analysis, the material was modelled by assuming elastic-perfectly plastic behavior, while a second analysis utilized measurements of mechanical response of the loaded structure including hardening of the steel.