Dynamic Fracture and Depressurization in Pipes. Annual Report.

摘要

This annual report contains predictive models for initiation and rapid propagations of ductile axial and circumferential cracks and the associated depressurization response in pipes developed during the sixth year of EPRI RP 231-1. Three dimensional static stress intensity factors of circumferential through cracks of various crack lengths and in a pipe subjected to uniform axial tension, uniform axial displacement, pure bending at pipe ends and three point bending with the crack on the tension side were obtained. The thermal hydraulic code LEAKER as well as an updated version of a closed form solution of depressurization equations for large, axial-crack-induced breaches was used to predict the depressurization and maximum rate of depressurization of axially cracking pipes. Further studies on the initiation and propagation of circumferential through cracks in the presence of large scale yielding in a 32 in. diameter pipe of SA 155 grade KCF 70 subjected to axial tension, axial displacement and fixed-end rotation were conducted by using the elastic-plastic finite difference shell code. (ERA citation 07:053969)