The next generation analysis methodology for cracked pipe systems subjected to dynamic loads

Evaluation procedures for cracked piping systems under dynamic loads, seismic and water hammer in particular, have evolved over the years from assuming an instantaneous brittle double-ended pipe break in the early years of the nuclear industry, to using peak load from a linear elastic analysis with elastic-plastic fracture mechanics over the past 10 years. With improvements in computing power and developments in the fracture mechanics analysis of cracked pipe, it is now possible, using work station computers, to perform nonlinear time-history cracked-pipe analyses that can predict, not only the maximum load, but an make reasonably accurate, but slightly conservative, predictions of the time to surface crack penetration, how far the crack may propagate around the circumference, and the crack opening history for leak rate, decompression, and jet-force calculations. This new analysis methodology, the so-called cracked-pipe element nonlinear FEA fracture analysis is currently being formulated and refined. The analytical methods and comparison with experimental cracked-pipe data, as well as some specific applications illustrating margins obtained by this methodology versus more traditional analyses will be summarized