Mechanisms of Metallic Failure: Flaw Initiation Techniques and Measurements in Thin-Wall Pressure Vessels

摘要

A hydraulic system was designed and constructed for the purpose of introducing surface or part-through-the-thickness cracks to thin-wall (0.065-in.) scale-model pressure vessels. The hoop stresses resulting from internal pressure, in the range 4000 to 5000 psi, will be applied as pressure pulses at frequencies up to 160 cycles per minute for numbers of cycles required to grow cracks of predetermined lengths. The system consists essentially of a motor-driven hydraulic pump, valves, fittings, tubing and appropriate instrumentation. A component of the system, a manually-operated hydraulic pump, will afford burst pressures up to 30,000 psi to test vessels containing induced cracks. Several vessels were fabricated from 18 per cent nickel (250 grade) maraging steel. (Author)