Crack Propagation and Arrest in Pressurized Containers

Abstract

The problem of crack propagation and arrest in a finite volume cylindrical container filled with pressurized gas is considered. It is assumed that the cylinder contains a symmetrically located longitudinal part-through crack with a relatively small net ligament. The net ligament suddenly ruptures initiating the process of fracture propagation and depressurization in the cylinder. Thus the problem is a coupled gas dynamics and solid mechanics problem the exact formulation of which does not seem to be possible. It is formulated by making two major assumptions, namely that the shell problem is quasi-static and the gas dynamics problem is one-dimensional. The problem is reduced to a proper initial value problem by introducing a dynamic fracture criterion which relates the crack acceleration to the difference between a load factor and the corresponding strength parameter. The main results are demonstrated by considering two examples, an aluminum cylinder which may behave in a quasi-brittle manner, and a steel cylinder which undergoes ductile fracture. The results indicate that generally in gas-filled cylinders fracture arrest is not possible unless the material behaves in a ductile manner and the container is relatively long.

Piping Inelastic Fracture Mechanics Analysis.

“…Following the introduction of the J-integral [71, J, has been accepted as a elastic/plastic fracture initiation criterion [10,11,12,13] Equation 17indicates that the loading increments will be proportional (de, E iii) if the first term dominates, which may be assured when a < <dJ (19) r J If there exists an annular region [55]. The effects of material strain hardening, small scale yield [54], and the correlation between tearing instability and Turner's -q factor [57] have also been investigated.…”