Fracture response of externally flawed aluminum cylindrical shells under internal gaseous detonation loading

Abstract

International Journal of Fracture (2005) 134:59-90Abstract. Experiments were performed to observe the fracture behavior of thin-wall and initiallyflawed aluminum tubes to internal gaseous detonation loading. The load can be characterized as a propagating pressure jump with speed of 2.4 km/s and magnitude ranging from 2 MPa to 6 MPa, followed by an expansion wave. Flaws were machined as external axial surface notches. Cracks ran both in the upstream and downstream directions as the hoop stress opened up the notch. Different kinds of crack propagation behavior were observed for various loading amplitudes and flaw sizes. For low-amplitude loading and short flaws, cracks tend to run in a helical fashion, whereas for highamplitude loading and long flaws, cracks tend to bifurcate in addition to running helically. Unless the cracks branched and traveled far enough to meet, resulting in a split tube, they were always arrested. Strain gages were used to monitor the hoop strains at several places on the tubes' external surface. Far from the notch, tensile vibrations were measured with frequencies matching those predicted by the steady-state Tang (1965, Proceedings of the American Society of Civil Engineers 5, 97-122) and Simkins (1987, Technical Report ARCCB-TB-87008, US Army Armament Research, Development and Engineering Center, Watervliet, N.Y. 12189-4050) models. Near the notch, compressive strains were recorded as a result of the bulging at the notch. Features in the strain signals corresponding to different fracture events are analyzed.

Finite Element Analysis of Deformation and Fracture of Cylindrical Tubes under Internal Moving Pressures

“…Also, it is clear the crack grows more in the forward direction, i.e., in the direction of movement of the detonation front. The same phenomenon was observed by Chao and shepherd in their experiments (Chao & Shepherd, 2005). This asymmetric growth, which is one of the specific features of detonation-driven fracture of tubes and occurs quite naturally as a result of the difference between the relative speeds of the structural waves with respect to the two crack tips, will be discussed in sequel.…”

“…There was no report in the open literature about confined crack growth in tubes under gaseous detonation, prior to the experimental study reported by Chao and Shepherd (2005). Their study was primarily motivated by accidents like those occurred in the nuclear power plants in Japan (Naitoh et al, 2003) and Germany in 2001.…”

“…The second problem is that crack curving and branching could not be simulated using the CTOA approach implemented in WARP3D. Cirak et al (2007) performed large-scale fluid-structure interaction simulation of viscoplastic deformation and fracturing of the experimental aluminum tube of Chao & Shepherd (2005). In practice, they used the static plain strain fracture toughness Ic K to obtain the properties of their cohesive elements.…”

“…(Chao, 2004;Chao & Shepherd 2005). This asymmetric growth occurs quite naturally as a result of the difference between the relative speeds of the structural waves with respect to the two crack tips.…”

Immersed particle method for fluid–structure interaction

“…A series of experiments concerned with the quasi-brittle fracture of shells has been reported by Chao and Shepherd [39], and Chao [40]. These experiments involve notched thin-wall pipes filled with a gaseous explosives through which a detonation wave is passed.…”