Morphology of fracture of cylindrical shells in the wave stage

Gryaznov, E. F.; Karmanov, E. V.; Selivanov, V. V.; Khakhalin, S. V.

doi:10.1007/bf01530294

Cited by 4 publications

(5 citation statements)

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“…The above results are in agreement with the experimental data of G.yaznov et al [15], who studied various schemes of explosive loading and shell failures and performed a thorough morphological analysis of the fragments formed. They obtained a moderate damage level for the glancing DW and observed spallation in the shell walls during oblique impact by a liner.…”

Section: K~ + 8#ssupporting

confidence: 92%

“…The experiments of [14], in which shell expansion was terminated at different stages, and the subsequent metallographic analysis of the cross-sections revealed internal radial cracks that do not emerge on either of the shell surfaces. This confirms the conclusions of [13] on the decisive influence of the SRZ on the formation of main cracks and fragmentation of thick-wailed shells.…”

Section: K~ + 8#smentioning

confidence: 99%

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Numerical simulation of spallation in thick-walled shells under explosive loads of various types

Герасимов¹

1996

J Appl Mech Tech Phys

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Problems of explosive expansion and failure of thick-walled shells are of interest from the viewpoint of technical applications and attract the attention of specialists [1][2][3][4]. The motion of cylindrical shells under the action of detonation products (DP) was discussed by Odintsov et al. [1] in Eulerian formulation and by Levitan et al. [2,3] in Lagrangian formulation. Relatively uniform strains are typical for expanding shells, while the outflowing detonation products are characterized by very high levels of displacements and strains. Therefore, the Lagrangian approach, which is convenient for study of expansion of closed shells, becomes inapplicable in the case of free DP flow into the surrounding space.Eulerian description of motion of a continuous medium leads to some difficulties in location and accurate determination of contact and boundary surfaces and in keeping track of fracture zones. These contradictory requirements on the numerical method of calculation of expanding shells can be satisfied by using Euler coordinates to describe DP motion and Lagrange coordinates to describe shell motion. One possible variant of the combined Euler-Lagrange method for solution of problems of expansion of thick elastoplastic shells accompanied by DP effusion into vacuum was proposed by Gerasimov and Lyukshin [4]. This variant is based on a combination of the methods of [5,6]; it combines the advantages of both methods and avoids their drawbacks. Problems of determination of parameters of the stress-strained state of expanding shells have been extensively investigated, whereas the numerical simulation of shell failure in a three-dimensional axisimmetric formulation has been studied much less [2,3]. Failure of an elastic shell was studied by Levitan and Moiseenko [2], and failure of an elastoplastic shell caused by a glancing detonation wave was studied by Kostin et al. [3].Below, using the approach proposed in [4], we study damage growth and the possibility of spallation in the walls of thick-walled elastoplastic shells both under the action of glancing detonation and in throwing of a liner shell onto the internal surface of the main shell. The model of a porous ideal elastoplastic body of [7,8] is applied to describe the behavior of damaged material. Failure is treated as a process of accumulation and growth of microcracks (micropores) by means of the kinetic equation proposed in [7]. A nonviscous nonthermoconducting gas model was used in description of DP.1. Statement of the Problem. We study a thick-walled cylindrical elastoplastic shell with the bottom filled with a high-explosive (HE) charge (see Fig. la). In the second variant (Fig. lb) the HE is in contact with a thin liner shell. There is clearance h between the liner and the main shell. On the left end OE the shell is not closed. Initially, a plane detonation wave (DW) is formed at this end. This wave propagates through the HE in the bottom direction. An oblique shock wave proragates along the liner shell, accelerating the particles of the material, while D...

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Section: K~ + 8#ssupporting

confidence: 92%

Section: K~ + 8#smentioning

confidence: 99%

Numerical simulation of spallation in thick-walled shells under explosive loads of various types

Герасимов¹

1996

J Appl Mech Tech Phys

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“…As a result of tube extension in the radial direction, first the main vertical cracks are formed throughout the specimen height, and then the main horizontal cracks are formed. This leads to the formation of 2D fragments, which corresponds to the scenario of the fracture of thin shells (the Mott model), when the form of distribution is affected only by the value of the load pulse [9,10]. The preliminary analysis of the structure of tubes made from one kind of the material has shown that the initial porosity has a direct effect on the formation of 3D fragments.…”

Section: Resultsmentioning

confidence: 99%

“…The existence of the collective modes in defect ensemble evolution leads to the power-law distribution of the defects at the damage process zone at the crack tip. The damage evolution will eventually lead to the separation of the material fragments from the fracture surface [9] and the formation of 3D fragments. …”

Section: Formation Of 3d Fragmentsmentioning

confidence: 99%

The effect of initial porosity of a sample under electric explosion loading

Bannikova¹,

Uvarov²,

Naimark³

2016

AIP Conference Proceedings

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Abstract. Tubular Al 2 O 3 ceramic samples were destroyed under shock wave loading using electrical explosion wire (EEW) in a liquid. The fragments were classified into two types: quasi-two-dimensional (2D) samples, the characteristic size of which, d*, was greater than (or equal to) the tube wall thickness; and three-dimensional (3D) samples of the size d* < d. The study of the influence of the initial sample porosity indicates a direct effect on the formation of 3D fragments, and the distribution of the porosity is described by the power law function with an exponent differing from that of the 3D fragments size distribution. According to the scenario, the initial defects (pores) provide conditions for multi-site fracture of ceramics under high-rate loading. The instability of fast crack propagation leads to micro-branching, which creates conditions for the formation of the 3D objects. The 3D fragments size distribution is described by the power law, which corresponds to the micro-branch distribution.

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“…The process of fracture of a shell loaded by detonation products of a contact HE charge has been well studied. Such shells become destroyed under the joint propagation of spall cracks in the outer zone affected by tensile stresses and shear cracks in the compressed inner zone [12,13]. Various criteria are used to describe crack propagation [14,15].…”

mentioning

confidence: 99%

Explosive projection of liquid from a thick-walled cylindrical container

Bykov

Gryaznov

Okhitin

2009

J Appl Mech Tech Phy

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The process of projection of a layer of an ideal liquid enclosed into a cylindrical elastoplastic shell by products of instantaneous detonation of a high explosive charge is studied numerically in a twodimensional plane formulation. The processes of shell fracture and liquid exhaustion through the resultant slots are considered. Numerical results are analyzed, and analytical relations for angular distributions of radial velocity and mass of the liquid escaping through the slots are derived.The method of explosive spraying of the liquid finds applications in various areas of human activities. This method implies blasting of a high explosive (HE) charge inside a container filled by the liquid. This method is used to generate water screens in mines dangerous in terms of dust and gas [1,2], to affect hail clouds [3], and to extinguish fires [4].The results of studying the explosive method of liquid spraying were obtained for models with a low-strength container or without it.In the present work, the process of projection of a layer of an ideal liquid enclosed into a cylindrical elastoplastic shell by products of instantaneous detonation of an HE charge is studied numerically in a two-dimensional plane formulation. A sketch of the model is shown in Fig. 1 (R 0 , a 0 , and b 0 are the initial radii of the charge, liquid layer, and shell, respectively).Two-dimensional plane motion of the system consisting of detonation products (DPs), the liquid, and the shell was described by a combined Eulerian-Lagrangian finite-difference method for the numerical solution of the system of equations of mechanics of continuous media. The system of equations that describe two-dimensional plane motion of an elastoplastic shell in polar Eulerian coordinates in the Lagrangian form can be found, e.g., in [5].To describe the flow in the region of the plastic state of the shell, we used the procedure of reduction of the calculated elastic stresses to the yield circle in accordance with the Mises yield condition [6]. The volume compressibility of the shell was defined in the form of the Tait equation [7].The system of differential equations that describe a two-dimensional plane adiabatic flow of an ideal liquid and gas in polar Eulerian coordinates (r, θ) was given, for instance, in [8].The system was supplemented with the equation of state of the media in the caloric form p = p(γ, ρ, E), which included an additional variable γ determining the phase composition of the medium, apart from two thermodynamic parameters (density ρ and specific internal energy E). If the Eulerian grid is used, it is impossible to draw a distinct boundary between the detonation products and the liquid at any instant of time, except for the initial one; therefore, the system of equations should be supplemented with a relation for separating the phases. A certain value of γ was assigned to particles of each medium. The condition dγ/dt = 0 had to be satisfied along the trajectory of each particle. In polar Eulerian coordinates, this condition acquires the form ∂γ ∂t + u...

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Morphology of fracture of cylindrical shells in the wave stage

Cited by 4 publications

References 1 publication

Numerical simulation of spallation in thick-walled shells under explosive loads of various types

Numerical simulation of spallation in thick-walled shells under explosive loads of various types

The effect of initial porosity of a sample under electric explosion loading

Explosive projection of liquid from a thick-walled cylindrical container

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