Separation of elastic energy under shock loading of cylindrical bodies from isotropic and anisotropic materials

Author(s):  
E.V. Tuch ◽  
◽  
M.N. Krivosheina
2009 ◽  
Vol 76 (6) ◽  
Author(s):  
Alexander A. Lukyanov

In this paper, the thermodynamically and mathematically consistent modeling of anisotropic materials under shock loading is considered. The equation of state used represents the mathematical and physical generalizations of the classical Mie–Grüneisen equation of state for isotropic material and reduces to the Mie–Grüneisen equation of state in the limit of isotropy. Based on the full decomposition of the stress tensor into the generalized deviatoric part and the generalized spherical part of the stress tensor (Lukyanov, A. A., 2006, “Thermodynamically Consistent Anisotropic Plasticity Model,” Proceedings of IPC 2006, ASME, New York; 2008, “Constitutive Behaviour of Anisotropic Materials Under Shock Loading,” Int. J. Plast., 24, pp. 140–167), a nonassociated incompressible anisotropic plasticity model based on a generalized “pressure” sensitive yield function and depending on generalized deviatoric stress tensor is proposed for the anisotropic materials behavior modeling under shock loading. The significance of the proposed model includes also the distortion of the yield function shape in tension, compression, and in different principal directions of anisotropy (e.g., 0 deg and 90 deg), which can be used to describe the anisotropic strength differential effect. The proposed anisotropic elastoplastic model is validated against experimental research, which has been published by Spitzig and Richmond (“The Effect of Pressure on the Flow Stress of Metals,” Acta Metall., 32, pp. 457–463), Lademo et al. (“An Evaluation of Yield Criteria and Flow Rules for Aluminium Alloys,” Int. J. Plast., 15(2), pp. 191–208), and Stoughton and Yoon (“A Pressure-Sensitive Yield Criterion Under a Non-Associated Flow Rule for Sheet Metal Forming,” Int. J. Plast., 20(4–5), pp. 705–731). The behavior of aluminum alloy AA7010 T6 under shock loading conditions is also considered. A comparison of numerical simulations with existing experimental data shows good agreement with the general pulse shape, Hugoniot elastic limits, and Hugoniot stress levels, and suggests that the constitutive equations perform satisfactorily. The results are presented and discussed, and future studies are outlined.


2011 ◽  
Vol 64 (4) ◽  
Author(s):  
Alexander A. Lukyanov ◽  
Steven B. Segletes

Studies of anisotropic materials and the discovery of various novel and unexpected phenomena under shock loading has contributed significantly to our understanding of the behavior of condensed matter. The variety of experimental studies for isotropic materials displays systematic patterns, giving basic insights into the underlying physics of anisotropic shock wave modeling. There are many similarities and significant differences in the phenomena observed for isotropic and anisotropic materials under shock-wave loading. Despite this, the anisotropic constitutive equations must represent mathematical and physical generalization of the conventional constitutive equations for isotropic material and reduce to the conventional constitutive equations in the limit of isotropy. This article presents the current state of the art in the constitutive modeling of this fascinating field.


Author(s):  
D. Faulkner ◽  
G.W. Lorimer ◽  
H.J. Axon

It is now generally accepted that meteorites are fragments produced by the collision of parent bodies of asteroidal dimensions. Optical metallographic evidence suggests that there exists a group of iron meteorites which exhibit structures similar to those observed in explosively shock loaded iron. It seems likely that shock loading of meteorites could be produced by preterrestrial impact of their parent bodies as mentioned above.We have therefore looked at the defect structure of one of these meteorites (Trenton) and compared the results with those made on a) an unshocked ‘standard’ meteorite (Canyon Diablo)b) an artificially shocked ‘standard’ meteorite (Canyon Diablo) andc) an artificially shocked specimen of pure α-iron.


Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.


Author(s):  
K. P. Staudhammer ◽  
L. E. Murr

The effect of shock loading on a variety of steels has been reviewed recently by Leslie. It is generally observed that significant changes in microstructure and microhardness are produced by explosive shock deformation. While the effect of shock loading on austenitic, ferritic, martensitic, and pearlitic structures has been investigated, there have been no systematic studies of the shock-loading of microduplex structures.In the current investigation, the shock-loading response of millrolled and heat-treated Uniloy 326 (thickness 60 mil) having a residual grain size of 1 to 2μ before shock loading was studied. Uniloy 326 is a two phase (microduplex) alloy consisting of 30% austenite (γ) in a ferrite (α) matrix; with the composition.3% Ti, 1% Mn, .6% Si,.05% C, 6% Ni, 26% Cr, balance Fe.


Author(s):  
J. A. Korbonski ◽  
L. E. Murr

Comparison of recovery rates in materials deformed by a unidimensional and two dimensional strains at strain rates in excess of 104 sec.−1 was performed on AISI 304 Stainless Steel. A number of unidirectionally strained foil samples were deformed by shock waves at graduated pressure levels as described by Murr and Grace. The two dimensionally strained foil samples were obtained from radially expanded cylinders by a constant shock pressure pulse and graduated strain as described by Foitz, et al.


Author(s):  
A. Christou ◽  
J. V. Foltz ◽  
N. Brown

In general, all BCC transition metals have been observed to twin under appropriate conditions. At the present time various experimental reports of solid solution effects on BCC metals have been made. Indications are that solid solution effects are important in the formation of twins. The formation of twins in metals and alloys may be explained in terms of dislocation mechanisms. It has been suggested that twins are nucleated by the achievement of local stress-concentration of the order of 15 to 45 times the applied stress. Prietner and Leslie have found that twins in BCC metals are nucleated at intersections of (110) and (112) or (112) and (112) type of planes.In this paper, observations are reported of a transmission microscope study of the iron manganese series under conditions in which twins both were and were not formed. High strain rates produced by shock loading provided the appropriate deformation conditions. The workhardening mechanisms of one alloy (Fe - 7.37 wt% Mn) were studied in detail.


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