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Simulation of Comet Impact and Survivability of Organic Compounds

Description: Comets have long been proposed as a potential means for the transport of complex organic compounds to early Earth. For this to be a viable mechanism, a significant fraction of organic compounds must survive the high temperatures due to impact. We have undertaken three-dimensional numerical simulations to track the thermodynamic state of a comet during oblique impacts. The comet was modeled as a 1-km water-ice sphere impacting a basalt plane at 11.2 km/s; impact angles of 15{sup o} (from horizon… more
Date: July 18, 2007
Creator: Liu, B T; Lomov, I N; Blank, J G & Antoun, T H
Partner: UNT Libraries Government Documents Department
open access

Patch-based Adaptive Mesh Refinement for Multimaterial Hydrodynamics

Description: We present a patch-based direct Eulerian adaptive mesh refinement (AMR) algorithm for modeling real equation-of-state, multimaterial compressible flow with strength. Our approach to AMR uses a hierarchical, structured grid approach first developed by (Berger and Oliger 1984), (Berger and Oliger 1984). The grid structure is dynamic in time and is composed of nested uniform rectangular grids of varying resolution. The integration scheme on the grid hierarchy is a recursive procedure in which the … more
Date: October 18, 2005
Creator: Lomov, I; Pember, R; Greenough, J & Liu, B
Partner: UNT Libraries Government Documents Department
open access

Numerical Simulation of Interaction of Hypervelocity Particle Stream with a Target

Description: We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In… more
Date: July 31, 2007
Creator: Lomov, I; Liu, B; Georgevich, V & Antoun, T
Partner: UNT Libraries Government Documents Department
open access

Explosion in the Granite Field: Hardening and Softening Behavior in Rocks

Description: Properties of rock materials under quasistatic conditions are well characterized in laboratory experiments. Unfortunately, quasistatic data alone are not sufficient to calibrate models for use to describe inelastic wave propagation associated with conventional and nuclear explosions, or with impact. First, rock properties are size-dependent. properties measured using laboratory samples on the order of a few centimeters in size need to be modified to adequately describe wave propagation in a pro… more
Date: July 12, 2001
Creator: Lomov, I N; Antoun, T H & Glenn, L A
Partner: UNT Libraries Government Documents Department
open access

Simulations of an underground explosion in granite

Description: This paper describes the results of a computational study performed to investigate the behavior of granite under shock wave loading conditions. A thermomechanically consistent constitutive model that includes the effects of bulking, yielding, material damage, and porous compaction on the material response was used in the simulations. The model parameters were determined based on experimental data, and the model was then used in a series of one-dimensional simulations of PILE DRIVER, a deeply-bu… more
Date: June 14, 1999
Creator: Antoun, T; Glenn, L A; Lomov, I N & Vorobiev, O Y
Partner: UNT Libraries Government Documents Department
open access

A Strength and Damage Model for Rock Under Dynamic Loading

Description: A thermodynamically consistent strength and failure model for granite under dynamic loading has been developed and evaluated. The model agrees with static strength measurements and describes the effects of pressure hardening, bulking, shear-enhanced compaction, porous dilation, tensile failure, and failure under compression due to distortional deformations. This paper briefly describes the model and the sensitivity of the simulated response to variations in the model parameters and in the inela… more
Date: December 1, 1999
Creator: Vorobiev, O. Y.; Antoun, T. H.; Lomov, I. N. & Glenn, L. A.
Partner: UNT Libraries Government Documents Department
open access

Three Dimensional Simulation of the Baneberry Nuclear Event

Description: Baneberry, a 10-kiloton nuclear event, was detonated at a depth of 278 m at the Nevada Test Site on December 18, 1970. Shortly after detonation, radioactive gases emanating from the cavity were released into the atmosphere through a shock-induced fissure near surface ground zero. Extensive geophysical investigations, coupled with a series of 1D and 2D computational studies were used to reconstruct the sequence of events that led to the catastrophic failure. However, the geological profile of th… more
Date: July 16, 2003
Creator: Lomov, I
Partner: UNT Libraries Government Documents Department
open access

SIMULATION OF SHOCK WAVE PROPAGATION AND DAMAGE IN GEOLOGIC MATERIALS

Description: A new thermodynamically consistent material model for large deformation has been developed. It describes quasistatic loading of limestone as well as high-rate phenomena. This constitutive model has been implemented into an Eulerian shock wave code with adaptive mesh refinement. This approach was successfully used to reproduce static triaxial compression tests and to simulate experiments of blast loading and damage of limestone. Results compare favorably with experimentally available wave profil… more
Date: September 17, 2004
Creator: Lomov, I; Vorobiev, O & Antoun, T H
Partner: UNT Libraries Government Documents Department
open access

SIMULATION OF GEOMATERIALS USING CONTINUUM DAMAGE MODELS ON AN EULERIAN GRID

Description: A new continuum model for directional tensile failure has been developed that can simulate weakening and void formation due to directional tensile failure. The model is developed within the context of a properly invariant nonlinear thermomechanical theory. A second order damage tensor is introduced which allows simulation of weakening to tension applied in one direction, without weakening to subsequent tension applied in perpendicular directions. This damage tensor can be advected using standar… more
Date: September 17, 2004
Creator: Lomov, I & Antoun, T H
Partner: UNT Libraries Government Documents Department
open access

Simulation of Shock Loading in Saturated Geologic Materials

Description: The effective stress model is used to model the stress-strain, volumetric, and strength behavior in saturated materials under shock loading. The effective stress concept provides a predictive model of the behavior of wet porous materials based on the dry material properties. An effective stress model that allows for arbitrary fluid and solid equations of state and varying levels of saturation is incorporated into an adaptive mesh refinement (AMR) Eulerian shock physics hydrocode. Good agreement… more
Date: September 17, 2004
Creator: Liu, B T; Lomov, I & Vorobiev, O
Partner: UNT Libraries Government Documents Department
open access

Simulation of a Spherical Wave Experiment in Marble using a Multidirectional Damage Model

Description: This paper presents experimental results and computational simulations of spherical wave propagation in Danby marble. The experiment consisted of a 2-cm-diameter explosive charge detonated in the center of a cylindrical rock sample. Radial particle velocity histories were recorded at several concentric locations in the sample. An extensively damaged region near the charge cavity and two networks of cracks were evident in the specimen after the test. The first network consists of radial cracks e… more
Date: July 18, 2003
Creator: Antoun, T H & Lomov, I N
Partner: UNT Libraries Government Documents Department
open access

Explosion in the Granite Field: Hardening and Softening Behavior in Rocks

Description: Properties of rock materials under quasistatic conditions are well characterized in laboratory experiments. Unfortunately, quasistatic data alone are not sufficient to calibrate models for use to describe inelastic wave propagation associated with conventional and nuclear explosions, or with impact. First, rock properties are size-dependent. properties measured using laboratory samples on the order of a few centimeters in size need to be modified to adequately describe wave propagation in a pro… more
Date: June 25, 2001
Creator: Lomov, I N; Antoun, T H & Glenn, L A
Partner: UNT Libraries Government Documents Department
open access

Numerical Simulation of Damage using an Elastic-Viscoplastic Model with Directional Tensile Failure

Description: A new continuum model for directional tensile failure has been developed that can simulate weakening and void formation due to directional tensile failure. The model is developed within the context of a properly invariant nonlinear thermomechanical theory. A second order damage tensor is introduced which allows simulation of weakening to tension applied in one direction, without weakening to subsequent tension applied in perpendicular directions. This damage tensor can be advected using standar… more
Date: March 17, 2003
Creator: Lomov, I
Partner: UNT Libraries Government Documents Department
open access

Development and Application of a Strength and Damage Model for Rock under Dynamic Loading

Description: Simulating the behavior of geologic materials under impact loading conditions requires the use of a constitutive model that includes the effects of bulking, yielding, damage, porous compaction and loading rate on the material response. This paper describes the development, implementation and calibration of a thermodynamically consistent constitutive model that incorporates these features. The paper also describes a computational study in which the model was used to perform numerical simulations… more
Date: March 12, 2001
Creator: Antoun, T H; Lomov, I N & Glenn, L A
Partner: UNT Libraries Government Documents Department
open access

Numerical Investigation into the Performance of a Rarefaction Shock Wave Cutter for Offshore Oil-Gas Platform Removal

Description: The phase change in iron at 13 GPa results in the formation of rarefaction shock waves upon release. The interaction of multiple rarefaction shock waves induces high tensile stresses within a narrow zone, causing smooth spall. This effect can be exploited to sever cylindrical cross-section pipes, such as those supporting decommissioned offshore oil and gas platforms, using a minimal amount of explosive. Consequently, costs can be reduced and environmental impact minimized. They discuss the nume… more
Date: June 14, 2001
Creator: Morris, J P; Glenn, L A; Antoun, T H & Lomov, I N
Partner: UNT Libraries Government Documents Department
open access

Simulation of Hypervelocity Penetration in Limestone

Description: A parameter study was performed to examine the (shock) damage obtained with long-rod and spherical mono-material penetrators impacting two varieties of limestone. In all cases, the impacts were assumed to be normal to the plane of the rock and at zero angle of attack (in the case of the rods). Impact velocities ranged to 15 km/s but most calculations were performed at 4 and 6 km/s and the penetrator mass was fixed at 1000 kg. For unlined underground structures, incipient damage was defined to o… more
Date: May 31, 2005
Creator: Antoun, T; Glenn, L; Walton, O; Goldstein, P; Lomov, I & Liu, B
Partner: UNT Libraries Government Documents Department
open access

APPROXIMATION OF MULTIFLUID MIXTURE RESPONSE FOR SIMULATION OF SHARP AND DIFFUSE MATERIAL INTERFACES ON AN EULERIAN GRID

Description: Multimaterial Eulerian and Arbitrary Lagragian-Eulerian (ALE) codes usually use volume fractions of materials to track individual components in mixed cells. Material advection usually is calculated either by interface capturing, where a high-order van Leer-like slope reconstruction technique is applied, or interface tracking, where a normal reconstruction technique is applied. The former approach is more appropriate for gas-like substances, and the latter is ideal for solids and liquids, since … more
Date: September 29, 2005
Creator: Lomov, I & Liu, B
Partner: UNT Libraries Government Documents Department
open access

Simulation of penetration into porous geologic media

Description: We present a computational study on the penetration of steel projectiles into porous geologic materials. The purpose of the study is to extend the range of applicability of a recently developed constitutive model to simulations involving projectile penetration into geologic media. The constitutive model is non-linear, thermodynamically consistent, and properly invariant under superposed rigid body motions. The equations are valid for large deformations and they are hyperelastic in the sense tha… more
Date: May 31, 2005
Creator: Vorobiev, O Y; Liu, B T; Lomov, I N & Antoun, T
Partner: UNT Libraries Government Documents Department
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