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Modeling and Simulating Blast Effects on Electric Substations

Description: A software simulation tool was developed at the Idaho National Laboratory to estimate the fragility of electric substation components subject to an explosive blast. Damage caused by explosively driven fragments on a generic electric substation was estimated by using a ray-tracing technique to track and tabulate fragment impacts and penetrations of substation components. This technique is based on methods used for assessing vulnerability of military aircraft and ground vehicles to explosive blasts. An open-source rendering and ray-trace engine was used for geometric modeling and interactions between fragments and substation components. Semi-empirical material interactions models were used to calculate blast parameters and simulate high-velocity material interactions between explosively driven fragments and substation components. Finally, a Monte Carlo simulation was added to model the random nature of fragment generation allowing a skilled analyst to predict failure probabilities of substation components.
Date: May 1, 2009
Creator: Roybal, Lyle G.; Jeffers, Robert F.; McGillivary, Kent E.; Paul, Tony D. & Jacobson, Ryan
Partner: UNT Libraries Government Documents Department

Test of Dribble-Type Structures

Description: From introduction: This task was conducted at Project Shoal to observe the response of simulated Dribble area building foundations to ground motions induced by a nuclear detonation.
Date: October 21, 1964
Partner: UNT Libraries Government Documents Department

Blast wave diagnostic for the petawatt laser system

Description: We report on a diagnostic to measure the trajectory of a blast wave propagating through a plastic target 400 {micro}m thick. This blast wave is generated by the irradiation of the front surface of the target with {approximately} 400 J of 1 {micro}m laser radiation in a 20 ps pulse focused to a {approximately} 50 {micro}m diameter spot, which produces an intensity in excess of 1O{sup 18} W/cm{sup 2}. These conditions approximate a point explosion and a blast wave is predicted to be generated with an initial pressure nearing 1 Gbar which decays as it travels approximately radially outward from the interaction region We have utilized streaked optical pyrometry of the blast front to determine its time of arrival at the rear surface of the target Applications of a self-similar Taylor-Sedov blast wave solution allows the amount of energy deposited to be estimated The experiment, LASNEX design simulations and initial results are discussed.
Date: June 3, 1998
Creator: Budil, K. S., LLNL
Partner: UNT Libraries Government Documents Department

Modeling Coal Seam Damage in Cast Blasting

Description: A discrete element computer program named DMC_BLAST (Distinct Motion Code) has been under development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employs explicit time integration and uses spherical or cylindrical elements that are represented as circles in two dimensions. DMC_BLAST calculations compare favorably with data from actual bench blasts (Preece et al, 1993). Coal seam chilling refers to the shattering of a significant portion of the coal leaving unusable fines. It is also refereed to as coal damage. Chilling is caused during a blast by a combination of explosive shock energy and movement of the adjacent rock. Chilling can be minimized by leaving a buffer zone between the bottom of the blastholes and the coal seam or by changing the blast design to decrease the powder factor or by a combination of both. Blast design in coal mine cast blasting is usually a compromise between coal damage and rock fragmentation and movement (heave). In this paper the damage to coal seams from rock movement is examined using the discrete element computer code DMC_BLAST. A rock material strength option has been incorporated into DMC_BLAST by placing bonds/links between the spherical particles used to model the rock. These bonds tie the particles together but can be broken when the tensile, compressive or shear stress in the bond exceeds the defined strength. This capability has been applied to predict coal seam damage, particularly at the toe of a cast blast where drag forces exerted by movement of the overlying rock can adversely effect the top of the coal at the bench face. A simulation of coal mine cast blasting has been performed with special attention being paid to the strength of the coal and its behavior at t he bench face during movement of the overlying material.
Date: November 23, 1998
Creator: Chung, S.H. & Preece, D.S.
Partner: UNT Libraries Government Documents Department

Approximate Near-Field Blast Theory: A Generalized Approach

Description: A method for analyzing strong shock waves in arbitrary one-dimensional geometry is presented. An approximation to classical Taylor-Sedov theory is extended to the near-field case where source mass is not negligible, accounting for differences in the chemical properties of the source mass and ambient medium. Results from example calculations are compared with previously published analytical formulae.
Date: October 25, 1999
Creator: Hutchens, G.J.
Partner: UNT Libraries Government Documents Department

Effects of Various Blowout Panel Configurations on the Structural Response of Los Alamos National Laboratory Building 16-340 to Internal Explosions

Description: Abstract: The risk of accidental detonation is present whenever any type of high explosives processing activity is performed. These activities are typically carried out indoors to protect processing equipment from the weather and to hide possibly secret processes from view. Often, highly strengthened reinforced concrete buildings are employed to house these activities. These buildings may incorporate several design features, including the use of lightweight frangible blowout panels, to help mitigate blast effects. These panels are used to construct walls that are durable enough to withstand the weather, but are of minimal weight to provide overpressure relief by quickly moving outwards and creating a vent area during an accidental explosion. In this study the behavior of blowout panels under various blast loading conditions was examined. External loadings from explosions occurring in nearby rooms were of primary interest. Several reinforcement systems were designed to help blowout panels resist failure from external blast loads while still allowing them to function as vents when subjected to internal explosions. The reinforcements were studied using two analytical techniques, yield-line analysis and modal analysis, and the hydrocode AUTODYN. A blowout panel reinforcement design was created that could prevent panels from being blown inward by external explosions. This design was found to increase the internal loading of the building by 20%, as compared with nonreinforced panels. Nonreinforced panels were found to increase the structural loads by 80% when compared to an open wall at the panel location.
Date: September 2005
Creator: Wilke, Jason P.; Pohs, Keith G. & Plumlee, Deidré A.
Partner: UNT Libraries Government Documents Department

Reliable estimation of shock position in shock-capturing compressible hydrodynamics codes

Description: The displacement method for estimating shock position in a shock-capturing compressible hydrodynamics code is introduced. Common estimates use simulation data within the captured shock, but the displacement method uses data behind the shock, making the estimate consistent with and as reliable as estimates of material parameters obtained from averages or fits behind the shock. The displacement method is described in the context of a steady shock in a one-dimensional lagrangian hydrodynamics code, and demonstrated on a piston problem and a spherical blast wave.The displacement method's estimates of shock position are much better than common estimates in such applications.
Date: January 1, 2008
Creator: Nelson, Eric M
Partner: UNT Libraries Government Documents Department

Detonation spreading in fine TATBs

Description: A test has been devised that permits rapid evaluation of the detonation-spreading (or corner-turning) properties of detonations in insensitive high explosives. The test utilizes a copper witness plate as the medium to capture performance data. Dent depth and shape in the copper are used as quantitative measures of the detonation output and spreading behavior. The merits of the test are that it is easy to perform with no dynamic instrumentation, and the test requires only a few grams of experimental explosive materials.
Date: December 31, 1998
Creator: Kennedy, J.E.; Lee, K.Y.; Spontarelli, T. & Stine, J.R.
Partner: UNT Libraries Government Documents Department

Investigations on deflagration to detonation transition in porous energetic materials. Final report

Description: The research carried out by this contract was part of a larger effort funded by LANL in the areas of deflagration to detonation in porous energetic materials (DDT) and detonation shock dynamics in high explosives (DSD). In the first three years of the contract the major focus was on DDT. However, some researchers were carried out on DSD theory and numerical implementation. In the last two years the principal focus of the contract was on DSD theory and numerical implementation. However, during the second period some work was also carried out on DDT. The paper discusses DDT modeling and DSD modeling. Abstracts are included on the following topics: modeling deflagration to detonation; DSD theory; DSD wave front tracking; and DSD program burn implementation.
Date: July 1999
Creator: Stewart, D. S.
Partner: UNT Libraries Government Documents Department

Gated IR Images of Shocked Surfaces

Description: Gated infrared (IR) images have been taken of a series of shocked surface geometries in tin. Metal coupons machined with steps and flats were mounted directly to the high explosive. The explosive was point-initiated and 500-ns to 1-microsecond-wide gated images of the target were taken immediately following shock breakout using a Santa Barbara Focalplane InSb camera (SBF-134). Spatial distributions of surface radiance were extracted from the images of the shocked samples and found to be non-single-valued. Several geometries were modeled using CTH, a two-dimensional Eulerian hydrocode.
Date: June 1, 2001
Creator: Lutz, S. S.; Turley, W. D.; Rightley, P. M. & Primas, L. E.
Partner: UNT Libraries Government Documents Department

Dynamics of window glass fracture in explosions

Description: An exploratory study was conducted under the Architectural Surety Program to examine the possibility of modifying fracture of glass in the shock-wave environment associated with terrorist bombings. The intent was to explore strategies to reduce the number and severity of injuries resulting from those attacks. The study consisted of a series of three experiments at the Energetic Materials Research and Testing Center (EMRTC) of the New Mexico Institute of Mining and Technology at Socorro, NM, in which annealed and tempered glass sheets were exposed to blast waves at several different levels of overpressure and specific impulse. A preliminary assessment of the response of tempered glass to the blast environment suggested that inducing early failure would result in lowering fragment velocity as well as reducing the loading from the window to the structure. To test that possibility, two different and novel procedures (indentation flaws and spot annealing) were used to reduce the failure strength of the tempered glass while maintaining its ability to fracture into small cube-shaped fragments. Each experiment involved a comparison of the performance of four sheets of glass with different treatments.
Date: May 1, 1998
Creator: Beauchamp, E.K. & Matalucci, R.V.
Partner: UNT Libraries Government Documents Department

Behavior and evaluation of an existing underground structure subjected to impulsive loads from an internal explosion

Description: An explosion is the result of a rapid chemical reaction which generates transient air pressure waves called blast waves. There has been much research on the processes of blast wave formation, propagation of blast waves, and quantification of the incident and reflected blast overpressures. The magnitude of blast overpressure, in a partially vented environment, is mainly a function of the type and quantity of detonating material, the amount of available venting, and the orientation and configuration of the reflecting surfaces. In addition to blast overpressure, an explosion can also generate high energy missiles (such as fragments), shock loads, and rapid rise of temperature in the confined space. This study concentrates on the effects of blast overpressure on a 40 feet diameter reinforced concrete cylinder with a hemispherical dome roof, supported on a 3 feet thick reinforced concrete pad, and buried under a minimum of 15 feet of soil used for radiation shielding at the top of the dome. The scope of this study is to determine whether the structure can withstand the blast overpressure generated by the postulated explosion without exceeding allowable design criteria.
Date: December 1, 1997
Creator: Keller, M.D. & Khan, P.K.
Partner: UNT Libraries Government Documents Department

Report on the suitability of Class 6, U.S. government security repositories for the storage of small quantities of high explosives

Description: The Explosives Review Committee initiated a study into the safety aspects of the common practice of storing small amounts (< 10 grams per drawer) of high explosives in safes. Although storage of HE in older asbestos lined safes was permitted, the newer style Class 6 Security safes are an unacceptable repository for even very small amounts of HE without the use of a blast mitigating insert. The authors have developed a drawer liner in the form of a laminated Lexan, foam, plywood box that will withstand the blast and contain the fragments from up to 10 grams of high explosives. This liner will fit into the drawer of any existing safe. The liner will provide blast and fragment protection, and the safe will provide security protection. This report describes the testing of modern safes and the performance of the liner insert.
Date: March 1, 1998
Creator: Harry, H. H. & Murk, D.
Partner: UNT Libraries Government Documents Department

Measuring explosive non-ideality

Description: The sonic reaction zone length may be measured by four methods: (1) size effect, (2) detonation front curvature, (3) crystal interface velocity and (4) in-situ gauges. The amount of data decreases exponentially from (1) to (4) with there being almost no gauge data for prompt detonation at steady state. The ease and clarity of obtaining the reaction zone length increases from (1) to (4). The method of getting the reaction zone length, &lt;x{sub e}&gt;, is described for the four methods. A measure of non-ideality is proposed: the reaction zone length divided by the cylinder radius. N = &lt;x{sub e}&gt;/R{sub o}. N = 0 for true ideality. It also decreases with increasing radius as it should. For N &lt; 0.10, an equilibrium EOS like the JWL may be used. For N &gt; 0.10, a time-dependent description is essential. The crystal experiment, which measures the particle velocity of an explosive-transparent material interface, is presently rising in importance. We examine the data from three experiments and apply: (1) an impedance correction that transfers the explosive C-J particle velocity to the corresponding value for the interface, and (2) multiplies the interface time by 3/4 to simulate the explosive speed of sound. The result is a reaction zone length comparable to those obtained by other means. A few explosives have reaction zones so small that the change of slope in the particle velocity is easily seen.
Date: February 17, 1999
Creator: Souers, P C
Partner: UNT Libraries Government Documents Department

Modeling coupled blast/structure interaction with Zapotec, benchmark calculations for the Conventional Weapon Effects Backfill (CONWEB) tests.

Description: Modeling the response of buried reinforced concrete structures subjected to close-in detonations of conventional high explosives poses a challenge for a number of reasons. Foremost, there is the potential for coupled interaction between the blast and structure. Coupling enters the problem whenever the structure deformation affects the stress state in the neighboring soil, which in turn, affects the loading on the structure. Additional challenges for numerical modeling include handling disparate degrees of material deformation encountered in the structure and surrounding soil, modeling the structure details (e.g., modeling the concrete with embedded reinforcement, jointed connections, etc.), providing adequate mesh resolution, and characterizing the soil response under blast loading. There are numerous numerical approaches for modeling this class of problem (e.g., coupled finite element/smooth particle hydrodynamics, arbitrary Lagrange-Eulerian methods, etc.). The focus of this work will be the use of a coupled Euler-Lagrange (CEL) solution approach. In particular, the development and application of a CEL capability within the Zapotec code is described. Zapotec links two production codes, CTH and Pronto3D. CTH, an Eulerian shock physics code, performs the Eulerian portion of the calculation, while Pronto3D, an explicit finite element code, performs the Lagrangian portion. The two codes are run concurrently with the appropriate portions of a problem solved on their respective computational domains. Zapotec handles the coupling between the two domains. The application of the CEL methodology within Zapotec for modeling coupled blast/structure interaction will be investigated by a series of benchmark calculations. These benchmarks rely on data from the Conventional Weapons Effects Backfill (CONWEB) test series. In these tests, a 15.4-lb pipe-encased C-4 charge was detonated in soil at a 5-foot standoff from a buried test structure. The test structure was composed of a reinforced concrete slab bolted to a reaction structure. Both the slab thickness and soil media were varied ...
Date: September 1, 2004
Creator: Bessette, Gregory Carl
Partner: UNT Libraries Government Documents Department

Computational Hydrocode Study of Target Damage due to Fragment-Blast Impact

Description: A target's terminal ballistic effects involving explosively generated fragments, along with the original blast, are of critical importance for many different security and safety related applications. Personnel safety and protective building design are but a few of the practical disciplines that can gain from improved understanding combined loading effects. Traditionally, any engineering level analysis or design effort involving explosions would divide the target damage analysis into two correspondingly critical areas: blast wave and fragment related impact effects. The hypothesis of this paper lies in the supposition that a linear combination of a blast-fragment loading, coupled with an accurate target response description, can lead to a non-linear target damage effect. This non-linear target response could then stand as the basis of defining what a synergistic or combined frag-blast loading might actually look like. The table below, taken from Walters, et. al. categorizes some of the critical parameters driving any combined target damage effect and drives the evaluation of results. Based on table 1 it becomes clear that any combined frag-blast analysis would need to account for the target response matching similar ranges for the mechanics described above. Of interest are the critical times upon which a blast event or fragment impact loading occurs relative to the target's modal response. A blast, for the purposes of this paper is defined as the sudden release of chemical energy from a given material (henceforth referred to as an energetic material) onto its surrounding medium. During the coupling mechanism a discrete or discontinuous shockwave is generated. This shockwave travels outward from the source transferring energy and momentum to any surrounding objects including personnel and engineering structures. From an engineering perspective blast effects are typically characterized by way of physical characteristics such as Peak Pressure (PP), Time of Arrival (TOA), Pressure-Impulse (PI) and Time of Duration ...
Date: March 24, 2011
Creator: Hatch-Aguilar, T; Najjar, F & Szymanski, E
Partner: UNT Libraries Government Documents Department

Confinement Vessel Dynamic Analysis

Description: A series of hydrodynamic and structural analyses of a spherical confinement vessel has been performed. The analyses used a hydrodynamic code to estimate the dynamic blast pressures at the vessel's internal surfaces caused by the detonation of a mass of high explosive, then used those blast pressures as applied loads in an explicit finite element model to simulate the vessel's structural response. Numerous load cases were considered. Particular attention was paid to the bolted port connections and the O-ring pressure seals. The analysis methods and results are discussed, and comparisons to experimental results are made.
Date: August 1, 1999
Creator: Stevens, R. Robert & Rojas, Stephen P.
Partner: UNT Libraries Government Documents Department

Proof testing of an explosion containment vessel

Description: A steel containment vessel was fabricated and proof tested for use by the Los Alamos National Laboratory at their M-9 facility. The HY-100 steel vessel was designed to provide total containment for high explosives tests up to 22 lb (10 kg) of TNT equivalent. The vessel was fabricated from an 11.5-ft diameter cylindrical shell, 1.5 in thick, and 2:1 elliptical ends, 2 in thick. Prior to delivery and acceptance, three types of tests were required for proof testing the vessel: a hydrostatic pressure test, air leak tests, and two full design charge explosion tests. The hydrostatic pressure test provided an initial static check on the capacity of the vessel and functioning of the strain instrumentation. The pneumatic air leak tests were performed before, in between, and after the explosion tests. After three smaller preliminary charge tests, the full design charge weight explosion tests demonstrated that no yielding occurred in the vessel at its rated capacity. The blast pressures generated by the explosions and the dynamic response of the vessel were measured and recorded with 33 strain channels, 4 blast pressure channels, 2 gas pressure channels, and 3 displacement channels. This paper presents an overview of the test program, a short summary of the methodology used to predict the design blast loads, a brief description of the transducer locations and measurement systems, some of the hydrostatic test strain and stress results, examples of the explosion pressure and dynamic strain data, and some comparisons of the measured data with the design loads and stresses on the vessel.
Date: October 1, 1996
Creator: Esparza, E.D.; Stacy, H. & Wackerle, J.
Partner: UNT Libraries Government Documents Department

Palanquin post-shot exploration

Description: This report defines the plan and purpose for the Palanquin post-shot exploration program. This program is necessary to obtain data that is needed in the understanding of the Palanquin experiment, and related explosion phenomena, which can be obtained in no other way.
Date: July 28, 1965
Creator: Meyer, L.; Hansen, S. & Toman, J.
Partner: UNT Libraries Government Documents Department

Gage cookbook: Tools and techniques to measure stresses and motions on explosive experiments

Description: Tools and techniques developed to measure stresses and motions on underground nuclear and high explosive tests in the tuff geologies at the Nevada Test Site are described in this document. The thrust of the measurements was to understand containment phenomenology. The authors concentrate on the fluid-coupled ytterbium gage; it was fielded to measure dynamic stress in the 0.2 to 20 kilobar range and the subsequent, low amplitude residual stress. Also described are accelerometer packages; their traces were integrated to obtain particle motion. Various cable survival techniques were investigated with field measurements for they wished to extend the measurements to late-time. Field measurements were also made to address the gage inclusion problem. Work to date suggests that the problem is a minimum when the stress level is above the yield strength of the host rock and grout. Below the yield level stress amplitudes in the grouted hole can range from 60 to 200% of the stress in the host rock.
Date: January 1, 1996
Creator: Smith, C.W.
Partner: UNT Libraries Government Documents Department

Probabilistic modeling of propagating explosions

Description: Weapons containing significant quantities of high explosives (HE) are sometimes located in close proximity to one another. If an explosion occurs in a weapon, the possibility of propagation to one or more additional weapons may exist, with severe consequences possibly resulting. In the general case, a system of concern consists of multiple weapons and various other objects in a complex, three-dimensional geometry. In each weapon, HE is enclosed by (casing) materials that function as protection in the event of a neighbor detonation but become a source of fragments if the HE is initiated. The protection afforded by the casing means that only high-momentum fragments, which occur rarely, are of concern. These fragments, generated in an initial donor weapon are transported to other weapons either directly or by ricochet. Interaction of a fragment with an acceptor weapon can produce a reaction in the acceptor HE and result in a second detonation. In this paper we describe a comprehensive methodology to estimate the probability of various consequences for fragment-induced propagating detonations in arrays of weapons containing HE. Analysis of this problem requires an approach that can both define the circumstances under which rare events can occur and calculate the probability of such occurrences. Our approach is based on combining process tree methodology with Monte Carlo transport simulation. Our Monte Carlo technique very effectively captures important features of these differences. Process tree methodology is described and its use is discussed for a simplified problem and to illustrate the power of Monte Carlo simulation in estimating fragment-induced detonation of an acceptor weapon.
Date: March 1, 1996
Creator: Luck, L.B.; Eisenhawer, S.W. & Bott, T.F.
Partner: UNT Libraries Government Documents Department