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Viewing 1 to 9 of 9
2017-03-28
Technical Paper
2017-01-0264
Venkatesh Babu, Ravi Thyagarajan, Jaisankar Ramalingam
In this paper, the capability of three methods of modelling detonation of high explosives (HE) buried in soil viz., (1) coupled discrete element & particle gas methods (DEM-PGM) (2) Structured - Arbitrary Lagrangian-Eulerian (S-ALE), and (3) Arbitrary Lagrangian-Eulerian (ALE),are investigated. The ALE method of modeling the effects of buried charges in soil is well known and widely used in blast simulations today Due to high computational costs, inconsistent robustness and long run times, alternate modeling methods such as Smoothed Particle Hydrodynamics (SPH) and DEM are gaining more traction. In all these methods, accuracy of the analysis relies not only on the fidelity of the soil and high explosive models but also on the robustness of fluid-structure interaction. These high-fidelity models are also useful in generating fast running models (FRM) useful for rapid generation of blast simulation results of acceptable accuracy.
2017-03-28
Journal Article
2017-01-0268
Venkatesh Babu, Richard Gerth
Friction Stir Processing (FSP) has been used to refine grain structure in sheet metals, and is based on friction stir welding (FSW) principles developed and patented by TWI Ltd, Cambridge, UK in 1991. In Friction Stir Processing (FSP) a tool generates heat from friction and pressure causing a material to become plastic without melting. The tool then mixes the base material in a circular motion as it traverses laterally through the material . It is possible to add 2D or 3D Nano particles to locally alter the material’s stiffness (young’s modulus). For example in, friction stirred TiB2 particles in cast iron resulted in over 2x hardness and wear resistance (by ASTM G35). Since FSP is not a forming process, the pattern of the ribs can be any 2D pattern (linear, circular, spiral, etc.). The main focus of the Nano-reinforced FSP is to achieve increased localized stiffness with minimal increase in density of the local material to achieve light weighting.
2017-03-28
Technical Paper
2017-01-1703
Ryan A. Howell, Richard Gerth
Abstract Fe-Mn-Al-C steel alloys have been previously studied for their potential as an alternative steel alloy for Rolled Homogeneous Armor (RHA). Prior examination of the material system has shown promise in this capacity due to the high strength and reduced density of Mn steels as compared to RHA. The prior tested materials were both wrought and cast versions but were all less than an inch in thickness. The alloy is once again being examined, but this time in thicker wrought plate. The aim of the current body of work is to develop a Military Specification (MIL-SPEC) for this new class of ballistically capable material. For industry and communities interested in such material development, the purpose of this paper, then, is to provide a summary of the processing parameters, the prior ballistic and dynamic material testing, cutting and welding approaches, and the extent of progress on industrial sized thick plate development.
2016-04-05
Journal Article
2016-01-0316
Dorin Drignei, Zissimos Mourelatos, Ervisa Kosova, Jingwen Hu, Matthew Reed, Jonathan Rupp, Rebekah Gruber, Risa Scherer
Abstract We have recently obtained experimental data and used them to develop computational models to quantify occupant impact responses and injury risks for military vehicles during frontal crashes. The number of experimental tests and model runs are however, relatively small due to their high cost. While this is true across the auto industry, it is particularly critical for the Army and other government agencies operating under tight budget constraints. In this study we investigate through statistical simulations how the injury risk varies if a large number of experimental tests were conducted. We show that the injury risk distribution is skewed to the right implying that, although most physical tests result in a small injury risk, there are occasional physical tests for which the injury risk is extremely large. We compute the probabilities of such events and use them to identify optimum design conditions to minimize such probabilities.
2011-10-18
Technical Paper
2011-01-2735
Daniel N. Valyou, Piergiovanni Marzocca, Leon Manole, Wilfredo Toledo
Newly developed technologies are enabling the design of Unmanned Aerial Vehicles (UAVs) and Micro Air Vehicles (MAVs) with heretofore unrealized capabilities. A tube-launch MAV would allow the increased flexibility to launch an aircraft rapidly without need for a runway or complex launching system, either from a vehicle, installation, or as a man-portable device. The MAV would fill the diameter of the launch tube and deploy aerodynamic lifting and control surfaces after launch. In order to deploy the lifting surfaces the MAV must be capable of deploying control surfaces, negating any tube-imparted roll rate, and developing an optimal flight attitude automatically. An experimental method was developed to characterize the aerodynamics and stability of a blunt body spinning under conditions of roll rate decay in the Clarkson University High Speed Wind tunnel. This method is to be used to evaluate the development of an active roll rate control system for spinning projectiles.
2010-08-10
Article
VACCO Industries has been awarded a five-year contract worth up to $35 million to supply T-700 anti-icing valves for use on U.S. Army UH-60 series Black Hawk helicopters. Based on the Army's historical usage patterns for this product, and previous T-700 contract quantities delivered, VACCO expects to receive additional purchase orders for the full quantity of products over the term of the contract.
2010-04-12
Technical Paper
2010-01-0650
Justin Madsen, David Lamb, Toby Heyn, Dan Negrut
This contribution demonstrates the use of high performance computing, specifically Graphics Processing Unit (GPU) based computing, for the simulation of tracked ground vehicles. The work closes a gap in physics based simulation related to the inability to accurately characterize the 3D mobility of tracked vehicles on granular terrains (sand and/or gravel). The problem of tracked vehicle mobility on granular material is approached using a discrete element method that accounts for the interaction between the track and each discrete particle in the terrain. This continuum approach captures the dynamics of systems with more than 1,000,000 bodies interacting simultaneously. Two factors render the approach feasible. First, the frictional contact problem between the terrain and the vehicle draws on a convex optimization methodology in which the solution becomes the first order optimality condition of a cone complementarity problem.
2008-11-11
Journal Article
2008-01-2864
Edward Dawidowicz
A study was made to determine the effectiveness of low power wind energy harvesting for mobile applications. Experimental and simulated data has shown that harvesting of alternative energy resources is viable for potential mobile applications. This conducted study incorporated a mobile configuration consisting of a wind-photovoltaic hybrid in concert with a vehicle generator. The study has demonstrated an improvement in overall efficiency of the power generation system.
2008-11-11
Journal Article
2008-01-2865
Terrill Atwater, Anthony Pellegrino, Anthony DeAnni, Ronald Thompson, Laura Cristo
This paper summarizes a series of papers investigating the, in use, behavior of lithium-ion cells and packs. Initial efforts concentrated on cell data 1, 2, 3 and 4 and were reported in 2003 through 2006. Follow-on efforts concentrated on battery pack data 5, 6 and 7 and were reported in 2007 through 2008. In these efforts lithium-ion cells and batteries (4P4S, 2P4S and 4S) were cycled at various conditions. Battery packs, fully augmented with control and monitoring electronics, were subjected to an external heat source at varying intensities which were applied to the base of the battery during both charge and discharge. This heat source effectively heated one cell of the battery string.
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