| Lighter-Than-Air and Pressurized Structures Technology for Unmanned Aerial Vehicles (UAVs) |
Jan 2010 |
30 pages |
| Authors:
Harris Edge; Jason Collins; Ainsmar Brown; Michael Coatney; Beatrice Roget; Nathan Slegers; Arthur Johnson; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
 | Several areas of unmanned aerial vehicle (UAV) performance need to be improved for the next generation of UAVs to be used successfully in expanded future combat roles. This report describes the initial research to improve the performance of UAVs through lighter-than-air or pressurized structures-based (PSB) technologies. Basically, we examined how to construct the UAV in such a way that a considerable percentage of its weight will be supported by or ... |
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| Bio-Inspired Metallo-Supramolecular Polymers for Combined Mechanical Properties |
Jan 2010 |
20 pages |
| Authors:
Robert H Lambeth; Kenneth E Strawhecker; Joshua A Orlicki; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The development of materials with combined mechanical properties remains a significant challenge in polymer synthesis. The preparation of such materials could potentially impact a wide range of Army applications. In this work, bio-inspired metallo- supramolecular polymers were designed, synthesized, and characterized. We anticipate these polymers will display enhanced mechanical properties due to the presence of intermediate strength metal-ligand bonds present in the polymer backbone, which forms a compacted, modular molecular ... |
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| Evaluation of Auditory Characteristics of Communications and Hearing Protection Systems (C&HPSs) Part II - Speech Intelligibility |
Jan 2010 |
|
| Authors:
Paula Henry; Rachel Weatherless; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
 | Devices that provide hearing protection, situational awareness, and radio communications are often referred to as Communications and Hearing Protection Systems (C&HPSs). Soldiers use these systems while deployed to navigate within their environment, communicate with their team members, and protect their hearing. Each of the three features of select C&HPSs (hearing protection, speech communication, and situational awareness) was evaluated by the U.S. Army Research Laboratory in order to obtain data that ... |
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| Synthesis and Characterization of Phosphonium-Containing Cationic Poly(styrene) Polymers |
Dec 2009 |
14 pages |
| Authors:
Kristoffer Stokes; Frederick L Beyer; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Alkaline fuel cells have been proposed as a cost effective alternative energy solution due to their cheap manufacture and low operating temperatures. Their mass utilization, however, is hindered by their electrolyte material. While relatively inexpensive solid proton exchange membranes have been available for some time now, alkaline fuel cells still rely on liquid electrolyte to provide mobility to the anionic species. In this technical note, we describe an ionomeric system ... |
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| Discrete Optimization of Electronic Hyperpolarizabilities in a Chemical Subspace |
04-Nov-2009 |
10 pages |
| Authors:
Jan Andzelm; Adam Rawlett; Weitao Yang; B C Rinderspacher; Joseph Dougherty; David N Beratan; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| We introduce a general optimization algorithm based on an interpolation of property values on a hypercube. Each vertex of the hypercube represents a molecule, while the interior of the interpolation represents a virtual superposition (alchemical mutation) of molecules. The resultant algorithm is similar to branch-and-bound/tree-search methods. We apply the algorithm to the optimization of the first electronic hyperpolarizability for several tolane libraries. The search includes structural and conformational information. Geometries ... |
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| Investigation of Proton Conductivity of Cation-Exchanged, Sulfonated Poly(b-Styrene-b-Isobutylene-b-Styrene) Membranes |
Sep-2009 |
26 pages |
| Authors:
Eugene Napadensky; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| In this study, membranes made with highly sulfonated (81%-97%) poly(styrene-b-isobutylene-b-styrene) polymer were exchanged with a variety of cations: Cu, Ba, Zn, Cs, Ag, Ca, and Mg. Absorption levels of the cation-exchanged materials was determined for water, methanol, and an equimolar water/methanol mixture, measured using a gravimetric technique. Proton conductivity of the membranes was measured in a dry state, as well as swollen in water, methanol, and the equimolar water /methanol ... |
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| Viscoelastic Models for Nearly Incompressible Materials |
Sep-2009 |
62 pages |
| Authors:
Mike Scheidler; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This report discusses linear and nonlinear constitutive models for the viscoelastic response of nearly incompressible solids undergoing moderate to large deformations and arbitrarily large rotations. For both the linear and nonlinear cases, the general theory is outlined first, then the Prony series approximation to the stress relaxation function is introduced, and this in turn is used to derive various incremental relations for the stress. These incremental relations can be easily ... |
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| U.S. Army Research Laboratory Meteorological Measurements for Joint Urban 2003 |
Sep-2009 |
90 pages |
| Authors:
David Ligon; Cheryl Kipp; Doyule S Elliott; Ed Creegan; San Chang; Manny Bustillos; Dennis Garvey; Giap Huynh; Ronald Cionco; Edward Measure; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The Joint Urban 2003 (JU2003) project, a multi-agency undertaking to study turbulent transport and diffusion in the urban boundary layer, was conducted in Oklahoma City, OK, in summer 2003. The field campaign involved extensive meteorological and gas tracer measurements to investigate the dispersion of simulated contaminants in and around the city. Instrumentation provided by the U.S. Army Research Laboratory's (ARL) Battlefield Environment Division (BED) included a Doppler lidar, a mobile ... |
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| Finite Deformations and Internal Forces in Elastic-Plastic Crystals: Interpretations From Nonlinear Elasticity and Anharmonic Lattice Statics |
Sep-2009 |
22 pages |
| Authors:
J D Clayton; D J Bammann; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Large deformation kinematics and internal forces arising from defects in crystalline solids are addressed by a nonlinear kinematic description and multiscale averaging concepts. An element of crystalline material with spatially uniform properties and containing defects such as dislocation lines and loops is considered. The average deformation gradient for this element is decomposed multiplicatively into terms accounting for effects of dislocation flux, recoverable elastic stretch and rotation, and residual elastic deformation ... |
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| CFD Prediction of Magnus Effect in Subsonic to Supersonic Flight |
Sep-2009 |
46 pages |
| Authors:
James DeSpirito; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The aerodynamic coefficients of the 7-cal. U.S. Army-Navy Spinner Rocket were characterized using computational fluid dynamic (CFD) calculations and validated using archival experimental data. The static aerodynamic coefficients, roll-damping, and pitch-damping moments were accurately predicted by steady-state Reynolds-averaged Navier-Stokes (RANS) as well as unsteady hybrid RANS/large-eddy simulation (LES) CFD. The Magnus moment was overpredicted in the subsonic and transonic regime. Unsteady RANS/LES computations did not improve the prediction of Magnus ... |
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| Using the Auditory Hazard Assessment Algorithm for Humans (AHAAH) Software, Beta Release W93e |
Sep 2009 |
56 pages |
| Authors:
Joel T Kalb; Mary S Binseel; G Richard Price; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The Auditory Hazard Analysis Algorithm for Humans (AHAAH) calculates the risk to human hearing of impulse noises, such as gunfire or airbag deployment. It achieves this by modeling the effects of the sound pressure wave from the free field, through the middle ear, and into the inner ear. The output of the algorithm is the number of auditory risk units (ARUs) associated with exposure to the given impulse sound. ARUs ... |
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| A Computational Analysis of a Shear Punch Test |
Aug-2009 |
14 pages |
| Authors:
Stephan R Bilyk; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The intense shearing that occurs in propellants and explosives during impulsive loading can lead to initiation. In an effort to determine useful shear initiation criteria, the U.S. Army Research Laboratory (ARL) has developed a shear punch test using a modified Kolsky bar. Varying the striker bar's velocity and length controls the shear rate and duration. Shear velocities approaching 100 m/s and durations as long as 200 microns are possible. Experimental ... |
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| Mechanical Response and Shear Initiation of Double-Base Propellants |
Aug-2009 |
16 pages |
| Authors:
Stephan R Bilyk; Michael J Scheidler; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The intense shearing that occurs in propellants during impulsive loading can lead to initiation. In an effort to determine useful shear initiation criteria, the U.S. Army Research Laboratory has developed a dynamic shear punch test using a modified split- Hopkinson bar. Varying the striker bar's velocity and length controls the shear rate and duration. Shear velocities approaching 100 m/s and durations as long as 0.2 ms are possible. Experimental results ... |
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| Modeling Effects of Crystalline Microstructure, Energy Storage Mechanisms, and Residual Volume Changes on Penetration Resistance of Precipitate-Hardened Aluminum Alloys |
Aug-2009 |
14 pages |
| Authors:
John D Clayton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| An anisotropic nonlinear crystal mechanics model is developed for a class of ductile aluminum alloys, with the intent of relating microscopic features and properties to performance of the alloys deformed at high strain rates that may arise during impact and blast events. A direct numerical simulation of dynamic tensile deformation of an aluminum polycrystal demonstrates a tendency for shear localization to occur in regions of the microstructure where the ratio ... |
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| The Computational Science Environment (CSE) |
Aug-2009 |
44 pages |
| Authors:
Jose C Rentria; Richard C Angelini; John M Vines; Kelly T Kirk; Eric R Mark; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| In order to provide a common platform for utilizing and developing data analysis and assessment applications in heterogeneous high-performance computing (HPC) environments, the Classified Data Analysis and Assessment Center has developed the computational science environment (CSE). CSE provides a stable suite of data analysis and assessment tools, applications, and libraries that are common across most HPC environments and standard 64-bit Linux workstations. CSE also provides an experimental, cutting-edge suite of ... |
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| Weapon-Centric Graphic Controller User Evaluation |
Aug 2009 |
86 pages |
| Authors:
Elizabeth S Redden; Christian B Carstens; Daniel D Turner; David E Miller; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The purpose of this research was to provide feedback to the designers of dismounted warfighter input devices on the performance and suitability of four different weapon-centric graphic control (WGC) designs. The Human Research and Engineering Directorate of the U.S. Army Research Laboratory's Fort Benning Field Element was requested by the Technology, Systems, and Program Integration Directorate (TSPID) within Natick to perform this research. The experiment took place at Fort Benning, ... |
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| Flexural Fatigue Response of Repaired S2-Glass/Vinyl Ester Composites |
Aug 2009 |
26 pages |
| Authors:
James M Sands; Uday K Vaidya; Biju Mathew; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Vacuum-assisted resin transfer molding is a promising, affordable technique for producing composite integral armor (CIA) and thick-section composites for U.S. Army-relevant applications. Among several constituents, the CIA uses S2-glass/epoxy and/or S2-glass/vinyl ester composites in its construction. The S2-glass-reinforced composite provides ballistic protection and load bearing due to the flexural loading caused from vehicle movement over various terrains. The S2-glass-reinforced composite is subjected to different levels of delamination when impacted by ... |
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| A Non-Linear Model for Elastic Dielectric Crystals with Mobile Vacancies |
Jul-2009 |
20 pages |
| Authors:
J D Clayton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A framework is developed for electromechanical behavior of dielectric crystalline solids subjected to finite deformations. The theory is formulated in the context of electrostatics; however, vacancies in the lattice may carry an electric charge, and their concentrations may be large. The material is treated as a continuous body with a continuous distribution of point vacancies, but volumes and charges of individual defects enter the description. The deformation gradient is decomposed ... |
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| Structural Performance of Aluminum and Stainless Steel Pyramidal Truss Core Sandwich Panels |
Jul-2009 |
22 pages |
| Authors:
Aristedes Yiournas; Yellapu Murty; Kevin J Doherty; Jordan A Wagner; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Future lightweight military vehicles will demand increasingly mass-efficient structures to satisfy design requirements such as increased mobility and survivability. One possible family of lightweight structures entails sandwich panels consisting of solid facesheets and a low-density core. The sandwich structures can provide both structural strength and stiffness, with load-bearing potential. In this study, sandwich panels consisting of metallic facesheets and a pyramidal truss core manufactured from either 6061-T6 aluminum or 316L ... |
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| Intense Collaboration: Human and Technical Requirements for Agile C2 |
Jun-2009 |
41 pages |
| Authors:
Denis Gouin; Tim Pattison; Elizabeth K Bowman; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Collaboration for Command and Control (C2) is becoming more intense in the Information Age. This is a result of the problems our leaders must confront; it is also the result of the burgeoning communications technologies available for their use. We present an emerging literature on intense collaboration (IC) and examine potential applications to military C2. We propose an integrated socio-technical approach that combines networked information technologies with individual and team ... |
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| Cognitive Impact of a C4ISR Tactical Network |
Jun-2009 |
40 pages |
| Authors:
Jeffrey A Thomas; Elizabeth K Bowman; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This report details a naturalistic study that investigates the effect of communications and sensor technologies used by Soldiers in a tactical organization to gain intelligence against an adaptive enemy threat. Communication and sensor technologies were used to simulate current and future force capabilities for networked systems. Soldiers comprised an experiment force and simulated two platoons of an Intelligence, Surveillance, and Reconnaissance (ISR) force. Data collection included observational, quantitative, and qualitative ... |
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| Protecting Identifiers in Cross-Domain Environments |
Jun-2009 |
31 pages |
| Authors:
Sam Chamberlain; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Unique identification of objects and their associated data representations have received significant attention in the past 10 years. Developing an efficient identifier allocation and tracking scheme that transparently spans security domains requires finesse. It is not uncommon for information to be created in a lower security domain and copied to a higher domain. The rigor by which the data is maintained varies widely, as does the resulting difficulty in maintaining ... |
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| The Effect of an Unconditioned Barrel on Temperature Conditioned 5.56mm Cartridges |
Jun-2009 |
26 pages |
| Authors:
Robert P Kaste; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Several organizations independently tested the same lot of 5.56mm ammunition temperature conditioned to -55, 125, and 160 deg F and reported discrepancies in chamber pressures and muzzle velocities. These discrepancies precipitated this investigation into the time required to temperature condition 5.56mm ammunition and the effect of using an unconditioned weapon to fire conditioned ammunition. The unconditioned weapon dramatically affected the temperature of the conditioned ammunition. Substantial changes in the cartridge ... |
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| The Use of Commercial Non-Hazardous Air Pollutant Monomers to Optimize the Properties of Fatty Acid-Based Resins |
May-2009 |
34 pages |
| Authors:
James M Sands; La; John J Scala; Priya Kamath; Anita Sahu; Giuseppe R Palmese; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Vinyl ester (VE) resins are used to make polymer matrix composites in military and commercial applications because of their good properties, low weight, and low cost. These resins typically contain high concentrations of reactive diluents, such as styrene, to allow these resins to be molded using resin transfer molding and other inexpensive liquid molding techniques. Because styrene is a hazardous air pollutant (HAP) and a volatile organic compound (VOC), the ... |
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| Henry's Law Constants for 2-Azidoethanamine Hypergols: Estimates From a Density Functional Theory/Polarizable Continuum Model |
May-2009 |
28 pages |
| Authors:
Michael J McQuaid; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Henry's law constants at 298 K [HLC(298)] for four 2-azidoethanamine (EA) hypergols and three aliphatic amines were estimated via a density functional theory/polarizable continuum model (DFT/PCM) method. The four EAs are 2-azido-N,Ndimethylethanamine (DMAZ), 2-azido-N-methylethanamine (MMAZ), 1-(2-azidoethyl)pyrrolidine (PyrrAZ), and 4-(2- azidoethyl)morpholine (MorphAZ), and the three aliphatic amines are dimethylamine, trimethylamine, and 1-methylpyrrolidine. The estimates for the three aliphatic amines are all within a factor of 5 of measured values that have ... |
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| Extreme Scalability: Designing Interfaces and Algorithms for Soldier-Robotic Swarm Interaction |
Apr-2009 |
20 pages |
| Authors:
MaryAnne Fields; Susan Hill; Christopher Stachowiak; Ellen Haas; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| In theory, autonomous robotic swarms can be used for critical Army tasks (i.e., accompanying convoys); however, the Soldier controlling the swarm must be able to monitor swarm status and correct actions, especially in disrupted or degraded conditions. For this two-year Director's Research Initiative (DRI), we designed metacognition algorithms and Soldier-swarm display concepts to allow Soldiers to efficiently interact with a robotic swarm participating in a representative convoy mission. We used ... |
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| Molecular Design of Novel Poly(urethane-urea) Hybrids as Helmet Pads for Ballistic and Blast Trauma Mitigation |
Mar-2009 |
22 pages |
| Authors:
Alex J Hsieh; Joshua A Orlicki; Rick L Beyer; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Polyurethane (PU) and poly(urethane urea) (PUU) based foams are currently being used as helmet pad materials. The U.S. Army still has a critical need for more efficient foam pad materials and designs that will provide warfighters with improved survivability against blast-induced traumatic brain injuries. Recent work has shown that tailoring the microphase-separated morphology is critical in controlling the high strain-rate mechanical deformation of bulk PU and PUU elastomers. In this ... |
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| Bio-Mimetic Millimeter-Scale Flapping Wings for Micro Air Vehicles |
Mar-2009 |
22 pages |
| Authors:
Eric Wetzel; Ronald G Polcawich; Christopher Kroninger; Jeffrey Pulskamp; Jessica Bronson; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| In this report, we present designs of Micro-Electro-Mechanical System (MEMS) fabricated millimeter-scale flapping wings with some characterization of their structural properties and flapping performance. Wings of varied bio-mimetic design, including membrane and ribs-like structures, are flapped at resonance from lead zirconate titanate (PZT) bending actuators at their base. Laser Doppler vibrometer (LDV) measurements and finite element (FE) analysis predictions of the flapping frequencies and mode shapes and the flapping amplitude ... |
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| Addressing the Challenges of a Thruster-Based Precision Guided Mortar Munition With the Use of Embedded Telemetry Instrumentation |
Mar 2009 |
10 pages |
| Authors:
Bradford Davis; Gregory Malejko; Rollie Dohrn; Scott Owens; Thomas Harkins; Gregory Bischer; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This article describes advancements made with the use of embedded telemetry instrumentation with a digital signal processor and shows the large volume of information that is available during flight tests. Unique measurement capabilities and analytical techniques used to determine and understand the Precision Guided Mortar Munition flight behavior during the thruster-based guided maneuvers will be highlighted. Ways in which these data were used to make key decisions influencing the projectile's ... |
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| An Open-Path Obstacle Avoidance Algorithm Using Scanning Laser Range Data |
Feb-2009 |
20 pages |
| Authors:
Von; Raymond Wahlde; Nathan Wiedenman; Wesley A Brown; Cezarina Viqueira; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The Open-Path Area algorithm described searches a region scanned by a laser range finder for the most open path that will allow a robot of a specified width to move the furthest distance. Range data are mapped into an array space in which the column indices are the beam numbers and the rows are the range values divided into an arbitrary number of bins. The path to be searched is ... |
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| Transient Stress Wave Propagation in One-Dimensional Micropolar Bodies |
Feb-2009 |
22 pages |
| Authors:
C L Randow; G A Gazonas; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Certain types of structures and materials, such as engineered multi-scale systems and comminuted zones in failed ceramics, may be modeled using continuum theories incorporating additional kinematic degrees of freedom beyond the scope of classical continuum theories. If such material systems are to be subjected to high strain rate loads, such as those resulting from ballistic impact or blast, it will be necessary to develop models capable of describing transient stress ... |
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| Magnesium Technology and Manufacturing for Ultra Lightweight Armored Ground Vehicles |
Feb-2009 |
14 pages |
| Authors:
Kyu Cho; Paul Moy; Tomoko Sano; Kevin Doherty; Chian Yen; George Gazonas; Jonathan Montgomery; Bruce Davis; Rick DeLorme; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The current paper summarizes magnesium alloy metallurgy and wrought manufacturing with an initial emphasis on the Elektron WE43 alloy system for lightweight armored ground vehicle applications. Engineering design factors are reviewed and initial mechanical property data are presented along with ballistic results and findings from blast simulations. Finally the future role of magnesium alloys in ultra light metallic armor is discussed in terms of material development and application. |
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| AH-64D Apache Longbow Aircrew Workload Assessment for Unmanned Aerial System (UAS) Employment |
Jan-2009 |
76 pages |
| Authors:
David B Durbin; Jamison S Hicks; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This study assessed whether workload was tolerable for AH-64D pilots when they employed an unmanned aerial system (UAS) during simulated missions. Ten AH-64D pilots participated in the study. Pilot workload, situation awareness, crew coordination, crewstation interface, switch actuations, simulator sickness, visual gaze and dwell times (using a head-eye tracker), audio-video, and tactics, techniques and procedures data were collected and analyzed. Pilot workload was found to be tolerable for the tasks ... |
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| Unmanned Ground Vehicle Tactical Behaviors Technology Assessment |
Jan-2009 |
86 pages |
| Authors:
Marshal A Childers; Barry A Bodt; Susan G Hill; Richard Camden; Robert M Dean; William F Dodson; Lyle G Sutton; Leonid Sapronov; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| During 4-14 February 2008, the U.S. Army Research Laboratory and General Dynamics Robotic Systems conducted an unmanned systems tactical behaviors technology assessment at three training areas of Ft. Indiantown Gap, PA. The purpose of the assessment was to examine the ability to use sensed information to locally orient an unmanned ground vehicle (UGV) in order to obtain line of sight for an onboard reconnaissance surveillance target acquisition system to scan ... |
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| An Automated Tool for Developing Experimental Designs: The Computer-Aided Design Reference for Experiments (CADRE) |
Jan-2009 |
26 pages |
| Authors:
Robert C Williges; Sam E Middlebrooks; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Based on past problems with data collection in experiments, experimental designers need a tool to assist in establishing effective experiments in which the data collection method minimizes the amount of data required and the data collection effort while maximizing the effectiveness and power of the data. A desktop tool, the Computer-Aided Design Reference for Experiments (CADRE), was developed for this purpose. The CADRE tool includes over 850 pages of reference ... |
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| On the New Evaluation of an Old Integral |
Dec-2008 |
12 pages |
| Authors:
William Walters; Michael Huber; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A simple technique is shown to evaluate dx over x to the m power (1 + x to the nth power). |
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| A Laser-Based Sensor for Ambient Detection of RDX and TNT |
Dec-2008 |
6 pages |
| Authors:
Stephen D Roberson; Rosario C Sausa; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| We detect trace residues of RDX and TNT by surface photofragmentation - fragment detection in real time at ambient conditions. An infrared or visible laser generates signature, NO molecular fragments, and a second, low energy, ultraviolet laser facilitates their detection by resonance enhanced multiphoton ionization. We present the effects of pump laser wavelength, laser energy, delay timing between the pump and probe beams, and analyze concentration on signal intensity. Sensitivity ... |
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| A Priori Design of Optimal Electro-Optic Materials for Laser Eye Protection |
Dec-2008 |
9 pages |
| Authors:
J Andzelm; M Davis; A Chafin; G Lindsay; Weitao Yang; D N Beratan; C Rinderspacher; T M Pritchett; J Dougherty; A Rawlett; P J Reynolds; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The task of protecting soldier eyesight and battlefield optical sensors from potentially damaging effects of high-intensity light has stimulated interest in electro-optic (EO) materials such as EO chromophores inserted into polymeric material. A priori design of optimal EO chromophores of Army relevance requires the capability to calculate accurately both the linear absorption properties (in effect, the color) and non-linear optical (NLO) properties of EO chromophores. Here we discuss two major ... |
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| Chemical Agent Performance of Sulfonated Ionomeric Membranes for Chem/Bio Applications |
Dec-2008 |
6 pages |
| Authors:
D M Crawford; J Sloan; E Napadensky; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The Army Research Lab (ARL) has developed a selectively permeable membrane that shows promising properties for chemical protective applications such as clothing or tenting. The flexible polymeric membrane exhibits high water vapor transport allowing reduced heat stress and barrier properties that resist penetration of chemical agents. This paper will discuss the development of this technology with a focus on the chemical agent performance, highlighting the best candidates for protective clothing ... |
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| Capabilities for Magnus Prediction in Subsonic and Transonic Flight |
Dec-2008 |
9 pages |
| Authors:
J DeSpirito; S I Silton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The Magnus characteristics of three spin-stabilized projectiles were characterized using steady-state RANS and time-accurate RANS/LES computational fluid dynamic simulations. RANS/LES simulations improved the Magnus moment prediction for projectiles with rounded or chamfered bases. No difference was found between the RANS and RANS/LES simulations for the projectile with a sharp-cornered base?either with or without a boattail. The near-body flow field was similar for RANS and RANS/LES simulations; but the RANS/LES simulations ... |
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| Molecular Dynamics Simulation of the Kinetic Reaction of Ni and Al Nanoparticles |
Dec-2008 |
9 pages |
| Authors:
B J Henz; T Hawa; M R Zachariah; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The U.S. Army has an interest in the use of alloys that produce excessive heat during formation and can be used for structural purposes such as shell casings. Molecular dynamics simulations have been used to provide a more thorough understanding of one of these alloys systems, namely the kinetic reaction of Ni and Al nanoparticles. We have considered the affect of primary particle size on sintering time and sintering temperature ... |
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| Quantum Mechanical Predictions Of Energetic Materials: When Good Theories Go Bad |
Dec-2008 |
8 pages |
| Authors:
Edward F Byrd; Betsy M Rice; Cary F Chabalowski; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The performance of density functional theories (DFT) in predicting structural parameters for six conventional energetic materials (EM) over various degrees of compression was examined for a wide range of pressures. The systems studied were nitromethane, 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), cyclotrimethylenetrinitramine (RDX), 2,4,6,8,10,12- hexanitrohexaazaisowurzitane (CL-20), 2,4,6-trinitro- 1,3,5-benzenetriamine (TATB), and pentaerythritol tetranitrate (PETN). Dependencies of results on basis set size, k-points, choice of pseudopotential and method were explored. The results indicate that at zero ... |
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| Effect of Rifling Grooves on the Performance of Small-Caliber Ammunition |
Dec-2008 |
9 pages |
| Authors:
Paul Weinacht; Sidra I Silton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A combined experimental and computational investigation was performed to examine the effect of rifling grooves on the aerodynamics of projectiles and determine whether the aerodynamics associated with the rifling grooves are a potential mechanism for in-flight trim angles. The experimental program consisted of spark-range firings of bullets from the standard twist barrel spanning the range of velocities typically encountered in flight. Additionally, sabot-launched smooth and pre-engraved bullets were fired from ... |
|
| Exploring Structural Bond Energy Release (SBER) in Nanodiamonds Using Quantum Molecular Dynamics and Static High Pressure |
Dec-2008 |
8 pages |
| Authors:
Betsy M Rice; Jennifer A Ciezak; William D Mattson; Radhakrishnan Balu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| We present a combined experimental and theoretical study on carbon nanodiamonds using Raman and DAC experimentation and ab initio calculations. Our calculations confirm the surface reconstruction to a fullerene-like structure, and indicate compression of the diamond core, producing an estimated internal pressure of 50 GPa. Quantum molecular dynamics simulations of hypervelocity collisions of NDs show that upon collision shock-induced amorphization first occurs, followed by complete disruption of the ND surface ... |
|
| Investigations of the Energy Release Mechanisms of Aluminum-Nickel Reactive Material System |
Dec-2008 |
9 pages |
| Authors:
Ravindra Pandey; Barrie E Homan; Kevin L McNesby; John Ritter; Joseph Colburn; Andrew Brant; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Reactive materials (RM) are a wide class of energetic materials with unique characteristics that can enable highly lethal munitions along with other applications. Most of the existing information on the behavior of these materials is phenomenological in nature with little evidence as to the initiation and reaction mechanisms at play, making full exploitation of the potential lethality gains difficult. To remedy this situation, a more fundamental understanding of the initiation ... |
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| Metastable Polymeric Nitrogen From N2H2 Alloys |
Dec-2008 |
9 pages |
| Authors:
Jennifer A Ciezak; Timothy A Jenkins; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Studies of high-density binary mixtures of simple molecular solids have uncovered a new aspect of high pressure chemistry. In contrast 10 the many previous studies on relatively inert mixtures, here we show that high pressures can lead 10 unexpected behavior in reactive compounds. Raman studies were performed on nitrogen and hydrogen binary alloys al room temperature to 83 GPa To pressures of 30 GPa, large vibron deviations from those of ... |
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| Using Plasticity Values Determined from Systematic Hardness Indentation Measurements for Predicting Impact Behavior in Structural Ceramics: A New, Simple Screening Technique |
Dec-2008 |
7 pages |
| Authors:
James W McCauley; Trevor E Wilantewicz; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| In general, it has long been known that the hardness of ceramics correlates with gross impact performance, however, not to a degree useful for materials development. Wilkins, Cline and Honodel, 1969, were the first to point out the apparent importance of ceramic plasticity or inelastic deformation mechanisms in BeO and AlN in impact performance. More recently, Lundberg et al., 2000, have made compelling arguments that the compressive yield strength (related ... |
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| Dynamic System Response of Truss Panels under High Dynamic Loading through Experimental & Computation Evaluation |
Dec-2008 |
10 pages |
| Authors:
Rahul Gupta; Tyrone L Jones; Matthew Burkins; Haydn Wadley; Yellapu Murty; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| The ability of computer simulations to accurately resolve dynamic responses of systems has significantly improved over the last decade. Simulations can now be a trusted source of parametric evaluation of complex systems. DARPA funded a program to investigate the dynamic performance of truss panel systems. Two configurations were computer simulated and their material responses were characterized. This manuscript documents the validity of computer simulation to correlate experimental system failure limits ... |
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| A Formal Experiment to Assess Pedestrian Detection and Tracking Technology for Unmanned Ground Systems |
Dec-2008 |
7 pages |
| Authors:
Barry A Bodt; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| An important area of investigation in robotics perception and intelligent control concerns the ability to detect, track, and avoid humans operating in proximity to an unmanned ground vehicle (UGV). Under the Army Research Laboratory (ARL) Robotics Collaborative Technology Alliance (RCTA), ARL and other member organizations have developed algorithms focused on human detection and tracking, which leverage program advances in stereo vision and LADAR. A recent assessment conducted by ARL and ... |
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| Environmentally Friendly Bio-Based Vinyl Ester Resins for Military Composite Structures |
Dec-2008 |
11 pages |
| Authors:
Michael Starks; John J Scala; Giuseppe R Palmese; Steven E Boyd; Ian McAninch; David Fudge; Dane Morgan; Maureen Foley; Jorge Gomez; John Jr; La; Xing Geng; Ken Patterson; Frank Bruce; Stephen Andersen; Lawrence Coulter; Roger Crane; James M Sands; Gillespie; Alexander Grous; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Liquid resins used for molding composite structures a significant source of volatile organic compounds (VOC) and hazardous air pollutant (HAP) emissions. One method of reducing styrene emissions from vinyl ester (VE) resins is to replace some or all of the styrene with fatty acid-based monomers. These fatty acid vinyl ester resins allow for the formulation of high performance composite resins with no more than 25 wt% styrene. As a result, ... |
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