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The overall objective of our audit was to evaluate ballistic testing requirements for body armor components. We specifically reviewed whether the Enhanced Small Arms Protective Inserts (ESAPI) first article testing criteria for Army contract W91CRB-04-D- 0040 (Contract 0040) were in accordance with the contract. We also reviewed the basis for first article testing criteria used by the U.S. Army and U.S. Special Operations Command (USSOCOM). Although an announced objective, we did not review first article testing criteria for the other contracts reviewed as part of DoD Inspector General (IG) Report No. D-2008-067, "DoD Procurement Policy for Body Armor," March 31, 2008. That objective will be addressed in DoD IG Project No. D2008- D000CD-0256.000, "Research on DoD Body Armor Contracts."

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., The original document contains color images. Published in Proceedings of the 2008 Army Science Conference Held in Orlando, FL on 3 Dec 2008.

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 work we focused on molecular influence and have successfully synthesized select model PU and PUU elastomers incorporating triptycene moieties. Adding triptycene-1,4 hydroquinone resulted in a 9C increase in the soft segment glass transition temperature compared to hydroquinone-containing PU. The 1,4-diaminotriptycene modified PUUs revealed improved tensile modulus and flow stress, which correlated well with the rubbery plateau modulus data determined from dynamic mechanical analysis and with the interdomain-correlation data from the small-angle X-ray scattering measurements., The original document contains color images. DRI(Director's Research Initiative)

The research efforts to develop a high-efficiency, moderate power THz device are discussed. The device structure is based upon the crystalline properties of GaN and its ability to handle large power and high fields. Physical device models were developed that include thermal and electrical simulations. Several device structures were produced in conjunction with the model development Initial negative differential conduction results from fabricated devices are presented as are the designs of co-planar resonant structures suitable for THz/emission.

A high-speed photographic method was set up to track a small projectile in flight and capture its subsequent impact on a glass shield. A 1.0-mm-diameter steel ball bearing was launched from a compressed helium gas gun. The flight of the projectile and the impact event were captured with high-speed cameras. The glass shield showed visible damage at an impact speed of more than 205 m/s., The original document contains color images.

The need for firearm identification systems by police services continues to increase with greater accessibility to weapons in the national and international contexts. The difficulties associated with traditional imaging of ballistics specimens are numerous, and include the smallness of the samples, the nature of the surfaces and shapes for the cartridge cases and projectiles. The digital holography has been introduced to create the 3D image of the fired bullets in order to identify firearms. In digital holography a CCD camera records optically generated holograms which is then reconstructed numerically by a calculation of scalar diffraction in the Fresnel approximation. The digital photography facilitates real time transmission of the message via traditional communication methods. In this paper the principle of digital holography and its application to the 3D image encryption decryption were reviewed. The experimental results of firearm identification recording using digital holography and their numerical reconstruction were presented

Cílem práce je shrnutí požadavků na automobilová skla. Zpřehlednění technologie výroby čelních automobilových skel. Dále se zaměřuji na podmínky pro zkoušení fyzikálních vlastností automobilových skel bez a s balistickou ochranou. Stěžejní část práce se zabývá posouzením vlivu balistické ochrany čelního skla na optické vlastnosti. V poslední části práce se jsou výsledky měření a závěr., The tendency of my dissertation thesis is summarize requirements on automobile glasses. Give precision to technology of production wind – screen. Further, I cover with conditions for testing physical features of automobile glass with ballistic security. The principal part of dissertation is about assessment of influence ballistic security wind – screen on optical features. In the last part are results of measure and conclusion., Katedra dopravních prostředků a diagnostiky, Dokončená práce s úspěšnou obhajobou

In the present work, a ballistic material-model development approach is combined with transient non-linear dynamics simulations of the projectile/armour interactions to explore the armour-hard-facing potential of multi-walled carbon nanotube (MWCNT) reinforced, polyvinyl- ester-epoxy (PVEE)-matrix composite mats. This approach is applied to improving the ballistic-protection performance of E-glass fibre-mat reinforced PVEE-matrix laminate armour. Two different architectures of the MWCNT-reinforced/PVEE-matrix composite mats were considered: (a) a MWCNT-ply mat structure in which the MWCNT reinforcements are aligned parallel to the armour faces and (b) a MWCNT-forest mat structure in which the MWCNT reinforcements are aligned orthogonally to the armour faces. The projectile/armour interaction simulation results showed that, at low volume fractions of MWCNTs, both armour architectures yield no discernable increase in the armour ballistic-protection performance as measured by the armour. On the other hand, at high MWCNT volume fractions of MWCNTs, the first armour architecture remained ineffective whereas the second showed a minor improvement in the ballistic-protection performance relative to the corresponding monolithic armour. These results were rationalized using published experimental observations pertaining to the effect of MWCNTs on the in-plane and the through-the-thickness properties of fibre-mat/polymer-matrix composite materials., Published in the Journal of Materials Design and Applications (Proc. IMechE), v222 Part L, p15-27, 2008. Supported in part by the U.S. Army Agreement no. W911NF-04-2-0024, Grant no. DAAD19-01-1-0661, ARL.

A series of transient non-linear dynamic finite-element method (FEM) analyses pertaining to the interaction of a single-ply plain-woven balanced square textile-fabric armour with a spherical steel projectile is carried out in order to compare the corresponding results obtained for two different yarn models: (a) a solid FEM model in which the warp and weft yarns are represented using first-order three-dimensional solid elements and (b) a membrane model in which the same yarns are represented using second-order membrane elements. The analyses are carried out under different yarn-yarn and projectile?fabric frictional conditions and under different far-field boundary conditions applied to the edges of the fabric. The results obtained showed that the two sets of analyses yield comparable predictions regarding the temporal evolution and the spatial distribution of the deformation and damage fields within the fabric, regarding the ability of the fabric to absorb the projectile's kinetic energy and regarding the relative contributions of the main energy absorbing mechanisms. The work also confirmed the roles yarn-yarn and projectile-fabric friction play in the impact process as well as the effect of the far-field boundary conditions applied to the edges of the fabric., Published in Proc. IMechE v222 pt. L, p259-276, 2008.

First there were sandbags, then came gabion baskets, and now a new element in field fortifications is emerging that could give sappers an enhanced, multifaceted capability for force protection. Since deploying to the Balkans more than 15 years ago, the Corps of Royal Engineers has become increasingly involved with the construction of static physical force protection in the form of blast walls, protective berms, sangars (fortified observation posts), and explosive ordnance disposal (EOD) protective works. We also continue to assist with infrastructure construction such as building roads, culverts, and flood protection measures. DefenCell is a relatively new military innovation that will provide additional options when undertaking all of these tasks. It has been successfully used in Afghanistan by the British Army s 39 Engineer Regiment (Air Support) to construct protective berms and ground stabilization structures at several locations and at the Defence Explosive Ordnance Disposal School in Britain to improve its EOD training area. DefenCell is a geotextile polymer structure that has great strength, not just because of the textile s properties, but because of the cellular form of each unit. The cells confine the fill material and give it such load-bearing strength that it can be driven on or even compacted with heavy rollers. This in turn enhances its ballistic protection properties and aids the stability of the structures. Walls of substantial heights can be achieved by field engineers, and DefenCell engineers can help in the design of even higher structures., Published in Engineer, p59-61 Jul-Dec 2008.

The known fiber and polymeric-matrix material properties, unit-cell microstructural characteristics and unit-cell level finite-element analyses are used to construct a new ballistic material model for 0 deg/90 deg crossplied oriented polyethylene fiber-based armor-grade composite laminates. The model is constructed in such away that it can be readily integrated into commercial finite-element programs like ANSYS/Autodyn [ANSYS/Autodyn version 11.0, User Documentation, Century Dynamics Inc., a subsidiary of ANSYS Inc., 2007] and ABAQUS/Explicit [ABAQUS version 6.7, User Documentation, Dessault Systems, 2007] as a user material subroutine. To validate the model, a series of transient non-linear dynamics simulations of the transverse impact of armor-grade composite laminates with two types of bullets/projectiles is carried out. The results obtained are next compared with their experimental counterparts. This comparison revealed that a relatively good agreement is obtained between the experimental and the computational analysis relative to: (a) the success of the armor panels of different areal densities in defeating the bullets at different initial bullet velocities; (b) post-mortem spatial distribution of damage within the panels; (c) the temporal evolution of a bulge at the back-face of the armor; and (d) the existence of three distinct armor-penetration stages (i.e. an initial filament shearing/cutting dominated stage, an intermediate stage characterized by pronounced filament/matrix de-bonding/decohesion and the final stage associated with the extensive bulging of the armor panel)., Published in the Journal of Materials Science and Engineering A, v498 n1 p231-241, 2008. Supported in part by U.S. Army/Clemson Univ. Cooperative Agreements Contract nos. W911NF-04-2-0024 and W911NF-06-2-0042. The original document contains color images.

Experiments were performed to determine the dwell-penetration transition velocity for an unconfined SiC target impacting a long gold rod. Some of the targets used a small copper buffer to attenuate the initial impact shock which increased the transition velocity significantly (by a factor of approximately 2). Transition velocity for bare SiC is approximately 800 m/s whereas the buffered targets had a transition velocity of approximately 1550 m/s. Once penetration is initiated, X-ray images show significant damage in the target. A possible scaling effect of the rod dimensions could be responsible for the slightly lower transition velocity compared to earlier experiments., Presented at the International Symposium on Balistics (24th), New Orleans on 22-26 Sep 2008, The original document contains color images.

Aircraft Survivability is published three times a year by the Joint Aircraft Survivability Program Office (JASPO) chartered by the US Army Aviation and Missile Command. Articles in this issue include: Vulnerability of unmanned aircraft systems to ballistic threats, Excellence in survivability, Unmanned aircraft system surviviability and safety, JASP 2008 survivability short course and Warfighters need a joint survivability library.

This case demonstrates the importance of trajectory analysis of blast and/or ballistic penetrating head and neck injuries. In particular, this case focuses on an intracranial vascular injury generated by a hand grenade with the diagnosis assisted by trajectory mapping using MDCT (Multi-Detector CT) volumetrically acquired datasets. Further, this case shows the usefulness of reformatted images to analyze projectile wound trajectories and reviews complex anatomic planes for use in triage, treatment, and incident analysis in penetrating trauma., Pub. in Military Medicine Radiology Corner, v172, Sep 2008.

Aircraft Survivability is published three times a year by the Joint Aircraft Survivability Program Office (JASPO) chartered by the U.S. Army Aviation & Missile Command, U.S. Air Force Aeronautical Systems Center and U.S. Navy Naval Air Systems Command. Articles in this issue include: Spacer survivability--time to get serious, Spacecraft survivability engineering--Project Orion, Optical diagnostics for ballistic aircraft survivability testing, excellence in survivability--Gregory Czarnecki, Control surface vulnerability to MANPADS, Satellite vulnerability to direct ascent, and Effectiveness to solid propellant gas generators.

This report results from a contract tasking Induced Gamma Emission Foundation as follows: The contractor will investigate the production and accumulation of the nuclear isomer 178m2 Hafnium by spallation of hafnium targets with high-energy protons. The Hafnium yield will be assayed and compared to predictions. The program will use Hf targets for the optimization of the 178m2Hf yield and for the minimization of the running cost related to the simplicity and availability of accelerators operating at such low energies. The operation cost for a small cyclotron that provides protons of energies around 150 MeV are order of magnitude lower than those for the operation of the Los Alamos 800 MeV meson factory facility. By the end of the first year the Foundation will have the results of the data analysis for the irradiation of the natural Hf targets and LAHET calculations will be recalibrated based on the new experimental data. The technical problems related to the design and mounting of Hf targets including heat removal solutions will be settled. Working from this base the Foundation will contract the irradiation of the enriched Hf targets at the Dubna synchrocyclotron establishing all the details concerning the beam energies, number of the irradiations and their duration., The original document contains color images.

Ballistic tests were conducted on a high manganese and high aluminum austenitic steel that is age hardenable. These lightweight steels (12 to 18% lower in density) were investigated as alternatives to MIL-PRF- 32269 steel alloys for application in P900 perforated armor currently used for Army ground combat systems. Two steel plates with nominal composition in weight percent of Fe-30Mn-9Al-1Si-0.9C-0.5Mo were evaluated for V50 against 0.30 caliber armor piercing and 0.50 caliber fragmentation simulation projectiles. At equivalent areal densities to current steels, both plates surpassed the required 0.30 caliber acceptance criteria by 188 and 151 ft/s. Against the 0.50 caliber fragmentation projectile, the calcium treated plate exceeded the MIL-A- 46100 V50 by 225 ft/s, but the non calcium treated plate underperformed by 39 ft/s., See also ADM002187. Presented at the Army Science Conference (26th) held in Orlando, Florida on 1-4 December 2008. Published in Proceedings of the Army Science Conference (26th), p1-7, Dec 2008. The original document contains color images.

The United States has historically capitalized on material and process advances to develop improved ballistic head protection for the warfighter. This also includes innovations in the design of various helmet elements based on careful consideration of the environment, patterns of use, interfacing with other equipment (e.g., weapons, body armor), and possible threat scenarios. As such the U.S. helmet bas evolved in both shape, composition, and manufacture, and this same trend driven largely by contemporary and anticipated demands - has provided an excellent opportunity to consider new levels of protection and complexity. Increased ballistic mass efficiency has traditionally been the most significant factor, but advances in materials and computational tools have made possible new approaches to address helmet pad and suspension systems, as well as higher levels of ballistic resistance through hybridization. Helmet shell material and design, padding, and suspension have significant influence over several areas including shock resistance (due to a non-penetrating fragment or bullet, or to a blast event), as well as comfort and thermal management. This paper provides an overview of novel material, processing, and concept development to provide a set of both modular and integrated tools and technologies for tailoring helmet performance., See also ADM002187. Presented at the Army Science Conference (26th) held in Orlando, Florida on 1-4 December 2008. The original document contains color images.

Extensive study on the fracture behavior of TROGAMID CX-7323 (CX-7323) nylon under ballistic impact was performed. Generally, CX-7323 exhibits ductile failure upon impact with a 17-grain fragment simulating projectile(s) (FSP). Penetration is initiated by ductile shearing upon impact. Subsequent tensile stretching allows the penetration event to progress. Material in front of the projectile is pushed out of the way during penetration. Significant elastic recovery of the exit hole is noticed after complete penetration. Upon impact of a right circular cylinder(s) (RCC) the failure behavior was mixed depending on the size of the fragment. With smaller RCC (2-grain, 4-grain) the failure is similarly ductile as when impacted with FSP. Larger RCC (16-, 17- and 64-grain) at impact velocities above the ballistic limit frequently cause a different failure mode in CX- 7323 nylon. Initial penetration is marked by ductile shearing with a hole similar in size to the projectile. Upon complete penetration, brittle, conoid spallation occurs. Annealing negatively affected notched Izod impact results, but ballistic performance was maintained past temperatures significantly higher than the Glass Transition (Tg) of CX-7323., See also ADM002187. Presented at the Army Science Conference (26th), held in Orlando, Florida on 1-4 December 2008. Prepared in collaboration with Paulson Mfg. Co., Temecula, CA. The original document contains color images.

We present a conceptual discussion of a numerical method to simulate the penetration of a ballistic gel by a projectile. The method draws on the computational advantages presented by asynchronous variational integrators (AVIs) and an immersed boundary method to result in an easily parallelizable, efficient and adaptive algorithm. The paper focuses on the algorithmic ideas involved - at the expense of details and a simplified model., See also ADM002187. Presented at the Army Science Conference (26th) held in Orlando, Florida on 1-4 December 2008. Published in the Proceedings of the Army Science Conference (26th), December 2008. The original document contains color images.

Modeling woven fabrics is challenging due to the need to capture the fabric response at both the macroscopic scale of the fabric and the "mesoscale" of the yarns that compose the weave. Here, we utilize a continuum-level modeling technique for woven fabrics which captures the macroscopic response of the fabric as well as the evolution of its mesostructure with deformation in a single efficient modeling step. A membrane element formulation of the model is implemented into a nonlinear finite element code with a fully explicit solver and hard contact. In addition to displacement degrees of freedom, degrees of freedom representing the crimp amplitude of each yarn family are defined in order to solve for the configuration of the fabric unit cell at each step in time. The accuracy of the model is verified by comparing the simulation results with the experiments of Weerasooriya et al. (2008)., See also ADM002187. Presented at the Army Science Conference (26th) held in Orlando, FL on 1-4 Dec 2008. The original document contains color images.

The objective of this research is to develop a modeling, simulation, and design tool for nanocomposites in order to predict, with accepted fidelity, nano-composite behaviors; and to design optimum nanocomposites for specific Army applications such as ballistic protection. Based on a unit cell model created for nanoclay-epoxy composites, the effect of nanoparticle distribution on the maximum stress developed in epoxy resin was investigated using the Meshfree Particle Method based simulation tool developed at MKP. The ensemble average of mechanical property for nanoclay-epoxy composite was also studied. The increase in the mechanical properties for nanoclay-reinforced epoxy was evidenced from the simulations. It is found that statistical analysis is crucial to predict the performance of nanoparticle reinforced composite. Several armor samples reinforced with nanoclay-epoxy composites were fabricated and ballistic tests were conducted on the nanoclay-reinforced composite armors. It was found that higher mechanical properties, such as modulus and strength, will help to improve the performances of composite armor system. A numerical simulation was initiated to investigate the protection difference between armor with nanoclay reinforced epoxy and armor with pure epoxy resin. Efforts have been made to reproduce similar ballistic protection behavior using the simulation tool in comparing with the actual test results., See also ADM002187. Presented at the Army Science Conference (26th) held in Orlando, FL on 1-4 December 2008. Published in the Proceedings of the Army Science Conference (26th), December 2008. The original document contains color images.

Enhancing the fragmentation capability of current and future projectiles is critical to meeting the armies Future Combat Systems, FCS, requirements. In order to meet these requirements, enhancements to the fragmentation capabilities of these future weapons is needed. Only through the use of the latest modeling tools can these goals be achieved. The U.S. Army Armament Research and Development Center, ARDEC, has continued its efforts to develop its modeling capabilities further to generate these optimized warheads., See also ADM002187. Presented at the Army Science Conference (26th), held in Orlando, Florida on 1-4 December 2008. The original document contains color images.

Ballistic fabrics such as Kevlar and Zylon are finding new uses not only as shielding for personnel but also in commercial and military aircraft protecting flight-critical components in the event of a high-speed ballistic impact. Since experimental tests on these materials are often expensive and time consuming, a computational model amenable to largescale numerical simulations on massively parallel processors would provide an ideal alternative. To this effect, a novel multi-scale approach has been developed for modeling ballistic fabric that extracts information from the micro-scale fibril material properties to build the macro-scale sheet. This approach incorporates the stochastic nature of the material due to the random variations in the yarn caused by the weaving process. Representing these variations is critical to capturing the heterogeneous damage and failure of the material as confirmed by experimental tests. A parallel implementation of the proposed multi-scale method has been developed with particular attention to the contact problem. The paper will focus on all of these issues and report on massively parallel large-scale computations for large sheet applications with both performance and validation results., See also ADM002187. Presented at the Army Science Conference (26th) held in Orlando, Florida on 1-4 December 2008. Published in the Proceedings of the Army Science Conference (26th), 2008. The original document contains color images.

We determined the equation of state for ballistic gelatin using the Brillouin scattering spectroscopy with a diamond anvil cell by measuring the pressure dependence of the sound velocities from ambient pressure to 12 GPa at room temperature. We extended these measurements to a temperature range of 0 to 100 deg C between ambient and 12 GPa. We analyzed the Brillouin data using a high temperature Vinet equation of state and obtained the bulk modulus, its pressure derivative, thermal expansion coefficient and the temperature derivative of bulk modulus at ambient pressure.

A novel method to delay transition in hypervelocity flows over slender bodies by injecting CO2 into the boundary layer of interest is investigated. The results presented here consist of both experimental and computational data. The experimental data was obtained at Caltech's T5 reflected shock tunnel, while the computational data was obtained at the University of Minnesota. The experimental model was a 5 degree sharp cone, chosen because of its relevance to axisymmetric hypersonic vehicle designs and the wealth of experimental and numerical data available for this geometry. The model was instrumented with thermocouples, providing heat transfer measurements from which transition locations were determined and the efficacy of adding CO2 in delaying transition was gauged. For CO2/N2 freestream blends without injection, the transition Reynolds number more than doubled for mixtures with 40% CO2 mole fraction compared to the case of 100% N2. For the cases with injection, shadowgraph visualizations were obtained, allowing verification of the injection timing. The computations provide encouraging results that for the injection schemes proposed CO2 is reaching high enough temperatures to excite vibrational modes and thus delay transition., To be presented at the AIAA Aerospace Sciences Meeting and Exhibit (47th), held in Orlando, FL, on 5-8 January 2009. Prepared in collaboration with Caltech, Pasadena, CA, and with University of Minnesota, Minneapolis. Document includes briefing charts in addition to text.

The U.S. Army Research Laboratory (ARL) and Magnesium Elektron North America (MENA) have conducted a joint effort to develop and evaluate rolled plate in commercially available magnesium alloy-temper AZ31B-H24. MENA produced the rolled product and conducted the mechanical analysis, while ARL performed the ballistic analysis. The magnesium alloy plates were parametrically compared with the minimum performance requirements of aluminum alloy 5083-H131 temper rolled plate using various armor-piercing and fragment-simulating projectiles (FSPs). The ballistic results and comparisons are presented herein. The yield strength of AZ31B-H24 is the dominant mechanical property that will improve the performance at increased weights., The original document contains color images. Prepared in cooperation with Magnesium Elektron North America, Inc., Madison, IL.

The highest-performing U.S. steel alloys for armor-piercing (AP) bullet protection are manufactured to MIL-DTL-46100E, high-hardness armor (HHA) with a hardness range of 477 534 Brinell hardness number (BHN), and to MIL-A-46099C, dual hardness armor (DHA), which is produced by roll bonding a 601 712 BHN front plate to a 461 534 BHN back plate. While these materials still serve their intended applications, monolithic ultra-high-hardness (UHH) steels with a hardness of 600 BHN or greater have been developed. This class of steels increases AP bullet defeat, reduces armor weight, and eliminates the manufacturing difficulties inherent in DHA. Swedish Steel Oxel sund AB (SSAB) produces a number of grades of steel, which have previously been assessed against AP ammunition. However, SSAB has two UHH armor steels designated ARMOX 600T and ARMOX ADVANCE that meet this hardness criteria. ARMOX 600T is a nominal 600 BHN steel while ARMOX ADVANCE has a nominal hardness of Rockwell C58-63 (>650 BHN). This report assesses the performance of these steels against two projectiles that will be used to generate a new military specification for UHH steel armor. The performance of these UHH steels will be compared to the current HHA MIL-DTL-46100E specification., Prepared in collaboration with SSAB Oxelosund AB, Sweden.

The urban environment is one of the most difficult mission areas for the warfighter. The purpose of this study is to characterize the effects of weapons and munitions in the context of Military Operations in Urban Terrain (MOUT), and to identify associated knowledge gaps. The result is an overview of current knowledge gaps and an approach for addressing these gaps in future research., The original document contains color images. All DTIC reproductions will be in black and white.

Tungsten carbide (WC) spheres are used as projectiles to study the ballistic performance of armor materials and systems. In order to properly understand and model the interaction between the projectile and the armor, it is necessary to have properties of both. In this study, the physical and mechanical properties of two commercially available WC spheres (nominally 0.25 inch in diameter) used in some ballistic impact studies were determined. One WC sphere had higher density, elastic properties, and hardness but lower strength and fracture toughness compared to the other sphere, indicating a significant difference in the binder content between the two materials., The original document contains color images. Prepared in cooperation with Univ. of Wisconsin, Plateville, WI and Oak Ridge National Lab., Oak Ridge, TN.

Spin-stabilized artillery munitions were originally designed to provide precise ballistic fire on long-range targets. Today the challenge is to utilize these ballistic munitions in military operations in urban terrain environments where significantly higher levels of precision are required to minimize collateral damage. One strategy is to retrofit these munitions with some level of low-cost precision. Unique challenges arise when munitions designed to be ballistically precise are guided. Projectile flight is often stabilized by a high spin rate, which induces complex dynamics. Flight mechanics are further aggravated by adding a control mechanism. The goal of this study was to provide a fundamental understanding of various control mechanism strategies for spin-stabilized projectiles. Flight control systems were developed and executed in a six degree-of-freedom simulation. Formulating a generalized model of a control mechanism allowed investigation of parameters such as control force magnitude, control axial location, control lift-to-drag ratio, and control force duration. Results showed that control authority linearly related to control force magnitude. Maximal control authority was obtained by placing the control mechanism at the rear of the projectile. The variation with axial location was also determined since these results were valuable for instances when the control was unable to be located near the projectile base. A lower lift-to-drag ratio of the control mechanism decreased control authority and maximum range. Lastly, the trade-offs associated with continuous and pulsed flight control systems were quantified. Physical explanations for the simulation results were provided., The original document contains color images.

Background and Study Objective: Background -Battlefield has changed since initial requirements for precision projectiles were developed: - Counterinsurgency vs. Mobile Armored Warfare - Combat among the population vs. on unoccupied terrain - Collateral Damage relationship to strategic outcome -FA is again relevant: cannon-delivered precision fires have been achieved, demonstrated in combat, and early expectations surpassed -Requirements have not yet reflected technology capability for AOF. Study Objective: -Quantify benefits of having steeper Angle of Fall (AOF) for precision projectiles within urban terrain -Measure of Merits include Engageable Area, Lethality, Operational Effectiveness, and Cost, See also ADM202527. Presented at the Military Operations Research Society Symposium (76th) held in New London, Connecticut on June 10-12, 2008. The original document contains color images.

This report presents the results of a computer simulation of a 45.36 kg 155-mm projectile as it moves through a scat gun assembly using a FORTRAN program. The experimental data was taken from a test performed by the Analysis Engineering and Technical Division at the U.S. Army Armament Research, Development and Engineering Center, Picatinny Arsenal, New Jersey on 7 April 2007 (test CBR5). The data was filtered using an Abaqus Butterworth Filter with a cutoff frequency of 500 Hz because the data plot exhibited "noisy" displays due to the electronic circuitry. The simulation entails aerodynamic deceleration of the projectile and the acceleration/deceleration of the piston inside the assembly in a long tube attached to the gun barrel. The projectile had an entrance velocity of 516 m/s and the shock wave preceding it ruptures the diaphragm. The projectile decelerates as high pressure builds between it and the free piston due to shock-wave propagation. The piston disengages and travels forward scooping water. The waterlog that forms in front of the piston effectively increases the piston's mass and also induces a braking force because of the water friction with the tube wall. The simulation predicts the piston will be decelerated with the piston coming to a rest about 22 m from the back end of the assembly. The computer simulation is based on the closed form formulas, incorporating unsteady one-dimensional fluid dynamics. This report details effects of shockwave induced pressure on the projectile and piston and how accurate the simulations are compared to the actual data lot., The original document contains color images. All DTIC reproductions will be in black and white.

Electronic components within a projectile are subjected to severe loads over an extremely short duration during the launch process. Failure of these components during launch can result in negative effects on the mission of the projectile. While experimental data can be helpful in understanding failure of electronic components within a projectile, collecting such data are [sic] usually difficult. There are also limitations on the reliability of sensors under these circumstances. Finite element modeling (FEM) can offer a means to better understand the behavior of these components. It can also be used to develop better shock mitigation features into the projectile design. This research has two objectives. The first objective is to develop an FEM that one describes the interaction of a typical projectile with the gun barrel during launch. The projectile includes a payload of a one-pound mass representing a typical electronic package supported by a plate. The second objective of this work is to investigate the use of composite plates to support electronic payload as a means to reduce the transmitted shocks during the projectile launch event. The proposed plate has carbon fibers embedded in an epoxy matrix. A parametric study of the effects of varying the thickness of the supporting plate and the fiber volume fraction on the accelerations and stresses is included. Results of the study are used to reach general recommendations regarding reducing failure of electronic components within a projectile., Published in International Journal of Impact Engineering, v35 p1326-1338, 2008. The original document contains color images.

Conventional transparent armor consists of glass laminates with polymer interlayer and backing. It has been demonstrated that the materials, the ratio of materials, and the type and thickness of the interlayers affect the ballistic efficiency of the laminate. Borosilicate glass, Starphire ultra-clear soda-lime glass, and the transparent, polycrystalline ceramic AION are materials being considered for transparent armor applications. A comprehensive series of Edge-on Impact tests has been conducted in order to examine wave and damage propagation through the single materials (baseline tests) and laminated structures. The numerical simulation part of this project focused on the modeling and simulation of projectile impact on the polycrystalline, transparent ceramic AION. In the approach chosen here, the ceramic was not treated as a continuum. In order to model the polyhedral microstructure of the ceramics, a code, which is based on the theory of power diagrams, was implemented. After having obtained a three-dimensional (3-D) grain structure that corresponds on average to what is observed in micrographs, these structures are being meshed in three dimensions using tetrahedra in 3-D vs. triangles in two dimensions. The generated and meshed microstructures were used as input for a commercial program package (LSDyna) and subsequent finite-element analyses., The original document contains color images.

In order to protect the U.S. industrial base during periods of adversity and war, Congress passed domestic source restrictions as part of the 1941 Fifth Supplemental Department of Defense (DOD) Appropriations Act; these provisions later became the Berry Amendment. The Berry Amendment requires DOD to give preference in procurement to domestically produced, manufactured, or home grown products, notably food, clothing, fabrics, and specialty metals. The Berry Amendment (Title 10 United States Code (U.S.C.) Section 2533a, Requirement to Buy Certain Articles from American Sources; Exceptions) contains a number of domestic source restrictions that prohibit DOD from acquiring food, clothing, fabrics (including ballistic fibers), specialty metals, stainless steel, and hand or measuring tools that are not grown or produced in the United States., CRS Report for Congress

This Test Operations Procedure (TOP) describes the selection, setup and operation of the various instrumentation used for measurement of dynamic displacement events, as a part of vehicle live fire vulnerability testing., The original document contains color images.

Many factors are considered during ballistic helmet design, including comfort, weight, fit, and maintainability. These factors affect Soldiers' decisions about helmet use; therefore, rigorous research about Soldiers' real-life experiences with helmets is critical to assessing a helmet's overall protective efficacy. This study compared Soldiers' satisfaction and problem experience wit the advanced combat helmet (ACH) and the personal armor system for ground troops (PASGT) helmet. Data were obtained from surveys of Soldiers at Fort Bragg, North Carolina. Ninety percent of ACH users were satisfied with their helmet, but only 9.5% of PASGT users were satisfied (p < 0.001). The most frequently reported problems for the ACH involved malfunctioning helmet parts. The most frequently reported problems for the PASGT involved discomfort. This analysis indicated that there was strong Soldier preference for the ACH over the PASGT, which could enhance its already superior protective qualities. It also demonstrated the usefulness of Soldiers' assessments of protective equipment., Pub. in Military Medicine, V172 n6, p586-591, June 2007, The original document contains color images.

The study of weapon delivery probabilities has historically been focused around analytical solutions and approximations for weapon delivery accuracy and effectiveness calculations. With the relatively recent increase in modern computing power many of the historical expressions can be simulated quickly with similar or more accurate results than the historical expressions and approximations. In this thesis simulation methods are used to evaluate weapon delivery probability parameters including circular error probable, range and deflection error probable, and weapon effectiveness in the single and salvo weapon scenarios. Comparisons of the simulation results and corresponding historical practices are made to validate simulation techniques. Additionally, standard deviations in the range and deflection direction are extracted from weapon impact data. Using these extracted standard deviations weapon effectiveness calculations are performed.

The U.S. Army Research Laboratory (ARL) was tasked to investigate the ballistic performance of aluminum alloy (AA) 5059 to determine if it was a desirable alternate alloy for use as vehicle armor. Current alloys, such as AA5083 and AA7039, have high yield and tensile strengths and provide increased ballistic protection but have significantly less corrosion resistance than AA5059. AA5059 generally provides greater ballistic protection levels than AA5083 but did not match the levels of AA7039. However, it does contain some of the desirable characteristics of the lower strength AA5083, mainly superior corrosion resistance. the combination of increased strength and corrosion resistance makes AA5059 an ideal choice for consideration as an alternate aluminum armor., The original document contains color images.

This report describes further development in the formulation of a primer model that is compatible with the ARL-NGEN3 code and small caliber weapons that takes in account multidimensional, multiphase interior ballistics codes, which employ coupled Eulerian-Lagrangian schemes to explicitly treat both the gas and solid phase. The model is based on the One Dimensional Turbulence modeling approach that has recently emerged as a powerful tool in multiphase simulations. Initial results are shown for the model run as a stand-alone code and are compared to recent experiments with small-caliber primers. Integration of the primer model with the Army's ARL-NSRG computational fluid dynamics code is presented and the results are compared to experiments with small-caliber primers fired into empty test chambers. It is proposed that this further progress sets the stage for coupling the primer model to the ARL-NGEN3 code., The original document contains color images.

Multi-layer armor containing ceramic and metallic layers has become more common in the past two decades. Typically, ceramics have high compressive strength; that feature combined with their low density make them highly desirable for armor applications. This research effort numerically simulates ballistic impact of a cylindrical penetrator with a hemispherical tip on multi-layer metallic and ceramic targets of finite thickness. The projectile is made of S7 tool steel, while the target consists of rolled homogenous armor and boron carbide ceramic. The Eulerian hydrocode CTH, ideal for studying cases of gross global and local deformation, is used to perform an axisymmetric analysis of the projectile and the target. The Johnson-Holmquist constitutive model (JH-2) for brittle materials is used for the ceramic layers, and the Johnson-Cook constitutive model is used for the metallic layers. Various arrangements of ceramic and metallic layers were simulated over a range of velocities to quantitatively determine ballistic limits. Comparison of the ballistic limits for each configuration will determine which ceramic-metal lay-up arrangement is optimal for resisting penetration of the given projectile. This research shows that replacing multiple metallic target layers with B4C ceramic decreases the resistance of the target to the penetration of the projectile for a target of given thickness., The original document contains color images.

Ultimate objective of this research is to transfer properties measured in the lab to ballistic simulations that can predict ballistic tests results. Conclusions of this research includes that: 1) Mohr-Coulomb (MC) captures very nicely both strength and failure phenomenon for bomb tests. 2) MC also captures failure angle and strength in the sleeve tests. 3) The overlap between bomb and sleeve tests support the results of the sleeve tests., The original document contains color images.

An analytical model of penetration by non-deforming pointy projectiles into dry sand is proposed. The model postulates that an oblique compaction wave in the sand is attached to the penetrator's tip. Sand is modeled by the P-alpha porosity model up to full compaction, then is taken as incompressible. The sand's compaction is considered the most important effect; strength and friction are neglected. The model handles wedges, for which a closed-form solution is derived, and cones, which require numerical integration. For a given penetration velocity, the model predicts the shock angle and the pressure on the penetrator surface. Hydrocode computations agree closely with the model., Submitted for presentation at the International Symposium 24th on Ballistics to be held in New Orleans, LA on 22-26 September 2008.

This program was intended to develop theory a broad range of algorithms and proof of concept in detection, estimation, and reconstruction of objects embedded in turbid media, which hamper visibility (such as fog, clouds, smoke, and other types of aerosol particles).

The Tate Theory of penetration of armor targets by long rod penetrators [1,2] has been the benchmark one-dimensional model of this event for decades. The model is applied to metal-on-metal normal impact of cylindrical rod penetrators. The key physical parameters in the model are the penetrator and target strengths and densities (assumed constant), as well as the penetrator length. With these parameters and the impact speed, penetration depth for all combinations of the parameters can be evaluated. In a recent paper, Walters et al [3] showed that all of the important effects of the classic Tate Theory could be captured by a regular perturbation solution of the fundamental equations. The small parameter that they used was epsilon=Y(sub p)/rho(sub p)v(sub 0)2, where Y(sub p) is the penetrator yield strength, rho(sub p) is the penetrator density and v(sub 0) is the impact speed. In 1987, Jones et al [4] modified the equation of motion of the undeformed section to include mass loss and mushrooming at the interface with the target. The changes to the theory that result from these modifications bring the strengths of the target and penetrator into line with laboratory levels while achieving reasonable penetration depths. In this paper, we will show that the regular perturbation analysis used by Walters et al [3] can be extended to the modified system of equations from Jones et al [4] using the same small parameter mentioned in the previous paragraph. The perturbation process is carried out to terms of first order and an approximate analytical solution is found. This solution is then used to repeat the reduction of data given by Wilson et al [5] for Aluminum and Steel alloy penetrators normally impacting Aluminum and Steel targets. Another case involving heavy metal penetrators impacting Rolled Hard Armor (RHA) targets is also presented., Pres. at the ASME Pressure Vessels and Piping Conference, held in San Antonio, TX on 22-26 Jul 2007. Pub. in the Proceedings of PVP2007, paper PVP200726046, p1-6, 2007. Prepared in collaboration with College of Engineering, University of Alabama, Tuscaloosa, AL.

Classical, one-dimensional theory of hydrodynamic penetration is used as the basis of establishing simplified analytical relationships describing energy, momentum, and power deposition during hypervelocity impact events. A concise overview of the 1-D model is given followed by a select grouping of terms into relationships that offer first-order criteria for making engineering design considerations on relevant applications and assist in the analysis of experimental observations. Momentum, energy, and power deposition are found to be proportional to second, third and fourth power exponents, respectively. These analytical terms are presented for constant velocity gradient, i.e. fixed length, rods as well as linear velocity gradient rods, such as shaped charge jets. The role of penetrator-to-target density ratio is then examined in terms of the backflow, or reverse flow of 1- D penetration. Again, the non-dimensional ratio of penetrator-to-target mass density is used to compare the relative velocity of material flow during penetration. The relationship highlights the role of penetrator materials for achieving desired effects in these hypervelocity, terminal ballistics events. Albeit the relationships are derived on the assumptions for hydrodynamic processes, their generality of form and ease of implementation make them a useful first-order description for engineering insight and application over a broad range of velocities., Submitted for publication in the International Journal of Impact Engineering.

Design and manufacturing of transparent armor have been historically carried out using experimental approaches. In this study, we use advanced computational modeling tools to perform virtual design evaluations of transparent armor systems under different projectile impact conditions. AHPCRC developed modeling software EPIC'06 is used in predicting the penetration resistance of transparent armor systems. LaGrangian-based finite element analyses combined with particle dynamics are used to simulate the damage initiation and propagation process for the armor system under impact conditions. It is found that a 1-parameter single state model can be used to predict the impact penetration depth with relatively good accuracy, suggesting that the finely comminuted glass particles follow the behavior similar to a viscous fluid. Even though the intact strength of borosilicate and soda lime glass are different, the same fractured strength can be used for both glasses to capture the penetration depth., The original document contains color images.

Polycrystalline aluminum oxide (Al2O3) based materials have both personnel and ground vehicle armor applications. However, their ballistic performance can vary significantly. At the root of this problem is the identification of the fundamental macro and micro mechanisms of deformation and failure in the ballistic event which has proven very elusive over the years. Using a newly developed soft recovery plate impact experiment, a multi-disciplinary, multi-national collaboration has, for the first time, determined micro and macro deformation and damage mechanism maps relating the experimentally measured global mechanical response of a material through matured shock wave diagnostics to the nature of concurrent deformation and damage generated at varying length scales under shock wave loading., The original document contains color images.

The penetration of 20% ballistic gelatin by rigid steel spheres is studied and analytically modeled. In order to properly capture the response for a wide variety of sphere sizes and impact velocities, a rate-dependent strength formulation is required for the ballistic resistance of gelatin.