2007-2008 Assessment of the Army Research Laboratory (2009) / Chapter Skim
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7 Weapons and Materials Research Directorate
7 Weapons and Materials Research Directorate
Pages 77-96
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From page 77... ...
was reviewed by the Panel on Armor and Armaments of the Army Research Laboratory Technical Assessment Board (ARLTAB) at Aberdeen Proving Ground, Maryland, during June 5-7, 2007, and July 15-17, 2008.
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From page 78... ...
work on developing phase diagrams for glassy grain boundary phases in grain boundary engineered boron carbide -- necessary for improving the consistency of armor protection of this very lightweight ceramic armor; (2) development of magnesium (Mg)
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From page 79... ...
Electromagnetic Gun Rail Wear The problem of rail wear has been worked on for more than 20 years within the DoD. The novelty of the work described here is in the use of novel materials for substrates and the use of cold spray coatings to reduce the wear and erosion during firing.
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From page 80... ...
While glassy grain boundary phases have been effective in some ceramic materials systems (for example, alumina) , they have not been effective in others (for example, titanium diboride)
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From page 81... ...
However, the computational polymer science work appears to have been used only to confirm the experimental results. It is suggested that an extension of this effort is needed if the end goal of developing physically based predictive capability is to be achieved.
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From page 82... ...
Computational Polymer Science The program in computational polymer science is developing a multiscaled modeling effort that makes use of available software in a standard fashion. The efforts here are the only evidence of serious computational work within this program.
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From page 83... ...
It is understood that finite element modeling (FEM) of the asymmetric wedge test is currently underway in the Survivability program, and WMRD should continue such an effort to facilitate future predictive capability in support of complex composite armor design and testing.
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From page 84... ...
The multidisciplinary approach employs such novel features as the following: (1) virtual wind tunnel tests and virtual fly-outs that allow a much larger range of designs to be explored at a much lower cost than would be the case for real wind tunnel tests; both significantly and surprisingly, results have been achieved in terms of nose and body interactions, jet interactions, and diverter interactions that have permitted avoidance of unstable designs; (2)
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From page 85... ...
and/or through a follow-on project continuing this research direction appears technically warranted and is encouraged. Military Operations on Urbanized Terrain Lethality Munitions directed at typical buildings in urban environments often penetrate walls and produce secondary fragments.
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From page 86... ...
is an example of excellent directed engineering that builds on unique capabilities recently brought online at ARL such as the Novel Energetic Research Facility. The development of an insensitive munitions explosive material, with performance, manufacturability, and cost near that of TNT, is a well-defined goal.
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From page 87... ...
However, there are clearly some advantages that the group could gain by fostering its own code-development skills directly as a part of the group's activities. It appears that the theoretical chemistry and advanced energetic materials group does not take advantage of other computational and theoretical development skills within other groups in ARL.
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From page 88... ...
It is important to be mindful that the research is still limited by thermodynamics laws. Reactive Material Energy Release Mechanisms The work on RM energy release mechanisms is focused on the development of modeling tools and experimental chemical measurements directed at understanding the energy release by reactive materials in conjunction with explosives.
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From page 89... ...
Fundamental investigations of RMs will involve the quantum chemistry group, and although there is research going on in this area (quantum chemistry and reactive materials) it does not, on the surface, seem to be influencing the development of RMs.
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From page 90... ...
Ceramic Armor Materials The work on ceramic armor materials is a piece of the larger work on ceramic composite armor. The stated goal is to achieve a fundamental understanding of deformation and failure mechanisms at ballistic conditions.
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From page 91... ...
There is every reason to expect that an active protection system will be deployable in the near future. Composite Materials Technology for Armor A very detailed model of the fibers, threads, and weave of the fabric for future composite armor components was presented.
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From page 92... ...
At these high strain rates, materials properties can be markedly different from what they are at slower rates, such as, for example, when tested in an Instron. Accordingly, when developing new armor concepts it makes little sense to use handbook values of materials properties such as tensile strength, yield stress, or fracture toughness, because these could be orders-of-magnitude different from high strain-rate properties applicable to armor.
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From page 93... ...
The development of materials for low strain-rate applications has benefited in the past from many years of intensive efforts by materials scientists, but currently as new and more demanding applications appear on the horizon, some reliance is being placed on computational materials science in which techniques such as molecular dynamics simulation and electronic structure calculations are employed to understand how features at the atomic, mesoscale, and microscale levels influence the structure/property relationships. Seemingly, no such effort has been made to focus the attention of computational materials science (CMS) on the problem of understanding what factors govern the markedly huge difference between the properties of many materials at high strain rates and their better-known properties at low strain rates.
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From page 94... ...
For empirical input into model development and validation, the program is examining historic data from the United States Army Wound Ballistics Laboratory at Edgewood Arsenal, Aberdeen Proving Ground, Maryland. In addition, WMRD is conducting high strain-rate experiments with tissues using the high-rate split Hopkinson pressure bar and is attempting to design clamping mechanisms to allow strain-to-failure experiments with tissues.
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From page 95... ...
. The development of anatomical models using grid geometries may not be optimal for use in all application areas and/or easily integrated with other geometrical models.
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From page 96... ...
Such integration requires a careful documentation of model assumptions, prudent choices of grid geometries, and the provision for data interchange with other models. OVERALL TECHNICAL QUALITY OF THE WORK The Weapons and Materials Research Directorate conducts activities across a very wide breadth and depth.
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