2013-2014 Assessment of the Army Research Laboratory (2015) / Chapter Skim
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3 Ballistics Sciences
3 Ballistics Sciences
Pages 57-86
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From page 57... ...
ACCOMPLISHMENTS AND ADVANCEMENTS The ARL has a strong record of achievement and timely support of the warfighter as it develops advanced capabilities for defeating many types of enemy targets and platforms over many years, and the recent and ongoing work described in this review of ballistics demonstrates how ARL continues to build on its tradition of excellence in protecting the warfighter. The reviews in 2013 and 2014 were divided into topic areas described in technical keynote presentations and posters covering materials for interior, exterior, and terminal ballistics, energetics, penetration mechanics, humans in extreme ballistic environments, and computational terminal ballistics.
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From page 58... ...
For example, investigation of next-generation Al alloy armor and the evolution of the Eglin armor steel are both promising research topics. Aluminum alloy armor design and the materials manufacturing technology for these alloys with superior ballistic performance are key to controlling material and fabrication costs while supporting lighter weight technologies for the Army.
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From page 59... ...
Quantification of the relationships among microstructure, defect type, and distribution of nondestructive characterization data, and ballistic behavior in armor ceramic materials is a laudable goal if used to support lot-acceptance testing for ceramic armor components. This nondestructive testing needs to be closely tied with both traditional ballistic testing and postmortem material damage analysis.
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From page 60... ...
The x-ray technique was used to determine dwell time during initial penetration and how that can be used to design stacked ceramic armor. ARL's ceramic material model development work was highlighted in several poster presentations.
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From page 61... ...
PFM is a good addition to ARL's suite of computational capabilities. Composite model development to support ballistics predictive capability is being pursued via numerical models aimed at understanding how the woven portion of the armor package can be optimized to increase penetration resistance.
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From page 62... ...
Humans in Extreme Ballistic Environments The humans in extreme ballistic environments activities appear to be well organized, the technical strategy is well posed, and the current state of science and technology in this area is well defined. The design, modeling, and testing of the warrior injury assessment manikin to test the effects of extreme acceleration and loading effects associated with underbody vehicle blast is an area unique to Army mission challenges and well connected to warfighter needs.
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From page 63... ...
Without more analysis of the Army modeling efforts and plans, one can discern neither the absolute necessity for such data nor the degree of accuracy required, but it seems certain that competence in this area is vital for the military. ARL is encouraged to continue to explore both experimental techniques/diagnostics and constitutive model development in the area of tissue mechanical behavior.
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From page 64... ...
It will be important to apply the ORCA code to all classes of warfighter protective equipment deployed in theatre as well as to new equipment being designed and tested, and to clearly link the applications to the effort to validate the ORCA code. Computational Terminal Ballistics The lethal mechanisms and the blast and ballistic protection projects provided an interesting and reasonably comprehensive review of the broad scope of ARL work in these areas.
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From page 65... ...
The computational terminal ballistics overview described exciting new work focused on the effects of electromagnetic (EM) fields on the formation and breakup of shaped-charge jets.
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From page 66... ...
As noted for segmented penetrators, it is imperative that credible baselines be established for performance comparisons to monolithic, nonextending rods. In the vehicle protection armor modeling project, the goal is to explore armor concepts using modeling and simulation to gain a fundamental understanding of the mechanisms at work and how ARL can exploit them to defeat current and future threats to Army platforms.
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From page 67... ...
The laser-generated shock-wave test to measure explosive performance of milligram quantities of energetic materials has demonstrated good correlation between measured blast wave velocities with conventional large-scale measurements of detonation velocity for a wide range of
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From page 68... ...
This research is impressive as a scientific study that also has very useful applications to energetic material research; the researcher is an expert in his field. The modeling efforts across the energetics research area are showing growth and progress.
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From page 69... ...
The in-house modeling efforts in the interior ballistics have greatly benefited from the long history of efforts at ARL, which is the leader in interior-ballistics modeling. ARL modeling tools are being effectively used for advancing gun technologies and related efforts.
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From page 70... ...
The effects of the length of the full bore and the tapered sections, and the taper angle, need to be assessed and predictive models developed. To explore this, an internal ballistics code, NGen, was coupled with a commercial solid mechanics code, Abaqus, explicitly to analyze projectile deformation.
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From page 71... ...
enterprise in terminal ballistics and (2) specific opportunities and challenges tied to particular terminal ballistics thrust topics or projects.
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From page 72... ...
Some of these areas are obvious: for example, energetics and interior, exterior, and terminal ballistics. However, the strategy needs to devote dedicated and concerted efforts to highlighting these capabilities.
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From page 73... ...
Given the importance of such models to develop a predictive design capability in support of current Army programs and future systems, platform, and equipment development, increased emphasis on validation is warranted. In addition to the need for an ARL-wide strategic approach to model validation, methods are needed to quantify the margin of uncertainty (QMU)
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From page 74... ...
The key questions are therefore these: Which of ARL's current areas of S&T are sufficiently mature in the area of materials for terminal ballistics to meet current and projected performance criteria in specific applications? Which have been found, for reasons of performance or cost, not to warrant further continued effort at the expense of new S&T areas?
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From page 75... ...
The focus on improved composite designs for helmets, which is exploring the effects of existing, commercial polymer yarn constructs for better ballistic protection while using state-of-the-art modeling to identify improved yarn ply orientation patterns, is very positive and forward thinking. While integration of this modeling with other types of body armor or lightweight vehicle armor was not discussed, it needs to be strongly encouraged even if the current goal of defeating of a 7.62-mm small arms threat represents a perhaps insurmountable objective in a helmet of a tolerable weight, although if this engenders outside-the-box thinking it may be a boon to future research.
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From page 76... ...
The development of models for ceramic materials is an activity of critical importance at ARL if it can lead to the creation of a predictive capability for the application of ceramics and other materials in Army armor and lethality systems. Much work has been carried out by a number of organizations over many years, including focused work supported by DARPA, that have not achieved the goal stated for the modest ARL effort.
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From page 77... ...
Will the model be able to effectively represent laminates of materials? Researchers on the project on tailored mechanisms for light armor ballistics articulated their goal: to develop a fundamental understanding of the deformation mechanisms and failure processes active under shock loading conditions for light armor materials such as aluminum and magnesium and then, using key discoveries, to control ballistic performance.
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From page 78... ...
Computational Terminal Ballistics The computational terminal ballistics presentation could have been made more effective by systematically addressing the modeling of KE penetrators, shaped-charge warheads, and EFPs in sequence --
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From page 79... ...
Throughout many of the terminal ballistics briefings and posters, reducing the weight of combat vehicles through lighter armor and faster and more effective lower-caliber munitions was central to ARL's strategic vision. However, it appeared there is no clear set of objectives associated with the operational concept options, just an interest in providing options for performance versus size and weight to the requirements community.
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From page 80... ...
Strategic planning of S&T to support future Army needs for advanced KE is also crucial. The armor modeling efforts described are important work and clearly will be helpful in guiding the development of ARL armor concepts while setting the stage for follow-on, well-defined, proof-ofconcept experiments and subsequent advances.
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From page 81... ...
Data mining of the numerical simulations needs to be done to assess the potential for energy release. In addition to releasing energy, an advanced energetic concept such as nanodiamonds must also release a copious quantity of gas to be useful as a propellant or warhead component.
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From page 82... ...
Based on the past and present activities at ARL, there appears to be sufficient experimental data for model validation in the interior ballistics area, and systematic quantitative comparisons with the database are strongly encouraged. In the area of large-caliber tank propellant, further work to complete the validation could provide a basis for developing designs that are less expensive than the German grain design (e.g., via 3D printing)
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From page 83... ...
The effort is unique and seems deserving of more freedom of scope to capitalize on the current investment. The ammunition compartment vulnerability effect is crucial to warfighter survivability and requires significant effort if predictive capability and not just curve-fitting is to be achieved.
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From page 84... ...
As for the development of advanced aerodynamic performance control algorithms, the basic flow physics of canard wake–vehicle interaction remains to be elucidated. The challenge is to have a fundamental focus when examining generic issues of how the wake interacts with the boundary layer on the body or fin to change the pressure distribution as well as cause flow separation.
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From page 85... ...
Similarly, the novel energetics synthesis, experimental characterization, and modeling efforts are excellent examples of a well-coordinated and integrated research program. Many of the posters displayed in-depth collaborations with outside organizations, including other DoD laboratories, academia, and especially the National Laboratories.
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From page 86... ...
The objective -- to observe penetration phenomena at ever-smaller scales and faster times -- is crucial to the development of predictive modeling capability in the area of terminal ballistics and penetration mechanics. The laser-generated shock wave test to measure explosive performance of milligram quantities of energetic materials, which was developed by ARL, is also very impressive.
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