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2015-2016 Assessment of the Army Research Laboratory: Interim Report (2016)

Chapter: 3 Sciences for Lethality and Protection

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Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
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3

Sciences for Lethality and Protection

INTRODUCTION

The Panel on Ballistics Science and Engineering at the Army Research Laboratory conducted its review of ARL’s programs on Battlefield Injury Mechanisms, Directed Energy, and Armor and Adaptive Protection on June 23-25, 2015.

ARL’s research into lethality and protection sciences during 2015 ranges from basic research that improves our fundamental understanding of scientific phenomena to technology generation that supports battlefield injury mechanisms, directed energy programs, and ballistics and blast programs that address weapon–target interactions and armor and adaptive protection developments. ARL’s human response, directed energy, and armor and adaptive protection mission scope work is performed within the Weapons and Materials Research Directorate (WMRD), the Survivability and Lethality Analysis Directorate (SLAD), the Human Research and Engineering Directorate (HRED), and the Sensors and Electron Devices Directorate (SEDD). These directorates execute their mission of leading the Army’s research and technology program and analysis efforts to enhance the protection and lethality of the individual soldier and advanced weapon systems.

BATTLEFIELD INJURY MECHANISMS

Understanding the mechanism of ballistic injury is essential to the mission of ARL, specifically for protecting the warfighter against traumatic brain injury and extremity fracture injuries. All of the presentations related to injury mechanisms supported ARL’s recognition of the importance of this issue. The biggest challenge is bridging the science/engineering gap between the materials science—intensity of soldier protective devices and the biomedical aspects of injury mechanisms, or, more precisely, quantifying the level of mechanical insult leading to significant injury. The program, as presented, is a start to bridging this gap. However, increased commitment of resources will be required for it to become state of the art, where it will have to be if it is to enable the protective devices relevant to the threats of the next 25 years. The program presented is a good starting point, but it needs to aspire to create state-of-the-art models of medical injury. This will require improved coordination with the technical leadership of the field. Understanding the mechanisms of injury to the degree needed to give effective protection is key to improved protective designs. Meeting this challenge is essential to the mission of ARL, and the areas of traumatic brain injury (TBI) and musculoskeletal injury will continue to be the main areas of concern, along with an increasingly sophisticated understanding of how mechanical insult impacts neural function. All models need experimental validation, and all experimental programs would benefit from increased use of statistical data evaluation and statistical experimental design.

Computational mechanics work on battlefield injury mechanisms and human response to threats and on protective equipment, including the mechanics of fibers and fiber composites, are being combined with experimental efforts to characterize, validate, and verify the computational results. This combination of efforts is laudable.

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
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The program in human responses to threats is performed mostly by junior staff, who are pursuing research objectives focused on short- to medium-term objectives. While the staff are capable, the research is generally not state of the art. Studies were described that focused on the assessment of neuronal response injury using a blast tube injury model with cells grown in monolayer on a flexible membrane. The flexible membrane is also subjected to defined strains in order to model the induction of cell injury. Primary end points include cell viability, calcium signaling, and cell morphology. Long-term goals are to develop a mechanistic understanding of neuronal responses in 2D and 3D culture systems in response to well-defined strain fields. Extension of these studies to assess damage to brain tissue, whole organs, and/or tissue-engineered models of the regional damage would be worthwhile. The results of clinical functional magnetic resonance imaging (fMRI) studies of TBI might help to target specific regions of the brain for in-depth analysis. Overall, given the current state of neurosciences and the advances in optogenetics and other techniques, the biological studies described were relatively rudimentary. It is unclear whether on-site senior investigators with expertise in neuroscience participated in this program of study. Collaboration seems to be taking place with one postdoctoral fellow’s former senior Ph.D. advisor, but further outreach is needed, including with neuroscience investigators in academia, to augment the military’s broader TBI research portfolio.

A second set of studies focused on the assessment of neuronal responses to injury using a microexplosion model involving cells grown in monolayer submerged in an aquarium-based environment. Primary end points include cell viability, calcium signaling, and cell morphology. Future plans are to study neuronal responses in 2D and 3D culture systems placed within a gel-contained model of a human skull. The quality of the biological studies is rudimentary. The investigations do not appear to include the use of a model system in which the stress fields imposed on the cells have been fully characterized. A gel-containing human skull is an interesting model system, but it will require careful correlation of the estimated in vivo force microenvironment with the in vitro system created in their model system.

A third set of investigations focused on assessing the impact of anthropomorphic variability on the mechanisms of human injury, identifying sites of maximum vulnerability, and determining options for designing improved protective garments and equipment. Clinical computerized tomography (CT) data sets are acquired of soldiers killed in action (KIAs) in order to refine existing computational models of human injury and protection. Collaborative efforts have been pursued with the University of Maryland Shock Trauma Center and other programs. The quality of the scientific studies is high and utilizes an appropriate mix of theory, computation, and experimentation applying state-of-the-art laboratory equipment and numerical models. Extension of these studies to CT and MRI data sets of personnel who are injured in the field but not KIA would be worthwhile. The work designed to predict lumbar burst strength is a start but does not represent the thinking of current investigators in the field. It is necessary that the researchers develop communication channels with research leaders to increase the sophistication and applicability of the approach. While the pig skull work was a reasonable approach, it is unclear if the pig skull is relevant to the critical human skull issues that need to be understood.

The computational efforts in the human biomechanics area are somewhat behind the state of the art in computational mechanics of soft tissue. Specific details include the use of linear tetrahedral elements instead of hexahedral elements for soft tissue response, and there was a lack of viscoelastic properties for material response at high strain rates and high pressures. Further, there was only limited inclusion of the effects of statistical variance into necessary parameters of the computational problem to assess these effects. Such information is essential when computationally modeling humans and humanlike responses. The computational team needs to increase the sophistication of the models appropriate for the problem and needs to interact more extensively with subject-matter experts in human and soft tissue material response in the Army research community and the wider research community.

Overall, the biological programs appear connected programmatically, but they seem isolated from a scientific perspective. There appears to be little synergy or communication between the individual researchers. This lack of synergy is particularly significant to the junior staff, who could benefit greatly from strong mentoring by the appropriate technical communities. They need to become familiar with the

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
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current state of the art in their research areas and move quickly to achieve that state. They could also benefit from increased management support to help them learn how to overcome the administrative barriers associated with purchasing supplies and equipment.

To bring the current program to state of the art will require increased coordination of ARL technical personnel with the relevant biomedical communities and the hiring of scientists experienced in the computational modeling and experimental exploration of the effects of mechanical trauma on people, especially in the cases of injuries to the brain and extremities. Current personnel would benefit from experienced mentorship and connections to the field as practiced in university and other government laboratories. The equipment was reported to be consistent with beginning stages of the work and commensurate with the early-career status of the researchers and the brief time (1-2 years) that the program has been in operation. There is little evidence in these projects of the longer-range vision of ARL. The work presented continues to concern itself with current or near-term Army needs.

The research to better characterize the properties of materials relevant to protective systems is sophisticated and mature and is providing the data needed to understand the mechanical performance of protective devices. The project on the ballistic response of knitted materials is a small, well-executed modeling effort that is very relevant and important to ARL needs. While the work is not particularly novel, the results are unique and will be useful for the future design of protective equipment. The study of fiber mechanical properties under very high strain rates is impressive and is likely to provide data needed to better model soft and hard armor design and performance. Nonetheless, the scope of both the experimental and computational programs need to be broadened.

ARL reported a new internal program to study the chemistry and processing of the next generation of protective fibers. This program is supported by newly installed facilities, and it will focus on the modification of existing polymers with additives designed to increase overall performance (nanocomposites) and gel spinning of polyethylene. These represent a reasonable start, but there are other areas of both chemistry (next-generation Kevlar, self-healing materials) and processing (nanofiber production, melt spinning precursors) that need to be assessed as potentially attractive research areas for ARL. The understanding and improvement of polymeric components in protective systems is core to the ARL mission. As with the new programs in biology, mentorship and interaction with area leaders is necessary to ensure that the program is state of the art and aimed at producing materials to satisfy current and future (2040) Army needs.

Overall, ARL is to be commended for initiating programs that link the biology of injury to the materials and constructs designed to protect the warfighter. It is difficult to move into new areas and quickly develop state-of-the-art programs—and to assume leadership. The programs reviewed generally demonstrated technical skill in the chosen areas but often were not state of the art, and they seemed out of touch with the relevant scientific communities. There is an obvious challenge in moving quickly from beginner to leader, but this also provides great opportunity to assess the relevant science and engineering and devise programs to leapfrog to the next level of understanding. The program in battlefield mechanisms, human response, and human protective equipment is conducted by a strong cadre of scientists, and a credible program is under way.

Summary of Accomplishments

Battlefield injuries are an important area of research for ARL, because a better understanding of the mechanisms of injury is vital to improving protective measures. This is especially true for protection of the head, where there is considerable uncertainty about allowable levels of shock, which greatly affects protective options. The research projects presented were appropriate to the problem, and the staff is competent. The projects are short to medium term, which is reasonable for the early stages of a new program. As would be expected in a new research area, there are challenges to be overcome.

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
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Challenges and Opportunities

Current projects are not the state of the art. Work at the cutting edge is difficult to maintain in a small program that does not have the option afforded to larger programs of pursuing multiple approaches simultaneously. Nevertheless, a greater effort could be made to assess the current research in the field and move closer to that cutting edge.

The program seems isolated both within ARL and from the larger outside scientific community. The burdens of being a small, new program in a new discipline within a large organization are many. There are fewer opportunities for constructive discussions and feedback, less chance for synergistic collaboration, and poorer awareness of current developments relevant to their own work. There are administrative burdens associated with procuring materials and supplies that are unfamiliar to the procurement branches of the laboratory. The cumulative effect of fighting through these issues will take a toll on the researchers’ time and is a distraction from the pressing needs of maintaining a competitive research program. Management could consider assigning a single administrative contact person, who would become familiar with the unusual needs of the program and, perhaps, act as an advocate for the program within the administrative channels. A long-term vision needs to be developed. The beginnings of this thinking were presented, but they are not yet sufficiently developed to be useful. Such a long-term vision could express a philosophy that helps guide resource allocation and program direction.

DIRECTED ENERGY

The ARL S&T campaign plans 2015-2035 and technical strategy documents1,2 categorize directed energy (DE) as a focused area under the much broader category of electronic warfare (EW), in accordance with the Army’s definitions. The ARL posture designations for both radio frequency (RF)-DE and laser-DE are collaborate rather than lead. The subsuming of DE under EW and a collaborate-only posture indicate that ARL has downgraded the priority of DE within its technology portfolio from its previous robust effort. The consequence of this status change was evident in the current programs presented: They appear to be a small collection of seemingly unrelated projects. In addition, the current program, with the exception of the project in solid-state laser sources for tactical applications, seems to be concluding soon. Noticeably absent from almost all presentations was any thought of how the operational needs that the current systems were designed to meet would be satisfied in the 2035 time frame highlighted by the ARL director.

In view of the currently fragmented DE program, ARL needs to take a strategic look at the DE area to determine its ongoing priority and refocus ARL’s effort with a view to the 2035 time frame. This strategic review needs to include consideration of future capabilities that the Army will need that DE might fill, and what DE capabilities might be fielded by our adversaries for which the Army will need countermeasures. A focused ARL DE program would benefit from a systems-level study addressing future Army missions in which DE could play a role and in which DE effectiveness and alternatives to DE are traded off. In this study, ARL could expand and diversify the laser program to seek avenues for integrating the technology with platforms of importance to the Army. Additional missions for DE could include illuminators; multispectral sensing, identification, tracking, targeting, and damage assessment; electronic protection/countermeasures for enhanced Army platform survivability against optical and IR guided weapons; and nonlethal weapons. Such a broadly based study is the necessary first step in planning a robust and relevant DE program to address the Army’s future requirements. ARL has a

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1 U.S. Army Research Laboratory, Army Research Laboratory S&T Campaign Plans 2015-2035, Adelphi, Md., September 2014.

2 U.S. Army Research Laboratory, Army Research Laboratory Technical Strategy 2015-2035, Adelphi, Md., April 2014.

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×

significant capability in solid-state laser development—an obvious focus area for the future. In most cases the six projects reviewed met or exceeded the evaluation criteria, which included the following: Does the technology maturation employ appropriate laboratory equipment and/or numerical models? Is the research team properly qualified? Do the facilities and laboratory equipment seem to be state of the art?3 Are the programs crafted to employ the appropriate mix of theory, computation, and experimentation? Specific concerns about individual projects related to these criteria are included in the following evaluations.

A highlight of the overall program in DE is the project on adaptive and scalable high-power, phase-locked fiber laser arrays. This work is a notable achievement, is recognized as such by the technical community, and appears to be ready for the next step, transition to the field.

The Department of Defense (DOD) recently articulated an electromagnetic (EM) maneuver warfare initiative. While ARL researchers did not reference this initiative, if all the services were to develop joint and independent programs as part of this effort, that could give ARL an opportunity to reexamine its role and strategic opportunities in EM maneuver warfare.

RF-Enabled Detection Location and IED Neutralization Evaluation

The scientific quality of RF-Enabled Detection Location and IED Neutralization Evaluation (REDLINE) research is comparable to that at leading federal, university, and industrial laboratories, both nationally and internationally. This is a first-class effort with full understanding of, and direct access to, operational needs and with a clear systems approach to reducing technical risks and delivering a successful experimental prototype.

The research program reflects a broad understanding of the underlying science and of research conducted elsewhere. The experimental confirmation of a complex propagation, detection, identification, and predetonation process is impressive.

This project is ready to begin the next step, deployment in the field. There is still an applied research effort needed to investigate detection, identification, and predetonation of increasingly advanced, emerging threats. The poster presenters mentioned the potential for mounting the capability on unmanned aerial vehicles. This seems to be a good idea, especially if ARL seeks to investigate the evolving improvised explosive device (IED) threat beyond the near term.

Hostile Fire Detection

In general, the scientific quality of the research is as good as that achieved at leading federal, university, and industrial laboratories, both nationally and internationally. The investigators used standard codes and modeling techniques. Although not strikingly novel, the work was credible and demonstrated useful integration of known techniques. The investigators also appeared to have access to intelligence about specific threats that may not be widely known.

The research program reflects a broad understanding of the underlying science and research conducted elsewhere. The researchers have addressed the major issues associated with detection and geolocation of threats such as rocket-propelled grenades and small arms. There was an appropriate level of modeling and predictive work to address near-term deployment but not longer-term strategic innovation. The prototype work that has been exercised in limited deployment responds to a near-term problem. Advanced (2035 horizon) modeling, diagnostic, sensor development, and test capabilities were not brought up.

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3 Note that the panel did not visit any laboratories during this year’s review, so the assessment of the state of the art of the equipment is based solely on the presentations and briefings.

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×

Operational data from full field deployments would drive next-generation innovation and improvement in identification and geolocation signature analysis for targeting support. This would produce results that could ultimately be transitioned to the field in a continuous upgrade process.

Adaptive Techniques for Advanced Radar Tracking and Optimization

The scientific quality of the research is basically sound in the context of unclassified university research, but it is not up to the standard of leading federal, university, and industrial laboratories working in this area. There appeared to be little or no awareness of existing, similar work in advanced radar development other than some unclassified university research. Reaching out to a major radar program, perhaps one of the Army’s programs, might have revealed similar, prior work and identified what is and is not already in existence.

As for appropriate laboratory equipment and numerical models, there appear to be adequate computing resources but no association with radar R&D facilities or laboratories to ensure a practical base of experiment and experience. It is also not clear whether the signal interference modeling is relevant to existing radar clutter, interference, or jamming environments. Such interference can depend on the design characteristics of the radar under consideration, so general approaches may not be directly relevant.

There could be projects that, with improved direction, access, and resources, produce results that can be transitioned ultimately to the field. Possible collaboration with the Navy’s extensive efforts in sonar tracking and optimization may be fruitful. The freshly conceived algorithms and use of greater computing power might provide useful insights to radar R&D facilities and developers. Some algorithms may be interesting for specific interference waveforms as spectral crowding increases.

Solid-State Lasers

The scientific quality of the research is comparable to that achieved by leading federal, university, and industrial laboratories. This research is aimed at identifying candidate materials, methodologies, and techniques for scaling solid-state lasers to mission-significant powers within the constraints of space, weight, and power (SWaP). Although many laboratories are doing similar work, ARL is concentrating its effort in eye-safer spectral regions that are of critical importance for the Army. The research program reflects a broad understanding of the underlying science and of research conducted elsewhere. ARL’s work is known and respected by laser scientists at other institutions.

Programs crafted to employ more modeling would provide an enhanced mix of theory, computation, and experimentation. Given the objective of this project, the researchers need the capability for simulating, even crudely, an entire system from wall plug to target. This is the only way an analysis of alternative materials and architectures can be performed. Such an analysis would permit more informed choices for R&D paths to follow.

Adaptive and Scalable High-Power, Phase-Locked Fiber Laser Arrays

This research program is devoted to developing high-power (tens of kilowatts) fiber lasers by coherently combining lower power systems. The researchers have successfully combined seven lasers, each of which can continuously produce as much as 1.5 kW. A novel method has been developed for coherently combining the multiple beams. This is the critical element of any high-power fiber system. Feedback from a diffractive element located at the output aperture provides an optical signal that serves to phase lock the laser array. Another strength of this method is the modest bandwidth requirement for the feedback system (only 15 kHz), which is very attractive from the perspective of developing a reliable

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×

weapons system. Coherently combining the individual laser beams occurs at approximately 10 m from the output aperture, which is well into the far field. Beam quality is also actively monitored in the far field so as to optimize the efficacy of the phase-locking process.

The impact of this ARL laser system appears to be significant. In follow-on work, the Defense Advanced Research Projects Agency and the Lincoln Laboratory of the Massachusetts Institute of Technology have scaled this system so as to combine as many as 21 lasers. Although it is not clear at this point whether the ARL system will ultimately be incorporated into a real weapons system, it is evident that the system architecture has influenced other work. Low-power versions of the ARL design are, for example, being developed for civilian use. Another impressive aspect of this program is that it has resulted in six patents.

The high-power fiber laser system is the result of a decade of work at ARL. This program demonstrates the value to DOD of investing in novel research over a prolonged time. A further accomplishment is the understanding of the physics of intense optical fields propagating in a fiber. One practical outcome of this understanding was the finding that fiber core diameters as large as 20 µm could be used while maintaining beam quality.

Nonlinear Propagation and Target Effects of Ultra-Short-Pulse Lasers

This basic research project examined nonlinear propagation in the atmosphere of an ultra-short-pulse (1 psec) laser beam in a self-generated, ionized channel. The researchers observed that the ionized channel through which the beam propagated was much more stable at a pulse repetition frequency (prf) near 1,000 Hz than at a frequency of 50 Hz. The causal physics was conjectured to be that the channel remained steady at the higher prf owing to the lack of thermal dissipation of energy of the nitrogen and oxygen plasma that formed the channel.

Also reported was that the beam, when incident on solid surfaces, created ripples in the surface of the material over the area covered by the beam. This phenomenon was previously reported by others for metals and semiconductors but was demonstrated for the first time on polymers by the ARL team.

The researcher showed a strong knowledge of the experimental laser techniques and knowledge of previous literature. It was not made clear, though, why the experimenter followed the path he did. The quality of the work appears to be high and the facilities used at ARL were adequate for investigating this phenomenon. It was not clear, however, if computational modeling was performed to substantiate the proposed model. The experimenter did not have a clear idea of where this work was headed and how the Army might benefit from it.

Summary of Accomplishments

The REDLINE team has developed a kill chain concept for the detection, geolocation, identification, and triggering of IEDs. Model predictions and prototype experiments verified the performance of the harmonics-based approach, and the program has advanced to early system prototype testing.

Investigators working in the hostile fire detection area have developed diagnostic, modeling, and prototype hardware capability of detecting and geolocating hostile fire for enhanced soldier survivability. The work addresses three major areas in disrupting the lethality chain: threat signature characterization and identification; analysis of intervening and interfering material; and sensor systems response.

Significant field testing has enabled the development of a large, well-understood archive of unique multispectral data that was used to construct databases for rapid threat identification. ARL’s work expands and improves the database of medium wavelength infrared (MWIR) and ultraviolet (UV) threat information. The analytical tools available to model EM propagation through both the atmosphere and various types of obscurants employed fundamental, well-understood concepts. The analytical tool for

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×

modeling intervening media and obscurants is a unique capability that was developed with academic collaborations and was empirically validated. The models have been integrated with various types of sensor payloads and packaged into the prototype hardware. The work has produced a patent on optical gunfire rocket and explosive flash detection that has been embedded in the electro-optical (EO)/IR sensor hardware. The investigators have taken the work from innovation to field prototype.

In the program developing adaptive techniques for advanced radar tracking and optimization, the concept involves a radar pre-look at the spectral signal environment prior to each dwell and uses algorithms to select quieter frequency gaps to form appropriate waveforms that minimize received interference while retaining required waveform resolution.

This experimental work on adaptive and scalable high-power phase-locked fiber laser arrays was outstanding; the experimenters clearly understood the issue and why it was being pursued, and they described well the problems that had to be overcome to produce the results of this beam combining experiment. Given the available laser power, the results were impressive and are headed in the right direction for producing a high-quality (M2 ~ 1) combined beam from 6 to 8 fiber lasers that are all phase-controlled using an innovative optical feedback technique. Effective use of laboratory equipment was demonstrated. Whether or not this work can combine a sufficient number of fiber lasers to produce a 100 kW class laser is not clear.

Challenges and Opportunities

Limited test results of the REDLINE team confirm theoretical predictions of range, detection, and identification. However, an ROC curve (probability of detection versus probability of false alarm) based on test results and model predictions is not yet complete. Similar test data are needed for the likelihood of killing an identified target. Such a comprehensive characterization is needed, especially in a cluttered urban environment, as part of the program to verify that the system is operationally viable. This information will be required if the range of the system, say, by utilizing an unmanned aerial vehicle, is to be considered.

Also, the REDLINE team indicated an upcoming transition to 6.3-6.4 development. However, there is still 6.2 R&D to be performed, including characterizing emerging trigger threats and other countermeasures and design modifications to accommodate those evolving threats. Because the IED threat is expected to continue, a critical need exists for a continuing research program to address the projected and potential advances of the threat in the coming decades.

No strategic plan was presented for further development and maturation of the models for hostile fire detection, for advanced sensor capabilities, or for continuing experimental evaluation of future threats. To be effective, contributors and researchers need to become involved with established radar S&T and R&D groups—for example, such groups within the Army—to gain feedback on the viability and value of the approach compared to earlier work. The qualifications of the research team in the area of adaptive techniques may not be up to the research challenge, given the team’s lack of access to operational radars and ongoing radar developments. There does not seem to be a core radar group within which this work is performed, so it is unclear why the work is under way in this particular research campaign. This may be a strategic question for ARL relative to the Army technical infrastructure. (The Naval Research Laboratory has had a robust radar research program for years.) The facilities and laboratory equipment may not be state of the art compared to the signal processing laboratories of advanced radar programs. Indeed, there appears to be no radar test site, data collection capabilities, or other laboratories associated with this work. The program is not crafted to employ the appropriate mix of theory, computation, and experimentation nor was there a connection to any existing or new radar and radar R&D facilities.

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
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ARMOR AND ADAPTIVE PROTECTION

ARL has a strong record of achievement in the basic and applied sciences and the engineering of penetration and protection. The ongoing work described in the review showed how ARL is building on this tradition of excellence to provide the knowledge basis for future Army needs. This is a core competency that underlies Army capabilities.

The presentation on penetration, armor, and adaptive protection provided an impressive overview of ongoing research aimed at meeting shorter- and longer-term issues. The shift of focus from the goal of addressing short-term Army needs to the goal of carrying out research that will maintain world leadership in this area for future Army needs was evident.

The depth of knowledge of the staff and the evidence of interaction between staff members were impressive. They were also aware of and knowledgeable about projects other than their own. It is important that ARL ensure a steady supply of new staff into this critical area and that newcomers can benefit from the experience of senior researchers.

There was significant evidence of teamwork and integration among the projects in, for example, adaptive protection. There were examples of linkage of experiments and computational modeling to provide physical insight into problems, to aid in new designs, and to explore new concepts. The combination of modeling and experiments is essential in many cases, but there are circumstances in which it is appropriate to focus on a single mode of inquiry: experiments carried out as discovery science; modeling to develop an understanding of scenarios that are impossible or prohibitively expensive to investigate experimentally; development of new modeling approaches and techniques that promise to enhance predictive capabilities of ballistic phenomena; and development of new experimental methods that promise to provide a better understanding of the physical mechanisms underlying ballistic phenomena. ARL described a ceramic armor concept that was made possible by a previously developed experimental technique aimed at enhancing a basic measurement capability.

The staff apparently have freedom to pursue new ideas that can lead to breakthroughs that might otherwise be found more slowly, if at all. An example was the armor concept, a serendipitous discovery developed nearly to completion before being fully funded.

Developing a predictive capability for damage and fracture in metals, ceramics, and polymers underlies the efficient development of new material systems for protection and for penetration. At present, there is no framework that has penetration capability. However, experimental, theoretical, and computational advances being worked on in other countries are making such a capability seem possible in the not-too-distant future. A systematic approach based on understanding the key physical processes is needed because of the wide range of material systems that are becoming available. There are so many possibilities that a trial error-and-correction approach would be too expensive. It is important that ARL develop a leadership capability in this area. That requires the ability to identify damage and failure mechanisms in material systems of interest, the theoretical expertise to model these failure mechanisms, and the computational ability to simulate armor concepts and designs for the range of conditions encountered in the field. It is unlikely that a detailed quantitative capability will be developed. A more realistic expectation is a predictive capability that ranks the response of proposed armor systems to various threats and provides scaling relations that can be confidently used to transfer laboratory-scale tests to field condition response. Success in this area requires hiring and developing a critical mass of staff and having the needed experimental and computational capabilities.

Modeling

As pointed out above, ARL uses both experiments and modeling to develop new armor concepts and designs. ARL’s use of modeling is maturing and is becoming better integrated into armor development and design. The researchers presented evidence that ARL was using numerical simulations to explore armor concepts more expediently than could be done through experiments. There were also

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×

examples of modeling being used to provide physical insight into experimentally observed phenomena, and there were examples of concepts and designs being examined that could not be tested experimentally with current capabilities.

Numerical simulation represents a key capability for ARL in the armor and adaptive protection area. ARL staff are customers for and collaborators with developers of advanced computational tools. Much of this activity involves codes developed at Department of Energy (DOE) National Nuclear Security Administration laboratories (Lawrence Livermore National Laboratory [LLNL] and Sandia National Laboratories [SNL]). These tools include ALE3D (LLNL), ALEGRA (SNL), and CTH (SNL). Some usage of multiphysics Sierra codes (SNL) was also reported. These are probably the appropriate tools for ARL’s problem set (impact, high rate, energetic materials, and electromagnetics), because they scale well on parallel platforms and are the most advanced tools available. There was some use of commercial codes (e.g., LS-DYNA) as well, which allows ARL to exploit developments in, for example, crashworthiness analysis as it relates to the automobile industry.

ARL’s relationship with the ALEGRA and CTH development teams at SNL has allowed it to drive the code development to address its own needs. ALEGRA is an arbitrary Lagrangian-Eulerian code with electromagnetics capabilities that is well-suited to a specific subset of ARL’s problems. ARL staff are trained in use of the code, and this seems to have improved the sophistication of the analyses conducted. ARL is a significant user of CTH (SNL Eulerian shock physics code) for armor and adaptive penetration applications; in fact it is perhaps the largest DOD user as measured by central processing unit hours. This is ARL’s workhorse code for impact problems. ALE3D is utilized for these problems as well. ARL staff members develop constitutive models to describe material behavior for all of these codes, which speaks to the level of sophistication of ARL modeling.

There was some evidence of the use of multiple codes to address different physics in a single problem. Use of the codes in this way will likely increase in the future, although coupling of codes is a challenging endeavor that will make the development of general frameworks for the coupling of codes increasingly useful.

ARL researchers indicated that their overall framework for multiscale modeling is also intended for armor and adaptive protection problems. The multiscale modeling work will likely become increasingly important for modeling complicated material behavior.

There was evidence that the researchers’ computational work was limited by the available classified computing capability. ARL indicated that a 100,000 (node or core) machine was available for unclassified work but only a 15k (node or core) machine existed for classified work. For 3D magnetohydrodynamic calculations with ALEGRA, thousands of cores are required for several days—a significant portion of the computing power available at ARL. ARL therefore does much work of this type in a 2D axisymmetric configuration. Although this is less computationally expensive and is useful for many problems, it limits ARL’s capability to explore oblique impact conditions and other scenarios that are not axisymmetric. Also, as ARL works to develop their its parametric studies and its verification, validation, and quantification of margins and uncertainties (V&V/QMU), many more simulations will be required, further straining the available computing power. ARL needs or will soon need more powerful classified computational platforms in order to accomplish its mission. A challenge in justifying more powerful classified machines is that ARL’s relatively small classified user community places high demands on the machines at some times and lower demands at others, potentially leaving significant portions of a large computing cluster idle. A potential solution to this is to utilize designs that allow sections of a large computing cluster to swing between unclassified and classified mode. In this manner, the allocation of resources can more effectively address the needs for the two types of computing resources.

Developing predictive models for damage and fracture for armor and adaptive protection applications is an important research direction, and in these circumstances the material response is not likely to be entirely deterministic. Therefore, the scientific and evidentiary value of this research effort will be greatly enhanced by adopting a ubiquitous statistical perspective. Understanding the nature of the assumptions and approximations underlying predicted or anticipated behavior and how these can be

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×

updated as data/knowledge is gained will improve ARL’s ability to develop technologies to adapt and survive in extreme and hostile environments. Furthermore, statistical scatter in experimental data could be an indication of subscale behavior with implications for modeling, so its impact on predictions needs to be explored through sensitivity studies and uncertainty quantification methods.

Experimental Aspects

ARL’s work in armor and adaptive protection is also supported by experimental work. ARL utilizes its in-house capabilities for ballistics testing, which appears to be fairly well developed. Nonetheless, ARL needs to develop a wish list for experimental capabilities as well as a timetable for obtaining them for future needs.

ARL is also utilizing unique national facilities such as the Dynamic Compression Sector at the Advanced Photon Source at Argonne National Laboratory and the proton radiography (pRad) capability at the Los Alamos National Laboratory (LANL). Utilizing advanced facilities in this manner will advance ARL’s science base and leverage these important national capabilities.

There were also instances in which ARL identified important technical developments and brought them to ARL. For example, it is developing a flash tomography capability and a capability to utilize photon Doppler velocimetry (PDV) in its work. It is important that ARL continue to find important technological developments and bring them to ARL when appropriate. In the case of PDV, ARL would benefit from engagement with the wider PDV community (e.g., the PDV workshop) and, if possible, seek out a short course that would train staff in the use of the PDV. ARL will also need to figure out how to exploit PDV effectively in its work.

The panel encourages continued development of the relationship with the additive manufacturing group at ARL and with experts around the country. Additive manufacturing has the potential to enable new armor concepts but could at the same time lead to new threats from adversaries.

There was significant discussion of the use of energetics to solve armor and adaptive protection problems, but there was little discussion of the science of energetics. The armor and adaptive protection group needs to engage more with the energetics group at ARL as well as with outside experts. For example, there are several concepts that rely on modification of explosive sensitivity that may be beyond current ARL capabilities. Technologies being developed in this area have the potential to enable significant advances in armor capabilities. Furthermore, state-of-the-art tools for modeling energetic materials are being developed elsewhere at ARL that may be applicable to armor and adaptive protection problems. The science of energetics in the context of armor and adaptive protection may be significantly different from that science in the context of warheads, so the ARL group working on armor and adaptive protection may benefit from a workshop on energetic materials for reactive armor. They might also encourage the Army Research Office to establish a Multidisciplinary University Research Initiative in this area.

Summary of Accomplishments

ARL has a strong record of achievement in the basic and applied sciences and the engineering of penetration and protection. Its presentation of experimental and modeling results and progress in penetration, armor, and adaptive protection provided an impressive summary of ongoing research aimed at meeting short- and longer-term mission needs.

There was significant evidence of teamwork and integration among the projects, in, for example, adaptive protection. Examples of the connection between experimentation and computational modeling that gave physical insight into problems were especially noteworthy, such work is likely to aid in developing new designs and exploring new concepts.

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×

The benchmarking of simulations with experiments and the emphasis on bringing advanced technology (particularly in the x ray region) to bear on diagnostics were impressive.

Challenges and Opportunities

One challenge for those working in applied classified areas of armor R&D is to figure out ways to interact with outside experts. Ways to do this include participating in appropriate forums (classified meetings, interlaboratory workshops, international exchanges); identifying canonical unclassified problems and cases that can serve as conduits for collaborations with universities and other outside experts; and conference participation, which is very important even for those who cannot present because their work is classified. Conference attendance by those working in classified areas helps them remain up-to-date in their fields.

Rigorous procedures for the validation of model-based predictions that are consistent with current state-of-the-art methods use experimental data and the propagation of uncertainty as well as the characterization of associated modeling errors. This requirement is exacerbated by the complex multiscale and multiphysics interactions relevant to many predictive efforts that are under way at ARL in the armor and adaptive protection areas.

As ARL works to develop its use of parametric studies and V&V/QMU, many more classified simulations will be required, further straining the available classified computing power. ARL needs to elucidate a strategic plan for more powerful classified computational platforms in order to accomplish its short-term and current mission needs and to support future mission needs and deliverables. It also needs to continue development of its relationships and projects examining the utilization of additive manufacturing (AM) to address current and future Army needs. There is an opportunity for the ARL additive manufacturing group to interact and collaborate with experts around the country at DOD facilities and federal agencies and in academia and industry. Additive manufacturing has the potential to enable new armor and protection as well as new weapon concepts; AM could also lead to new threats from adversaries, which means new challenges to our warfighters. There is a need as well for procedures to qualify and certify AM materials to meet Army needs. AM has become a realm where new ideas are being developed and where the future Army is being enabled, so that ARL must become involved in AM work, and ARL needs to develop a strategic plan in this area. ARL’s modeling programs must embrace the importance of variations, errors, and margins for establishing thresholds and statistics that support the development of predictive capability and design capability.

The presentations on damage and failure modeling demonstrated that modeling of damage evolution, fracture, and failure is a critical prerequisite for developing predictive and design capabilities in penetration mechanics. It is critical that ARL establish a focus in this area as soon as possible.

OVERALL QUALITY OF THE WORK

ARL’s research on lethality and protection ranges from basic research that improves its basic understanding of scientific phenomena to the generation of technology that supports (1) battlefield injury mechanisms, human response to threats, and human protective equipment; (2) directed energy programs; and (3) ballistics and blast programs that address weapon–target interactions and armor and adaptive protection developments.

Its research on battlefield injury mechanisms is important for ARL because a better understanding of these mechanisms is vital to improving protective equipment. This is especially true for protection of the head, where there is considerable uncertainty about allowable levels of shock, which greatly affects protective options. The most impressive accomplishment of the battlefield mechanisms–human response–human protective equipment program is that a highly competent cadre of scientists is at work and a credible program is under way. A long-term vision for the battlefield injury mechanisms projects could

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×

serve as philosophy that helps allocate resources and set program direction. Almost all the topics presented in this subsection—battlefield mechanisms, human response, and human protective equipment—had a combination of computational and experimental approaches. The real-time interplay of experiment and computation is needed.

ARL’s campaign plans categorize directed energy (DE) as a focused area under the much broader category of electronic warfare (EW), in accordance with the Army’s definitions. The ARL posture designations for both radio frequency-DE and laser-DE are to collaborate rather than lead. The subsuming of DE under EW and a collaborate-only posture indicate that ARL has downgraded the priority of DE within its technology portfolio from its previous robust effort. The consequence of this status change was evident in the current programs presented: They appear to be a small collection of seemingly unrelated projects. ARL needs to take a strategic look at the area of DE to determine its ongoing priority and focus the effort accordingly, with a view to the 2035 time frame; the strategic review needs to include consideration of future capabilities that the Army will need that DE might fill, and what DE capabilities might be fielded by our adversaries for which the Army will need countermeasures. A focused ARL DE program would benefit from a systems-level study addressing future Army missions in which DE could play a role and in which DE effectiveness and alternatives to DE are traded off. A highlight of the overall program in DE is the project on adaptive and scalable high-power-phase-locked fiber laser arrays. This work is a notable achievement, is recognized as such by the technical community, and appears to be ready for the next step in transition toward field deployment.

ARL has a strong record of achievement in the basic and applied sciences and engineering of penetration and protection. The research and development described in the armor and adaptive protection area showed how ARL is building on its tradition of excellence to provide the knowledge basis for current and future Army needs in protecting our warfighters. This remains a core competency that underlies Army capabilities across the entire DOD, and it needs to be preserved and nurtured. There was significant evidence of teamwork and integration among the projects in, for example, adaptive protection. Examples of the link of experiments and computational modeling to provide physical insight into problems were especially noteworthy, with potential to aid in developing new designs and exploring new concepts. Benchmarking simulations with experiments and the emphasis on bringing advanced technology (particularly in the x ray region) to bear on diagnostics were impressive. Developing a predictive capability for damage and fracture in metals, ceramics, and polymers underlies the efficient development of new material systems for protection and for developing approaches to needed penetration capabilities. At present, there is no framework that has this capability. However, experimental, theoretical, and computational advances being developed in other countries are making such a capability seem possible in the not-too-distant future. A systematic approach based on understanding the key physical processes is needed because of the wide range of material systems that are becoming available. Material modeling for these systems would beneficially include reliable modeling of the effects of temperature and pressure—two effects that are mostly underrepresented in much of the computational and experimental effort.

Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 32
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 33
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 34
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 35
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 36
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 37
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 38
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 39
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 40
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 41
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 42
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 43
Suggested Citation:"3 Sciences for Lethality and Protection." National Academies of Sciences, Engineering, and Medicine. 2016. 2015-2016 Assessment of the Army Research Laboratory: Interim Report. Washington, DC: The National Academies Press. doi: 10.17226/21916.
×
Page 44
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The National Academies of Sciences, Engineering, and Medicine's Army Research Laboratory Technical Assessment Board (ARLTAB) provides biennial assessments of the scientific and technical quality of the research, development, and analysis programs at the Army Research Laboratory (ARL), focusing on ballistics sciences, human sciences, information sciences, materials sciences, and mechanical sciences.

This interim report summarizes the findings of the Board for the first year of this biennial assessment; the current report addresses approximately half the portfolio for each campaign; the remainder will be assessed in 2016. During the first year the Board examined the following elements within the ARL's science and technology campaigns: biological and bioinspired materials, energy and power materials, and engineered photonics materials; battlefield injury mechanisms, directed energy, and armor and adaptive protection; sensing and effecting, and system intelligence and intelligent systems; advanced computing architectures, computing sciences, data-intensive sciences, and predictive simulation sciences; human-machine interaction, intelligence and control, and perception; humans in multiagent systems, real-world behavior, and toward human variability; and mission capability of systems. A second, final report will subsume the findings of this interim report and add the findings from the second year of the review.

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