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Weapons and Materials Research Directorate Research Areas

Weapons Systems and Battlefield Simulation

Projectile, Missile, and Weapons Systems: Aeroballistics, Launch and Flight Dynamics, Propulsion, and Gas Dynamics

Advisor: P Plostins

Key words: missile and rocket launching, aerodynamics, missiles and rockets, aerodynamic drag

Research opportunities range from studies on the aeroballistics of projectiles, rockets, and missiles for major weapons systems to guidance navigation and control technology. We are interested in:

  • the effects of fluid mechanics, gas dynamics, and real gas dynamic effects on the integrity, stability, drag, and flight dynamics of vehicles.
  • velocity ranges from subsonic to hypersonic, with emphasis placed on high Reynolds number, low-altitude flight regimes.
  • multiple body flight dynamics, multiple body separation, and aerodynamic interaction.
  • data analysis and reduction techniques for estimating complex structural and aerodynamic interactions from flight data, as well as new techniques in obtaining accurate flight data.
  • electronics, telemetry and sensor system technologies for gun launched munitions.
  • novel cost effective guidance navigation and control technology for highly spun munitions.
  • multidisciplinary empirical, analytical, experimental, and computational techniques for predicting, analyzing, and designing all aspects of complex projectile weapons systems launch and flight dynamics.

Experimental free flight range facilities are available that can obtain sea level flight dynamics data for projectiles from 1 millimeter to 210 millimeters in diameter over trajectories spanning 1 meter to 1000 meters and a wide variety of velocities. Extensive supercomputing resources and work stations are available for computational fluid dynamics and visualization.

Electromagnetic Effects in Ballistic Research

Advisor: CR Hummer

Key words: electrodynamics, plasma processes (physics), electromagnetic propulsion, ballistics

By various mechanisms, electromagnetic armor and railguns generate plasmas of dense metal vapors at high temperatures that have substantial electrical conductivity.  These plasmas may divert the current from its intended path in these devices and degrade their performance.  The opportunity of this effort is to conduct studies of the electrical conductivity of these dense metal plasmas generated by using pulsed power technology.

Areas of investigation include:

  • imaging and diagnostics on nanosecond time scales.
  • pulsed power technology.
  • theoretical study of these plasmas.
  • application of these results to electromagnetic armor and railguns. 

High-speed computers, pulsed power supplies, streak cameras, and a wide range of other capabilities are available at the laboratory.  Interested applicants are encouraged to propose any research within the above guidelines.

Impact Damage Characterization of Composite and Transparent Materials

Advisor: JM Sands

Key words: transparent armor, transparent ceramic, debris impact, high velocity impact, damage assessment

A key interest for soldier equipment is the ability to sustain low velocity impacts resulting from tossed debris from persons of interest or from vehicles in convoy.  The current research focus involves characterization of energy absorption characteristics in laminated transparent and composite systems.  The laminated transparencies consist of glass, polymeric and ceramic materials, while composite systems are composed of S2-glass, e-glass, aramid, and carbon-fibers. 

Anecdotal evidence implies that soft materials, such as polymers, or ultra-hard materials, like ceramics, mitigate damage propagation or retard damage initiation from low velocity impacts.  The proposed research area will involve characterization of damage in polymer, glass, ceramic and laminated composite materials impacted with simulated projectiles. 

The use of high-speed video capability will be applied to capture on-set of damage in the impact zone, while Doppler radar will be used to look at energy transfer into the structure on impact.  Engineering will be applied to design structures that minimize damage size, damage initiation, and damage propagation in the structures.

Damage Control in Multi-Material Layered Structures Under Impulse Loadings

Advisor: KA Iyer

Soldier and vehicle protection technologies are assembled with ceramic, glass and composite laminates, in addition to traditional and advanced metallic plates. Alongside increasing structural/material complexity in advanced armor systems, modern threats interrogate the strength (failure mechanisms) of these materials. Consequently, the strength-augmented hydrodynamic approach — established for very high-rate fluid-like interactions in which the solid mechanical response is of second-order consequence — is no longer sufficient for developing design principles for ballistic performance of new systems. Although direct computation of ballistic performance with solids is possible with recent advances such as particle methods, system calculations are often prohibitive and still only useful when accompanied by numerous experience-based engineering decisions and interpretations.

RESEARCH:  An objective theory-based design methodology for multi-material, multi-layered ballistic protective systems is required. As a first step towards a broad methodology, we wish to investigate formulations and solutions for optimizing the stacking sequence of a multi-material layered structure in which each layer will undergo strength-dependent damage/failure when subjected to high-rate loading scenarios. Problem formulation will include development of approximate models for impactor-armor interaction and failure for a variety of material classes. The formulation will be used to:

  • obtain analysis-based paradigms for design.
  • quantitatively define tradeoffs between different ballistic performance metrics (e.g. failure modes).

This work will be collaborative with ongoing computational and experimental efforts to outline dynamic damage evolution in materials of interest to the Army.

Multiscale Material Modeling and Simulation

Advisor: JK Brennan

Key words: molecular simulation, mesoscale simulation, multiscale modeling, Monte Carlo, molecular dynamics, coarse grain modeling, energetic materials, polymers, dissipative particle dynamics, free-energy calculations, phase transitions

Research opportunities exist in multiscale modeling and simulation which span from quantum mechanical calculations, to molecular and mesoscale techniques.  The development of novel methods and models and the refinement of existing approaches and forcefields are key components of our research.  While most research is performed using in-house codes, we have nearly unlimited accessibility to commercially-available codes.

We use modeling and simulation to characterize the thermodynamic, transport and mechanical properties of a wide range of materials, including; energetic materials, reactive materials, polymers, gels, materials under extreme conditions, and fluids adsorbed in porous materials and biomembranes.  We model the chemical and physical processes of shock and detonation, polymerization, gelation, and shear.  We use free-energy calculations to predict phase behavior including, solid-liquid and solid-solid coexistence.

Research is performed in close collaboration with other teams within ARL and DoD laboratories as well as the DoE laboratories, the Czech Academy of Sciences, North Carolina State University, Pennsylvania State University, and the University of Alabama.  We encourage multidisciplinary work with other researchers in particular with experimental groups.  We encourage publication in the open literature and presentations at professional meetings.  The vast array of computing resources and laboratory facilities are outstanding and well-equipped. 

References
Lisal M, Brennan JK, Smith WR: Journal of Chemical Physics 125: 164905, 2006
Brennan JK, Rice BM, Lisal M: Journal of Physical Chemistry C 111: 365, 2007

 

Materials Technologies for Transparent Military Applications

Advisor: JM Sands

Key words: transparent, ceramic, glass, characterization, armor, composite, polymer, NDE

Certain transparent materials can provide effective means of ballistic, thermal and mechanical protection in equipment that requires transmission of light and other electomagnetic radiation.  Examples include face-shields, goggles, vehicle vision, blocks, windshields and windows, radomes, blast shields, and rotorcraft canopies. 

The Transparent Materials Team at the U.S. Army Research Laboratory is engaged in efforts to develop advanced transparent systems for all military platforms.  ARL scientist and engineers investigate advanced cutting edge materials based on next generation ceramics, novel polymer formulations, engineered adhesive interfaces, and cutting edge glass formulations. Additionally, effects of additives, such as nano-materials, into current systems are investigated for potential property enhancements. 

Characterization of new materials continues to allow the Transparent Team to lead the word in ballistic design and protection schemes for transparent armor technologies. The current openings include opportunities to leverage existing ARL capabilities in advanced fabrication and characterization for transparent materials.  Multiple positions exist whereby an expert in non-destructive characterization methods, including x-ray computed tomography, phased array ultrasonics, and stress field mapping is desired.  Experiences with high-speed videography is also of value.  Persons with synthesis capabilities in ceramics, polymers, and glass are also welcomed.

Modeling and Simulation of the Mechanics of Heterogeneous Materials

Advisor: JD Clayton

Key words: continuum mechanics, nanoscale, fracture, multiscale modeling, plasticity, polycrystal, mesoscale, elasticity, finite elements

Scientifically innovative research on modeling of the mechanical behavior of heterogeneous polycrystalline materials is solicited.  Specific materials of interest include, but are not limited to, one or more of the following: polycrystalline metals, ceramics, energetic materials, geological materials, or urban structural materials (e.g. concrete). 

The behavior of such materials at small length scales, spanning from nanometers to millimeters (e.g., 'mesoscale'), and at high strain rates, is of primary concern. This research program seeks to advance the state-of-the-art in continuum physics, mathematical modeling, numerical methods, and scientific computing.

Specifically, theoretical constitutive model development and numerical implementation in solid mechanics or multi-physics simulation codes of one or more of the following phenomena are sought: large deformations, non-linear elasticity, plasticity, defects, fracture, and fragmentation. Models capturing non-local effects and/or multiscale aspects are also of interest.   

Continuum mechanics models are deemed of primary importance. However, multiscale techniques involving atomistic calculations, discrete defects, or phase field theories, for example, indicating aspects of material behavior at increasingly fine length scales, are also relevant. The Research Associate will have access to exceptional computing resources at the U.S. Army Research Laboratory. These include: parallel supercomputers featuring thousands of processors; numerous commercial software for materials modeling (finite element, mult-physics,  molecular mechanics, and scientific visualization); 'in-house' research codes for advanced non-linear materials modeling; and newly available 3-D microstructural rendering software.

Guarded Mobility and Other Forms of Human-Robot Interaction

Advisor: K. McDowell

Key word: engineering

Developments in the autonomous control of manned ground vehicles are providing a unique capability to construct systems that can provide safe, rapid mobility through an environment and also potentially reduce operator workload. However, the performance of algorithms that perceive the local environment on the timescale required for high-speed mobility is unlikely to match human performance in the foreseeable future.

This effort seeks to synergize the strengths of autonomous mobility with the strengths of human perception to create nearly autonomous mobility systems that outperform the human operators of today. Unique perspectives on human-robotic interaction (e.g., safeguarded teleoperations, supervisory, cooperative, traded, or shared control, sliding autonomy) that arise from a fundamental understanding of the human operator are highly encouraged.

Specific topics involving the use of computational modeling, neuroscience, behavioral, and/or multidisciplinary approaches to understand the effective acquisition, processing, and integration of information for human-in-the-loop control include:

  • understanding the perception of intent leading to the prediction of future motion and actions within the environment
  • fusing temporally and spatially mismatched local environmental information from multiple sensors and algorithms
  • identifying and validating human-centric approaches to integrating risk-limiting control constraints from autonomous mobility control into semi-manual vehicle control
  • addressing cognitive issues with autonomous mobility operation of manned vehicles.

The Real-time Assessment of Humans in Operational Environments

Advisor: K. McDowell

Key word: engineering

Current technologies have begun to enable the development of human monitoring systems that can be used in real world environments. For example, both wearable, wireless EEG systems and eye- and head-tracking systems have been designed to acquire recordings during the performance of dynamic tasks in environments that have traditionally been considered too noisy to allow valid and robust measurement.

However, as such monitoring systems are used in increasingly complex and dynamic environments, issues arise with applying laboratory-derived measures for human assessment. This effort seeks to develop real-time human assessment systems that integrate state-of-the-art eye-and head-tracking, EEG recording and analysis systems, physiological monitors, task performance indicators, adaptive displays or combinations of the above.

Specific issues to be addressed include:

  • What are the limits to the ability of emerging and future technologies to overcome the inherent problems of measurement in dynamic task environments?
  • What metric(s) can be derived that adequately assess human operators?
  • Which technology, or combination of technologies, can be integrated into to maximize system performance and usability?

The capability goal of recording quality neuroimaging, behavioral, and performance data in ecologically valid environments is to advance our understanding of the cognitive and sensorimotor processes of humans engaged in realistic tasks, and in turn, contribute to technological advances in equipment design.