Physical Sciences

Confocal Imaging System for Ultra-Fast, Three-Dimensional Transport Studies in Thermal Management Applications

The objective of this work was to develop a high-speed, three-dimensional (3D) confocal imaging system to study coupled fluidic and heat transport processes for high-performance thermal management applications. However, to successfully implement these approaches, fundamental understanding of interfacial dynamics and transport processes was necessary.

Posted in: Briefs, Physical Sciences, Imaging, Thermal management

Evaluating a Data Clustering Approach for Lifecycle Facility Control

Given the current emphasis on sustainability, there is a growing interest in monitoring various facets of building resource consumption. Building monitoring and automation systems most commonly exist as closed-loop systems for security, fire safety, water, electrical, and HVAC (Heating, Ventilation, and Air-Conditioning). One of the fundamental requirements of a mature engineering process model is the comparison of planned versus actual results for cost, risk, and quality control. For facility engineering, this implies that there must be a structured specification of building space requirements and a mechanism for detecting divergent system and occupant behaviors. Such a mechanism would have broad applicability for commissioning, energy efficiency, sustainability, diagnostics, maintenance, and a variety of other problems.

Posted in: Briefs, Physical Sciences, Sustainable development, Cost analysis, Risk management, Total life cycle management, Quality control

Portable Data Recorder for Measuring Sand Grain Fracture After Blasts

Abullet cannot penetrate through a sandbag while an arrow can, so understanding the behavior of granular materials such as sand and its energy absorption in a blast is critical in the design of armor. To this end, as part of the “Soil Blast Modeling and Simulations” project sponsored by the Office of Naval Research’s Multidisciplinary University Research Initiative (MURI), experiments were performed using a portable data recorder to determine the mechanical behavior of sand grains under confined compression.

Posted in: Briefs, Physical Sciences, Particulate matter (PM), Soils, Materials properties, Event data recorders, Military vehicles and equipment

Localization of Head-Mounted Vibrotactile Transducers

T he human sensory systems most frequently used in military displays (vision and audition) are sometimes overloaded. When soldiers rely on visual or auditory displays, their situation awareness can be degraded due to the need to attend to the display. A proposed alternative sensory channel for soldier displays is the tactile channel. In military applications, VT displays are primarily being used to aid in orientation, navigation, and communication. Tactile displays can also be used to impart more abstract information such as in command-and-control applications.

Posted in: Briefs, Physical Sciences, Displays, Vibration, Helmets, Military vehicles and equipment

High-Resolution, Measurement-Based, Phase-Resolved Prediction of Ocean Wavefields

Given remote and direct physical measurements of a realistic ocean wavefield, the goal of this work was to obtain a high-resolution description of the wavefield by integrating the measurements with phase-resolved wave prediction models including realistic environmental effects such as wind forcing and wave breaking dissipation. The measurements necessary for achieving this reconstruction were guided, and the validity, accuracy, and limitations of such wavefield reconstructions were addressed.

Posted in: Briefs, Physical Sciences, Measurements, Simulation and modeling, Water

Measuring Impact Damage to Toughened CFRP Laminates with Time Domain Reflectometry

Laminated Carbon Fiber Reinforced Polymer (CFRP) composites are very effective in weight saving in aeronautical structural components. For these laminated CFRP structures, it is difficult to detect damage such as delamination, matrix cracks, and local fiber breakages caused by low-velocity impact loading because these damages are difficult to detect from the outside of the structure. This difficulty of inspection of the laminated CFRP structures demands the development of automatic monitoring or damage detection systems.

Posted in: Briefs, Physical Sciences, Measurements, Composite materials, Lightweight materials

Testing Mechanical Properties of Polymer-Based Multi- Phase Particulate Composites

Polymer composites comprised of metallic particles distributed throughout a contiguous polymer matrix can often be modified to produce advanced composites that exhibit multifunctional characteristics. The properties of the particulate composites often depend on varying particle size, loading fractions, particle type, and the adhesion between the particulate and the matrix. Studies have shown that particle size, shape, and concentration, and properties of the constituents can affect mechanical properties. This work compared aluminum and nickel particles in PMMA thermoplastic prepared by injection molding, with the same particles in epoxy prepared in a cast-cure process.

Posted in: Briefs, Physical Sciences, Composite materials, Test procedures

Humanlike Articulated Robotic Headform for Respirator Fit Testing

The testing of individual respiratory protection (IRP) devices is now accomplished with panels of human wearers. Historical at tempts to simulate the human face and head have been unsuccessful for a variety of reasons that include imprecision in reproduction of facial dimensions and unrepresentative textures of the surfaces applied to headforms.

Posted in: Briefs, Physical Sciences, Human factors, Medical equipment and supplies, Robotics

Bi-Axial Vibration Energy Harvesting

For air platforms, the installation of Structural Health Monitoring (SHM) systems is complicated by the fact that the majority of SHM devices need to be fitted on internal aircraft structure, underneath the aircraft’s skin. If the SHM device is in a location that is difficult to access, then powering the device may be problematic because traditional powering methods are generally not feasible. For example, replacing batteries on many SHM devices deployed across a fleet would be impractical, and accessing an onboard power system to supply SHM devices may lead to flight worthiness and certification issues.

Posted in: Briefs, Physical Sciences, Aircraft structures, On-board energy sources, Vehicle health management, Vibration

Quantitative Analysis of a Hybrid Electric Humvee for Fuel Economy Improvement

The Army has acquired several hybrid platforms to assess the applicability of hybrid technology for military missions. These hybrid platforms include both series and parallel hybrid topologies. This work compares a conventional HMMWV (High Mobility Multi-purpose Wheeled Vehicle) M1113 with a series hybrid HMMWV XM1124 in terms of fuel economy improvements over three military drive cycles.

Posted in: Briefs, Physical Sciences, Architecture, Fuel economy, Hybrid electric vehicles, Military vehicles and equipment