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The MX-2 neutral buoyancy space suit analogue has been designed and developed at the University of Maryland to facilitate analysis of space suit components and assessment of the benefits of advanced space suit technologies, The MX-2 replicates the salient features of microgravity pressure suits, including the induced joint torques, visual, auditory and thermal environments, and microgravity through the use of neutral buoyancy simulation. In this paper, design upgrades and recent operations of the suit are outlined, including many experiments and tests of advanced space suit technologies, This paper focuses on the work done using the MX-2 to implement and investigate various advanced controls and displays within the suit, to enhance crewmember situational awareness and effectiveness, and enable human-robotic interaction.

The introduction of carbon fiber reinforced polymer (CFRP) composites to structural components in lightweight automotive structures necessitates an assessment to evaluate that their crashworthiness dynamic response provides similar or higher levels of safety compared to conventional metallic structures. In order to develop, integrate and implement predictive computational models for CFRP composites that link the materials design, molding process and final performance requirements to enable optimal design and manufacturing vehicle systems for this study, the dynamic mechanical response of unidirectional (UD) and 2x2 twill weave CRFP composites was characterized at deformation rates applicable to crashworthiness performance. Non-standardized specimen geometries were tested on a standard uniaxial frame and an intermediate-to-high speed dynamic testing frame, equipped with high speed cameras for 3D digital image correlation (DIC).

A completely nondestructive means of r-value measurement is being developed. Unlike the modul-r method, it requires no specimen removal and has potential for on-line measure-ment. The method employs noncontacting ultrasonic transducers which generate waves propagating at three different angles relative to the sheet rolling direction. A prototype instrument based on these principles has been jointly developed by researchers at Ford Motor Company and National Institute of Standards and Technology (NIST). At present, there are correlations between ultrasonic and mechanical measurements of r̄. The ultrasonic measurements generally agree with mechanical measurements to 0.1 or better. A method based on metallurgical theories is being developed to use ultrasonic velocity measure-ments to predict not only r̄, but individual r values. To date, all measurements have been made on static sheet. We are currently developing a device to move sheet metal at controlled velocity.

The Pride of Maryland is a single seat solar powered trans-continental race car designed and built by engineering students at the University of Maryland. The car competed in G.M. Sunrayce USA, placing third, and has gone on to compete in the World Solar Challenge. This paper outlines the three general areas of design and development for the solar vehicle: aerodynamic, electrical, and mechanical. An exercise in high efficiency, the Pride of Maryland has been extremely successful as both a race car and as an educational tool for training student engineers in “real world” problems.

Smoke detection experiments were conducted in the Microgravity Science Glovebox (MSG) on the International Space Station (ISS) during Expedition 15 in an experiment entitled Smoke Aerosol Measurement Experiment (SAME). The preliminary results from these experiments are presented. In order to simulate detection of a prefire overheated-material event, samples of five different materials were heated to temperatures below the ignition point. The smoke generation conditions were controlled to provide repeatable sample surface temperatures and air flow conditions. The smoke properties were measured using particulate aerosol diagnostics that measure different moments of the size distribution. These statistics were combined to determine the count mean diameter which can be used to describe the overall smoke distribution.

Computational fluid dynamic (CFD) simulations that include realistic combustion/emissions chemistry hold the promise of significantly shortening the development time for advanced high-efficiency, low-emission engines. However, significant challenges must be overcome to realize this potential. This paper discusses these challenges in the context of diesel combustion and outlines a technical program based on the use of surrogate fuels that sufficiently emulate the chemical complexity inherent in conventional diesel fuel.

The development of surrogate mixtures that represent gasoline combustion behavior is reviewed. Combustion chemistry behavioral targets that a surrogate should accurately reproduce, particularly for emulating homogeneous charge compression ignition (HCCI) operation, are carefully identified. Both short and long term research needs to support development of more robust surrogate fuel compositions are described. Candidate component species are identified and the status of present chemical kinetic models for these components and their interactions are discussed. Recommendations are made for the initial components to be included in gasoline surrogates for near term development. Components that can be added to refine predictions and to include additional behavioral targets are identified as well. Thermodynamic, thermochemical and transport properties that require further investigation are discussed.

This study examines the types of hydrogen leaks that can support combustion and the effects on stainless steel of long term hydrogen flame exposure. Experimental and analytical work is presented. Hydrogen diffusion flames on round burners were observed. Measurements included limits of quenching, blowoff, and piloted ignition for burners with diameters of 0.36 - 1.78 mm. Results are compared to measurements for methane and propane. A dimensionless crack parameter was identified to correlate the quenching limit measurements. Flow rates were 0.019 - 40 mg/s for hydrogen, 0.12 - 64 mg/s for methane, and 0.03 - 220 mg/s for propane. Hydrogen flames were found to be corrosive to 316 stainless steel tubing.

A serpentine flow channel is one of the most common and practical channel layouts for a PEM fuel cell since it ensures the removal of water produced in a cell. While the reactant flows along the flow channel, it can also leak or cross to neighboring channels via the porous gas diffusion layer due to a high pressure gradient. Such a cross flow leads to effective water removal in a gas diffusion layer thus enlarging the active area for reaction although this cross flow has largely been ignored in previous studies. In this study, neutron radiography is applied to investigate the liquid water accumulation and its effect on the performance of a PEM fuel cell. Liquid water tends to accumulate in the gas diffusion layer adjacent to the flow channel area while the liquid water formed in the gas diffusion layer next to the channel land area seems to be effectively removed by the cross leakage flow between the adjacent flow channels.

The calibration of yield functions for numerical sheet forming simulations is done using different experimental approaches such as the uniaxial tensile test, the bulge test, etc. How accurately the material behavior of dedicated aluminum, conventional and high strengths steel grades subjected to various loading conditions can be modeled is investigated using e.g. uniaxial tensile test data only. Different formulations of yield functions that are widely used in industry (e.g. Hill'48, Hosford'79, Hill'90) are considered. It is shown that tensile test data is insufficient to successfully calibrate yield functions for numerical sheet forming simulations especially for aluminum and pronounced anisotropic steel. The use of improved formulations of yield functions is emphasized.

The need for improvement of EVA gloves has been identified by NASA and the user community. Particularly important, especially for near to long term goals in the space program, is the need to reduce the fatigue associated with manual tasks. The University of Maryland Space Systems Laboratory (SSL), together with ILC Dover are currently developing an unobtrusive, power-assisted EVA glove that will attempt to provide a suited crewperson with as close to nude-body hand dexterity as possible. The power-assisted joint is designed to provide sufficient force to offset the resistance of the pressurized glove itself, thus alleviating manual fatigue, but provides no additional strength augmentation. This paper describes the initial prototype power-assist mechanism which has been developed, reviewing the relevant design issues and discussing the initial test results from the prototype.

Task-based intensity and fatigue metrics were developed and applied to neutral buoyancy simulations of extravehicular activities (EVA). Surface electromyographic (EMG) signals from hand flexor and extensor musculature were recorded during neutral buoyancy EVA simulations at Marshall Space Flgiht Center (MSFC) in August-September 1996. A task intensity index, based on the cumulative histogram of EMG amplitude, was developed and used to determine relative physical difficulty of handgripping, knob turning, bolt manipulation, and j-hook release tasks. A fatigue index, based on the task intensity metric and task duration, was used to provide a measure of task-related fatigue.

Near to long term goals in the nation's space program would benefit from a significant reduction of the fatigue associated with manual tasks performed by suited astronauts, and the corresponding increase in the comfort, safety, and productivity of EVA operations this would enable. To this end, the University of Maryland Space Systems Laboratory and ILC Dover Inc. have developed an electromechanical, power-assisted EVA glove which has demonstrated the ability to substantially reduce manual fatigue while simultaneously increasing range of motion. The lessons learned from the construction and testing of this initial prototype have been used to guide a second generation design for this power-assist concept, which achieves comparable or superior performance with significantly less hardware and power consumption. This paper describes the new, second generation power-assist mechanism, reviewing the relevant design issues and comparing its performance with the initial design.

This paper presents results from a smoke detection experiment entitled Smoke Aerosol Measurement Experiment (SAME) which was conducted in the Microgravity Science Glovebox on the International Space Station (ISS) during Expedition 15. Five different materials representative of those found in spacecraft were pyrolyzed at temperatures below the ignition point with conditions controlled to provide repeatable sample surface temperatures and air flow conditions. The sample materials were Teflon®, Kapton®, cellulose, silicone rubber and dibutylphthalate. The transport time from the smoke source to the detector was simulated by holding the smoke in an aging chamber for times ranging from 10 to1800 seconds. Smoke particle samples were collected on Transmission Electron Microscope (TEM) grids for post-flight analysis.

The complex strain states that exist within a real metal stamping are likely to generate different surface morphologies when compared to the same level of plastic strain produced via single pass deformation. This study quantifies the surface morphology that develops when an as-received traditional plain carbon steel sheet is deformed under two different single-pass, in-plane stretching operations. Roughness measurements performed in the as-received condition with a high resolution scanning laser confocal microscope revealed that an initial surface roughness did not appear to influence the deformation generated with biaxial strain. However, the initial surface roughness could have affected the deformation generated with uniaxial strain. The roughness data were fitted to a probability density function (PDF) and resulted in a near-ideal Gaussian distribution of the surface profile heights.

The University of Maryland team converted a model year 2000 Chevrolet Suburban to an ethanol-fueled hybrid-electric vehicle (HEV) and tied for first place overall in the 2000 FutureTruck competition. Competition goals include a two-thirds reduction of greenhouse gas (GHG) emissions, a reduction of exhaust emissions to meet California ultra-low emissions vehicle (ULEV) Tier II standards, and an increase in fuel economy. These goals must be met without compromising the performance, amenities, safety, or ease of manufacture of the stock Suburban. The University of Maryland FutureTruck, Proteus, addresses the competition goals with a powertrain consisting of a General Motors 3.8-L V6 engine, a 75-kW (100 hp) SatCon electric motor, and a 336-V battery pack. Additionally, Proteus incorporates several emissions-reducing and energy-saving modifications; an advanced control strategy that is implemented through use of an on-board computer and an innovative hybrid-electric drive train.

The potential for thermoelectric power generation via waste heat recovery onboard automobiles to displace alternators and/or provide additional charging to a hybrid vehicle battery pack has increased with recent advances in thermoelectric materials processing. A preliminary design/modeling study was performed to optimize waste heat recovery for power generation using a modified radiator incorporating thermoelectric modules. The optimization incorporates not only thermoelectric performance but also critical systems issues such as accessory power consumption, vehicle drag, and added system weight. Results indicate the effectiveness of the thermoelectric module is extremely sensitive to ambient heat rejection and to the operating temperature range of the thermoelectric device.

How a system ages is central to the assessment of the effective utilization life of the system. Utilization life represents more than estimating the remaining life in an aged system, it is determining how to optimally plan a system's future management and future use to minimize the life cycle cost incurred. The consideration of utilization life of a system includes the physics of aging, damage accumulation techniques, mitigation of aging, qualified use of aged parts for spare replenishment, prognostics, and quantification of cost avoidance. Any approach to evaluating utilization life depends on a making an effective evaluation of the reliability, durability and safety of the system. Traditional Mean Time Between Failure (MTBF) metrics that assume a constant failure rate are likely to be less useful in the evaluation and practical implementation of utilization life concepts than Failure Free Operating Period (FFOP).

The University of Maryland FutureTruck Team has redesigned a 2002 Ford Explorer to function as a charge-sustaining parallel hybrid electric vehicle for the 2002-2003 FutureTruck competition. Dubbed the Excite, it is powered by a dedicated E85 3.0L V6 engine coupled to a 21.6 kW peak (10kW continuous), electric motor using a 144V NiMH battery pack. The philosophy behind the UMD plan is to use a smaller, lightweight, dedicated E85 engine in parallel with an electric motor to provide starting and mild assist capabilities. The engine provides similar power to the stock 4.0 L Explorer engine and the electric motor functions as a starter, an alternator, and assists the engine during high power demands. The combination of the two systems provides the Excite with engine-off-at-idle capability, increased efficiency and fuel economy, and decreased emissions while maintaining the utility of a stock SUV.

Prediction of springback has become a major focus in sheet metal forming. Validation of finite element codes that are being developed to predict springback require accurate property data and a more complete understanding of the residual stresses that are involved. To provide experimental data for these calculations, neutron and synchrotron X-ray diffraction measurements were carried out to determine the through-thickness distribution of axial and hoop (or tangential) residual stresses in deep-drawn steel and aluminum cups. The techniques are able to provide true spatial resolutions as low as 0.05 mm for a strain measurement on cups with ≤ 1 mm wall thickness. It was found that the stresses exhibit non-linear gradients through the thickness that also depend on the axial position.