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Because niobium-clad 304L stainless steel sheets are considered for use as bipolar plates in polymer electrolyte membrane (PEM) fuel cells, their mechanical behavior and failure mechanism are important to be examined. As-rolled and annealed specimens were tested in tension, bending and flattening. The effects of annealing temperature and time on the mechanical behavior and failure mechanism were investigated. Micrographic analyses of bent and flattened specimens showed that the as-rolled specimens have limited ductility and that the annealed specimens can develop an intermetallic layer of thickness of a few microns. The annealed specimens failed due to the breakage of intermetallic layer causing localized necking and the subsequent failure of Nb layer. The springback angles of the as-rolled and annealed specimens were also obtained from guided-bend tests.

Diesel injection parameters effect on liquid-phase diesel spray penetration after the end-of-injection (EOI) is investigated in a constant-volume chamber over a range of ambient and injector conditions typical of a diesel engine. Our past work showed that the maximum liquid penetration length of a diesel spray may recede towards the injector after EOI at some conditions. Analysis employing a transient jet entrainment model showed that increased fuel-ambient mixing occurs during the fuel-injection-rate ramp-down as increased ambient-entrainment rates progress downstream (i.e. the entrainment wave), permitting complete fuel vaporization at distances closer to the injector than the quasi-steady liquid length. To clarify the liquid-length recession process, in this study we report Mie-scatter imaging results near EOI over a range of injection pressure, nozzle size, fuel type, and rate-of-injection shape. We then use a transient jet entrainment model for detailed analysis.

The local equivalence ratio, Φ, was measured in fuel jets using laser-induced spontaneous Raman scattering in an optical heavy duty diesel engine. The measurements were performed at 1200 rpm and quarter load (6 bar IMEP). The objective was to study factors influencing soot formation, such as gas entrainment and lift-off position, and to find correlations with engine-out particulate matter (PM) levels. The effects of nozzle hole size, injection pressure, inlet oxygen concentration, and ambient density at TDC were studied. The position of the lift–off region was determined from OH chemiluminescence images of the flame. The liquid penetration length was measured with Mie scattering to ensure that the Raman measurement was performed in the gaseous part of the spray. The local Φ value was successfully measured inside a fuel jet. A surprisingly low correlation coefficient between engine-out PM and the local Φ in the reaction zone were observed.

Quantitative planar laser-induced fluorescence (PLIF) of gaseous acetone as a fuel-tracer has been used in an optically accessible engine, fueled by direct hydrogen injection. The purpose of this article is to assess the accuracy and precision of the measurement and the associated data reduction procedures. A detailed description of the acetone seeding system is given as well. The key features of the experiment are a high-pressure bubbler saturating the hydrogen fuel with acetone vapor, direct injection into an optical engine, excitation of acetone fluorescence with an Nd:YAG laser at 266 nm, and detection of the resulting fluorescence by an unintensified camera. Key steps in the quantification of the single-shot imaging data are an in-situ calibration and a correction for the effect of local temperature on the fluorescence measurement.

A laboratory study was performed to optimize a zoned configuration of an iron (Fe) SCR catalyst and a copper (Cu) SCR catalyst in order to provide high NOx conversion at lean A/F ratios over a broad range of temperature for diesel and lean-burn gasoline applications. With an optimized space velocity of 8,300 hr-1, a 67% (by volume) Fe section followed by a 33% Cu section provided at least 80% NOx conversion from approximately 230°C to 640°C when evaluated with 500 ppm NO and NH3. To improve the lean lightoff performance of the SCR catalyst system during a cold start, a Cu SCR catalyst that was 1/4 as long as the rear Cu SCR catalyst was placed in front of the Fe SCR catalyst. When evaluated with an excess of NH3 (NH3/NO ratio of 2.2), the Cu+Fe+Cu SCR system had significantly improved lightoff performance relative to the Fe+Cu SCR system, although the front Cu SCR catalyst did decrease the NOx conversion at temperatures above 475°C by oxidizing some of the NH3 to N2 or NO.

A laboratory study was performed to assess the effects of SO2 poisoning on the NOx conversion of iron (Fe) and copper (Cu) SCR catalysts. Thermally aged samples of the catalysts were poisoned with SO2 under lean conditions. At various times during the poisonings, the samples were evaluated for NOx conversion with NO and NH3 using lean temperature ramps. The low temperature NOx conversions of both catalysts decreased by 10 to 20% after 1 to 4 hours of poisoning but were stable with continued exposure to the SO2. The poisoned Cu SCR catalyst could be desulfated repeatedly with 5 minutes of lean operation at 600°C. Initially, the poisoned Fe SCR catalyst required 5 minutes of lean operation at 750°C to recover its maximum NOx conversion.

The Soft X-Ray Telescope (SXT) is an instrument on the International X-Ray Observatory (IXO). Its flight mirror assembly (FMA) has a single mirror configuration that includes a 3.3 m diameter and 0.93 m tall mirror assembly. It consists of 24 outer modules, 24 middle modules and 12 inner modules. Each module includes more than 200 mirror segments. There are a total of nearly 14, 000 mirror segments. The operating temperature requirement of the SXT FMA is 20°C. The spatial temperature gradient requirement between the FMA modules is ±1°C or smaller. The spatial temperature gradient requirement within a module is ±0.5°C. This paper presents thermal design considerations to meet these stringent thermal requirements.

Many engineers have been working to reduce brake noise in many ways for a long time. So far, a progress has been made in preventing and predicting brake noise. Nevertheless, there are some discrepancies of brake noise generation propensity between testing for the prototype and the production. As known in general, the reason for this unpredicted brake noise occurrence in production is partly due to the variation of the resonant frequency, material and the other unpredictable or unmanageable variations of the components in a brake system. In this paper, effects of chemical components and casting process of gray iron brake disc on its resonant frequency variation have been studied. Especially this paper is focused on the variation in material aspects and manufacturing parameters during disc casting in usual production condition. And their effects are investigated by the variation of out-of-plane modal resonant frequency.

The paper explains the compact fixturing based on magneto-rheological (MR) fluids that have been designed and validated for aeronautic stringers milling. The MR fluid based tooling developed is flexible and reconfigurable as it can be adapted to different profile's lengths and sections and it is able to fix compliant workpieces without reference faces as the MR fluid adapts to the outer shape of each profile. The MR fluid based tooling is suitable to hold non-magnetic materials such as aluminum and also materials that do not admit high clamping forces, such as titanium, because they will appear as deformation after machining due to the memory effect of titanium. The MR fluid based tooling has been tested in a machine environment under real machining conditions and promising results have been obtained.

This paper describes the principles of a new method to compensate for tool wear when drilling in complex materials such as Carbon Fibre Reinforced Plastics (CFRP), Carbon Fibre Reinforced Plastics / Titanium (CFRP/Ti) and Carbon Fibre Reinforced Plastics / Alloy (CFRP/AI) stacks. A reliable and repeatable hole quality is essential, especially in automatic drilling applications with robots or gantries. The method combines the unique feature to dynamically adjust the drilling diameter in very small steps in an Orbital drilling End-effector and a new type of software algorithm to predict and compensate for the tool wear in different materials. With this method a large number of holes can be drilled without changing the cutting tool, and a Cpk value of more than 2,5 can be achieved.

Once qualified, manufacturing processes for safety critical components in aero engines are “frozen”, that is no changes are permitted to be made without a time consuming and costly re-validation. Moreover, the material selection for components in modern aero engines, due to high mechanical and thermal loads in operation, is limited to a small range of super alloys. These difficult to machine titanium and nickel based alloys are on the one hand a significant expense factor themselves, and cause considerable costs due to high tool wear on the other hand. Thus, it is intended to carry out time and resource saving experiments and - ideally - being able to transfer available results to similar processes. Using smart experimental design deploying relationships of physical measures involved, the effort of testing can be reduced. This paper explains the method's mathematical background, how the selection of the regarded parameters is carried out as well as the reduction of system inputs.

Requirements analysis for aircraft simulators is often driven by photographs and videos of the actual aircraft. An engineer may gather and organize hundreds or even thousands of source photos of various instruments and devices unique to the aircraft. Managing all of this source information and referencing it to generate software requirements can be challenging and time-consuming. This paper explores Content Based Image Retrieval (CBIR) techniques to automatically process and search those images to generate basic requirements and to facilitate reuse. An unsupervised clustering algorithm groups source images based on minimal user input. Images processed in this way can also be queried by image similarity, thereby allowing project managers to find common source material among projects. The effectiveness of these techniques is demonstrated on an example cockpit.

The present paper describes the first results of a cooperative research project between GM Powertrain Europe and Istituto Motori of CNR aimed at studying the impact of Fatty-Acid Methyl Esters (FAME) and gas-to-liquid (GTL) fuel blends on the performance, emissions and fuel consumption of modern automotive diesel engines. The tests were performed on the architecture of GM 1.9L Euro4 diesel engine for passenger car application, both on optical single-cylinder and on production four-cylinder engines, sharing the same combustion system configuration. Various blends of biodiesels as well as reference diesel fuel were tested. The experimental activity on the single-cylinder engine was devoted to an in-depth investigation of the combustion process and pollutant formation, by means of different optical diagnostics techniques, based on imaging multiwavelength spectroscopy.

The applicability, interpretation, and implementation of the testing requirements, in various aerospace and military tubing material specifications have caused confusion across the tubing industry. Despite the release of AMS specifications, procurement entities continue to purchase material produced to the older and often cancelled Mil-T specifications. In addition to mechanical properties, these specifications cover requirements including composition, grain size, heat treating, passivation, pressure testing, formability, non-destructive testing, and sampling frequency. Confusion may result for tubing producers who also supply commercial grade tubing having similar mechanical properties aerospace tubing. Ultimately it is the responsibility of the tubing manufacturer to understand the risks involved in meeting the requirements of the aerospace material specifications, both Military and AMS.

Cavitation in the nozzles of various shapes and liquid jets discharged from the nozzles are visualized using a high-speed camera to investigate the effects of cavitation on liquid jet deformation. Cylindrical nozzles and two-dimensional (2D) nozzles of various upstream diameters and length-to-diameter ratios (L/D) are used. For simultaneous high-speed visualizations of cavitation and a jet, a tilted acrylic plate is placed in front of the jets injected through the 2D nozzles, while three mirrors are used to capture both the front view of the jet injected through a cylindrical nozzle and the side view of cavitation. The visualizations confirm that the collapse of a cavitation cloud near the exit induces a ligament formation in 2D and cylindrical nozzles of various L/Ds. Although no vapor film is formed in short nozzles, cavitation clouds are shed near the exit and induce ligaments.

Compliance with tighter emission regulations has increased the proportion of parasitic weight in commercial vehicles. In turn, the amount of payload must be reduced to comply with transportation weight requirements. A re-design of commercial vehicle components is necessary to decrease the vehicle weight and improve payload capacity. Side rails have traditionally been manufactured from high strength steels, but significant weight reductions can be achieved by substituting steel side rails with 6013 high strength aluminum alloy side rails. Material and stress analyses are presented in this paper in order to understand the effect of manufacturing process on the material's mechanical behavior. Metallographic and tensile test experiments for the 6013-T4 alloy were performed in preparation for residual stress measurements of a punching operation. Punched holes are critical to the function of the side rail and can lead to high stress levels and cracking.

This paper develops a novel integrated navigational system for autonomous vehicle motion control. Vehicle control is defined in terms of the required vehicle steering angle, rate of steering change and speed. This paper proposes predictive control in the image plane. The proposed predictive control enables the navigation on the desired path, reduces the control complexity and increases the application space for multiple types of vehicles. The paper investigates vehicle control stability; especially in scenarios containing varying curvature turns and variable vehicle speeds. The primary emphasis of this paper is on vehicle control rather than scene analysis. To demonstrate the proposed vehicle control, a computer vision based multi-lane detection algorithm is introduced. The control strategy is applied such that the vehicle maintains position within the lane boundaries. Stability of the control algorithm is tested and demonstrated in multiple scenarios using 3-D simulation results.

The physical and optical properties viz., water absorption pattern, density, color and opacity of oil palm fiber-LLDPE composites were studied. The effect of fiber size, fiber loading and fiber treatment on the above parameters was also studied. Alkali treatment on fibers was done to reduce the hydrophilic nature of composites. It was found that the water absorption in most of the combinations followed typical fickian behavior. The rate of water absorption and swelling increased with fiber loading. However alkali treatment on fibers resulted in reduction of water absorption at higher fiber loading only and composites with higher fiber size exhibited higher water absorption. True density of oil palm fiber-LLDPE composites were in the range of 967-1177 kg m-₃, whereas the bulk density ranged from 942-1122 kg m-₃. The dielectric constant of the composite was in the range of 3.22 to 6.73.

Diesel spray experimentation at controlled high-temperature and high-pressure conditions is intended to provide a more fundamental understanding of diesel combustion than can be achieved in engine experiments. This level of understanding is needed to develop the high-fidelity multi-scale CFD models that will be used to optimize future engine designs. Several spray chamber facilities capable of high-temperature, high-pressure conditions typical of engine combustion have been developed, but because of the uniqueness of each facility, there are uncertainties about their operation. For this paper, we describe results from comparative studies using constant-volume vessels at Sandia National Laboratories and IFP.

The soot distribution as function of ambient O₂ mole fraction in a heavy-duty diesel engine was investigated at low load (6 bar IMEP) with laser-induced incandescence (LII) and natural luminosity. A Multi-YAG laser system was utilized to create time-resolved LII using 8 laser pulses with a spacing of one CAD with detection on an 8-chip framing camera. It is well known that the engine-out smoke level increases with decreasing oxygen fraction up to a certain level where it starts to decrease again. For the studied case the peak occurred at an O₂ fraction of 11.4%. When the oxygen fraction was decreased successively from 21% to 9%, the initial soot formation moved downstream in the jet. At the lower oxygen fractions, below 12%, no soot was formed until after the wall interaction. At oxygen fractions below 11% the first evidence of soot is in the recirculation zone between two adjacent jets.