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Technical Paper

Uses for Stabilized Aluminum Foam in Crashworthiness and Strengthening Applications

Stabilized Aluminum Foam (SAF) is a material produced by introducing gas bubbles into molten aluminum. Two examples will be used to illustrate the potential use of SAF in energy absorption and structural reinforcement applications. The first is use of SAF in a crashbox to absorb energy in a 15km/hr collision and prevent damage to the rails as part of a front-end energy management system. The second is as a filler in a hollow structure subject to bending loads, which potentially could find application in rails and pillars. By filling a hollow structure with SAF, the bending strength is increased dramatically while the weight increases are not significant. Numerical modeling using LS DYNA gave very good agreement with experimental results.
Technical Paper

Use of Rigid and Deformable Child Restraint Seats in Finite Element Simulations of Frontal Crashes

This research focuses on the injury potential of children seated in forward facing child restraint seats during frontal vehicle crashes. Experimental sled tests were completed in accordance to the Federal Motor Vehicle Safety Standard 213 using a Hybrid III three-year-old dummy in a five point child restraint system. A full vehicle crash test was completed in accordance to the Canadian Motor Vehicle Safety Standard 208 with the addition of a three-year-old Hybrid III crash test dummy, seated behind the passenger seat, restrained in the identical five-point child safety seat. Different child restraint finite element models were developed incorporating a subset of the apparatus used in the two experimental tests and simulated using LS-DYNA.
Journal Article

Transient Build-up and Effectiveness of Diesel Exhaust Gas Recirculation

Modern diesel engines employ a multitude of strategies for oxides of nitrogen (NOx) emission abatement, with exhaust gas recirculation (EGR) being one of the most effective technique. The need for a precise control on the intake charge dilution (as a result of EGR) is paramount since small fluctuations in the intake charge dilution at high EGR rates may cause larger than acceptable spikes in NOx/soot emissions or deterioration in the combustion efficiency, especially at low to mid-engine loads. The control problem becomes more pronounced during transient engine operation; currently the trend is to momentarily close the EGR valve during tip-in or tip-out events. Therefore, there is a need to understand the transient EGR behaviour and its impact on the intake charge development especially under unstable combustion regimes such as low temperature combustion.
Technical Paper

Thermal Efficiency Analyses of Diesel Low Temperature Combustion Cycles

Thermal efficiency comparisons are made between the low temperature combustion and the conventional diesel cycles on a common-rail diesel engine with a conventional diesel fuel. Empirical studies have been conducted under independently controlled exhaust gas recirculation, intake boost, and exhaust backpressure. Up to 8 fuel injection pulses per cylinder per cycle have been applied to modulate the homogeneity history of the early injection diesel low temperature combustion operations in order to improve the phasing of the combustion process. The impact of heat release phasing, duration, shaping, and splitting on the thermal efficiency has been analyzed with zero-dimensional engine cycle simulations. This paper intends to identify the major parameters that affect diesel low temperature combustion engine thermal efficiency.
Technical Paper

The Impact of Intake Dilution and Combustion Phasing on the Combustion Stability of a Diesel Engine

Conventionally, the diesel fuel ignites spontaneously following the injection event. The combustion and injection often overlap with a very short ignition delay. Diesel engines therefore offer superior combustion stability characterized by the low cycle-to-cycle variations. However, the enforcement of the stringent emission regulations necessitates the implementation of innovative diesel combustion concepts such as the low temperature combustion (LTC) to achieve ultra-low engine-out pollutants. In stark contrast to the conventional diesel combustion, the enabling of LTC requires enhanced air fuel mixing and hence a longer ignition delay is desired. Such a decoupling of the combustion events from the fuel injection can potentially cause ignition discrepancy and ultimately lead to combustion cyclic variations.
Technical Paper

Suitability Study of n-Butanol for Enabling PCCI and HCCI and RCCI Combustion on a High Compression-ratio Diesel Engine

This work investigates the suitability of n-butanol for enabling PCCI, HCCI, and RCCI combustion modes to achieve clean and efficient combustion on a high compression ratio (18.2:1) diesel engine. Systematic engine tests are conducted at low and medium engine loads (6∼8 bar IMEP) and at a medium engine speed of 1500 rpm. Test results indicate that n-butanol is more suitable than diesel to enable PCCI and HCCI combustion with the same engine hardware. However, the combustion phasing control for n-butanol is demanding due to the high combustion sensitivity to variations in engine operating conditions where engine safety concerns (e.g. excessive pressure rise rates) potentially arise. While EGR is the primary measure to control the combustion phasing of n-butanol HCCI, the timing control of n-butanol direct injection in PCCI provides an additional leverage to properly phase the n-butanol combustion.
Technical Paper

Study of Low Temperature Combustion with Neat n-Butanol on a Common-rail Diesel Engine

This study investigates neat n-butanol, as a cleaner power source, to directly replace conventional diesel fuels for enabling low temperature combustion on a modern common-rail diesel engine. Engine tests are performed at medium engine loads (6∼8 bar IMEP) with the single-shot injection strategy for both n-butanol and diesel fuels. As indicated by the experimental results, the combustion of neat n-butanol offers comparable engine efficiency to that of diesel while producing substantially lower NOx emissions even without the use of exhaust gas recirculation. The greater resistance to auto-ignition allows n-butanol to undergo a prolonged ignition delay for air-fuel mixing; the high volatility helps to enhance the cylinder charge homogeneity; the fuel-borne oxygen contributes to smoke reduction and, as a result, the smoke emissions of n-butanol combustion are generally at a near-zero level under the tested engine operating conditions.
Technical Paper

Study of Heat Release Shaping via Dual-Chamber Piston Bowl Design to Improve Ethanol-Diesel Combustion Performance

In this work, an innovative piston bowl design that physically divides the combustion chamber into a central zone and a peripheral zone is employed to assist the control of the ethanol-diesel combustion process via heat release shaping. The spatial combustion zone partition divides the premixed ethanol-air mixture into two portions, and the combustion event (timing and extent) of each portion can be controlled by the temporal diesel injection scheduling. As a result, the heat release profile of ethanol-diesel dual-fuel combustion is properly shaped to avoid excessive pressure rise rates and thus to improve the engine performance. The investigation is carried out through theoretical simulation study and empirical engine tests. Parametric simulation is first performed to evaluate the effects of heat release shaping on combustion noise and engine efficiency and to provide boundary conditions for subsequent engine tests.
Technical Paper

Roof Strength Requirement for Vehicles Involved in Rollover Crash

Rollover crash is one of the most serious safety problems for light weight vehicles. In the USA, rollover crashes account for almost one-third of all occupant fatalities in light weight vehicles. Similar statistics are found for other countries. Thus, rollover crashes have received significant attention in recent years. In the USA and Canada, automotive manufacturers are required to comply with the roof strength requirement of “1.5 times the unloaded vehicle weight” to ensure safety in rollover. NHTSA is currently considering a set of countermeasures to improve the rollover safety, where one of the proposals is to increase the roof strength limit to “2.5 times the unloaded vehicle weight”. This increased roof strength limit seemingly has been motivated based on the benchmark study of current vehicle fleet.
Technical Paper

Responses of the Q3, Hybrid III and a Three Year Old Child Finite Element Model Under a Simulated 213 Test

This research focuses on the response of the Q3, Hybrid III 3-year-old dummy and a child finite element model in a simulated 213 sled test. The Q3 and Hybrid III 3-year old child finite element models were developed by First Technology Safety Systems. The 3-year-old child finite element model was developed by Nagoya University by model-based scaling from the AM50 (50 percentile male) total human model for safety. The child models were positioned in a forward facing, five-point child restraint system using Finite Element Model Builder. An acceleration pulse acquired from an experimental 213 sled test, which was completed following the guidelines outlined in the Federal Motor Vehicle Safety Standard 213 using a Hybrid III 3-year-old dummy, was applied to the seat buck supporting the child restraint seat. The numerical simulations utilizing the Q3, Hybrid III 3-year-old and the child finite element model were conducted using the explicit non-linear finite element code LS-DYNA.
Technical Paper

Real-time Heat Release Analysis for Model-based Control of Diesel Combustion

A number of cylinder-pressure derived parameters including the crank angles of maximum pressure, maximum rate of pressure rise, and 50% heat released are considered as among the desired feedback for cycle-by-cycle adaptive control of diesel combustion. For real-time computation of these parameters, the heat release analyses based on the first law of thermodynamics are used. This paper intends to identify the operating regions where the simplified heat release approach provides sufficient accuracy for control applications and also highlights those regions where its use can lead to significant errors in the calculated parameters. The effects of the cylinder charge-to-wall heat transfer and the temperature dependence of the specific heat ratio on the model performance are reported. A new computationally efficient algorithm for estimating the crank angle of 50% heat released with adequate accuracy is proposed for computation in real-time.
Technical Paper

Prompt Heat Release Analysis to Improve Diesel Low Temperature Combustion

Diesel engines operating in the low-temperature combustion (LTC) mode generally tend to produce very low levels of NOx and soot. However, the implementation of LTC is challenged by the higher cycle-to-cycle variation with heavy EGR operation and the narrower operating corridors. The robustness and efficiency of LTC operation in diesel engines can be enhanced with improvements in the promptness and accuracy of combustion control. A set of field programmable gate array (FPGA) modules were coded and interlaced to suffice on-the-fly combustion event modulations. The cylinder pressure traces were analyzed to update the heat release rate concurrently as the combustion process proceeds prior to completing an engine cycle. Engine dynamometer tests demonstrated that such prompt heat release analysis was effective to optimize the LTC and the split combustion events for better fuel efficiency and exhaust emissions.
Technical Paper

Preliminary Energy Efficiency Analyses of Diesel EGR Fuel Reforming with Flow Reversal and Central Fuelling

The diesel fuel reforming process in an exhaust gas recirculation (EGR) loop of a diesel engine is capable of utilizing the engine exhaust energy to support the endothermic process of hydrogen gas generation. However, the EGR stream commonly needs to be heated to enable the operation of the reformer and thus to sustain higher yield of hydrogen. A central-fuelling and flow-reversal embedment that is energy-efficient to raise the central temperatures of the catalytic flow-bed is therefore devised and tested to drastically reduce the supplemental heating to the EGR reformer. One-dimensional modeling analyses are conducted to evaluate the fuel delivery strategies and temperature profiles of the reformer at various reforming gas flow rates and engine-out exhaust temperatures and compositions. This research attempts to quantify the energy saving by the catalytic flow-reversal and central-fuelling embedment in comparison to a unidirectional flow EGR reformer.
Journal Article

Plasmonic in Metallic Nanostructures – Fabrication, Characterization and Applications in Surface-Enhanced Spectroscopy

We are witnessing a rapid and ongoing expansion of nanoscience, driven by potential applications in advanced materials and nanotechnology. There is a race to develop techniques that may allow controlling the size, shape of nanostructures that can allow the tuning of their optical and electronic properties. Plasmonics is a field that encompasses and profits from the optical enhancement in nanostructures that support plasmon excitations. One of these new techniques is surface-enhanced Raman scattering (SERS), commonly used for nanostructure characterization. In the present report, we present a theoretical model for plasmon excitation and electric field enhancement that help to provide an explanation for the special features observed in experimental SERS. Two sets of experimental results are discussed illustrating the make out of the signature of the plasmonics producing the optical enhancement.
Technical Paper

Observations of the Relative Performance of Magnesium and Aluminum Steering Wheel Skeletons with Identical Geometry

Automotive steering wheels depend on a structural skeleton made of steel, aluminum, or magnesium to be the basis for the mechanical properties of the finished part. The mechanical properties of concern are the fatigue properties and the crash performance. The purpose of this study was to evaluate the crash and the fatigue performance of a steering wheel skeleton fabricated by high pressure die casting. Two materials were used to produce two groups of wheels with identical geometry. The production part was designed, optimized and fabricated with AM50A magnesium. The production magnesium component met all of the regulatory design and performance requirements. A small sample run was made in a proprietary aluminum - magnesium alloy. The fatigue and crash properties were evaluated empirically. In fatigue testing, the aluminum skeletons displayed a significant improvement, with respect to the magnesium skeletons, in the number of cycles to failure at the loads tested.
Technical Paper

Neat Biodiesel Fuel Engine Tests and Preliminary Modelling

Engine performance and emission comparisons were made between the use of 100% soy, Canola and yellow grease derived biodiesel fuels and an ultra-low sulphur diesel fuel in the oxygen deficient regions, i.e. full or high load engine operations. Exhaust gas recirculation (EGR) was extensively applied to initiate low temperature combustion. An intake throttling valve was implemented to increase the differential pressure between the intake and exhaust in order to increase and enhance the EGR. The intake temperature, pressure, and EGR levels were modulated to improve the engine fuel efficiency and exhaust emissions. Furthermore, a preliminary ignition delay correlation under the influence of EGR was developed. Preliminary low temperature combustion modelling of the biodiesel and diesel fuels was also conducted. The research intends to achieve simultaneous reductions of nitrogen oxides and soot emissions in modern production diesel engines when biodiesel is applied.
Technical Paper

Low Temperature Combustion Strategies for Compression Ignition Engines: Operability limits and Challenges

Low temperature combustion (LTC) strategies such as homogeneous charge compression ignition (HCCI), smokeless rich combustion, and reactivity controlled compression ignition (RCCI) provide for cleaner combustion with ultra-low NOx and soot emissions from compression-ignition engines. However, these strategies vary significantly in their implementation requirements, combustion characteristics, operability limits as well as sensitivity to boundary conditions such as exhaust gas recirculation (EGR) and intake temperature. In this work, a detailed analysis of the aforementioned LTC strategies has been carried out on a high-compression ratio, single-cylinder diesel engine. The effects of intake boost, EGR quantity/temperature, engine speed, injection scheduling and injection pressure on the operability limits have been empirically determined and correlated with the combustion stability and performance metrics.
Technical Paper

Jack Stands in North American Rally - A Design Proposal

Rally cars are among the most technologically advanced and complex race cars, with intercooled forced induction, adaptive all wheel drive and high-feature engine management being standard features for open class racers in all major North American Rally series. This high level of technology and complexity places additional burden on the service crews and mechanics charged with the task of preparing and repairing the vehicles during the competition. As such, it is of great importance that the brief service stops (thirty minutes per FIA regulation 17.2.2 [2008]) be executed as efficiently as possible. In the pursuit of valuable seconds, rally mechanics have shown a great deal of ingenuity, creating tools and procedures which are unique to the sport. One such innovation is the peg-style jack stand.
Technical Paper

Investigating Process Parameters and Microhardness Predictive Modeling Approaches for Single Bead 420 Stainless Steel Laser Cladding

Laser cladding is a novel process of surface coating, and researchers in both academia and industry are developing additive manufacturing solutions for large, metallic components. There are many interlinked process parameters associated with laser cladding, which may have an impact on the resultant microhardness profile throughout the bead zone. A set of single bead laser cladding experiments were done using a 4 kW fiber laser coupled with a 6-axis robotic arm for 420 martensitic stainless steel powder. A design of experiments approach was taken to explore a wide range of process parameter settings. The goal of this research is to determine whether robust predictive models for hardness can be developed, and if there are predictive trends that can be employed to optimize the process settings for a given set of process parameters and microhardness requirements.
Technical Paper

Influence of Biodiesel Fuel on Diesel Engine Performance and Emissions in Low Temperature Combustion

The exhaust emission and performance characteristics of a 100% biodiesel fuel was evaluated on a single cylinder direct injection diesel engine that had been modified to allow multi-pulse diesel fuel injection at the intake port and independent control of intake heating, exhaust gas recirculation and throttling. Firstly, conventional single-shot direct injection tests were conducted and comparisons made between the use of an ultra-low sulphur diesel fuel and the biodiesel fuel. Secondly, tests for the premixed combustion of neat biodiesel were performed. Exhaust gas recirculation was applied extensively to initiate the low temperature combustion for the conventional in-cylinder single injection operation and to moderate the timing of the homogeneous charge compression ignition for the intake-port sequential injection. Because of the high viscosity and low volatility of the biodiesel, pilot-ignited homogeneous charge compression ignition was used.