Dissertations / Theses on the topic 'Automotive Engineering'

Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, 2006.
Includes bibliographical references (p. 104-108).
The global automotive industry has entered a stagnating period. Automotive OEMs and their tier suppliers are struggling for business growth. One of the most important strategies is to improve the engineering efficiency in the product development process. The engineering uncertainties have been identified as the main obstacles in the Lean Engineering practices. This study will be focused on the engineering development process of ArvinMeritor Emission Technologies. The lean engineering principles and techniques are applied to the current product development process. The Value Stream Mapping and Analysis method is used to identify the information flow inside the current engineering process. Based on the value stream map, the uncertainties at various development stages in the process are identified. The Design Structure Matrix is used to identify any unplanned design iteration, which results in lower engineering efficiency. The House of Quality is used to prioritize the importance of the iterations. The suggested excel program can effectively evaluate the effect of task duration, probability, impact and learning curve assumption.
(cont.) In order to quantitatively predict the effects of the uncertainties, a System Dynamic model is specifically developed for the current engineering of Emission Technologies. The results clearly indicate the control factors for on-time delivery, efficient resource allocation, and cost reduction. This study has integrated the techniques from system engineering, system project management, and system dynamics. An improved automotive exhaust engineering process is proposed.
by Xitian Fang and Deming Wan.
S.M.

Vibration measurements conducted in three vehicles windshields are used to determine frequency content in the windshield of moving vehicles. A piezoelectric energy harvester is modeled, and used in simulations to determine output voltage and power with measured acceleration signal as input.

With nonrigid parts, it is most convenient for designers to specify the desired shape in the design condition; that is, the shape is specified with all loads present that the part will experience in service (gravity, assembly constraints, etc.). The flexibility of the part begins to pose challenges for the dimensional inspection of the part profile when the deformations due to design loads exceed 10% of the dimensional tolerances. A common approach to negotiate the inspection of nonrigid parts is to construct an inspection fixture that mimics the design condition (identical mounting points and orientation to gravity). Although effective, inspection fixtures have the limitation of cost, calibration maintenance, procurement time, and the inspection is limited to a small subset of parts. This thesis builds on the fixtureless inspection literature which has emerged in response to these limitations.

The proposed fixtureless inspection method uses finite element simulations to adjust the nominal design shape into the fixtureless measurement condition. Finite element simulations are used to remove deformations from the nominal shape due to design condition loads and add deformations due to measurement condition loads. In this way, the part can be inspected under different constraints than the design condition and without specialized fixtures. The details of the method are outlined including the finite element simulations (using Abaqus), conditioning of the finite element mesh (using MATLAB^®), optical point cloud acquisition (using a ROMER Absolute Arm with integrated scanner), and the processing of the point cloud data (using MATLAB ^®).

This method is first demonstrated on a cantilevered flat plate where the design condition is defined with a mass hanging on the end and the measurement condition is defined under the influence of gravity only. The proposed method is used to measure the profile deviation of the plate in the measurement condition (gravity only). For validation, the profile deviation is also measured in the design condition (mass hanging on the end). The profile deviation from the measurement condition is shown to match the directly measured profile deviation from the design condition to within 25 µm. This is two orders of magnitude lower than the 3 mm design condition deflections of the cantilevered plate.

The method is extended to an automotive fender where an original modal decomposition technique is used to deform the nominal model to the measurement data. The modal decomposition compensates for deformation of the part during assembly and provides a means to predict the required assembly forces. The profile deviation is measured using the proposed method with the fender in a fixtureless state resting on a flat table. For validation, the profile deviation of the fender is also measured in a specialized fixture to hold the fender in the design condition. The two profile deviations match within 0.6 mm, more than an order of magnitude lower than the 10 mm measurement condition deflections of the fender. This thesis provides one of the first automotive examples of fixtureless inspection and offers improved computational efficiency as finite element simulations for every measured part are not required.

The electronic system of a modern vehicle is essential to achieve a successful automotive product. Vehicle development is performed by integrating components that include embedded electronics from several suppliers.

This thesis present results on the subject of integration of automotive electronic systems. Our studies aim at providing knowledge on how to integrate automotive electronic systems successfully in a setting where vehicles are developed based on existing platforms. We focus on early phases of automotive electronic system development and in particular on the decisions taken in integration of electronic sub-systems. The contribution is the presented support for making decisions to successfully integrate electronic systems for modern vehicles. The contribution includes an overview of driving factors of automotive electronics system design, a validated set of success practices for the integration of electronic components, and the proposal and demonstration of a decision model. The influential factors and the validated set of practices stems from case studies of products and projects while the proposed decision model is a result of combining two general models for architecture analysis and decision making, ATAM and AHP.

We demonstrate that choices in strategy and design preceding integration are central to achieve a successful integration. Our studies show that problems arise from omitted strategy decisions and we provide a checklist for decision making in the areas; functionality, platform, integration design, and assigning responsibilities. We provide a recommendation that we validate in a multiple cases study where fulfillment of recommendations is demonstrated to affect project success in integration projects.

The potential gain for OEMs using our results lies in achieving more solid foundations for design decisions. Designers and managers could potentially find central decisions on integration strategy early that, if omitted, could cause delays. Thus, applying the result could avoid pitfalls and enable successful integration projects.

Thesis: M. Eng. in Logistics, Massachusetts Institute of Technology, Engineering Systems Division, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 54-55).
Improvement in sales forecasting allows firms not only to respond quickly to customers' needs but also to reduce inventory costs, ultimately increasing their profits. Sales forecasts have been studied extensively to improve their accuracy in many different fields. However, for automotive batteries, it is very difficult to develop a highly accurate forecast model because many variables need to be considered and their correlations are complex. Additionally, current sales forecasts are derived from historical data and thus do not include any other causal factor analysis. In this study we applied causal factor analysis to determine how the forecast accuracy could be improved. We focused on understanding the relationship between temperature and sales. Using regression modelling, we found that there is a quadratic relationship between temperature and battery sales. We validated the model by comparing the actual and predicted sales for various geographies and times. We concluded that the model is more robust for predicting sales across various times than through various geographies.
by Vinod Bulusu and Haekyun Kim.
M. Eng. in Logistics

This thesis seeks to bring together advances in control theory, modelling and controller hardware and apply them to automotive powertrains. Automotive powertrain control is dominated by PID controllers, look-up tables and their derivatives. These controllers have been constantly refined over the last two decades and now perform acceptably well. However, they are now becoming excessively complicated and time consuming to calibrate. At the same time the industry faces ever increasing pressure to improve fuel consumption, reduce emissions and provide driver responsiveness. The challenge is to apply more sophisticated control approaches which address these issues and at the same time are intuitive and straightforward to tune for good performance by calibration engineers. This research is based on a combustion model which, whilst simplified, facilitates an accurate estimate of the harmful NO_x and soot emissions. The combustion model combines a representation of the fuel spray and mixing with charge air to give a time varying distribution of in-cylinder air and fuel mixture which is used to calculate flame temperatures and the subsequent emissions. A combustion controller was developed, initially in simulation, using the combustion model to minimise emissions during transient manoeuvres. The control approach was implemented on an FPGA exploiting parallel computations that allow the algorithm to run in real-time. The FPGA was integrated into a test vehicle and tested over a number of standard test cycles demonstrating that the combustion controller can be used to reduce NO_x emissions by over 10% during the US06 test cycle. A further use of the combustion model was in the optimisation of fuel injection parameters to minimise fuel consumption, whilst delivering the required torque and respecting constraints on cylinder pressure (to preserve engine integrity) and rate of increase in cylinder pressure (to reduce noise).

The research assessed how best to transition engineering-based automotive firms towards more customer-orientated design and development approaches, whilst identifying the main barriers and concerns facing such a shift. The research investigates the ability of a firm to empower individual engineers with user centred design tools traditionally used by designers, whilst understanding the company-wide needs to facilitate their implementation.

Radar has emerged as an important sensor for scenario perception in automated driving and surveillance systems. The exponential increase of radar units in traffic and their operating frequency limitations have given rise to the problem of mutual interference. Radar's performance degrades in the presence of interference, which can result in false alarms and missed detections. In the case of safety-oriented systems (such as automatic emergency braking, blind-spot detection and obstacle detection at level crossings), radar's degraded performance can result in accidents. Therefore, it is important to mitigate the effect of mutual interference to make modern radar applications safe and reliable. The goal of this work is to develop signal processing techniques for interference mitigation in frequency modulated continuous wave (FMCW) radars operating at 77-81 GHz. The thesis investigates radar interference suppression in the spatial domain, using antenna arrays. The interference is suppressed by placing notches in the antenna radiation pattern in the direction of the interference source by employing digital beamforming. The array aperture (size) determines the beam-width and notch resolution of the receiving antenna. Narrow notches are desirable since they lead to a smaller suppressed region in the radar's field of view. It is demonstrated that an extended virtual aperture in a multiple-input-multiple-output (MIMO) FMCW radar does not offer an improved notch resolution for interference suppression due to a non-coherent interference signal in the virtual aperture. Moreover, it is shown that the calibration mismatches of the receiving array completely change the final antenna beam-pattern compared to the theoretical one. Additionally, an adaptive beamforming approach of interference suppression based on the least mean squares (LMS) algorithm is presented, which is evaluated using outdoor measurements from a 77GHz FMCW radar. The results demonstrate that the proposed technique suppresses interference successfully, resulting in a signal to interference plus noise ratio (SINR) improvement. It is also shown that complex-baseband (IQ) receivers achieve better interference suppression compared to real-baseband receivers when spatial domain methods are employed. The final research publication deals with interference mitigation in the time-domain intermediate frequency signal. The disturbed samples in the received signal are detected, removed, and reconstructed based on an estimated autoregressive (AR) signal model. The baseband signal coherence in both fast- and slow-time makes it possible to perform signal reconstruction in both dimensions. With the help of outdoor measurements covering selected scenarios, it is demonstrated that by carefully selecting the signal reconstruction dimension, a better SINR and side-lobe suppression can be achieved.

A thermoelectric generator (TEG) converts thermal energy into electrical energy corresponding to temperature gradient across both hot and cold surfaces with a conversion efficiency of approximately 5%. In spite of the conversion efficiency, TEGs can be implemented effectively for waste heat recovery systems within the power rating of kilowatts. The insufficiency of natural resources, frequently increasing oil costs and emission regulations have become an incentive factor of the recent increased interest in TEG applications. This thesis introduces a practical implementation of the thermoelectric generator for an automotive exhaust system which has a rapid transient response to produce electrical energy from the waste heat which flows through the exhaust pipe. In addition to automotive TE power generator implementation, an H-Bridge DC-DC converter within the operation of maximum power point tracking method is introduced in this thesis to obtain the maximum power transfer between the thermoelectric power generator and the load. This thesis presents a transient solution to the two-dimensional heat transfer equation with variant ambient temperature that determines heat transfer and electrical potential across the thermoelectric pellet. This equation is applied into a designed two-dimensional heat transfer MATLAB model and a comparison of simulation and experimental results approves the accuracy of the designed model. In addition to heat transfer simulation, a dynamic large scale thermoelectric power generator simulation program is introduced in this thesis to provide data analysis of actual implementation.

The previously introduced fuel droplet heating and evaporation models, taking into account temperature gradients, recirculations, and species diffusion within droplets, are further developed and generalised for the application to a broad range of automotive fuel droplets. The research has been conducted in three directions: modelling of biodiesel fuel droplets, modelling of Diesel fuel droplets, and modelling of gasoline fuel droplets.

Increasingly stringent emissions targets are encouraging vehicle manufacturers to prioritise reduction of vehicle mass. The falling cost of carbon fibre is increasing the viability of lightweight carbon-based body panel systems across a broad range of production volumes. In the present work an automated process has been developed for the manufacture of random fibre preforms at medium volume production levels (30-50,000ppa). This thesis seeks to understand the influence of key microstructural parameters on the mechanical and physical properties of carbon fibre laminates produced by directed fibre preforming. The principal parameters studied are fibre length, tow filament count and laminate thickness. A statistical process simulation has been developed to predict preform density variation and the results are compared with experimental tensile properties. Experimental studies have shown that there is a notable reduction in areal density variation and consequently an increase in tensile properties with shorter fibres (115mm to 6mm) and thicker laminates (1.5mm to 4mm for a constant volume fraction). Shorter lengths improved preform coverage and gave higher tensile strength, whilst thicker laminates reduced the presence of unreinforced areas which cause stress concentrations. Tow filamentisation has been induced by pneumatic means to reduce the mean filament count and maximise the mechanical performance when using inexpensive, 24K bundles. By maximising the level of filamentisation both stiffness and strength can be increased by 20% and 45% respectively. An analytical stiffness model is presented to predict the effect of tow filament count on the in-plane elastic constants. Filament count and out-of-plane fibre orientation distributions are determined from optical microscopy and are incorporated into a multi-level Mori-Tanaka based model. Predictions are within 8% of the experimental data for laminates containing large fibre bundles and 10% for laminates with highly filamentised bundles. An expression for critical bundle length has been developed for more accurate strength prediction, based on the number of filaments within the bundle. Experimental results confirm that the critical tow length is proportional to the tow filament count. Directed fibre preforming has been benchmarked against other competing processes in respect of mechanical properties, weight saving potential and cost. A full-scale demonstrator component has been manufactured using a variety of carbon composite solutions, which can all provide 40 to 50% weight saving for an equivalent bending stiffness to steel and greatly improved dent resistance. Directed fibre preforming has shown great promise for both semi-structural and structural components for medium volume applications, particularly when aligned fibres are introduced. The results from this work can be directly scaled for industrial application to provide a cost effective, lightweight alternative to steel.

Existing in-vehicle network technologies are becoming bottlenecks because of insufficientbandwidth. Automotive Ethernet is therefore being adopted more and more broadly due toincreased demand for bandwidth-intensive applications, including autonomous driving,navigation and infotainment functionalities. Support of determinism, bandwidth allocationand prioritization of messages, which were not available before, are possible nowadaysthanks to modern switches and the new range of IEEE standards. However, requirementsapplied for heavy vehicles like trucks and buses still require careful network design anddeployment in regard to safety and robustness.In this thesis, we consider future use cases, and evaluate different configuration strategieson layer-2 switches via simulations. We evaluate the effect of the number of traffic classes,and the performance of stream reservation and traffic shaper. The goals are to investigatehow they affect the network and to find the solution which leads to best-balanced Qualityof Service. At the same time, efforts have been made for understanding what features theswitches should include in order to support the configurations. The final outcome ofconfigurations along with features on switches aims at acting as guideline to deployAutomotive Ethernet in the future.
Dagens inbyggda nätverksteknologier i fordon blir alltmer en flaskhals på grund avotillräcklig bandbredd. Den ökade efterfrågan för bandbredd-intensiva applikationer medfunktioner som autonom körning, navigation och infotainment har gjort att automotiveEthernet har börjat användas i större utsträckning. Tack vare moderna switchar och en nyuppsättning av IEEE standarder finns nu ett stöd för determinism, bandbreddsallokeringoch prioritering av meddelanden på en nivå som tidigare inte varit tillgänglig. Dock ställerkraven för tunga fordon likt bussar och lastbilar fortfarande en försiktigt samt noggrannnätverksdesign och en tillämpning ställt med hänsyn till säkerhet och robusthet.I den här tesen behandlas framtida tillämpningsfall samt utvärdering av olikakonfigurationsstrategier på layer-2 switchar genom simuleringar. Vi utvärderar effekten avantalet trafikklasser, och prestandan på stream reservation och traffic shaper. Målet är attundersöka hur nätverksprestandan påverkas av dem, och att hitta lösningen som leder tillbästa balansen för Quality of Service. Samtidigt har tid ägnats åt att förstå vilka funktionerswitcharna skall inkludera för att stödja konfigurationerna. Det slutliga resultatet avkonfigurationer tillsammans med funktioner i switcharna ämnar att agera som en riktlinjeför att automotive Ethernet i framtiden.

The air conditioning systems currently utilized in automobiles are the vapor compression systems. This type of system has many disadvantages: the refrigerant used is not environmentally friendly, the compressor is in competition with the engine coolant system, and the compressor uses a significant portion of the engine power. A waste heat driven absorption refrigeration system is one alternative to the current systems that could address these problems. The absorption refrigeration system uses solutions for the absorbent-refrigerant pair that do not harm the environment. This investigation includes a theoretical analysis of the feasibility of absorption air conditioning system in automotive applications. Also, a comparison of the power requirements of the proposed system and the vapor compression system is performed.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2007.
Includes bibliographical references (p. 195-201).
The design of existing suspension systems typically involves a compromise solution for the conflicting requirements of comfort and handling. For instance, cars need a soft suspension for better comfort, whereas a stiff suspension leads to better handling. Cars need high ground clearance on rough terrain, whereas a low center of gravity (CG) height is desired for swift cornering and dynamic stability at high speeds. It is advantageous to have low damping for low force transmission to vehicle frame, whereas high damping is desired for fast decay of oscillations. To eliminate these trade-offs, a novel design for a customizable automotive suspension system with independent control of stiffness, damping and ride-height is proposed in this thesis. This system is capable of providing the desired performance depending on user preference, vehicle speed, road conditions and maneuvering inputs. The design, fabrication and control of the customizable suspension prototype are discussed. The application of variable stiffness and variable ride-height suspension system to achieve improved vehicle dynamics is studied. Application to control of vehicle dynamics parameters required bandwidth and power input beyond the capability of the first prototype.
(cont.) To eliminate the bandwidth restrictions of the prototype, a variable-stiffness pneumatic suspension system capable of instantaneous stiffness change with essentially no power input and no ride-height change, is developed. This is done by supporting the vehicle on air springs and connecting each air spring volume to multiple auxiliary volumes through On-Off valves. By adequately choosing N unequal auxiliary volumes, this system can achieve 2N stiffness settings. This suspension has been incorporated in a car suspension. The design, fabrication, and testing of the suspension system are reported in this thesis. A detailed frequency-domain model for the air-spring with auxiliary volumes is developed. Based on this modeling and testing, the performance limits and practical applicability of this system are discussed. The proposed variable stiffness isolator is capable of instantaneous stiffness change with no power input and no dimension change; moreover the isolator is inexpensive, robust and light. As a result, it is readily applicable to several other vibration isolation applications with conflicting stiffness requirements (such as a precision motion stages) or time-varying stiffness requirements (such as prosthetic limbs) and these applications are discussed.
by Hrishikesh V. Deo.
Ph.D.

O presente trabalho destina-se a resumir o processo de desenvolvimento de automóveis, mostrando os vários itens que influenciam na velocidade deste desenvolvimento, e propor uma base de raciocínio para se diminuir o tempo total para o projeto.
The present volume is destined to summarize the development process of automobiles, showing the many items responsible for speed up this development, and make a proposal for a thinking basis to shorten development time.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1993.
Includes bibliographical references (v. 2, leaves 369-375).
by Christophe G.E. Mangin.
Ph.D.

PS-23® is a new oil conditioner developed in South Africa by Lubrioil S.A. Chemical and physical analysis, and experimental studies were conducted to investigate the possibility of using PS-23® as an engine oil additive package. Mobil 1OW-30 is used as the engine oil. The experimental results indicate that PS-230 contains unexpectedly high levels of calcium and phosphorus, and that mixing 10% PS-23® in volume decreases the lubricant viscosity and increases its volatility. The start-stop tests using small engines were used to test PS-23® in a severe operating condition. The experimental observation suggests that under such an adverse combustion environment, the PS-23® 1OW-30 mixture is more likely to degrade. Further studies were conducted using a block-on-pin machine to determine the tribological behavior of PS-23 as an additive using a prepared steel sample and rotating piston pin, under both full film and boundary lubricating conditions. Both 1OW-30 motor oil and 80W-90 gear oil were used for these tests as the reference oil. It was found that under full film lubrication there were no substantial differences in the frictional coefficient with the use of PS-23®. However, under boundary lubricating conditions it was found that the use of PS-23@ extended the time before failure was observed by a substantial amount. Other popular lubricant additives such as Slick-50 and Duralube were also used in the boundary lubrication tests, and although they performed better than the reference oil alone, they did not achieve the level of performance achieved with the use of PS-23®.

O trabalho apresenta também um estudo de confiabilidade e estabelece uma faixa de valores para o esforço de fechamento de portas baseado na variação de algumas componentes chaves no cálculo. A curva característica que é um dos parâmetros de saída do modelo apresenta forma extremamente próxima da medição realizada em laboratório. No Brasil, a indústria automotiva é conhecida por sua grande influência e peso na economia do país, assim como em diversos outros países. O conjunto porta na concepção do veículo é de extrema importância, visto que é região do veículo com que o consumidor trava contato primeiro. Um valor de esforço elevado para realizar a abertura e fechamento das mesmas pode levar a uma imagem indesejada pela montadora do veículo. O valor do esforço necessário para fechar a porta é um item de extrema importância, pois além de influenciar a imagem do veículo e da marca, é um item do pacote de conforto e ergonomia do veículo. O evento fechamento da porta parte do instante em que a porta está na condição aberta e seus componentes se encontram em descanso. O evento é modelado matematicamente e em planilha dinâmica admitindo como parâmetros de entrada dados específicos do veículo e seus componentes, como saída têm-se o valor da energia de fechamento de portas e a parcela de cada componente envolvido. São apresentados resultados experimentais para que o modelo seja considerado válido. Com a conclusão do modelo é possível estimar a queda de energia em função da vida de alguns componentes como a fechadura e o pacote de guarnições, bem como a influência do uso de sobreinjetados autolubrificantes na fechadura. Este trabalho contribui com os profissionais de Engenharia de Produto nas áreas de Carroceria, Mecanismos e Partes Móveis com a elaboração de uma ferramenta de cálculo para uso em qualquer fase de projeto, principalmente para estimar o valor da energia de fechamento de porta no momento de sua conceituação e até na validação de veículos protótipo.
The Brazilian automotive industry is known by its great influence on the country economy, similar to several other countries. It is important to highlight the door assembly importance on the vehicle concept, as it is the first contact made to the customer. The vehicle ingress is through the side access area, established by the doors and a high door closing effort may lead to a wrong impression. The door closing effort or also known as door closing energy is an extreme importance asset, as well as influencing the image of the vehicle and the brand, it is an item of ergonomics and vehicle comfort. The automotive door closing event starts at the moment door is open and pushed to close itself. This event is math modeled and implemented as an excel dynamic calculation plan, considering as input the vehicle and components specific data, its output is the door closing effort and each components portion. It is presented a series of values so the model is considered valid. This work also presents a reliability study defining a range of experimental values for the door closing effort based on tolerances of components used in the model calculations. The characteristic curve which is one of the parameters of the model output is extremely close to the measurement performed in the laboratory. With the completion of the model is possible to estimate the energy loss due to the life of certain components such as latches and weatherstrips, and the influence of using self-lubricating over molding in the latch. This study contributes to the Product Engineering professionals in the areas of Body, Mechanisms and Body Closures, with the elaboration of a calculation tool for use in any design phase, but mostly serving to estimate the door closing effort at the moment of conception until the validation of prototype vehicles.

How to display objects which were detected from different devices in one coordinate system? Nowadays most vehicles are equipped with front and back sensors to help the driver in driving process. Companies who provide this technology need to have an application which enables them for easy data fusion from these sensors and recording the process. Besides sensor’s design, programming of them is an important aspect. BASELABS Connect has the solution in a user friendly way. Creating Sensor Central component for BASELABS Connect is the main goal of this thesis. Sensor Central from BASELABS Connect requires six variables of sensor’s position for each sensor to demonstrate the objects from all sensors to one unique coordinate system. In this thesis, it was intended to create such a component which was mounted between all the sensors and the charting component to convert the objects location from different sensor’s position to one coordinate system and to be usable from other vehicles too.
www.baselabs.de

The aim of this research was to assess the effect of oxygenated hydrocarbons on the knocking characteristics of an engine when blended with low-leaded gasoline. Alcohols, ethers, esters and ketones were tested individually and in various combinations up to an oxygen content of 4% wt/wt in a blend with Series F-7 gasoline of 90, 92, 94 and 96 RON. Tests were carried out at wide open throttle, constant speed and standard timing setting. Engine speed was varied using a dynamometer and knock was detected by two piezoelectric transducers, one on the cylinder head monitoring all four cylinders and one monitoring the cylinder most prone to knock. The engine speeds associated with trace and light knock of a continuous nature were noted. Curves were produced for each oxygenate blend of base RON used against engine speed for the two knock conditions which were compared with those produced using pure Series F-7 fuels. From this a suggested RON of the blend was derived. RON increase was less when using a higher RON base fuel in the blend. Most individual oxygenates showed similar effects in similar concentrations when their oxygen content was comparable. Blends containing more than one oxygenate showed some variation with methanol/MTBE/3 methylbutan-2-one and methanol/MTBE/4 methyl pentan-2-one knocking less than expected and methanol/MTBE/TBA also showing good knock resistance. Further tests to optimise initial findings suggested a blend of methanol and MTBE to be superior although partial replacement of MTBE by 4 methyl pentan-2-one resulted in a fuel of comparable performance. Exhaust emissions were tested for a number of oxygenated blends in 2-star gasoline. 2-star and 4-star fuels were also tested for reference. All oxygenate blends reduced carbon monoxide emissions as expected and hydrocarbon emissions were also reduced. The largest reduction in carbon monoxide occurred using a 14.5 % (1 : 1 : 1) methanol/MTBE/4 methyl pentan-2-one blend. Hydrocarbon emissions were most markedly reduced by a blend containing 25.5 % 4 methyl pentan-2-one. Power output was tested for the blends and indicated a maximum increase of about 5 % at low engine speeds. The most advantageous blends were methanol/4 methyl pentan-2-one (6 : 5) 11% in 2-star and methanol/MTBE/4 methyl pentan-2-one (6 : 3 : 2) 11% in 2-star. In conclusion methanol/MTBE (6 : 5) and (5 : 5), and various combinations of methanol/MTBE/4 methyl pentan-2-one, notably (6 : 3 : 2) gave good results in all tests conducted. CFR testing of these blends showed them to increase both RON and MON substantially.

Vehicle bodies are generally constructed from galvanized steel, which, together with phosphate and e-coat paint treatments, ensures corrosion resistance. The use of these materials alone cannot provide adequate corrosion protection to certain features that are inherent to vehicle body construction but are also vulnerable to corrosion, such as cut edges of panels and creviced joints. The use of further corrosion protection measures, (e.g. sealers, lacquers and waxes), is undesirable because they require additional manufacturing processes, increase weight and reduce recyclability of the vehicle. The potential benefits of using zinc-magnesium alloy coated steel (ZMG) as a substitute for conventional galvanized steel were investigated in this work. Cyclic corrosion testing in sodium chloride and acid rain-based environments was conducted on panels of ZMG and conventional galvanized steel and the resistance of each material to red rust initiation and propagation was assessed. ZMG offered approximately a 3-fold improvement in red rust resistance compared to galvanized steel in the sodium chloride test but ZMG's corrosion benefit was attenuated in the acid rain environment. Cyclic corrosion testing was also conducted on painted test panels incorporating geometric features; enhanced edge and crevice corrosion resistance was also observed for panels constructed from ZMG. Corrosion products formed in each environment were characterized using a suite of analysis techniques and mechanisms to explain the enhanced corrosion resistance of ZMG were proposed based on these products and on the literature. An inhibiting corrosion protection mechanism was suggested for ZMG whereby cathodic activity was retarded via the precipitation of insulating, sparingly soluble magnesium hydroxide. Further inhibition of cathodic activity has been attributed to the specific oxide layer (possibly magnesium oxyhydroxide doped with zinc) present at the ZMG surface. The observed efficacy of the corrosion protection mechanisms suggests that ZMG may allow improvement of the vehicle body corrosion protection system for vehicle weight and recyclability targets.

This study investigates rapid changes in contact resistance, termed intermittences or short duration discontinuities, on tin-plated electrical contacts that are undergoing fretting tests. Voltage and current levels are comparable to the levels found in automotive systems. The thesis begins with an overview of the theory of mechanical and electrical contact, factors that determine the performance of an electrical contact and previous work on intermittences. Building upon this background information a low frequency fretting apparatus and a high¬speed data acquisition system are developed, capable of monitoring the voltage-drop across and current through the contact with a sample rate of up to 1 gigasamples per second. During the fretting experiments the build-up of debris is observed. As expected in this type of experiment the contact resistance rises with increasing number of fretting cycles. An increase in current accelerates the contact degradation. The contact surface is analysed using SEM and SEM/EDX. Several features are found in the recorded signals. These include plateaus, slopes of several tens of kilovolts per second, voltage-drops across the contact interface of above the melting voltage of tin and intermittences that can occur, when no forced relative motion between the contact partners is present. The observations are combined to a set of requirements of a model to explain intermittency phenomena. Previously proposed models are evaluated on the basis of these findings. Finally the asperity model is extended to incorporate the results of the experiments. It is proposed that melting of asperiti.es causes short-duration discontinuities and events that occur when no forced relative motion is present. Both could not be explained within the asperity model before. The thesis concludes with a definition of the term 'intermittence' as the temporary disruption of metallic conduction in a closed electrical contact. This definition is an improvement over the previous definition, because it allows setting a specific resistance threshold to detect intermittences in fretting experiments. Future work is suggested.

Because Industry 4.0 is bringing connectivity the automotive manufacturing industry is meeting more disruption coming years than usual. As more manufacturing equipment is becoming connected the focus in the development of products and business strategies is changing from products and their isolated functionalities to the product’s contribution to an overall system. The automotive manufacturers are expressing uncertainty on how the manufacturing ecosystem is changing and how to handle the change. The purpose of this study is to find a business strategy for a manufacturing equipment supplier in a disrupted automotive manufacturing ecosystem. In order to fulfill the purpose of this study, data was gathered using three different methods; a pre-study, a literature review and an empirical study. The pre-study was necessary to understand the focal case study company’s current situation and challenges. The literature review identified previously known research in the automotive manufacturing ecosystem as well as a theoretical framework; business strategies. An empirical study was conducted, where 16 interviews were performed at nine of the largest customers and suppliers in the automotive manufacturing industry in Sweden in order to investigate the possible future structures of the ecosystem. There are two possible future structures of the automotive manufacturing ecosystem, but one is more probable and more beneficial for a manufacturing equipment supplier. The business strategy for a manufacturing equipment supplier would be to take a larger role and responsibility in the ecosystem, becoming a total solutions provider. The most important implication is that the relationship between the supplier and customer must become closer allowing the supplier to understand how their products contribute to the ecosystem and how they can apply knowledge of their own processes to improve it. Manufacturing equipment suppliers should start working towards this strategy already today to ensure that they influence the development of the ecosystem into the most beneficial structure for them.
Industry 4.0 som medför uppkoppling gör att biltillverkningsindustrin står inför fler förändringar någonsin. När mer tillverkningsutrustning blir uppkopplad kan man integrera utrustningen med varandra, vilket tillåter dem att förbättra varandra och därigenom förbättra prestandan av all sammanlagd utrustning. Fokus inom utveckling av produkter och affärsstrategier skiftar från utveckling av enskilda tillverkningsutrustningar till utrustningens roll i hela systemet. Bilindustrin uttrycker dock en osäkerhet inför hur tillverkningsekosystemet förändras. Av denna anledning är syftet med denna studie att hitta en genomförbar affärsstrategi för en leverantör av tillverkningsutrustning till bilindustrin. För att kunna uppfylla syftet med studien har data samlats in via tre olika metoder; en förstudie, en literaturstudie och en empirisk studie. Förstudien var nödvändig för att förstå fallstudieföretagets nuvarande situation och utmaningar. Literaturstudien identifierade tidigare känd forsking i bilindustrins tillverkningsekosystem såväl som teoretiskt ramverk för affärsstrategier. En empirisk studie genomfördes för där 16 intervjuer hos nio av de största kunderna och leverantörerna inom biltillverkningsindustrin i Sverige gjordes för att utforska möjliga framtida strukturer av tillverkningsekosystemet. Det finns två möjliga framtida strukturer av ekosystemet men en av dem är mer trolig och dessutom mer gynnsam för leverantörer av tillverkningsutrustning. Affärsstrategin som har hittats för en leverantör av tillverknings-utrustning innebär att ta en större roll och ett större ansvar i ekosystemet och därmed bli en komplett lösningsleverantör. Den viktigaste innebörden av denna affärsstategi är att relationen mellan leverantör och kund måste bli närmare för att levarantören ska förstå hur deras produkter bidrar till ekosystemet och hur de kan tillämpa deras kunskap om deras egna processer för att förbättra det. Leverantörer av tillverkningsutrustning bör dock redan nu börja arbeta mot denna strategi för att försäkra sig om att de kan påverka utvecklingen av ekosystemet till den mest gynnsamma för dem.

The risk of collision increases, as the number of cars on the road increases. Automotive radar is an important way to improve road traffic safety and provide driver assistance. Adaptive cruise control, parking aid, pre-crash warning etc. are some of the applications of automotive radar which are already in use in many luxury cars today. In automotive radar a commonly used modulation waveform is the linear frequency modulated continuous waveform (FMCW); the return signal contains the range and velocity information about the target related through the beat frequency equation. Existing techniques retrieve target information by applying a threshold to the Fourier power spectrum of the returned signal, to eliminate weak responses. This method has a risk of missing a target in a multi-target situation if its response falls below the threshold. It is also common to use multiple wide angle radar sensors to cover a wider angle of observation. This results in detecting a large number of targets. The ranges and velocities of targets in automotive applications create ambiguity which is heightened by the large number of responses received from wide angle set of sensors. This thesis reports a novel strategy to resolve the range-velocity ambiguity in the interpretation of FMCW radar returns that is suitable for use in automotive radar. The radar ambiguity function is used in a novel way with the beat frequency equation relating range and velocity to interpret radar responses. This strategy avoids applying a threshold to the amplitude of the Fourier spectrum of the radar return. This novel radar interpretation strategy is assessed by a simulation which demonstrates that targets can be detected and their range and velocity estimated without ambiguity using the combined information from the radar returns and existing radar ambiguity function.

The effects of swirling flow and spark locations on the specific rate of growth of flame area, the flame speed and the convection velocity are investigated experimentally in a constant volume vessel near the lean misfire limit for an equivalence ratio of 0.645 using the shadowgraph technique. The circular and the elliptical models are used as flame contours to calculate the flame speed and the convection velocity. The circular model indicates that the flame speed decreases as the swirl flow decays and as the spark location is moved towards the center of the combustion chamber. The modified elliptical model shows the same result for the average flame speed $S\sb{ws}$. Both models show an overlap in convection velocity when comparison is made at a given spark location for different swirl levels because of cyclic variation; even though the average is higher for higher swirl level. The specific rate of growth of flame area (${1\over A}{dA\over dt}$) is obtained using three models for flame area A: (i) 2-D flame area $A\sb{f}$ measured from the photographs, (ii) spherical flame geometry model, and (iii) ellipsoidal geometry model. The stretch factor $K=({\delta\sb{l}\over u\sb{l}}) ({1\over A}{dA\over dt})$ at 0.5 ms from ignition time for the 2-D and the spherical models at ${r\over R}=0.68$ was within the range 0.63-0.97 and at ${r\over R}=0.55$ was within the range 0.5-0.59. The stretch factor for the ellipsoidal model at ${r\over R}=0.68$ was within the range 0.53-1.05 and at ${r\over R}=0.55$ was within the range 0.46-0.53. All three models for flame area indicate that the specific rate of growth of flame area and stretch factor at 0.5 ms from ignition time decrease as the swirl flow decays and as the spark location approaches the center of the combustion chamber.

Experimental measurements and model predictions of ignition delay times for single component and two-component liquid fuels are presented. The methodology used is the suspended-droplet/moving-furnace technique, in which a droplet of fuel is suspended from the tip of a thin quartz fibre. A preheated electric furnace moves towards and encompasses the droplet locality, producing a sudden rise in ambient temperature, and thus initiating the ignition process. The entire apparatus is enclosed in a pressure vessel and is remotely operated. Data were collected for pressures up to 18 atm absolute and in a temperature range of 773 K to 973 K. Fuels tested comprised n-paraffins (decane, dodecane, and hexadecane), aromatics (mesitylene, o-xylene, and isobutylbenzene) and a cycloparaffin (decalin), as well as selected binary combinations: n-decane/n-dodecane, n-dodecane/n-hexadecane, n-decane/decalin, n-decane/isobutylbenzene, n-decane/mesitylene, and n-decane/o-xylene. Paraffin measurements at low pressures and high temperature revealed a monotonic decrease in ignition times with increasing pressure. However, higher pressure ignitions at lower temperatures showed more complex behaviour by the measurement of two or "twinned" ignition times for the same pressure and temperature condition, indicating a change in reaction mechanism, possibly from one-stage to two-stage ignition. Aromatic fuels did not show "twinned" ignition time behaviour and responded with a slight increase in ignition times with increasing pressure, owing to a weaker reaction rate dependence on pressure. The cycloparaffin behaved analogously to the n-paraffin family. The behaviour of mixtures was largely controlled by the more volatile component. (Abstract shortened by UMI.)

This dissertation describes a methodology for the vehicle dynamics control of a wheel motored vehicle. All theory is developed assuming that the driver has control of the front wheel steering angle, and that wheel torque is solely generated by independent wheel motors at each corner of the vehicle. Theoretical work is presented for the general case with four independent wheel motors, but can be easily reduced to a situation with only two wheel motors. Indeed, all theory developed in this work is evaluated experimentally on a production automobile converted to be driven by two independent rear wheel motors.

As opposed to directly allocating wheel torques, the proposed philosophy operates in the slip-ratio domain. Doing so helps to prevent excessive tire saturation and allows the system to adapt to changing road surfaces. To that end, this dissertation first proposes a method of estimating slip-ratio utilizing only sensors currently available on modern automobiles. A slip-ratio controller is then developed approximating the disturbance observer structure. This allows the controller to be robust to changing road surface and as a byproduct provide an accurate estimate of longitudinal tire force. Combining the estimated longitudinal tire force with the estimated slip-ratio it is then possible to ascertain some degree of tire saturation. With this in mind, an optimal control allocation problem is proposed which attempts to achieve the desired vehicle dynamics while at the same time minimizing tire saturation.

It is shown experimentally that the proposed control methodology effectively achieves desired vehicle dynamics. In addition, the system adapts its behavior to changing road surfaces resulting in optimal performance regardless of operating conditions.

Innovative clutching mechanisms for hybrid automotive transmissions that yield low losses, while still satisfying the conflicting requirements of compactness, quick response, and high power density are explored in this thesis. Moreover, a systematic approach to automotive-transmission clutch design is proposed. The goal is to provide a complementary tool to aid the designer's judgment. The various design variants chosen serve two purposes, to demonstrate the foundation and to showcase approaches and solutions to specific problems that have a direct application in transmission design. The analysis of design variants goes into sufficient depth to be useful to both practicing automotive design engineers and academics.The phenomenon of "spin loss" is well known in the automotive industry, for it affects all transmissions. One energy sink identified in this regard lies in traditional wet clutches and brakes, wherein an open clutch or, correspondingly, an open brake, creates drag on the transmission because of the oil churning around and between the rotating friction plates. A second source of spin loss, or energy sink, is of electromagnetic origin, as it occurs by virtue of spinning inactive motors that carry permanent magnets. Apart from spin losses, the hydraulic actuation of clutches and brakes suffers from head losses. Seals, pumps and valves incur leakages that cause energy loss.Using the techniques outlined in this thesis, two separate novel clutch variants are demonstrated to improve clutch and brake technology. One variant, the electromechanical clutch actuator, is based on a high-performance screw joint with a built-in locking mechanism. The screw joint was tested with two sub-variants, namely, a lead screw and a ball screw. One prototype of each of the two sub-variants was installed on a testbed, to mimic the installation of the actuator in place of the corresponding hydraulic components. To better reflect the elastostatic behaviour of the clutch disk assembly, a new model for its stiffness as a hardening spring was formulated. Proof-of-concept tests of both sub-variants, lead and ball screws, demonstrated their feasibility.The second variant, the electromagnetic dog clutch, is directly aimed at minimizing spin and hydraulic actuation losses for clutched electric motors, wherein the motor is connected to a clutch. The system includes a unique contactless electromagnetic synchronizer and a synchronizing sleeve with dog teeth on the input and output components. The design study, focused on the electromagnetic part, strives to reduce clutch slip and control torque. The novel design features claw-like stator and salient rotor poles with good machinability within a restrictive design volume. A complete design analysis with physical proof-of-concept testing was conducted.Reducing "spin-loss" in transmission assemblies will improve system efficiency and yield better fuel economy. The technologicalimpact will benefit not only the user, who will obtain more mileage for her or his dollar, but also the environment.
Dans cette thèse sont étudiés des mécanismes innovants d'embrayage pour transmissions automobiles hybrides qui n'engendrent que de faibles pertes, tout en satisfaisant les besoins parfois conflictives de compacité, de haute vitesse de réaction et de haute densité d'énergie. Une approche systématique de la conception de transmissions automobiles est proposée, dont l'objectif est d'offrir un outil complémentaire au jugement du concepteur. Les divers alternatives choisises servent à présenter les concepts fondamentaux, ainsi qu'à mettre en valeur les différentes approches et solutions à des problèmes spécifiques qui ont une application directe dans le domaine des conceptions de transmissions. L'analyse d'alternatives de conception va suffisamment en profondeur pour être utile à la fois aux ingénieurs de conception automobile et aux théoriciens.Le phénomène de pertes d'énergie cinétique de rotation (PECR) est bien connu dans l'industrie automobile, car cela affecte toutes les transmissions. Un puits d'énergie mis en évidence à ce propos concerne les embrayages et freins traditionnels à fluides, pour lesquels un embrayage ouvert ou un frein ouvert, crée une traînée dans la transmission parce que l'huile tourbillonne autour et dans les plaques tournantes de friction. Un second puits d'énergie est d'origine électromagnétique, car générée par la rotation de moteurs inactifs contenant des aimants permanents. Hormis le PECR, l'actionnement hydraulique d'embrayages ou de freins entraîne des pertes de charges. Les joints, pompes et valves encourent des fuites qui engendrent de puits d'énergie.En utilisant les techniques mises en avant dans cette thèse, deux nouvelles alternatives d'embrayages démontrent leurs capacités à améliorer les technologies des freins et des embrayages. L'une de ces alternatives, l'actionneur {\em électromécanique d'embrayage}, est basée sur une liaison à vis et dispose d'un mécanisme intégré de verrouillage. La liaison à vis a été testée au travers de deux sous-alternatives, à savoir une vis à filet trapézoïdal et une vis à billes. Un prototype de chacune des alternatives a été installé sur un banc d'essai, afin de reproduire l'installation de l'actionneur en lieu et place des composants hydrauliques correspondants. Pour mieux refléter le comportement élastostatique de l'assemblage des disques d'embrayage, un nouveau modèle de sa raideur, assimilée à un ressort durcissant, a été formulé. Des tests de preuve de concept des deux variantes, vis à filet trapézoïdal et vis à billes, ont montré leur faisabilité.La seconde variante, l'embrayage électromagnétique à interférence, est directement utilisable pour minimiser les pertes en rotation et en actionnement hydraulique pour les moteurs électriques à embrayage, pour lesquels un moteur est connecté à un embrayage. Le système inclut un unique synchronisateur et des bagues de synchronisation avec des dents-de-chien sur les composants en entrée et en sortie. Le travail de conception a été concentré sur la partie électromagnétique, qui essaie de réduire le glissement de l'embrayage et le couple de commande. Le nouveau système conception est doté d'un stator en forme de griffes et des pôles de rotor saillants faciles à usiner et à installer dans un espace restreint dans la voiture. Une étude complète de conception avec des tests concrets de preuve de concept a été accomplie.Rééduire le PECR dans les assemblages de transmissions améliorera l'efficience du système et mènera à davantage d'économie de carburant. L'impact technologique sera ainsi bénéfique non seulement pour l'utilisateur, qui profitera d'un kilométrage plus élevé pour son argent, mais aussi pour l'environnement.

The objective of this research is to develop an integrated system engineering methodology for the customization design to maximize vehicle performance upgrade freedom while ensuring vehicle dynamics compliance.

A post-delivery modification framework, which is led by an aftermarket umbrella organization and involve various stakeholders has been established. The umbrella organization will be in charge of developing the design envelope and distribute to various aftermarket kit suppliers to generate specific products according to their brand essence.

A generic mathematical representation of a (proprietary) ESC system has been developed for virtual certification purposes. This approach is a cost-effective alternative to physical on-road testing and hardware-in-the-loop (HiL) simulations. Furthermore, based on the stability control model, the modification impacts on the vehicle dynamics and stability performance was assessed using the Taguchi design of experiment (DOE) method. DOE results provide three distinct ways for supporting aftermarket modifications. First, main effects help customizers to understand which modification bring benefits or risks. Second, a regression model of the lateral offset metrics helps suppliers to predict closed-loop performances with open-loop testing information which require much less time and cost. Finally, the pass/fail criteria regarding federally mandated ESC compliance (FMVSS 126) brought on the ‘Pass Region’ which consisted of feasible configurations such that customizers may configure their options within a safe zone. Each of these methods complements others for supporting the aftermarket modification.

In order to improve the computation efficiency, two lower fidelity models were developed: A linear model and a surrogate model. The linear model is derived from the high fidelity model with reduced degrees of freedom (DOF) and linearized parameters. Tire cornering stiffness is treated as constants for gentle maneuvers, and varying parameters for high-dynamic driving maneuver. The linear system is either a linear time-invariant (LTI) system or a linear parameter-varying (LPV) system depending on the application context. The PD yaw stability control algorithm, which is inherited from the high fidelity model, was simplified but retained with critical nonlinear features. A quadratic regression model that was dedicated for compliance metrics was developed as a surrogate model incorporated in an interactive rule-based design envelope.

An interactive design envelope has been created incorporating the rules established using computational efficient linear and surrogate models. The constraint satisfaction problem is described in the nonlinear programming context and solved using sequential quadratic programming. The quasiconvexity of the design space, which is the necessary condition for the proposed approach, is also investigated by inspecting the constraint functions. Finally, two case studies were developed to demonstrate the framework developed which was validated against the high fidelity co-simulation model.

The reinforcement of an Al casting with ferrous inserts (hybrid systems) through a joining technique to utilize both Al alloys (lightness) and Fe-based alloys (stiffness) is of interest, especially in the transportation sector. This work focuses on different technological aspects of cast joining of cast iron to an Al alloy using an intermediate material (or coating). The experimental set up consisted of preparing the insert surface followed by coating the insert, and then, immersing it into an Al melt, and allowing the system to cool down to room temperature. The effects of flux treatment, decarburization, and the coating application, as well as the immersion time in the Al melt on the Al-Fe joint quality were investigated. The microstructure evolution of the reaction layer forming at the insert-coating interface was determined as a function of the coating time and the coating composition, and their effects on the joint properties were evaluated. The relationship between the microstructure and microhardness of the joint zone was established. Decarburization, flux treatment, suitable coating, and optimizing the process parameters improved the joint properties. Combination of "McGill 2" coating alloy and 1 min immersion time (in the Al melt) resulted in the formation of an Al-Fe joint with optimized characteristics. The results showed that the cast joining could be used to strengthen the Al castings and improve their performance.
Le renfort des pièces coulées en aluminium par l'assemblage d'insertions ferreuses (systèmes hybrides) permet de combiner la légèreté de l'aluminium avec la rigidité des alliages à base de fer. Cette technique présente donc un grand intérêt pour plusieurs applications, spécialement dans le secteur des transports. Ce projet porte sur les différents aspects technologiques de la coulée de pièces avec joint aluminium-fonte auquel est ajouté une couche intermédiaire (ou revêtement). La procédure expérimentale a consisté à préparer la surface des insertions, à appliquer le revêtement, puis immerger la pièce dans un bain d'aluminium liquide, pour finalement refroidir le système jusqu'à la température de la pièce. Les effets du traitement par flux, de la décarburisation, et des paramètres de revêtement ainsi que la durée d'immersion dans l'aluminium liquide sur la qualité du joint aluminium-fonte ont été étudiés. L'évolution de la microstructure par la formation d'une zone de réaction à l'interface de l'insertion de réaction et zone du revêtement a été déterminée en fonction de la composition du revêtement er du temps d'immersion dans le revêtement liquide, et leurs effets sur les propriétés du joint été évalués. La corrélation entre la microstructure et la microdureté du joint ont a été établie. La décarburisation, le traitement par flux, l'utilisation d'un revêtement approprié et l'optimisation des paramètres du procédé améliorent significativement les propriétés du joint. L'utilisation du revêtement "McGill 2" avec un temps d'immersion dans le bain d'aluminium d'une minute permet la formation d'un joint Al-Fe avec des caractéristiques morphologiques, d'épaisseur, de microdureté et de composition optimisées. Les résultats montrent que l'insertion de pièces formant un joint peut être utilisée pour renforcer les pièces d'aluminium et

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.
Includes bibliographical references (p. 122-129).
Energy management is of vital concern in the automotive industry and many components need to satisfy stringent 'impact-safe' requirements. These energy absorption requirements conflict with the design demands for more compliant, thinner materials leading to a conflict of stiffness problem. A 'novel' energy absorbing material that adapts to environmental conditions and user specifications has been conceptualized, designed, modeled and tested in the present work. This adaptive energy absorbing material consists of an elastomeric foam impregnated with a field-responsive fluid such as a magnetorheological fluid or a shear-thickening fluid. Stable and inexpensive magnetorheological (MR) fluids based on carbonyl iron powder have been synthesized in the laboratory. The rheological properties, including the field dependent yield-stress, of the fluid have been measured at magnetic fields varying from 0.0 to 0.4 Tesla using a custom-built fixture for the AR 2000/ 1000N rheometers. Steady shear rheological experiments and transient creep tests have also been performed on a shear-thickening fluid consisting of 56% w/w corn-starch in water. The large, reversible changes in the rheological behavior of field-responsive fluids have been utilized for controlling the stress-strain behavior and energy absorption characteristics of cellular solids. The mechanical properties of 'dry' and field-responsive fluid-impregnated cellular solids have been determined using Texture Analyzer modified with a custom-built attachment. Foams impregnated with MR fluids have shown a tremendous improvement in the energy-absorption capacity. The energy absorbed per unit volume at moderate magnetic fields (B ~/~ 0.2 T) has been found to increase by 30 to 50 times as compared to the energy absorbed at zero-field. A 'two-layer' scaling model has been proposed to explain the increase in the foam plateau stress based on an assumption that the MR fluid forms a secondary layer on the solid edges of the foam and determines the composite elastic modulus. Experiments have been carried out to determine the effect of control parameters such as the magnetic field, volume fraction of the fluid impregnating the foam and the strain rate on the mechanical behavior of the composite. The magnetic field has been varied from 0.0 to 0.2 T, the volume fraction from 0% to 60% and the strain rate from 0.02 to 2.0 s-1. All the experimental data has been found to collapse onto a single master curve using appropriate shift factors based on the proposed theoretical model. Impact testing using a 'drop-ball' test apparatus, built in-house, has been performed for a scaled down headrest model. Designs for an adaptive headrest and various automotive components have also been described in detail. The present work has thus presented a 'novel' class of conformable field-responsive fluid based composites that can be used for rapidly switching energy absorbing applications.
by Suraj Sharadchandra Deshmukh.
S.M.

L'industrie automobile des systèmes embarqués critiques est confrontée de nos jours à une complexité croissante, tandis que les coûts, les performances en termes d'intelligence, les caractéristiques, les capacités et les délais de commercialisation de leurs produits sont constamment remises en question. Face à cela, l'objectif principal pour les constructeurs et fournisseurs automobiles devient désormais de contrôler la qualité et la fiabilité des systèmes mécatroniques et embarqués. L'existence de normes internationales comme le HIS Automotive SPICE et l'ISO26262 est une contrainte supplémentaire qu'ils doivent prendre en compte s'ils veulent atteindre cet objectif. De plus, assurer la bonne gestion de la sécurité et la qualité du produit ne suffit pas: il est essentiel de veiller à ce que nous produisons un système qui n'est pas seulement sécuritaire et bien, mais aussi que nous produisons le bon système. Cela induit donc une plus grande prise en compte des exigences.Dans cette thèse, nous traitons le challenge du développement des systèmes embarqués automobiles suivant l'Ingénierie Dirigée par les Modèles (IDM) qui répondent aux exigences des utilisateurs et des standards du domaine et qui permettent de maîtriser davantage la qualité des produits développés. Le problème à résoudre a été abordé sur plusieurs phases qui sont ensuite utilisés conjointement. En premier, nous définissons un métamodèle fusionnant les approches orienté qualité produit et qualité processus selon respectivement les normes ISO26262 et SPICE. Puis, dans un but de certification, nous proposons une méthodologie générique basée sur ce métamodèle commun où une évaluation du processus de développement induite par l'HIS standard ainsi qu'une évaluation de la sécurité fonctionnelle induite par l'ISO2626 sont simultanément effectuées. Ce résultat est traduit au travers de la définition d'un framework outillé où nous appliquons la méthode d'évaluation propre au standard SPICE. En deuxième phase, nous définissons un métamodèle pour gérer les actifs de sécurité concernant ces normes automobiles au niveau produit. Ce métamodèle définit comment capturer les exigences et l'architecture d'un système de telle manière qu'ils puissent être traçables entre eux et également traçables depuis des documents de spécifications d'origine. Enfin, une approche à base de modèle où l'interaction des modèles de processus et le produit est géré afin de répondre aux besoins identifiés dans la première phase est développé pour soutenir la gestion de projet. L'approche utilise la modélisation des processus et leur mesure pour améliorer le contrôle et le suivi de projet et de réduire par la même les coûts et les fréquences de replanification.Les avantages de la contribution sont démontrés sur une application pilote automobile, validant ainsi le travail de recherche au vue des faiblesses identifiées préalablement dans le contexte.

Thesis (S.M.)--Massachusetts Institute of Technology, System Design & Management Program, 2004.
Includes bibliographical references (p. 79-80).
In the 1940s and 1950s poor air quality in major metropolitan areas throughout the United States started to negatively influence the health of citizens throughout the country. After numerous studies the government concluded that mobile sources of air pollution were a significant contributor to the deteriorating air quality. From that point onwards, the automobile manufacturers have been forced to comply with ever tightening emission regulations. This thesis describes an original investigation into the conflicting clockspeeds that prohibit rapid integration of new automobile emission technologies into production automobiles. Common themes and barriers to technology implementation are uncovered by systematically analyzing current production emission technology and exhaust gas after-treatment systems, and investigating how those systems have evolved over the years. A heuristic for analyzing the technology clockspeed is developed by decomposing the problem into four interconnected cycles. These four cycles correspond to the government's process to develop new automobile emission control regulations and the automobile manufacturer's ability to engineer and certify vehicle platforms, engines, and combustion after-treatment systems. This thesis analyzes the emission control technology development process in six chapters. The first chapter deals with setting the scope and defining the boundaries of the systems that will be analyzed. Chapter two analyzes the driving forces behind the creation of emission regulations and the legislative processes that transform ideas into law. Chapter three analyzes the second level decomposition of the problem at the vehicle level with a specific emphasis on Ford Motor Company's Fox vehicle platform.
(cont.) The fourth chapter decomposes the problem to the engine system level with a focus on the production history of American V8 engines. Chapter five investigates the management of a catalytic converter development program and recommends an organizational structure to efficiently develop catalytic converter systems. The organizational structure recommendation is based on results obtained from a task oriented design structure matrix and a system engineering decomposition.
by John Penney.
S.M.