Spin Testing Improves Electrified Propulsion Rotor Design for Production and Certification

<div class="htmlview paragraph">Evaluations were made of the short-term (5 minute) durability at high temperatures of 85 mm outer diameter ceramic radial turbine rotors made of silicon nitride using an improved hot gas spin test rig.</div> <div class="htmlview paragraph">Under no load conditions, the rotors withstood a maximum turbine tip speed (Ut) of 550 m/s without bursting at a turbine inlet gas temperature (TIT) of 1240°C.</div> <div class="htmlview paragraph">Under partially loaded conditions, they withstood up to Ut of 500 m/s at TIT of 1280°C without bursting.</div> <div class="htmlview paragraph">The test results indicated that the knee point temperature in terms of TIT at which the failure tip speed decreased sharply was about 40°C higher under partially loaded condition than under no load condition.</div> <div class="htmlview paragraph">The temperature and stress distribution in the turbine in the hot gas spin test were calculated by the finite element analysis, which supported the dependence of the knee point temperature in terms of TIT at spin test on load condition.</div>

<div class="section abstract"><div class="htmlview paragraph">The paper presents a numerical activity directed at the analysis and optimization of internal combustion engine water cooling jackets, with particular emphasis on the fatigue-strength assessment and improvement.</div><div class="htmlview paragraph">In the paper, full 3D-CFD and FEM analyses of conjugate heat transfer and load cycle under actual engine operation of a single bank of a current production V6 turbocharged diesel engine are reported.</div><div class="htmlview paragraph">A highly detailed model of the engine, made up of both the coolant galleries and the surrounding metal components, i.e., the engine head, the engine block, the gasket, the valve guides and valve seats, is used on both sides of the simulation process to accurately capture the influence of the cooling system layout under thermal and load conditions as close as possible to actual engine operations.</div><div class="htmlview paragraph">Concerning the CFD side, a 50-50 binary mixture of ethylene-glycol and water is used in order to correctly reproduce the coolant behavior, while boundary conditions are derived from a combination of experimental measurements and a CFD-1D model of the whole engine.</div><div class="htmlview paragraph">In order to find a proper CFD setup for the optimization of the thermal behavior of the engine, a preliminary comparison between experimental temperature distribution within the engine head and CFD forecasts is carried out. Eight thermocouples are used to measure the engine head local temperature at some critical locations.</div><div class="htmlview paragraph">Among the many competing numerical sub-models involved in the CFD simulations, particular attention is devoted to the modeling of phase transition and vapor nuclei formation within the coolant galleries.</div><div class="htmlview paragraph">Concerning the FEM side, thermo-mechanical analyses are carried out aiming at addressing the design optimization of the engine in terms of fatigue strength. In view of the wide range of thermal and load conditions, both high-cycle and low-cycle fatigue must be properly characterized by means of ad-hoc criteria. An energy-based criterion specifically suited for low-cycle fatigue regions is therefore superimposed to well-established S-N o ε-N criteria for the high cycle fatigue regions.</div><div class="htmlview paragraph">The proposed methodology shows very promising results in terms of point-wise detection of possible engine failures and proves to be an effective tool for the accurate thermo-mechanical characterization of internal combustion engines under actual life-cycle operations.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Strict emission regulations and the need of higher efficiency of future dual fuel engines require an optimized combustion process. For getting a better understanding of the in-cylinder combustion process optical investigations represent a powerful tool. For medium speed dual fuel engines, optical investigations are pretty rare respectively not available. Especially the avoiding of knock events within the combustion process is a key development topic to realize high engine load and high engine efficiency.</div><div class="htmlview paragraph">For the investigations a fully flexible dual fuel test engine was used. The engine is operated with a natural gas / air cylinder charge which is ignited by a small micro pilot diesel injection within the gas mode.</div><div class="htmlview paragraph">Beside standard development measurement techniques like cylinder pressure measurement and exhaust gas emission measurement, optical measurement techniques were used to gain information about the in-cylinder combustion process of the pilot fuel combustion as well as the combustion of the natural gas / air cylinder charge. It is desirable to realize an entire visualization of the combustion within the combustion chamber under real engine conditions at full load. This means the need for a minimal invasive measurement technique with small modifications of the combustion chamber design and surface temperatures.</div><div class="htmlview paragraph">Due to these requirements a tomographic, fiber based measurement technique was used synchronal to a high speed visualization of the in-cylinder OH* chemiluminescence. The fiber based measurement technique uses 128 optical fibers in which every single fiber measures the luminescence of a special observation volume. The raw data of the single fibers is used to calculate, based on a tomographic algorithm, the in-cylinder light emission intensity distribution to visualize the combustion in a horizontal cutting plane over the whole bore diameter. To complete the information of the combustion by the third dimension, a synchronized, intensified high speed camera was used to record the OH* chemiluminescence. Both measurement techniques in combination give a far-reaching image of the in-cylinder combustion process.</div><div class="htmlview paragraph">To increase the understanding of the in-cylinder processes and to optimize the combustion process, typical combustion relevant parameters like pilot injection nozzle, pilot injection timing, pilot injection pressure and excess air ratio were varied. In this publication the basic combustion mechanisms are described for two different injection timings at full load. In addition the isolated pilot fuel combustion in pure air for an injection timing which gives a transient point between partly premixed and strongly premixed combustion is shown.</div><div class="htmlview paragraph">The measurement results show an ignition process which is strongly influenced by the reaction kinetic mechanisms. Especially for early injection timings a long ignition delay was measured which result in a well premixed pilot fuel within the natural gas / air mixture. Moreover, the flame propagation speed was calculated and a reaction kinetically controlled post flame combustion process was observed.</div><div class="htmlview paragraph">In addition a different mechanism for in-cylinder pressure oscillation, which usually is detected as engine knock, was shown which differs from the generally known mechanism in spark plug ignited passenger car engines.</div></div>

<div class="section abstract"><div class="htmlview paragraph">A vehicle’s structure has more than 4000 spot welds, which can be considered as one of the main design criteria that affects the general stiffness as well as the durability of an automobile. Considering the essential role of finite element-based simulations of the spot-welded structures on the design phases of vehicle development, accuracy of analyses can be considered as one of the main concerns to meet the design objectives. This study examines the sensitivity of solid element spot weld modeling technique to nugget diameter. Comparative stress and multi-axial low cycle fatigue analyses are conducted for the inspection of the effect of weld diameter on solid element spot weld simulations. Displacement contours as well as local stress profiles at the vicinity of the spot welds are examined to evaluate the effect of nugget diameter on general stiffness and safety. Multi-axial low cycle fatigue analyses are conducted for the specimens composed of U-profiles, and different thickness levels are simulated for a set of nugget diameters. Simulation results are compared with the low cycle fatigue tests’ life cycles to determine the accuracy of the solid element spot weld modeling methodology and its sensitivity to nugget diameter.</div></div>

<div class="htmlview paragraph"> </div> <div class="htmlview paragraph"> </div> <div class="htmlview paragraph">Five systems, fuel injection, ignition modulation, intake port flow control, exhaust after-treatment, and electric propulsion systems, are discussed here in terms of engine design modifications and new systems retrofitted to the motorcycle to reduce the exhaust emission.</div> <div class="htmlview paragraph"> </div> <div class="htmlview paragraph">A fuel injection system has been implemented to a 125cc air-cool four-stroke engine, and the results show that the improvement on the fuel economy, reduction of emission on HC and CO, and the fuel economy are 20%, 68%, and 10% respectively. By implementing the electrical ignition system into the target engine, the fuel economy and emission have slightly improved. The application of the inlet air flow control to a target engine also obtains 75% on CO reduction. The effectiveness of the exhaust after-treatment on a 80cc 2-stroke engine has demonstrated that the emission can be reduced up to 75%. The last emission reduction development is the electric propulsion system development which provide a zero emission and better energy efficiency solutions for the future motorcycle usage in the urban areas.</div> <div class="htmlview paragraph"> </div> <div class="htmlview paragraph">The authors will overview the development methodologies of the mentioned systems and the effectiveness of emission and fuel economy improvement from these engineering efforts in this article.</div> <div class="htmlview paragraph"> </div>

<div class="htmlview paragraph">The problem of cracks in cylinder heads due to low cycle fatigue (thermal fatigue) is well known for engines with high specific power output. However it is still difficult to predict the lifetime of a new cylinder head due to the number of influencing parameters and the complexity of material behavior. Better understanding of cylinder head fatigue can improve the development process of a new engine concerning CAE as well as mechanical testing efficiency.</div> <div class="htmlview paragraph">Therefore a CAE tool which can calculate strains and stresses as a function of time for a defined operating cycle of the engine was developed. In parallel a measuring technique was developed which allows to measure strains on the surface of the combustion chamber side of the cylinder head during fired engine operation.</div> <div class="htmlview paragraph">For different Aluminum-Silicon casting alloys the material behavior was described in the Finite Element Program ABAQUS by a nonlinear kinematic / isotropic hardening model. The numerical parameters were determined by measurement results. The cyclic thermal load (55°C - 210°C.) was applied to the assembled cylinder head FE-model.</div> <div class="htmlview paragraph">A strain gage application was developed which allows dynamic strain and surface temperature measurements during fired engine operation. The results are used for comparison to and calibration of the calculations. More-over they can serve to optimize thermo-shock-test cycles. The measured time behavior of the material strains makes it possible to optimize the hot and cold cycle duration of thermo-shock tests regarding complete test duration and lifetime validity.</div> <div class="htmlview paragraph">In this paper, the potential for improving of the numerical model is discussed and the successful use of conventional strain gages during fired engine operation is described. A comparison of calculated and measured strain in a temperature cycle validates the results.</div>

<div class="htmlview paragraph">Back in the first two decades of automobile development, electric propulsion was a serious competitor for the internal combustion engine.</div> <div class="htmlview paragraph">Electrically-propelled vehicles, however, soon proved unable to satisfy users' increasing performance demands in terms of range, acceleration, top speed and hill-climbing, together with such factors as operating life, initial purchase price, running costs and reliability.</div> <div class="htmlview paragraph">Engineers investigating electric propulsion today face precisely the same unwelcome legacy as their predecessors, despite many and varied attempts in the meantime to improve the components of the electric vehicle's drive system (energy storage device, motors, controller).</div> <div class="htmlview paragraph">Progress in battery development, particularly in the case of the NaS system, has nevertheless enabled us at least partly to overcome the previous problems associated with electric drive systems, though it cannot be claimed that all obstacles to its commercial application have been eliminated as yet.</div> <div class="htmlview paragraph">This is a report on the experience gained at BMW to date, the current state of work and development trends.</div>

<div class="section abstract"><div class="htmlview paragraph">Fatigue failure is one of the major failure modes for internal combustion engines, especially with reduction in engine size and increase in combustion pressure and operating temperature. Dynamometer tests are devised to ensure engine durability for high and low cycle fatigue. With the advent of CAE technology, the dynamometer test behavior can be simulated using CAE analysis and engine durability can be assessed. The data generated in CAE analyses can be used to predict failure of the engines or future engine design modifications.</div><div class="htmlview paragraph">The present paper has two parts - first is running finite element analysis (FEA) to get stress, strain data and running high cycle fatigue analysis to get safety factors and second is creating a predictive tool to assess failures using data from the first part as inputs. Using advancements in the field of machine learning, the paper presents use of support vector machine (SVM) algorithm to predict failure of the engine based on inputs.</div><div class="htmlview paragraph">The paper discusses procedure to build the data driven model and its results. Such data driven model can be used as a tool to predict failure of engine arising from future design changes or as a variation tool to predict failure arising from changes in inputs.</div></div>

<div class="htmlview paragraph">Cost reduction is an essential and continuous process to meet the competitive environment of product pricing and to increase the profitability of an organization. Integrated cost reduction exercise encompass all the possible avenue., e.g. Alternate material & it's procurement system, batch size, material handling, manufacturing process improvements, logistics and finally review & make changes to derive an optimum design and cost reductions to maximum extent.</div> <div class="htmlview paragraph">This paper presents a systematic approach for achieving the cost reduction of an existing 5.7Tonnne LCV truck frame from design consideration. The methodology involves, identification of the components of the frame for the cost reduction, redesign of existing frame compatible to the cost reduction need, preliminary performance evaluation of the present frame and the cost reduction frame, redesign of the frame for the performance, detailed cost evaluation, prototype manufacturing, laboratory testing, vehicle level testing and final release for the mass production. Chassis designers contributed for major design changes to derive maximum cost reduction without compromising durability or performance deterioration due to bending or torsional stiffness changes from existing frame.</div> <div class="htmlview paragraph">After a comprehensive study, it is identified that deletion of the boxing plate and the replacement of the tubular cross members with channel type cross members will contribute for the potential cost savings of the frame. With these inputs concept design of the cost reduction frame is arrived.</div> <div class="htmlview paragraph">The important performance characteristics of a chassis frame are structural integrity (Strength and Stiffness) and durability. The existing and the cost reduction frames are evaluated based on these performance characteristics.</div> <div class="htmlview paragraph">The final design of the cost reduction frame is arrived based on CAE analysis of the frame for structural integrity, Number of iterative operations got eliminated due to the use of multidisciplinary optimization (MDO) package. Different load cases which focus on strength and stiffness of the frame are considered as an example.</div> <div class="htmlview paragraph">Bending and torsional stiffness of the existing and the cost reduction frames are also measured in the test rig. It is found that bending stiffness of the cost reduction frame is 9.15% more than the existing frame and torsional stiffness of the cost reduction frame is closer to the existing frame. It was also found that the durability of the existing and the cost reduction frame in bending is almost same. The test specifications are arrived based on strain measurements on the existing frame in our torture track.</div> <div class="htmlview paragraph">The above methodology helped us in deriving a estimated cost saving of Rs.311/- by the modified frame design. There are other intangible benefits like savings in labour cost due to elimination of the boxing plate, savings in the processing cost of boxing plate welding etc. The estimated cost savings is likely to be double of the above amount and would result in 3.5% of the Chassis frame aggregate cost.</div>

<div class="htmlview paragraph">A comprehensive strategy for applying quasi-static and dynamic tests in the development of automobile side impact protection systems is presented. The approach is geared towards providing an understanding of how vehicle components relate to occupant protection as measured by the FMVSS 214 dynamic side impact test. These test methods are viewed as being complimentary, rather than competitive, tools to be employed in the overall strategy.</div> <div class="htmlview paragraph">The approach begins with obtaining detailed data from an FMVSS 214 dynamic test. Additional instrumentation is required so that the results of the test can be used to form the basis for setting conditions for subsequent quasi-static and dynamic tests.</div> <div class="htmlview paragraph">The Composite Test Procedure (CTP) is an integral part of the process. As described here, the CTP can be conducted under three different methods; three step procedure, continuous computer control, and continuous manual control. The principal value of the CTP method is to obtain spatial relationships within the door structure, overall force-deflection properties of the vehicle body structure, and input for a simplified, linear spring mass model to represent the FMVSS 214 dynamic test.</div> <div class="htmlview paragraph">Door structures are tested to provide a preliminary evaluation of door modifications, including both structure and trim panel, without resorting to full vehicle body development and build. The methods for door tests include both quasi-static, where the door structure and trim panel are evaluated, and dynamic (sled), where door trim panels are evaluated. Results obtained from these component tests can be related to full scale crash testing through mathematical modelling.</div> <div class="htmlview paragraph">The complimentary nature of these test methods is then discussed relative to improving performance in an FMVSS 214 dynamic test. A flow chart showing the relationship to a complete vehicle development program is presented and discussed.</div>

<div class="htmlview paragraph">Low-cycle fatigue is a term used to describe the thermal and/or mechanical loading conditions which cause premature failure of materials at less than 20,000 cycles. These cyclic stress conditions are prevalent during engine start-up or shut down and in severe flight maneuvers. From the design standpoint, it is important to assess and predict the behavior of compressor and turbine component materials under these severe conditions.</div> <div class="htmlview paragraph">This paper presents the low cycle fatigue data on six candidate materials which were considered for an advanced engine. The materials were investigated simultaneously by pull-pull and by modified rotating beam fatigue testing techniques. Results indicate that the candidate materials can sustain appreciable cycling at stress levels beyond design limit before fracture occurs by the low cycle fatigue mechanism. Of the materials investigated, Udimet 630 exhibited the optimum low cycle fatigue resistance.</div>

<div class="section abstract"><div class="htmlview paragraph">The design and testing of innovative components and control logics for future vehicular platform represents a challenging task in the automotive field. The use of scale model vehicles constitutes an interesting alternative for testing assessment by decreasing time and cost efforts with a potential benefit in terms of safety.</div><div class="htmlview paragraph">The target of this research work is the development of a customized scale vehicle platform for verifying and validating innovative control strategies in safe conditions and with cost reduction. Consequently, the electrification of a radio-controlled 1:5 scale vehicle is carried out and a customized remote real-time controller is installed onboard. One of the main features of this commercial product is its modular characteristics that allows the modification of some component properties, such as the viscous coefficient of the shock absorbers, the stiffness of the springs and the suspension geometry. The original vehicle is equipped with a 2-stroke internal combustion engine, whose throttle command is provided by a common radio transceiver/receiver unit. The original configuration is commonly adopted for radio-controlled race car competitions, but the presence of a noisy combustion engine is not well suited for implementing a precise and accurate control logic based on onboard sensor measurements; hence, the conversion into an electric vehicle represents the adopted solution in this research activity.</div><div class="htmlview paragraph">In particular, the electrification process accounts for the replacement of the internal combustion engine and fuel tank with a brushless DC motor, a battery pack, and a planetary gearbox. CAD tools are exploited for the selection of the replacement components and the design of the mounting systems. Additionally, a Speedgoat Baseline Real-Time Target Machine is installed for implementing the customized control logic, developed in MATLAB/Simulink environment, for controlling the traction electric motor and the steering servomotor.</div><div class="htmlview paragraph">After a preliminary bench testing phase, a remote control is implemented for the validation of the system through maneuvers typically carried out for vehicle handling analysis.</div></div>

<div class="htmlview paragraph">Electric vehicles today clearly represent the only solution fulfilling the zero emission vehicles (ZEV) standard. However, they are still not an equivalent alternative to gasoline driven cars due to the well known problems of today's batteries. The concept of a parallel hybrid drive line can be an optimal combination of both principles of propulsion in that the gasoline engine guarantees a wide range operation, while electric propulsion can be used within the restricted zero emission zones [<span class="xref">20</span>].</div> <div class="htmlview paragraph">The parallel hybrid drive train described here has been realized at the Swiss Federal Institute of Technology (ETH), Zurich, Switzerland. For the first time a drive line consisting of a spark ignition engine, an electric asynchronous machine, a flywheel, and a wide range continuously variable transmission (CVT) is realized. An overall control system has been developed for the drive train. This drive line has been integrated in a multi purpose van for real road testing. This paper describes the experimental results from the testing of various individual components, from the power train on a dynamic test bench and from the test vehicle on a chassis dynamometer test bench. Fuel consumption is cut near by half in the European urban driving cycle (ECE-R15/04), based on fuel without the use of electricity.</div>

<div class="htmlview paragraph">Driver fatality rate of a passenger vehicle is considerably high when struck on the side by an LTV (light truck and van). Aggressivity of LTVs, particularly in side crashes, needs to be reduced to improve this incompatible situation.</div> <div class="htmlview paragraph">Crash energy absorption share of a passenger car struck on the side by an LTV was measured through component tests. As a result, B-pillar of the struck passenger car was found to receive most of the crash energy intensively. This intensive energy triggered large B-pillar deformation. Computer simulation proved that B-pillar deformation was closely related to occupant injury. The key to mitigate the injury of side-struck car occupant, therefore, is to disperse crash energy to other structural parts than B-pillar.</div> <div class="htmlview paragraph">Front-end structures of LTVs that realize crash energy dispersion were designed and examined. The structures include (a) optimization of the vehicle height, and (b) adoption of a forward-extended sub-frame. The aggressivity-reducing effects were confirmed by computer simulation.</div> <div class="htmlview paragraph">The aggressivity-reducing structures were found effective in frontal impact as well. The effect was confirmed by using the aggressivity parameters, i.e., Coefficient of Variance and Average Height of Force in vehicle-to-barrier full frontal impact simulation.</div>

<div class="htmlview paragraph">Designers of mobile and off-highway equipment are developing more efficient systems to meet the demands of increased competition. Improving designs often includes a review of the hydraulic system, as engineers seek more efficient means of transmitting power. Increasingly, the focus is on reducing the size of hydraulic components or concentrating power in smaller package sizes. This can be accomplished by using higher operating pressures.</div> <div class="htmlview paragraph">To meet this challenge, developers of new off-highway hydraulic components must be able to test under those more demanding high pressure conditions. Fortunately, there are now more test-stand components available to support these manufacturers, as they design and qualify their products for higher operating pressures.</div> <div class="htmlview paragraph">Component testing is currently being conducted at pressures as high as 15 000 psi (1040 bar). As this trend toward higher pressures continues, component manufacturers will need durable high-pressure test systems to qualify products to meet the requirements of future mobile equipment.</div> <div class="htmlview paragraph">THE PURPOSE OF THIS PAPER is to review some of the high pressure hydraulic components currently available for use on test-stands. The paper will describe some existing test systems being used in the mobile equipment industry. These types of test-stands will increasingly be essential to qualify mobile hydraulic component suppliers' products for higher pressure ratings.</div>