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Automotive Electronic Control Unit (ECU) has semiconductor devices performing various time dependent functions. It is essential to understand the transient thermal behavior of these devices for designing a reliable system. Detailed thermal model (DTM) is the need of the hour to understand the characteristics by performing a transient system level simulation. The information to build DTM is not readily available in the public domain due to intellectual property protection from the device suppliers. To overcome this, the present work showcases the procedure to develop Transient Thermal Network Model (TTNM) using resistance and capacitance values extracted from the impedance curve provided by the semiconductor manufacturer. TTNM model is developed for a typical DPAK and D2PAK device and validated by comparing impedance curve derived from simulation with datasheet.

This paper discusses simplified lumped parameter thermal modeling of power train components. In particular, it discusses the tradeoff between model complexity and the ability to correlate the predicted temperatures and flow rates with measured data. The benefits and problems associated with using a three lumped mass model are explained and the value of this simpler model is promoted. The process for correlation and optimization using modern software tools is explained. Examples of models for engines and transmissions are illustrated along with their predictive abilities over typical driving cycles.

In response to demands for higher fuel economy and stringent emission regulations, OEMs always strive hard to improve component/system efficiency and minimize losses. In the driveline system, improving the efficiency of an automotive rear-axle is critical because it is one of the major power-loss contributor. Optimum oil-fill inside an axle is one of the feasible solutions to minimize spin losses, while ensuring lubrication performance and heat-dissipation requirements. Thus, prior to conducting vehicle development tests, several dyno-level tests are conducted to study the thermal behavior of axle-oil (optimum level) under severe operating conditions. These test conditions represent the axle operation in hot weather conditions, steep grade, maximum tow capacity, etc. It is important to ensure that oil does not exceed its thermal limits (disintegration of oil leading to degradation).

An analytical thermal model of the project Apollo Lunar Module and a digital computer routine for processing the thermal model are described. The thermal model simulates the environmental control system, the crew, and the vehicle structure. The computer routine utilizes a unique computation technique to minimize computer time requirements. Experimental data from thermal vacuum tests of the Lunar Module and results of the transient thermal analysis are compared. Thermal predictions for nominal missions are compared with the Apollo 9 and 11 flight data.

With the constant need to meet new environmental regulations, the improvement of automotive exhaust systems technologies to be cleaner and more effective is a necessity. To achieve these regulations the automakers have been focused on the development of better particle filters and more effective cleaning processes. Catalyst Oxidation and Diesel Particle Filter Regeneration are good and effective techniques to accomplish these objectives but the amount of heat generated by these processes is a concern in the thermal management of the vehicle. To gain a better understanding of these effects Finite Element Thermal Analysis has proved to be a useful tool to predict and observe the increment of temperature during these processes. This work is focus on a simulation process using several 1-D and 3-D techniques to predict the skin exhaust temperature during the regeneration process moment in which the system achieve the maximum temperature.

An analytical thermal model of the project Apollo Command Module has been developed by the General Electric Co., Apollo Support Dept. for the National Aeronautics and Space Administration, Manned Spacecraft Center. This model simulates the entire spacecraft structure and the four closed fluid loops of the Environmental Control System. The configuration of the model is discussed as well as the correlation of this type model with test data. Also covered are the environmental data used in conjunction with the model for mission analysis. Typical results of the mission analyses are discussed in more detail.

The bearing load in today's engines has increased significantly due to the improvement of the combustion method and the increasingly demanded output power. Numerous studies including thermo-elastic deformation have already been done for steady state loading. However, engine bearings cannot be considered as working under such steady state. Recently, few transient THD analyses took place to get close to the engine actual working conditions. In this work, a numerical method is developed for the analysis of transient thermo-elasto-hydrodynamic behavior of connecting rod big-end bearings. The energy equation of the oil film and the heat transfer equation of the bearing solids together with the Reynolds' equations are solved. The bearing mechanical and thermal deformations are calculated using Finite element method.

The passby noise is the net effect of the noise from the engine, tires, vehicle panels, the fan and the exhaust silencer. Exhaust noise is probably the loudest component of the passby noise in diesel trucks. The passby noise is measured when the vehicle is in transient condition according to the standards. A technique is developed to simulate the transient noise from the exhaust using 1-d simulation software AVL-Boost. It considers thermodynamics of combustion in the engine including the turbocharger, inertia of the engine and the vehicle. The technique helps in optimizing exhaust silencer, acceleration and in-cylinder parameters in transient conditions and the turbocharger fatigue. A 165 kW 6-cylinder turbocharged and intercooled engine is simulated. The transient performance of the engine in the vehicle is validated by comparing the predicted results with the observed fuel consumption on road, time to accelerate to 60 km h−1 and the fluctuations in the turbocharger speed.

“More electric” aircraft requires more power electronics integration. Traditional cooling systems reach their maximal performances because of too high thermal dissipation of these components. Thanks to their heat transport capacity and their passive pumping, two-phase fluid capillary pumped loops appear among identified alternative solutions. Before being used in aircrafts, some investigations are needed to estimate the ability of these systems to ensure thermal transfer under harsh environment: vibrations, accelerations, cooling temperature range … If lots of steady state modeling are available in the literature, few transient models exist. However, transient phases set the main problem for two-phase fluid capillary pumped loops in airplane environment. This paper proposes a transient thermohydraulic modeling approach of a capillary pumped loop developed for gravitational applications: the Capillary Pumped Loop for Integrated Power (CPLIP).

This paper identifies and analyzes steady-state and transient tire properties affecting vehicle directional response characteristics. The study is limited to the relationship between lateral force and slip angle. It shows fundamental differences between steady-state and transient properties. Tire transient properties are described by a force-slip angle loop with cornering stiffness and dynamic lateral force offset as parameters. Cornering stiffness is presented as a variable that changes with speed and steer rate. An interrelationship between cornering stiffness and dynamic lateral force offset resulting from the time lag between lateral force and slip angle is shown. Ramp steer techniques for measuring transient tire properties on a road trailer and on an external drum machine are described. A need for transient tire data for computer simulations of vehicle transient steer maneuvers is shown.

The objective of this project was to investigate the transient performance of a three-element torque converter used in automotive applications. The investigation was conducted by running lab tests as well as numerical simulations. Lab tests subjected various torque converters to transient conditions similar to that seen in automotive applications. Numerical simulations were focused on solving a set of nonlinear differential equations that result from application of energy and momentum conservation laws. A computer model was created that successfully predicts the transient behavior of the torque converter. Validation of the computer model was accomplished by comparing simulation results to test data for three separate torque converters. Excellent agreement between test and simulation was seen across the range of data. Out of a need for various design parameters required in the transient model, a technique to reverse engineer the torque converter was developed.

Details of the development of metal transfer and friction were studied by drawing cold-rolled bare, galvannealed, electrogalvanized, and hot-dip galvanized strips with a mineral-oil lubricant of 30 cSt viscosity at 40 C, over a total distance of 2500 mm by three methods. An initial high friction peak was associated with metal transfer to the beads and was largest with pure zinc and smallest with Fe-Zn coatings. Insertion of a new strip disturbed the coating and led to the development of secondary peaks. Long-term trends were governed by the stability of the coating. Stearic acid added to mineral oil delayed stabilization of the coating and increased contact area and thus friction with pure zinc surfaces. The usual practice of reporting average friction values can hide valuable information on lubrication mechanisms and metal transfer.

Aircraft power demands continue to increase with the increase in electrical subsystems. These subsystems directly affect the behavior of the power and propulsion systems and can no longer be neglected or assumed linear in system analyses. The complex models designed to integrate new capabilities have a high computational cost. This paper investigates the possibility of using a hardware-in-the-loop (HIL) analysis with real time integration. A representative electrical power system is removed from a turbine engine model simulation and replaced with the appropriate hardware attached to a 350 horsepower drive stand. In order to update the model to proper operating conditions, variables are passed between the hardware and the computer model. Using this method, a significant reduction in runtime is seen, and the turbine engine model is usable in a real time environment. Scaling is also investigated for simulations to be performed that exceed the operating parameters of the drive stand.

Localization and ranking of sound radiating regions on tyres under transient conditions is very difficult both because of the transient nature and because it is difficult to measure sufficiently close to the sound radiating regions. Using Near-field Acoustic Holography it is possible to measure at some distance and then extrapolate back to the surface of the tyre. With the Time Domain Acoustical Holography it is further possible to study the transient nature of the sound generation in any desired detail. As an example, the present paper compares the sound radiation under stationary and under accelerating conditions.

The California Air Resources Board (CARB) has tested the utility of the Model 3090 Engine Exhaust Particle Sizer (EEPS™) by TSI in measuring pre- and post-trap particulate matter (PM) emissions from a medium-duty truck. Pre- and post-trap measurements are used to evaluate the effect of engine operation on PM emissions and trap effectiveness. Because of mounting evidence that ultrafine (UF) particles are harmful, regulatory agencies are investigating new and promising instrumentation for improved characterization of such particles in emissions. This is especially true for fast-response instruments that can be used to size-resolve real-time UF emissions from prominent sources such as diesel engines. The EEPS uses diffusion charging, electrical mobility segregation, and electrometers. It is designed for the number measurement of transient aerosols in the size range of 5.6 to 560 nm. It collects 10 measurements per second at a flow rate of 10 lpm.

As emissions regulations and carbon footprint are more and more demandingly controlled, thermal efficiency of engine components must be optimized. Valve group components have to allow for ever increasing temperatures, endure aggressive condensates or even contribute directly to rising efficiency and emissions demands. Even with integrated and cooled exhaust manifolds, the exhaust valves are meeting full combustion temperatures, especially for stoichiometric combustion. MAHLE has developed a new technology in order to measure valve temperatures in real time, i.e. Transient Valve Temperature Measurement (TVTM). This is a complex methodology using thermocouples installed inside of the valves, offering the possibility to run the engine at different conditions, without any functional changes in the valve train system at all. Specifically valve rotation is not affected and thus temperatures all around the valve seat can be captured during rotation.

The accuracy of low-level emission measurements has become increasingly important, due to the development and implementation of ULEV, SULEV, and PZEV vehicles. Measurement of these decreasing levels of automotive emissions requires new sampling and measuring techniques. Several alternative emission sampling techniques have been investigated to minimize measurement variability and maximize system repeatability. An alternative technique to obtain accurate low-level emissions measurement from SULEV vehicles is the Bag Mini-Diluter, which uses a proportional signal from an Exhaust Volume Measurement Device to sample vehicle exhaust. Crucial to successful proportional sampling of vehicle exhaust flow is the performance of the Exhaust Flow Measurement Device. This study evaluates an Exhaust Volume Measurement Device commonly used with a Bag Mini-Diluter.

A formula is developed for computing the energy loss per unit distance (or the “rolling loss”) of tires operating under transient conditions. The formula is applied to two transient test schedules - a warm-up test with constant speed and zero torque (free-rolling), and an urban driving test with rapidly varying speeds and braking/driving torques. Test results indicate that the average rolling loss during warm-up is 9%, and during urban driving, 26 to 47% higher than the steady-state rolling loss. Equipment problems associated with transient testing are indicated.

The door closing sound is one of the important quality of a vehicle, and it is useful to study the improvement method of closing sound. As a step to clarify the relationship between the door structure and closing sound, it is attempted to correlate the formation of closing sound with the vibration, and explained that the effect of structural modification aimed to improve the closing sound from the viewpoint of vibration. First, the formation process of the vibration during the door closing is clarified through the analysis method of transient vibration using the pulse laser holography. And the quality of closing sound are evaluated based on the time historical fluctuation of frequency characteristics. Next, the correlation between the closing vibration and sound are studied, and for the case of that the closing sound are changed by the structural modification, the correlation are confirmed.

Predicting the vibration of a motor gearbox assembly driven by a PWM inverter in the early stages of development is demanding because the assembly is one of the dominant noise sources of electric vehicles (EVs). In this paper, we propose a simulation model that can predict the transient vibration excited by gear meshing, reaction force from the mount, and electromagnetic forces including the carrier frequency component of the inverter up to 10 kHz. By utilizing the techniques of structural model reduction and state space modeling, the proposed model can predict the vibration of assembly in the operating condition with a system level EV simulator. A verification test was conducted to compare the simulation results with the running test results of the EV.