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This research aims to develop an inverse control method capable of adaptively simulating dynamic models of car subsystems in the rig-test condition. Accurate simulation of the actual vibration conditions is one of the most crucial factors in realizing reliable rig-test platforms. However, most typical rig tests are conducted under simple random or harmonic sweep conditions. Moreover, the conventional test methods are hard to directly adapt to the actual vibration conditions when switching the dynamic characteristics of the subsystem in the rig test. In the present work, we developed an inverse controller to adaptively control the vibration exciter referring to the target vibration signal. An adaptive LMS filter, employed for the control algorithm, updated the filter weights in real time by referring to the target and the measured acceleration signals.

This research addresses the pressing need for reducing vehicle aerodynamic resistance, with a specific focus on mitigating wheel and tire resistance, which constitutes approximately 25% of the overall vehicle drag. While the prevailing method for reducing resistance in mass production development involves wheel opening reduction, it inadvertently increases wheel weight and has adverse effects on brake cooling performance. To overcome these challenges, novel complementary resistance reduction methods that can be employed in conjunction with an appropriate degree of wheel opening reduction are imperative. In this study, we introduce symmetrical wheels with a fan-like shape as a solution. The fan configuration influences the surrounding flow by either drawing it in or pushing it out, depending on the direction of rotation. Application of these fan-type wheels to a vehicle's wheels results in the redirection of flow inwards or outwards during high-speed driving due to wheel rotation.

Lithium-ion battery has advantages of high energy density and cost effectiveness than other types of batteries. However due to the low mechanical stability, their performance is strongly influenced by environmental conditions. Especially, external pressure on a cell surface is a crucial factor because an appropriate force can improve battery cycle life, but excessive force may cause structural failure. In addition, battery pack is composed of various components so that uncertainties in dimension and material properties of each component can cause a wide variance in initial pressure. Therefore, it is important to optimize structural design of battery pack to ensure initial pressure in an effective range. In this paper, target stiffness of module structure was determined based on cell level cycle life test, then structural design has been optimized for weight reduction. Cell cycling tests were performed under different stiffness conditions and analyzed with regression model.

Automotive OEMs have introduced a new development paradigm, modular architecture development, to improve diversity quality and production efficiency. It needs solid fundamentals of system-based performance evaluation and development for each system level and single component level. When it comes to NVH development, it is challenging to realize the modular concept because noise and vibration should be transferred through various transfer path consisting of many parts and systems, which interact with each other. It is challenging for a single system of interest to be evaluated independently of the adjacent parts and environments. In this study, a new system-based development process for a vehicle suspension was investigated by applying blocked force theory and FRF-based dynamic substructuring. The objective is to determine the better dynamic stiffness distribution of many bushes installed in a suspension system in the frequency range corresponding to road noise.

Since the introduction of the DrivAer in 2012 this model has become the standard generic aerodynamic benchmark and aerodynamic research model used by automotive OEMs, software vendors and researchers. In 2017, the relevance of the DrivAer has been furthered by the inclusion of a simplified engine bay. Whilst the DrivAer has become the popular standard, the availability of detailed wind tunnel test data, a key enabler for more sophisticated aerodynamic benchmarking and research, remains limited. This paper presents a comprehensive set of wind tunnel test data of the notchback version of the Ford Open Cooling DrivAer, including aerodynamic force measurements, detailed surface pressure measurements and flow field measurements at 3 cross-sections in the vicinity of the model. In addition, the paper will discuss the sensitivity of the experimental data to wind tunnel repeatability and facility-to-facility variations.

This paper examines the effect of pulse-and-glide (PnG) driving strategies on the fuel efficiency when applied on parallel HEVs. Several PnG strategies are proposed, and these include the electrical, mechanical, and combined PnG strategies. The electrical PnG strategy denotes the hybrid powertrain control tactics in which the battery is charged or discharged according to the power demanded while maintaining the constant vehicle speed. On the other hand, the mechanical PnG strategy denotes the powertrain control tactics in which the vehicle accelerates or decelerates according to the power load while minimizing the battery usage. The combined PnG strategy involves both electrical and mechanical strategies to find a balanced point in between them. Here, a tradeoff relationship between the fuel efficiency and the vehicle drivability related to the tracking performance of the desired target speed is revealed.

This paper presents the direct liquid-cooled power module with the circular pin fin which is the inverter parallel cooling system for high output EV/FCEV. The direct cooling system of a conventional inverter is designed to supply coolant along the direction in which the heating element such as Si-chip is disposed and discharge coolant to the opposite side. In case of the inverter, the higher the output is, the larger temperature difference between inlet and outlet becomes due to the heat exchange of the heat generation element, so that temperature difference depends on the position of Si-chip. Since lifetime is judged on the basis of maximum temperature of Si-chip, the inverter itself must be replaced or discarded due to durability of the inverter even though Si-chip can drive further. The simple way to solve this problem is to increase cooling flow rate, but this leads to excessive increase in pressure loss due to circular pin fin.

The tire is the vital element in vehicle dynamics, as its contact patch transmits all forces and moments to the ground (accelerating, braking, cornering, rolling).Over the recent decades tire development for passenger cars has been continuously improved and optimized in order to achieve a good overall vehicle performance in R&H that is in balance with all other tire performances (Wear, Durability, NVH, RR, Miles). This general development process has to be suitable for various vehicle types from regular passenger cars over eco-friendly hybrid or electric vehicles to high performance sport cars. The balance between Ride and Handling performance is further adjusted to local customer preferences that are usually distinguished by markets (US, EU, Asia). The tire development process, which is embedded in the overall vehicle development, is usually realized in a mutual collaboration between OEM and tire supplier.

The performance and marketability of eco-friendly vehicles highly depend on their high-voltage battery system. Lithium-ion pouch cells have advantages of high energy density and cost-effectiveness than other types of batteries. However, due to their low mechanical stability, their characteristics are strongly influenced by external conditions. Especially, external pressure on pouch cell is a crucial factor for the performance, life cycle, and structural safety of battery pack. Therefore, optimizing pressure level has been a critical consideration in designing battery pack structures for lithium-ion pouch cell. In this work, we developed an optimized structure of the battery module and pack to apply appropriate pressure on pouch cells. They also include a standardization strategy to meet the varied demand in capacity and power for automotive application.

The engine indicated torque is not delivered entirely to the wheels, because it is lowered by losses, such as the pumping, mechanical friction and front auxiliary power consumption. The front auxiliary belt drive system is a big power consumer-fueling and operating the various accessory devices, such as air conditioning compressor, electric alternator, and power steering pump. The standard fuel economy test does not consider the auxiliary driving torque when it is activated during the actual driving condition and it is considered a five-cycle correction factor only. Therefore, research on improving the front end auxiliary drive (FEAD) system is still relevant in the immediate future, particularly regarding the air conditioning compressor and the electric alternator. An exertion to minimize the auxiliary loss is much smaller than the sustained effort required to reduce engine friction loss.

Impact resistance of plastic underbody parts was studied using simulated injection-molded specimen which can be tested according to different types of material used, injection molding variants like position and number of injection molding gates, and features of ribs. Material applied was glass fiber reinforced polyamide which can be used in underbody parts. Test was performed using several combinations of injection molding gates and rib types. From the test result, optimal design guide for plastic underbody parts was determined. Also, new high impact resistant plastic material made of glass fiber reinforced polyamide 66 (PA66) and polyamide 6 (PA6) alloy was developed and the material properties useful for CAE were determined. As a case study, oil pan and muffler housing were designed following the optimal design guide and CAE. And the reliability of the sample muffler housing designed was verified.

The present study focused on CrN-Cu nanocoatings composed of nano-meter grains with CrN, Cr and Cu functioning low-friction, anti-wear and heat resistance. The coatings were synthesized by hybrid PVD including metal arc source, magentron sputter source and ion-gun source. Although Cu has low hardness, the hardness of CrNCu is not declined because it was composed of below 20nm sized grains of CrN, Cr, and Cu. However, CrN-Cu had lower friction than CrN owing to Cu’s low shear strength. CrN-Cu films optimized using the Reaction Surface Method (RSM) showed the excellent tribological behavior and low coefficient of friction compared with DLC. The tribological properties of the Cr-Cu-N demonstrated superior wear resistance and low friction at normal and high temperature conditions. The CrN-Cu nanocoatings can be used for the downsizing automotive engines working at severe tribological conditions.

In the brake system, unevenly distributed disc-pad contact pressure not only leads to a falling-off in braking feeling due to uneven wear of brake pads, but also a main cause of system instability which leads to squeal noise. For this reason there have been several attempts to measure contact pressure distribution. However, only static pressure distribution has been measured in order to estimate the actual pressure distribution. In this study a new test method is designed to quantitatively measure dynamic contact pressure distribution between disc and pad in vehicle testing. The characteristics of dynamic contact pressure distribution are analyzed for various driving conditions and pad shape. Based on those results, CAE model was updated and found to be better in detecting propensity of brake squeal.

In order to apply an effective noise reduction treatment determining the contribution of different engine components to the total sound perceived inside the cabin is important. Although accelerometer or laser based vibration tests are usually performed, the sound contributions are not always captured accurately with such approaches. Microphone based methods are strongly influenced by the many reflections and other sound sources inside the engine bay. Recently, it has been shown that engine radiation can be effectively measured using microphones combined with particle velocity sensors while the engine remains mounted in the car [6]. Similar results were obtained as with a dismounted engine in an anechoic room. This paper focusses on the measurement of the transfer path from the engine to the vehicle interior in order to calculate the sound pressure contribution of individual engine sections at the listener's position.

Most bucket type valvetrain engines use DLC coated tappet for low friction and fuel efficiency. However the requirements on coating robustness have been increased as the tribological environments have become more severe by use of low viscosity oil or higher engine output. In order to obtain higher coating efficiency and improved wear resistance, 5∼9 at.% Si doped DLC (Si-DLC) coated tappet has been developed using PACVD process. Thermal stability and wear resistance of Si-DLC were improved impressively than those of DLC, although mechanical properties such as hardness and adhesion were degradated. It seems that Si suppresses a graphitization of DLC and thin SixOy film on coating surface acts as a barrier to oxidation or flash heat.

For (benchmark) tests it is not only useful to study the acoustic performance of the whole vehicle, but also to assess separate components such as the engine. Reflections inside the engine bay bias the acoustic radiation estimated with sound pressure based solutions. Consequently, most current methods require dismounting the engine from the car and installing it in an anechoic room to measure the sound emitted. However, this process is laborious and hard to perform. In this paper, two particle velocity based methods are proposed to characterize the sound radiated from an engine while it is still installed in the car. Particle velocity sensors are much less affected by reflections than sound pressure microphones when the measurements are performed near a radiating surface due to the particle velocity's vector nature, intrinsic dependency upon surface displacement and directivity of the sensor. Therefore, the engine does not have to be disassembled, which saves time and money.

Hydroforming process is an emerging manufacturing technology which allows engineers to use continuous closed section without flange for spot weld in a given package envelope. In this research, Hydroforming is applied to a front pillar and a roof side rail for improvement of obstruction angle, body stiffness and roof crush resistance. In addition, the joints of front / center pillar that were integrated into the hydroforming part and structure of package tray were improved. As a result, front pillar width is reduced by 23%, body torsional stiffness is increased by 45% and roof crush resistance is improved by 35%.

In order to reduce brake squeal noise, it is important to identify operational deflection shape (ODS) of brake disc while squeal arises. However, in the conventional modal analysis and optical measurement, it is only able to identify limited ODS because of the technical limits. This paper details the test method to identify ODS in radial and tangential as well as axial direction of a brake disc in driving condition. Vibrational signal of a rotating disc was obtained by triaxial accelerometer installed to solid type discs/cooling fins of ventilated type discs, then ODS of disc were analyzed through digital signal processing.

Systematic numerical simulations were performed for the improvement of fuel efficiency and thermal performance of a compact size passenger vehicle. Both aerodynamic and thermal aspects were considered concurrently. For the sake of systematic evaluation, our study was conducted employing various design changes in multiple steps: 1) analysis of the baseline design; 2) elimination of the engine room components; 3) modification of the engine room component layout; 4) modification of the aerodynamic components (such as under body cover and cooling ducts). The vehicle performance characteristics corresponding to different design options were analyzed in terms of aerodynamic coefficient, engine coolant temperature, and surface temperatures of thermally critical components such as battery and exhaust manifold. Finally optimal design modification solutions for better vehicle performance were proposed.

Copper has been regarded as one of the indispensable ingredients in the brake friction materials since it provides high thermal diffusivity at the sliding interface. However, the recent regulations against environmentally hazardous ingredients limit the use of copper in the commercial friction material and much effort has been made for the alternatives. In this work, the role of the cuprous ingredients such as copper fiber, copper powder, cupric oxide (CuO), and copper sulfide (CuS) are studied using the friction materials based on commercial formulations. The investigation was performed using a full inertial brake dynamometer and 1/5 scale dynamometer for brake performance and wear test. Results showed that the cuprous ingredients played a crucial role in maintaining the stable friction film at the friction interface, resulting in improved friction stability and reduced aggressiveness against counter disk.