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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%.

The Design For Six Sigma (DFSS) process consists of four phases, identification & definition of opportunity, concept development, design optimization, and design verification. In the phase of concept development, TRIZ (Russian acronym for Theory of Inventive Problem Solving) is useful for creating new ideas from the present ideas, which includes the trimming strategy, the antidote strategy, and the picket fence strategy. In this paper, systems of a vehicle such as Variable Compression Ratio (VCR) engine, windshield wiper blade, and Continuously Variable Valve Actuation (CVVA) of engine, are selected and new concepts for each system are created by applying the previously mentioned three strategies. FMEA (Failure Mode and Effects Analysis), the latter part in the phase of concept development in DFSS, is conducted for newly generated concepts of systems that are mentioned above. As a result of FMEA, it is found that the wind lift of the wiper blade can be a serious problem.

Emissions regulations are becoming more severe, and they remain a principal issue for vehicle manufacturers. Many engine subsystems and control technologies have been introduced to meet the demands of these regulations. For diesel engines, combustion control is one of the most effective approaches to reducing not only engine exhaust emissions but also cylinder-by-cylinder variation. However, the high cost of the pressure sensor and the complex engine head design for the extra equipment are stressful for the manufacturers. In this paper, a cylinder-pressure-based engine control logic is introduced for a multi-cylinder high speed direct injection (HSDI) diesel engine. The time for 50% of the mass fraction to burn (MFB50) and the IMEP are valuable for identifying combustion status. These two in-cylinder quantities are measured and applied to the engine control logic.

The efficiency of a gap-type of deflector for suppressing vehicle sunroof buffeting is studied in this work. Buffeting is an unpleasant low frequency booming caused by flow-excited Helmholtz resonance of the interior cabin. Accurate prediction of this phenomenon requires accounting for the bi-directional coupling between the transient shear layer aerodynamics (vortex shedding) and the acoustic response of the cabin. Numerical simulations were performed using a CFD/CAA numerical method based on the Lattice Boltzmann Method (LBM). The well established LBM approach provides the time-dependent solution to the compressible Navier-Stokes equations, and directly captures both turbulent and acoustic pressure fluctuations over a wide range of scales given adequate computational grid resolution. In this study the same gap-type deflector configuration is installed on two different types of vehicles, a SUV and a sedan.

Luxury sound is one of the most important sound qualities in a premium passenger car. Previous work has shown that, because of the effects of many different interior sounds, it is difficult to evaluate the luxury sound objectively by using only the A-weighted sound pressure level. In this paper, the characteristics of such sound were first investigated by a systematic approach and a new objective evaluation method for luxury sound-the luxury sound quality index--which was developed by the systematic combination of the seven major interior sound quality indexes based on path analysis. The seven major sounds inside a passenger car were selected by a basic investigation evaluated by the members of a luxury automotive club. Seven major interior sound quality indexes were developed by using sound metrics, which are the psychoacoustic parameters, and the multiple regression method used for the modeling of the correlation between objective and subjective evaluation.

With the recent development of technologies for interpreting vibration and noise of vehicles, it has become possible for carmakers to reduce idle vibration and driving noise in the phase of preceding development. Thus, the issue of noise generation is drawing keen attention from production of prototype car through mass-production development. J. D. Power has surveyed the levels of customer satisfaction with all vehicles sold in the U.S. market and released the Initial Quality Study (IQS) index. As a growing number of emotional quality-related items are added to the IQS evaluation index, it is necessary to secure a sufficiently high quality level of low-frequency speaker sound against rattle noise. It is required to make a preceding review on the package tray panel, which is located at the bottom of the rear glass where the woofer speakers of a passenger sedan are installed, the door module panel in which the door speakers are built.

Shudder vibration of a hydraulic power steering system during parking maneuver was studied with numerical and experimental methods. To quantify vibration performance of the system and recognize important stimuli for drivers, a shudder metric was derived by correlation between objective measurements and subjective ratings. A CAE model for steering wheel vibration analysis was developed and compared with measured data. In order to describe steering input dependency of shudder, a new dynamic friction modeling method, in which the magnitude of effective damping is determined by average velocity, was proposed. The developed model was validated using the measured steering wheel acceleration and the pressure change at inlet of the steering gear box. It was shown that the developed model successfully describes major modes by comparing the calculated FRF of the hydraulic system with measured one from the hydraulic excitation test.

In this study a new model is proposed for turbulent premixed combustion in a spark-ignition engine. An independent transport equation is solved for the mean reaction progress variable in a propagation form in KIVA-3V. An expression for turbulent burning velocity was previously given as a product of turbulent diffusivity in unburned gas, laminar flame speed and maximum flame surface density. The model has similarity with the G equation approach, but originates from zone conditionally averaged formulation for unburned gas. A spark kernel grows initially as a laminar flame and becomes a fully developed turbulent flame brush according to a transition criterion in terms of the kernel size and the integral length scale. Simulation of a homogeneous charge pancake chamber engine showed good agreement with measured flame propagation and pressure trace. The model was also applied against experimental data of Hyundai θ-2.0L SI engine.

The purpose of the study is to investigate the ergonomic issues for control types and menu design types of in-vehicle information system (IVIS). The results showed that 1) linear-type controls with linear-type menu design had better performance 2) rotary-type control with rotary-type menu design had good subjective preference score 3) the performance and subjective preference of IVIS interface were strongly influenced by the compatibility between control types and menu design types of IVIS 4) there was a tendency that the performance of IVIS tasks was better when the display was located at higher level on center fascia. The results can be applied to develop a new control and menu design of IVIS from ergonomic view points.

Numerous machine elements are operated in mixed lubrication regime where is governed by a combination of boundary and fluid film effects. The direct contact between two surfaces reduces a machines life by increasing local pressure. In order to estimate machine's life exactly, the effect of asperity contact should be considered in the lubrication model. In this study, new 3-dimensional partial elasto-hydrodynamic lubrication (PEHL) algorithm is developed. The algorithm contains the procedures to find out solid contact regions within the lubricated regime and to calculate both the pressure by fluid film and the contact pressure between the asperities of the solids. Using the algorithm, we conducted the PEHL analysis for the contact between the rotating shaft and the inside of pinion gear. To investigate the effect of surface topology two different surfaces with sinusoidal profile are used. Both film thickness and pressure are calculated successfully through the PEHL algorithm.

Door slam noise is very important sound, because Door Slam noise gives a big effect in high-class feeling of vehicle and brand identity. But it is very difficult to analyze door slam noise by traditional analysis and overall sound level. Moreover, the short occurrence time of Door Slam noise makes the analysis more difficult. In this paper, we used the latest developed sound quality methods for analyzing Door Slam noise. And we had performed jury test for luxury vehicles. After that we had carried out correlation analysis between objective analysis and subjective test. Finally, we could suggest Door Slam noise Index by linear regression analysis.

In this study, two-phase flow simulations have been performed for the intake system of a commercial truck. The intake duct, which is the first component in heavy-duty engine, is located in the upper side of a cabin. The flow in the intake system is a typical two-phase flow with the air as the continuous phase and the water as the dispersed phase during rainy weather. The numerical two-phase simulation is performed by using the Largrangian model as implemented in STAR-CD. The influence of the water droplets on the airflow as well as droplet break-up and interactions of the droplets with the walls can be taken into account. Two and three cyclone model inside the intake system have been investigated by numerical simulations. The computational results can be used to get a better understanding of the physics of the flow inside the intake system and to optimize the water separation.

It is considered that improper usage of rubber bushes and weak dynamic characteristics of chassis and body structures yield interior road noise problems. This paper describes systematic processes for road noise improvement along with measurement and analysis process. Firstly, the noise sources are identified by using a source decomposition method. Secondly, the main noise paths are identified by using a noise path analysis (NPA) method. Thirdly, the design modification of body panels is suggested for road noise reduction by using a panel contribution analysis. Finally the method is validated by applying to road noise improvement process for a new vehicle.

Conventional combustion models are suitable for predicting flame propagation for a wrinkled flamelet configuration. But they cannot predict the burned gas composition. This causes the overestimation of burned gas temperature and pressure. A modified method of combustion simulation was established to calculate the chemical composition and to investigate their ultimate fate in the burned gas region. In this work, the secondary products of combustion process, like CO and H2, were considered as well as the primary products like CO2 and H2O. A 3-dimensional CFD program was used to simulate the turbulent combustion and a zero dimensional equilibrium code was used to predict the chemical composition of burned gas. With this simple connection, more reasonable temperature and pressure approaching the real phenomena were predicted without additional time costs.

The combustion characteristics of a HSDI diesel engine were analyzed numerically using a reduced chemical kinetics. The reaction mechanism consisting of 26 steps and 17 species including the Zel'dovich NOx mechanism for the higher hydrocarbon fuel was implemented in the KIVA-3V. The characteristic time scale model was adopted to account for the effects of turbulent mixing on the reaction rates. The soot formation and oxidation processes are represented by Hiroyasu's model and NSC's model. The validation cases include the homogenous fuel/air mixture and the spray combustion in a constant volume chamber. After the validation, the present approach was applied to the analysis of the spray combustion processes in a HSDI diesel engine. The present approach reasonably well predicts the ignition delay, combustion processes, and emission characteristics in the high-pressure turbulent spray flame-field encountered in the practical HSDI diesel engines.

Peak pressure fluctuation amplitudes in the ¾ open-jet test-section of the Hyundai Aeroacoustic Wind Tunnel have been reduced from root-mean-square levels equal to 6% of the test-section dynamic pressure to levels of less than 0.5% over almost the full wind speed range of the tunnel. The improvement was accomplished using a retrofit of the test-section collector. Using an analysis of the physics of the problem, it was found that the HAWT pressure fluctuations could be accurately modeled as a resonance phenomenon in which acoustic modes of the full wind tunnel circuit are excited by a nozzle-to-collector edgetone-feedback loop. Scaling relations developed from the theory were used to design an experiment in 1/7th scale of the HAWT circuit, which resulted in the development of the new collector design. Data that illustrate the benefit of the reduction in pressure fluctuation amplitudes on passenger-car aerodynamic force measurements are presented.

The ride and noise characteristics of a vehicle is significantly affected by vibration transferred to the body through the chassis mounting points from the engine and suspension. It is known that body attachment stiffness is an important factor of idle noise and road noise for NVH performance improvement. And high stiffness helps to improve the flexibility of bushing rate tuning. This paper presents the procedure of body attachment stiffness analysis, which contains the correlation between experimental test and FEA. It is concluded that the most important factors are panel thickness, section type and mounting area size. This procedure makes it possible to find out the weak points before proto car and to suggest proper design guideline in order to improve the stiffness of body structure.

The mobility technique is used to analyze the transfer functions of road noise between the suspension and the body structure. In the previous analyses, the suspension system and the body structure are altogether modeled as subsystems in the noise transfer path. In this paper, the mobility between the suspension and the body structure is analyzed by the dynamic stiffness at the connecting points. The measured drive point acceleration FRF at the connecting point in the transfer path was used to estimate the contributions of subsystems. The vibration modes of tire, the acoustic noise of tire's interior cavity, the vibration modes of the car's interior room, and the vibrations of body structure and the chassis are also considered to analyze the coupling effects of the road noise. Analyzing the measured results, direction for modification of car components is suggested.

The experimental study on the automotive body panel shape has researched a way to reduce the damping material. Among each differently designed panel shapes, the curved panel shape, with high rigidity, or dynamic stiffness, and uneven deformation mode, has found to most reduce the vibration energy and damping material application. This study shows how could the panel shape influence the NVH performance, which would be measured according to several specifically designed panel shapes in order to compare with the conventional bead panel. And this research proposes the way to optimize the damping material to minimize its weight.

The topology optimization made a great success in pure structural design in an actual industrial field. However, a lot of factors interact each other in a actual engineering field in highly complicated manner. The typical conceptual trade-off is that cost and performance, that is, since they are competing factors, one can't improve the specific system without consideration of interaction. The vehicle has lots of competing factors, especially like fuel economy and acceleration performance, mass and stiffness, roominess and cost, short front overhang and crash-worthiness and so on. In addition, they interact each other in a more complicated manner, that is, fuel economy has something to do with not only engine performance but also mass, roominess, stiffness, the length of overhang, trunk volume, etc. So, most of decision-makings have been made by management based on subjective knowledge and experience.