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This paper presents a tire slip-angle based speed control race driver model. In developing a chassis control system for enhancement of high-speed driving performance, analysis of the vehicle-driver interaction at limit handling is one of the main research issues. Thus, a driver model which represents driving characteristics in a racing situation is required to develop a chassis control system. Since a race driver drives a vehicle as fast as possible on a given racing line without losing control, the proposed driver model is developed to ensure a lateral stability. In racing situation, one of the reasons which cause the lateral instabilities is an excessive corner-entry speed. The lateral instability in that moment is hard to handle with only a steering control. To guarantee the lateral stability of the vehicle while maximizing a cornering speed, a desired speed is determined to retain a tire slip-angle that maximizes lateral tire forces without front tire saturation.

This Study describes about the development of new concept' rear wheel guards for the reduction of Road Noise in the passenger vehicles. The new wheel guards are proposed by various frequency chamber concept and different textile layers concept. Two wheel guards were verified by small cabin resonance and vehicle tests. Through new developing process without vehicle test, Result of road noise will be expected if this concepts and materials of wheel guard are applied into automotive vehicle. As this concept consider tire radiation noise frequency and multilayers sound control multilayers, 2 concepts reduced road noise from 0.5 to 1.0dB. The proposed method of part reverberant absorption is similar to results of vehicle tests by part absorption index. Furthermore, optimization of frequency band in wheel guards will reduce more 0.5 dB noises. As a result of the application of Aimed Helmholtz and Multilayers concept, this paper classifies reduction of the road noise, cost and weights.

A semi-empirical index to evaluate the noise propensity of brake friction materials is introduced. The noise propensity index (NPI) is based on the ratio of surface and matrix stiffness of the friction material, fraction of high-pressure contact plateaus on the sliding surface, and standard deviation of the surface stiffness of the friction material that affect the amplitude and frequency of the stick-slip oscillation. The correlation between noise occurrence and NPI was examined using various brake linings for commercial vehicles. The results obtained from reduced-scale noise dynamometer and vehicle tests indicated that NPI is well correlated with noise propensity. The analysis of the stick-slip profiles also indicated that the surface property affects the amplitude of friction oscillation, while the mechanical property of the friction material influences the propagation of friction oscillation after the onset of vibration.

A piston in a diesel engine is subject to the high pressure and the high thermal load. The high structural reliability is required to the piston in the automotive diesel engine and it is important to confirm the design parameters of piston in initial design stage. There are lots of research works proposing new geometries, materials and manufacturing techniques for engine pistons. But, the failures of piston occur frequently in development stage. Failure mechanisms are mainly fatigue related. This paper presents failure mechanisms of the high cycle fatigue and low cycle thermal fatigue cracks which occur on the piston during durability test using engine dynamometer. In this study, FE analysis was carried out to investigate the root cause of piston failure. The analysis includes the FE model of the piston moving system, temperature dependent material properties, mechanical and thermal loadings.

In this study, the preliminary validation method of the steering system is constructed and the objective is to satisfy the target performance in the conceptual design stage for minimizing the problems after the detailed design. The first consideration about steering system is how to extract the reliable steering effort for parking. The tire model commonly used in MBD(Multi-Body Dynamics) has limited ability to represent deformations under heavy loads. Therefore, it is necessary to study adequate tire model to simulate the behavior due to the large deformation and friction between the ground and the tire. The two approaches related with F tire model and mathematical model are used. The second is how to extract each link’s load in the conceptual design stage. Until now, each link’s load could be derived only by actual vehicle test, and a durability analysis was performed using only pre-settled RIG test conditions.

In this research, the influence of tire size and shape on sound radiation in the mid-frequency region was studied. First, the relationship between the structural wave propagation characteristics of a tire excited at one point and its sound radiation was identified by using FE and BE analyses. Then, by using that relationship, the effect of modifying a tire's aspect ratio, width and wheel diameter on its sound radiation between 300 Hz and 800 Hz was investigated. Finally, an optimization of the sound radiation was performed by modification of the tire structure and shape. It was found that most of a tire's structural vibration does not contribute to sound radiation. In particular, the effective radiation was found to occur at the frequencies where low wave number components of the longitudinal wave and the flexural wave first appear.

This paper describes the optimal design process of the steering column system and the supporting system. At the initial concept stage of development process, a design guide is proposed to obtain sufficient stiffness of the steering system while reducing idle vibration sensitivity of the system. Case studies on resonance isolation are summarized, in which separated vibration modes among systems by applying Vibration Mode Map at the initial stage of design process. This study also makes it possible to provide design guideline for optimal dynamic damper system using CAE (computer aided engineering) analysis. The damper FE (finite element) model is added to vehicle model to analyze the relation between the frequency and the sensitivity of steering column system. This analysis methodology enables target performance achievement in early design stage and reduction of damper tuning activity after proto car test stage.

The mechanical energy of an engine is lost by engine friction and in driving the engine's auxiliary components, which is then transferred to transmission. Thus, it is very important to know the exact value of engine friction and the driving torque of engine's auxiliary components in order to reduce fuel consumption of an engine by reducing these losses. And, it is also helpful to know the braking torque of an engine in actual vehicle so as to improve vehicle's driving performance. For these reasons, present study developed an engine torquemeter for in-vehicle application, and measured braking torque of an engine in vehicle and analyzed fuel consumption contributions of engine's auxiliary components.

This paper proposes a modeling technique which is able to not only reliably and easily represent the hysteretic characteristics but also analyze the dynamic stress of a taper leaf spring. The flexible multi-body dynamic model of the taper leaf spring is developed by interfacing the finite element model and computation model of the taper leaf spring. Rigid dummy parts are attached at the places where a finite element leaf model is in contact with an adjacent one in order to apply contact model. Friction is defined in the contact model to represent the hysteretic phenomenon of the taper leaf spring. The test of the taper leaf spring is conducted for the validation of the reliability of the flexible multi-body dynamic model of the taper leaf spring developed in this paper. The test is started at an unloaded state with the excitation amplitude of 1∼2mm/sec and frequency of 132mm. First, the simulation is conducted with the same condition as the test.

Suspension system of vehicle is very important because it has an effect on ride comfort and safety. And the leaf spring is one of the major parts of commercial vehicle. By that reason it has to be designed to operate under severe condition to ensure enough endurance. But the traditional method for fatigue design needs repeated fatigue tests for each design according to its geometry, material, and operating condition. This means that a lot of time and money is needed for those tests. Thus, in this paper, a fatigue design method for leaf spring based on numerical analysis is proposed. At first, stress analysis is performed to get the stress under operation load or rig tests. And fatigue analysis is performed to get the fatigue life and to ensure the safety of leaf spring. Through this study, design parameters that play vital role in fatigue life of the leaf spring can be found out.

The use of light-weight materials in automotive engine components has increased in order to achieve better fuel efficiency and engine performance. In this study, Al alloy (AI5056) valve spring retainer can reduce a weight by 63% in comparison to steel and improve the upper limit of engine speed by about 500rpm. The Al valve spring retainer was fabricated by cold forging and coated with hard anodizing, DLC (diamond like coating), cold spray and thermal spray for better wear resistance and durability. We conclude that among these materials the DLC coating improves the wear resistance of Al valve spring retainer and has a sufficient durability after endurance testing.

All vehicles have some or all accessories such as alternators, air conditioner compressors, power steering pumps, and water pumps. These devices are mounted on the front of the engine and are powered by a pulley mounted on the front of the crankshaft. This power represents a parasitic loss and this loss is greater at higher engine speeds. To reduce the impact of the accessories on the engine, a two speed transmission that reduces the accessories speed at off-idle conditions was designed, implemented, and tested on several vehicles. The vehicles were tested for fuel economy on the Japanese 10.15 Mode driving cycle, the FTP75 city cycle, and the HWFET Highway Cycle. Results showed an average of 5% reduction in fuel consumption and a corresponding 5% in CO2 with no impact of accessory performance and vehicle drivability. Simulations with GT-Drive software was used to determine the optimum speed reduction and the threshold switching speed that maximizes fuel savings.

The design of a product is becoming more important and it affects product preference and buying decision. The objectives of this study are first to determine the major elements affecting the feeling of exterior design from aesthetic engineering point of view, and then to extract the highly correlated design factor within the experimental result. Firstly, the buying preference is highly affected by the dynamic and elegant factors. Through deepening analysis using only 2-door type car, the ‘Cowl and Deck Point Angle * Overall Length / Overall Height’ factor is highly positive correlated, and the ‘Rear Overhang’ factor is highly negative correlated with buying preference. There are three special features of a sports car; firstly, stable (long wheel base) and aggressive (lean towards the front) design makes consumers feel dynamic. Secondly, the consumers prefer modern and sedan-like coupe design. Thirdly, sleek design line and consistent character line are preferred.

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.

As the use of diesel engines increases in the transportation industry and emission regulations tighten, the implementation of diesel particulate filter systems has expanded. There are many challenges associated with the design and development of these systems. Some of the key robustness parameters include regeneration, efficiency, fuel penalty, engine performance, and durability. One component of durability in a diesel particulate filter (DPF) system is the filter's ability to resist ring-off-cracking (ROC). ROC is described as a crack caused primarily by thermal gradients, differentials, and the resulting stresses within the DPF that exceed its internal strength. These cracks usually run perpendicular to the substrate flow axis and typically result in the breaking of the substrate into separate halves.

Applying BSM (Balance shaft module) is a very common and effective way to reduce the 2nd-order powertrain vibration which is caused by the ill-balanced inertia force due to the oscillating masses inside an engine. However, the adoption of a BSM can also produce undesirable things especially in cost, fuel economy, starting performance, and so on. Therefore, for small vehicles, in which case cost and weight are key factors at the development stage, it is often required to develop competitive NVH performance without the expensive apparatus like a BSM. In this paper, in order to develop interior noise and vibration of a 4-cylinder vehicle without a BSM, we analyzed the contribution of some transfer paths for powertrain vibration, and could reduce interior booming noise by tuning the dynamic characteristic of the engine mount which was one of the largest transfer paths.

In this paper, front and rear 5-link independent suspension systems are introduced which are developed for the Hyundai Genesis. The front suspension has two upper links, two lower links, and a tie-rod. In the rear suspension, there are two upper links, a lower link, a trailing link, and a toe control link. The design concepts of front and rear suspension systems are explained, respectively. Also, it is presented how the suspension characteristics are designed and optimized to satisfy the desired performances such as luxurious ride feeling and precise handling.

The automotive shock absorber has various functions in car performance. Particularly, it is a dominant tuning parameter to get good primary and secondary ride characteristics within 1-35Hz ranges in car development. Thus, understanding of characteristics of shock absorber in this frequency range is indispensable to both test and analysis engineers for an effective and systematic approach. In this study, tire is also investigated from the same point of view. Frequency dependent stiffness and damping coefficient are extracted by discrete sine swept test under constant velocity of 25, 50, 100mm/sec which represent typical road surface conditions[1]. The responses are analyzed on frequency domain and the basic theoretical background for this approach is introduced.

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.

The Representative Interactive Flamelet(RIF) concept has been applied to numerically simulate the combustion processes and pollutant formation in the direct injection diesel engine. Due to the ability for interactively describing the transient behaviors of local flame structures with CFD solver, the RIF concept has the capabilities to predict the auto-ignition and subsequent flame propagation in the diesel engine combustion chamber as well as to effectively account for the detailed mechanisms of soot and NOx formation. In order to account for the spatial inhomogeneity of the scalar dissipation rate, the Eulerian Particle Flamelet Model using the multiple flamelets has been employed. Special emphasis is given to the turbulent combustion model which properly accounts for vaporization effects on turbulence-chemistry interaction.