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This paper focuses on the optimization of the cross-section of a panel type impact door beam. The key parameters of the cross-section of the beam were artificially changed by using a geometry morphing tool FCM (Fast Concept Modeler), which is plugged in to CATIA. Then, the metamodel of FE (Finite Element) analysis results was created and optimized using LS-OPT. The ANOVA (Analysis of Variance) analysis of results was carried out to find the factor of weight reduction. Finally, a new cross section concept was proposed to overcome the limitation of old structure. The optimization was carried out for the beam with the final cross-section to have 10 % or more reduction in total weight.

Fuel sloshing noise is involved with flow motion inside fuel tanks as well as structural characteristics of vehicles. Therefore it is necessary to introduce Fluid-Structure Interaction (FSI) analysis to predict sloshing noise phenomena more accurately. Purposes of this paper are to verify the reliability of the FSI method and suggest new CAE analysis processes to predict fuel sloshing noise. The vibration of floor panels induced by sloshing impact is evaluated through FSI analysis. A series of tests is carried out to validate simulation results. The numerical optimization of parameters is also carried out to reduce computation time. In addition, effects of sloshing noise factors are discussed based on simulation and test results. Lastly, a method to predict fuel sloshing noise by exerting sloshing load on a vehicle is suggested.

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.

A sliding door is one of the car door systems, which is generally applied to the vans. Compared with swing doors, a sliding door gives comfort to the passengers when they get in or out the car. With an increasing number of the family-scale activities, there followed a huge demand on the vans, which caused growing interests in the convenience technology of the sliding door system. A typical sliding door system has negative effects on the vehicle interior package and the operating effort. Since the door should move backward without touching the car body, the trajectory of the center rail should be a curve. The curve-shaped center rail infiltrates not only the passenger shoulder room, but also the opening flange curve, which results in the interior package loss. Moreover, as the passenger pulls the door outside handle along the normal direction of the door outer skin, the curved rail causes the opening effort loss.

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.

On-center feel is a multivariate problem that a performance is represented using put-together several sub-characteristics such as torque feedback, response, torque linearity, hysteresis, returnability, etc. For the improvement of a multivariate problem, multi objective optimization should be carried out. However each characteristic which ignores correlation between characteristics is usually optimized up to now. The objective of this research, Mahalanobis Taguchi System (MTS) technique is grafted to on-center steering feel to obtain the efficient improvement. MTS technique can optimize the unified on-center index which is generated in consideration of correlation between characteristics. In this research, first an effective value of MTS technique is verified with on-center steering feel which has the multivariate characteristic. Second, on-center steering feel is improved using MTS technique and Design of Experiments (DOE).

The multi-function drive plate used for a high performance engine was developed by optimizing its structure, material and design features. To do so, the investigation of the load characteristics was done in order to increase FEA reliability. DFSS was utilized for optimizing the design features and defining the effect of geometric parameters on the durability. The durability of the optimized drive plate was verified by comparing the FEA and test results with other drive plates which were already verified. Finally, the real powertrain test was done to confirm its durability for a high performance engine.

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.

In order to reduce total drag during aerodynamic optimization process of the passenger vehicle, induced drag should be minimized and pressure drag should be decreased by means of applying streamlined body shape. The reduction of wake area could decrease pressure drag, which was generated by boundary layer separation. The induced drag caused by rear axle lift and C-pillar vortex can be reduced by the employing of trunk lid edge and kick-up or an optimized rear spoiler. When a rear spoiler or kick-up shape was installed on the rear end of a sedan vehicle, drag was reduced but the wake area became larger. This contradiction cannot be explained by simply using Bernoulli’s principle with equal transit or longer path theory. Newtonian explanation with COANDA effect is adopted to explain this phenomenon. The relationships among COANDA effect, down wash, C-pillar vortex, rear axle lift and induced drag are explained.

In this paper, an optimization technique for thin walled beams of vehicle body structure is proposed. Stiffness of thin walled beam structure is characterized by the thickness and typical section shape of the beam structure. Approximate functions for the section properties such as area, area moment of inertia, and torsional constant are derived by using the response surface method. The approximate functions can be used for the optimal design of the vehicle body that consists of complicated thin walled beams. A passenger car body structure is optimized to demonstrate the proposed technique.

A systematic process of optimization is suggested to obtain the best control maps for a parallel type hybrid electric vehicle. Taking the fuel consumption as the cost function and driving cycle as part of the constraints, an optimization problem for CVT pulley ratio control and motor torque control can be formulated. The change of the battery charge state between the start and end point of the given driving cycle also works as a constraint. In order to see the effect of various control strategies on system behavior and overall fuel consumption, a simulation model was built to accommodate the functional blocks representing hybrid powertrain subsystem components and corresponding control units.

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.

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 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.

Recently, upon customer’s needs for noise-free brake, carmakers are increasingly widely installing damping kits in their braking systems. However, an installation of the damping kits may excessively increase softness in the brake system, by loosening stroke feeling of a brake pedal and increasing compressibility after durability. To find a solution to alleviate this problem, we first conducted experiments to measure compressibility of shims by varying parameters such as adhesive shims (e.g., bonding spec., steel and rubber thickness), piston’s shapes (e.g., different contact areas to the shims), and the numbers of durability. Next, we installed a brake feeling measurement system extended from a brake pedal to caliper. We then compared experimental parameters with brake feeling in a vehicle. Finally, we obtained an optimized level of brake feeling by utilizing the Design for Six Sigma (DFSS).

This study presents the NVH characteristics of a passenger vehicle with a three-cylinder engine and a Continuously Variable Transmission (CVT) and an optimization procedure to achieve balance between fuel economy and NVH. The goal of this study is to improve fuel economy by extending the lock-up area of the damper clutch at low vehicle speed and to minimize booming noise and body vibration caused by the direct connection of the engine and transmission. Resonance characteristics of the chassis systems and driveline have been studied and optimized by the experiment. NVH behavior of the vehicle body structure is investigated and modifications for refinement of booming and body vibration are proposed by simulation using MSC NASTRAN. Calibration parameters for CVT control are optimized for fuel economy and NVH. As a result, the lock-up clutch area has been extended by 300RPM and the fuel economy has been improved by about 1%, while the NVH characteristics of the vehicle satisfy the targets.

This paper presents a novel method predicting the variation of sound quality of interior noise depending on the change of the proprieties of absorption materials. At the first, the model predicting the interior noise corresponding to the change of the absorption material in engine room is proposed. Secondly the index to estimate the sound quality of the predicted sound is developed. Thirdly the experimental work has been conducted with seven different materials and validated the newly developed index. Finally, this index is applied for the optimization of absorption material to improve the sound quality of interior noise in a passenger car.

An efficient method to determine optimal bushing stiffness for improving noise and vibration of passenger cars is developed. In general, a passenger vehicle includes various bushings to connect body and chassis systems. These bushings control forces transferred between the systems. Noise and vibration of a vehicle are mainly caused by the forces from powertrain (engine and transmission) and road excitation. If bushings transfer less force to the body, levels of noise and vibration will be decreased. In order to manage the forces, bushing stiffness plays an important role. Therefore, it is required to properly design bushing stiffness when developing passenger vehicles. In the development process of a vehicle, bushing stiffness is decided in the early stage (before the test of an actual vehicle) and it is not validated until the test is performed.

As automotive technology has been developed, gear whine has become a prominent contributor for cabin noise as the masking has been decreased. Whine is not the loudest source, but it is of high tonal noise which is often highly unpleasant. The gear noise originates at gear mesh. Transmission Error acts as an excitation source and these vibrations pass through gears, shafts and bearings to the housing which vibrates to produce noise on surrounding air. As microgeometry optimization target to reduce the fundamental excitation source of the noise, it has been favored method to tackle gear whine noise, especially for manual transmission. However, practicality of microgeometry optimization for the planetary gear system has been still in question, because of complex system structure and interaction among multi mesh gear sets make it hard to predict and even harder to improve. In this paper, successful case of whine noise improvement by microgeometry is presented.

Since the fuel efficiency of vehicle has become one of the big issues due to environmental pollution problems, many studies have been conducted on various methods such as improving powertrain performance and aerodynamic performance, reducing the weight of the vehicle and so on. There have been many new attempts to reduce weight but mostly about improving material property. In the case of vehicles sharing the same platform, the weight and cost of vehicle are mainly changed by the exterior styling. But, there is no solution to control the exterior styling in terms of the weight and cost of vehicle, yet. The purpose of this study is to find the way to save the weight and cost of vehicle while achieving the various performance and requirements of vehicle (safety, aerodynamics, driver’s visibility and so on) from exterior styling point of view. We focused on the weight difference of the vehicles that shared the platform and were same overall dimensions.