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Technical Paper

6 Speed Automatic Transmission Vibration Magnitude Prediction and Whine Noise Improvement through Transmission System Modeling

2011-05-17
2011-01-1553
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.
Technical Paper

Impact of Hilly Road Profile on Optimal Energy Management Strategy for FCHEV with Various Battery Sizes

2013-10-14
2013-01-2542
This study investigates how hilly road profiles affect the optimal energy management strategy for fuel cell hybrid electric vehicle (FCHEV) with various battery sizes. First, a simplified FCHEV model is developed to describe power and energy flows throughout the powertrain and evaluate hydrogen consumption. Then, an optimal control problem is formulated to find the globally optimal energy management strategy of FCHEV over driving cycles with road elevation profile. In order to solve the optimal energy management problem of the FCHEV, Dynamic Programming, a dynamic optimization method, is used, and their results are analyzed to find out how hilly road conditions affect the optimal energy management strategies. The results show that the optimal energy management with a smaller battery tends to actively prepare (e.g. pre-charge/pre-discharge) for uphill/downhill roads in order not to violate the battery state of charge (SoC) bounds.
Journal Article

The Prediction of Fuel Sloshing Noise Based on Fluid-Structure Interaction Analysis

2011-05-17
2011-01-1695
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.
Journal Article

A Study on the Role of TRIZ in DFSS

2012-04-16
2012-01-0068
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.
Technical Paper

Analysis of Sensitivity and Optimization for Chassis Design Parameters on the X-Wind Stability

2015-03-10
2015-01-0025
In the view point of driving safety, the crosswind sensitivity of a vehicle becomes more important, as the driving speed in highway gets higher in these days. The sensitivity of a vehicle to crosswind depends on many factors, including the design of the suspension and aerodynamics of the body, etc. However, the knowledge about this phenomenon has still to be improved, in order to develop vehicle with optimum characteristics for crosswind stability. In this research, the physics behind the sensitivity of a vehicle is discussed in detail through various kinds of virtual test using computer aided engineering (CAE) simulation scheme. In the first, a reliable simulation model for vehicle, driver, wind generator and interactions among them is built. This simulation model is verified by comparison with test results of real vehicle. Then, the sensitivity analysis is carried out to find out the most influential design parameters.
Technical Paper

The Optimization of Vehicle Performances Using Dynamic Models with Two Steps

2015-03-10
2015-01-0028
This paper presents an industrial application of the Analytical Target Cascading (ATC) methodology to the optimal design of commercial vehicle steering and suspension system. This is a pilot study about the suspension and steering design of a semi medium bus, whose objective is to develop and introduce an ATC methodology to an automobile development process. In the conventional process, it is difficult not only to find design variables which meet the target of Ride and Handling (R&H) performance using a detailed full car model, but also to figure out the interrelation between the vehicle and its subsystems. In this study, ATC methodology is used in order to obtain the optimal values such as geometric characteristics satisfying both the vehicle's R&H target and the subsystem (suspension and steering system) 's target.
Technical Paper

Optimization of WRC Race Car Body and Rollcage Structure

2015-03-10
2015-01-0064
The rollcage for WRC race body/rollcage has been developed and optimized by DFSS methodology. It is designed on the principle of reducing it to a Min. of weight compared to the other OEM and the initial set-up model with the torsional stiffness and strength increased. As a result, 12% increased torsional stiffness, maximized strength and 3.7% weight reduction could be achieved. In terms of economics, it is feasible to have a production cost savings of about 11% per car and the effect is further, considering the development period is substantially decreased, 5 to 2 months. Also, in the process of optimizing rollcage structure, applicable items to monocoque body are suggested by investigating the parts and structures that highly affect the body performance.
Technical Paper

A BIW Structure Research of Light Weight Vehicle with High Stiffness by Steel

2015-03-10
2015-01-0061
The focus of this paper is to develop an innovative vehicle layout and optimize vehicle body structure with the latest lightweight steel technologies, such as hydro-forming and hot stamping. Our BIW structure achieved a mass savings of 28 kg (−10%) compared to the mass of baseline BIW structure. (Base BIW : MD_Elantra)
Technical Paper

The Study on the Optimization of Attachment Stiffness in Vehicle Body

2007-05-15
2007-01-2346
The achievement of improved NVH performance with light weighted body and low cost is very important, but difficult job to be accomplished in vehicle development. One of the various methods for the accomplishment of this goal is the optimization of the stiffness attached to a vehicle body and chassis. It is known that sufficient stiffness at the body attachments improves the flexibility of bushing rate tuning. In this paper, the theoretical consideration and analysis tool to estimate local stiffness value quantitatively are introduced. Also, the local stiffness values at various attachment locations in trimmed body are measured. The operational forces at body attachments are estimated through the TPA (Transfer Path Analysis). The suitability of attachment stiffness is judged based on the required NVH target to attain the optimal attachment stiffness in vehicle body.
Technical Paper

A Study on the Analysis Method for Optimizing Mounting Brackets

2006-04-03
2006-01-1480
Various optimization schemes have successfully been utilized to design mounting brackets of chassis components, especially suspension systems, in the large commercial vehicle development process. Depending on the design status, different optimization schemes, i.e. size, topology, and shape, are applied. There are two key elements that determine types of optimization schemes used, which are design freedom and available analysis time. First, in a case that the design is already frozen near the mass production, so that only minimal design change and time is allowed, the size optimization is attempted. Second, in the middle of the design process where relatively more room for the change is available, the topology optimization is adequate to carry out, based on the basic CAD model.
Technical Paper

Performance Analysis and Valve Event Optimization for SI Engines Using Fractal Combustion Model

2006-10-16
2006-01-3238
On the basis of the newly-developed fractal combustion model, the engine-thermodynamic-cycle simulations were conducted with the 1D engine-cycle-simulation program AVL-BOOST for a passenger-car SI engine with a fully-variable valve train. Results of the simulations showed a good agreement with measurements for both full and part load at various engine speeds. On the basis of the thermodynamic model for the engine, the valve event optimization was carried out for both full and part load with a partial factorial DoE plan consisting of various valve event durations and timings. For each of the selected cases, an independent optimization for the ignition timing was performed to determine the minimum BSFC under a constraint on specified knock criteria. Satisfactory results for the valve event optimization were achieved.
Technical Paper

Numerical Simulation on the Raindrop Transportation in the Turbulent Flow Field of the Heavy-Duty Intake System

2006-04-03
2006-01-1191
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.
Technical Paper

A Study on the Optimization of Body Structure for Rattle Noise by Exciting Woofer Speakers

2009-05-19
2009-01-2110
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.
Technical Paper

A Study on Optimization of the Multi-function Drive Plate for High Performance Engine

2007-04-16
2007-01-0798
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.
Technical Paper

The Study for the Improvement of On-Center Feel with MTS Technique

2007-04-16
2007-01-0990
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).
Technical Paper

A Study on the Development Process of a Body with High Stiffness

2005-05-16
2005-01-2464
Design optimization of a vehicle is required to increase a product value for noise and vibration performances and for a fuel-efficient car. This paper describes the development process of a high stiffness and lightweight vehicle. A parameter study is carried out at the initial stage of design using the mother car, and a design guide with a good performance is achieved early prior to the development of the proto car. Influences of body stiffness based on the relative weight ratio of the floor and side structures are analyzed. Results show that bending and torsional stiffness has a significant effect on weight distribution ratio. Influences of the distribution of side joint stiffness are analyzed through numerical experiments. Results reveal that the stiffness difference between the upper and lower parts should be small to increase the stiffness of a body.
Technical Paper

Influence of Tire Size and Shape on Sound Radiation from a Tire in the Mid-Frequency Region

2007-05-15
2007-01-2251
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.
Technical Paper

A Study on Optimum Design for Thin Walled Beam Structures of Vehicles

2002-07-09
2002-01-1987
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.
Technical Paper

Design Optimization Analysis of Body Attachment for NVH Performance Improvements

2003-05-05
2003-01-1604
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.
Technical Paper

The Experimental Study on the Body Panel Shape to Minimize the Weight of the Damping Material

2003-05-05
2003-01-1715
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.
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