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Technical Paper

A Study on the Acoustic Simulation for the Components of an Intake System

The reduction of intake noise is a very important factor in controlling the interior noise levels of vehicles, particularly at low and major engine operating speeds. A vehicle intake system generally consists of air cleaner box, hose, duct, and filter element. Also, resonators and porous duct are included, being used to reduce intake noise. For more accurate estimation of the transmission loss (TL), it seems important to develop a CAE model that accurately describes this system. In this paper, simple methods, which can consider the effects of filter element and vibro-acoustic coupling, are suggested which could remarkably improve estimation accuracy of the TL. The filter element is assumed as equivalent semi-rigid porous materials characterized by the flow resistivity defined by the pressure drop, velocity, and thickness.
Technical Paper

An Improvement Research of Under-floor of Midsize Sedan-Focusing on 2010 New YF Sonata Development Examples-

Hyundai Kia Motors started developing the under-floor of YF sonata, the base platform for mid-to-large size sedans, in order to reduce weight and improve body performance. For local dynamic rigidity, there are design improvement and additional support structures at suspension mounting area. The strength at the joint where longitudinal and transverse members meet is increased to improve the overall body stiffness, and also the riding comfort and handling. Impact performance and safety is also improved by straightening the major structural members and strengthening the joint areas, efficiently absorbing and inducing the impact energy through load paths. As the body of a vehicle is the constitution of numerous parts, increased strength at the joints and major structural members with more linear profiles have played crucial roles in the improvement in overall body performance.
Technical Paper

Accurate Reproduction of Wind-Tunnel Results with CFD

Aerodynamic simulation results are most of the time compared to wind tunnel results. It is too often simplistically believed that it suffice to take the CAD geometry of a car, prepare and run a CFD simulation to obtain results that should be comparable. With the industry requesting accuracies of a few drag counts when comparing CFD to wind tunnel results, a careful analysis of the element susceptible of creating a difference in the results is in order. In this project a detailed 1:4 scale model of the Hyundai Genesis was tested in the model wind tunnel of the FKFS. Five different underbody panel configurations of the car were tested going from a fully paneled car to a car without panels. The impact of the moving versus static ground was also tested, providing over all ten different experimental results for this car model.
Journal Article

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

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.
Technical Paper

Development of Polymer Composite Battery Pack Case for an Electric Vehicle

A battery pack case of an electric vehicle was developed with a fibrous thermoplastic composite material. Due to cost effectiveness, long-fiber-reinforced thermoplastics by direct process (D-LFT) were adopted. PA6 (Polyamide 6)-based composites were processed using a D-LFT pilot machine at the temperature range between 250° and 290°. Glass and carbon fibers were added in the matrix varying the mixture ratio of the fibers while keeping the weight fraction 40%. The increase of carbon fibers in the mixture increased tensile modulus and strength, however, decreased Izod impacts strength. The fatigue life of developed composites was evaluated by fatigue tests in tension, which were over one million cycles at the maximum fatigue loading less than 60% of the composite strength. Associated with fiber orientation, anisotropic mechanical behavior was investigated in terms of flexural properties and mold shrinkage.
Technical Paper

Co-operative Control of Regenerative Braking using a Front Electronic Wedge Brake and a Rear Electronic Mechanical Brake Considering the Road Friction Characteristic

In this study, a co-operative regenerative braking control algorithm was developed for an electric vehicle (EV) equipped with an electronic wedge brake (EWB) for its front wheels and an electronic mechanical brake (EMB) for its rear wheels. The co-operative regenerative braking control algorithm was designed considering the road friction characteristic to increase the recuperation energy while avoiding wheel lock. A powertrain model of an EV composed of a motor, and batteries and a MATLAB model of the control algorithm were also developed. They were linked to the CarSim model of the vehicle under study to develop an EV simulator. The EMB and EWB were modeled with an actuator, screw, and wedge to develop an EMB and EWB simulator. A co-simulator for an EV equipped with an EWB for the front wheels and an EMB for the rear wheels was fabricated, composed of the EV and the EMB and EWB simulator.
Technical Paper

The Procedure for Improving R&H Performance of the New 2010 Hyundai Sonata by Modal Parameter Modification of Its Body

Various deformation shapes of the vehicle body were investigated for the purpose to establish vehicle body's performance criteria which correlates well to handling performance and ride comfort. Using CAE tool, the dynamic behavior of a structure by its modal parameter can be described instead of by its nodes and elements. Each modal characteristic in a dynamic system is reduced by its modal stiffness, its modal mass and its damping parameter in the model. This technology offers not only computational efficiency but also parametric model enabling easy what-if simulation. This reduced model can be obtained by modal test as well as simulation of full FE model. It was also investigated that which mode is sensitive to ride or handling performance using the parameterized model. The body stiffness of the brand new 2010 SONATA was improved on reference to the sensitivity analysis. The ride and handling performance of the 2010 SONATA were verified by computer simulation and vehicle field test
Technical Paper

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

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

A Study on the Advanced Technology Analysis Process of Steering System for Idle Performance

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.
Technical Paper

Development of Input Loads for Road Noise Analysis

To predict structure-borne interior noise using CAE simulation, it is important to establish a model for both the noise and vibration transfer path, as well as the excitation source. In the passenger vehicle, powertrain and road induced loads are major input sources for NVH. This paper describes a process to simulate the structure-borne road noise to 150Hz. A measured road surface is used for input for the simulation. Road surface data, in the form of height vs. distance, is converted to enforced motions at the tire patch in the frequency domain for input to the vehicle system model. The input loads are validated by the comparison of wheel hub excursions. The ability of the CAE simulation model to predict interior acoustic responses is shown by the comparison of the simulation results with measured vehicle interior responses.
Journal Article

A Study on the Impact Resistance of Plastic Underbody Parts

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.
Technical Paper

The Analysis of Brake Squeal Noise Related to the Friction Properties of Brake Friction Materials

The friction properties related to squeal noise was analyzed with the development histories and simplified computational method. Firstly, the development histories were investigated especially focusing on the case which the friction materials were modified to improve squeal noise occurrence. Based on the histories, the friction properties of selected friction materials were newly measured using dynamometer. The average friction coefficient levels, torque oscillations, the increment of friction coefficient during full-stop, and etc. were compared with the squeal noise occurrence, and the results showed that increase of friction properties cause production of squeal noise. The result suggested that the size of friction energy was important factors related to triggering the squeal noise. Also, the contact conditions between rotor disc and friction materials were significant factors deciding the noise occurrence.
Technical Paper

Development of an Automated Seat Dimension Evaluation System

The dimensions of an automobile seat are important factors affecting a driver’s seating comfort, fit, and satisfaction. In this regard, seat engineers put forth tremendous efforts to evaluate the dimensions of a product seat until the dimensions are consistent with the design reference in a computer aided design (CAD). However, the existing evaluation process is heavily reliant on seat engineers’ manual tasks which are highly repetitive, labor intensive, and time-demanding tasks. The objective of this study is to develop an automated system that can efficiently and accurately evaluate seat products by comparing estimated seat dimensions from a CAD model or a 3D scan model. By using the developed system, the evaluation time for comparing 18 seat dimensions on CAD and scan models has been substantially reduced to less than one minute, which is 99% time saving compared to two hours in the manual process.