Chan-Jung Kim

A Study on the Analysis of Squeal Noise for Brake Design

The phenomenon of squeal noise in the disk brake system has been, and still is, a. problem for the automotive industry. Extensive research has been carried out in an attempt to understand the mechanism that causes squeal noise and In developing design procedures to reduce squeal noise to make vehicles more comfortable. In this paper, the study on the analysis of squeal noise is performed by using computer aided engineering to design the anti-squeal noise disk brake system. The first part describes the chassis dynamometer and the testing procedure, and second part explains the finite element model and the complex eigenvalue analysis. Finally, it is shown that the proposed squeal noise analysis could be useful to investigate the design parameters that affect the squeal noise characteristics.

Experimental Research on the Power Saving Effect Evaluation of a Variable Displacement Vane Pump for an Automatic Transmission

Abstract : A variable displacement vane pump is possible to improve the fuel economy by varying the pump capacity with a vane mechanism according to the engine operating speed range and reducing its driving torque. In general the experimental evaluation of the vane pump for the transmission has been performed mainly not with the vehicle or dynamometer test rig but with component test rig due to the implementation and safety problems. In this paper, in order to evaluate the performance of the developed vane pump as well as the compatibility with other rotary and hydraulic components of the target transmission, the transmission dynamometer based test rig is implemented where the developed pump is built into it and then the variable pump capacity and effect of power reduction are investigated experimentally. Key words : Lubrication(윤활), Vane pump(베인 펌프), Variable displacement(가변용량), Automatic transmission(자동 변속기), Transmission dynamometer test( 변속기 다이나모미터 평가), Discharge flow rate control( 토출 유량 제어)

Fatigue Damage Prediction Using Design Sensitivity Analysis

It was previously suggested the design sensitivity analysis based on transmissibility function to identify the most sensitive response location over a small design modification. On the other hand, energy isoclines were used to predict the fatigue damage with acceleration response only. Both of previous studies commonly tackle the engineering problem using the acceleration response alone such that it may be possible to investigate the relationship between sensitivity analysis and accumulated fatigue damage. In this paper, it is suggested the novel method of vibration fatigue prediction using design sensitivity analysis to enhance the accuracy of predicted accumulated fatigue. Uni-axial vibration testing is performed with a simple notched specimen and the prediction of fatigue damage is conducted using accelerations measured at different locations. It can be concluded that the accuracy of predicted fatigue damage is proportional to the sensitivity index of the responsible location.

Verification on Damage Calculating Method of Vibration Fatigue Using Uni-axial Vibration Test

The vibration fatigue is suitable case of fatigue problem that system is exposed to the random or other irregular sources. Even some kinds of effort using power spectral density (PSD) and statistical concept was presented to cope with the intangible force signal, it is still lack of providing a reasonable solution when its exciting frequency is near or beyond of first eigenvalue. In this paper, energy approach method is presented to calculate a vibration induced fatigue damage in frequency domain. Since the corresponding damage become much larger than nominal case when the vibration is coupled with a mode shape of given structure, the new technique compensate the characteristics of structure with a measured frequency response function (FRF) between forcing acceleration and responding stress.

Generating Method of the Input Profile in the MAST System

Vibration test using the MAST(multi axial simulation table) provide a more reliable testing environment than any conventional one. The multi axial simulation could be possible with a advanced control algorithm and hardware supports so that most of the operation is automatically conducted by MAST system itself except the input information that is synthesized by the measured response signals. That means the reliability of the vibration test is highly depended on the quality of the input profile. In this paper, the optimal algorithm based on the energy method is introduced to construct a best combination of candidated input PSD data could be constructed. Since the optimal algorithm renders time information, the nitration fatigue test is completely possible for any measured signals one wants. The proposed method is explained with representing acquired road signals from the candidate input PSD obtained from a proving ground.

Element Design of Balancing Shaft for Reducing the Vibration in Engine Module

Vibration in Engine module could be reduced by introducing a balance shaft module which has one or more unbalanced rotors. Since the unbalanced rotor is installed in an opposite direction of the free force or unbalance moment by engine component, the unexpected vibration could be decreased kinematically. The essential equation of the unbalanced rotor was Presented for two cases, 3 in-line and 4 in-line cylinder engine type, And the efficiency of the balance shaft is investigated by the vehicle testing that is focused on measuring the reduced vibration level when adapting a balancing module. With the signal processing of measured signals, some important issues on design the balancing shaft could be derived and the overall design process is explained in the final part including the peripheral component, i.e. housing and bush.

Dynamic Analysis of Vehicle Sub-frame

The vibration of Powertrain are one of the import design characteristics of a vehicle. Powertrain is mostly mounted to the front subframe and powertrain mounting has an important role in determining the vehicle vibration characteristics. In this paper, the accuracy of the vibration analysis for the front subframe is discussed. The dynamic characteristic of subframe are measured from vehicle test and the finite element model updating are performed that natural frequency, mass and MAC of the experimental and theoretical modal analysis are compared. The subframe mounting stiffness are obtained the iteration method based on the vibration of subframe from vehicle test. Finally, the result of dynamic analysis which is operated dynamic load is compared with experimental one of vehicle test.

Accelerated Slam Testing of Vehicle Door Plate Module Using Vibration Exciter

Slam testing is an important test for evaluating the fatigue resistance of a door plate module prior to its delivery to the car manufacturer. In such testing, one experimental specimen is subjected to more than 8 days of continuous testing. In this paper, a vibration testing method is proposed that is intended to replace the conventional swing-type slam testing of a door plate module. The method is based on the concept of duplicating the same failure mode at the clamping part of the glass in a door, where the stress is concentrated. After a review of the feasibility test performed with a multi-axial vibration simulator, a similarity test for a door module was developed that uses a uni-axial vibration exciter that required the door glass to be exposed to a critical spectrum of vibration for less than 2 h. The validity of the proposed testing method was demonstrated by comparing the failure modes of both the conventional and the proposed slam tests.

Estimation of Strain at Elastic System Using Acceleration Response

This paper investigates the prediction of the dynamic strain response using acceleration response only. Two methods are proposed for the strain prediction; one is based on beam theory and the other is calculated by the frequency response function between acceleration and strain. First, it is estimated the dynamics of the simple notched beam, including the non-linearity, through the uni-axial vibration testing. Then, the dynamic strain response is predicted under two different methods using acceleration response. The validation of proposed methods is conducted by the comparison between measured strain and predicted values. The comparison reveals that the proposed method based on the FRF between acceleration and strain is more reliable one than that stemmed from beam theory and the maximum relative error is less than 8 %.

A Study on the Dynamic Characteristics of Door Module Plate

Currently, automotive industries improve the vehicle performance and reduce the development period of vehicle using each module part for the high quality and performance of vehicles. However each component part doesn`t generate the noise and vibration problems, sometime these problems are generated on the assembly status between vehicle chassis frame and each module part. On this study, in order to analysis the dynamic characteristics of a shield door module that is a typical module part of vehicles, the acquisition and evaluation process about the vibration and noise of shield door module is developed. Also the possibility to apply to shield door module of the developed process is verified by the comparison with the dynamic characteristics between plastic and steel module plate.