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Chassis dynamometer를 이용한 Road Noise 전달경로 분석에 관한 연구
김달식(Dalsik Kim),최은수(Eunsoo Choi),김인동(Indong Kim) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper describes a method to analyze road noise transfer path through using chassis dynamometer. This chassis dynamometer was made only for road noise test condition so the relationship was good between the chassis dynamometer and outside rough road. To investigate the relationship between each suspension group and structure-borne road noise at the baseline test, multiple coherence analysis method was studied. The measurements are performed neutral coast down method from 120 to 20 KPH. And front and rear suspension group was measured separately so the analysis method was also performed separately. To analyze the structure-borne road noise Transfer path analysis (TPA) was used. In TPA method direct force method and matrix inversion method were combined. Using of strain gauge was studied for direct force method. And normally road noise TPA input data was acquired from PCA but this study not using PCA method but calculating reference related spectrum manually.
Hybrid modeling을 이용한 Road noise 분석에 관한 연구
김달식(Dalsik Kim),박광서(Kwangseo Park),김영호(Yongho Kim),김인동(Indong Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper describes a method to analyze road noise analysis through using hybrid modeling. Hybrid modeling means combining test and math data. TPA method is used to predict interior road noise and matrix inversion method is used to estimate operational forces. In this paper three TPA models are used. In first model, operational vibration data is based on test data from chassis dynamometer. In second model, operational vibration data is based on analysis data and third model is based on FBS method. And the others trimmed body FRF data are commonly used. In FBS case, rear suspension FRF data is acquired from FRF synthesis. From this study the global influence of substructure modification can be easily assessed by reformulating subcomponent FRF data. And besides finite element analysis can be used to rapidly define the frequency characteristics of subcomponent.
차량 공력소음에 대한 주관평가와 계량적 접근 방법의 상관관계
김중한(Jounghan Kim),오혁진(Hyukjin Oh),김달식(Dalsik Kim) 한국자동차공학회 2014 한국자동차공학회 학술대회 및 전시회 Vol.2014 No.11
Wind noise has been highlighted as one of main ingredient of interior noises and shows important customer issues steadily. So in the automotive industries are doing efforts to enhance wind noise performance of excellent quality for satisfying customers’ needs. In general wind noise consist of rush noise, leak noise, buffeting noise, hoot noise etc. Each component shows different sound characteristic depend on what is sound source. And this sound characteristic could be classified with several sound metrics such as articulation index, loudness, sound pressure level and so on. This paper is aimed to investigate which sound metric is well correlated with subjective evaluation especially focused on rush noise and leakage noise. For the correlation function study, regression analysis method is used.
차량의 공력 소음에 대한 품질지수 추정을 위한 손실함수 연구
김중한(Jounghan Kim),오혁진(Hyukjin Oh),김달식(Dalsik Kim) 한국자동차공학회 2015 한국자동차공학회 학술대회 및 전시회 Vol.2015 No.11
Recently, passenger vehicle manufacturing companies are endeavoring to improve noise control technologies very much. Among them, the wind noise has been highlighted as a main ingredient of interior noises owing to passenger vehicle performance improvement. Passenger vehicle industries are doing efforts so as to enhance passenger vehicle wind noise performances of excellent quality for satisfying customer’s needs on it. This study is aimed to develop a wind noise loss function intended for customer satisfaction prediction from based on vehicle interior noise levels, and loss function play a fundamental role in every quality engineering method. Also, Loss function of wind noise and initial quality index is a reasonable approach method to design concept development, excellent initial quality, and robust in the wind noise performance development of vehicle.
Analysis of hill road vibration for 3cylinder powertrain
Jungwoog Sun(선정욱),Namcheol Kim(김남철),Dalsik Kim(김달식),Byoungro Lee(이병로) 한국자동차공학회 2015 한국자동차공학회 학술대회 및 전시회 Vol.2015 No.11
At the hill road, during the launch, we can get the severe body vibration such as seat track, steering wheel and even interior noise. Especially for the 3cylinder, it could be worse than 4cylinder due to the 1<SUP>st</SUP> order imbalance. It means, in the case of 3cylinder, there are two kinds of sources, 1<SUP>st</SUP> and 1.5<SUP>th</SUP> orders. This study deals with assessment process for root cause. First step is to define the source - higher axle torque and imbalance level. Higher axle torque at the hill can make higher tractive road load and input force to the engine mount. Measured axle torque characteristic well matches with seat track vibration. Engine 1.5<SUP>th</SUP> order gas torque fluctuation at the hill is also much higher than at the flat road. Another source is 1st order imbalance which is 3cylinder specific issue. Second step is to look for the path – engine mount stiffness change and powertrain rigid body mode. Engine mount stiffness increased at the hill due to the higher axle torque. It can change powertrain rigid body mode at hill with stiffer engine mounts which can be increased up to max axle torque, or max input source. Additionally, through the 12DOF analysis using measured mount stiffness under the hill road condition, yaw mode at the hill is closed with issued frequency for the 1<SUP>st</SUP> order. So, powertrain rigid body mode could be one of the reason to increase the body vibration at the hill. Regarding body sensitivity, there is no changes even for the higher, almost double mount stiffness. However, it does not exactly reflect the hill road condition during the test. Further study is required. Therefore, source wise, we need to check the powertrain rigid body mode and higher gas torque fluctuation at hill. Path wise, we should check the engine mount stiffness change at the hill.
DOE를 이용한 Acoustic cavity modeling과 NTF 해석 개선
이주형(Joohyung Lee),이상윤(Sangyun Lee),김달식(Dalsik Kim),김영호(Youngho Kim) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
Acoustic cavity model is very important role in noise prediction of vehicle by using CAE. The results of analysis can be very different as a modeling method and properties of acoustic cavity model. However it is difficult to make a precise model due to simplicity of cavity model according to its limited mesh size. In this paper we will find a reasonable values fitting in it through DOE, Kriging method and verify the model by comparison to acoustic cavity modal test results. Also, we will check acoustic cavity model used to predict road noise by means of comparing test and analysis of NTF. This will make it possible to predict reliable noise analysis results.
엔진 마운트의 interm 브라켓 공진 주파수 target 설정에 관한 연구
선정욱(Jungwoog Sun),우성근(Sunggeun Woo),전병근(Byounkeun Jeon),김달식(Dalsik Kim),강신남(Shinnam Kang) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.10
When developing engine mount, interm mount bracket 1st resonance is critical to make sound quality better or worse. So, at the initial stage of development, we need to consider some design parameter to setup the target of interm bracket 1st resonance. Especially, 3cylinder interm bracket guideline is not well known. So, this paper deals with some important sensitivity which should be considered during the development of vehicle. From source to interior side, we should know the component sensitivity like body sensitivity p/F or bracket gain etc. Through this paper, we could get the knowledge of design guideline and key consideration points.