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채기상(Ki-Sang Chae) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Statistical Energy Analysis (SEA) is a nearly unique method to predict vehicle airborne interior noise in the mid and high frequency range at present, and after about the year of 2000, SEA has been one of the effective CAE tools in the global automotive industry. In this paper, a process of building a vehicle model to predict airborne interior noise is described: vehicle modeling, material data preparations and correlation efforts for material level, component level, and vehicle level. Even though full correlations were not made for material and component level, in vehicle level, there were strong similarities between the predicted and the measured vehicle interior noise. It seems that SEA could be an effective CAE tool to deal with the vehicle airborne noise in early stage of vehicle development.
채기상(Ki-Sang Chae),최정순(Jeongsoon Choi),염성우(Sung Woo Yeom),이승(Seung Lee),남궁재균(Jaekyun Namgung) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
In order to develop the vehicle insulation performance efficiently in the view point of weight and cost, it is necessary to perform detailed studies for the insulation performances of a current production vehicle’s major panels in the predevelopment stage of a successor vehicle. In this study, the insulation performances of dash and floor system are experimentally studied for a sedan vehicle which is sold in the market (production vehicle). A window method is applied in order to estimate the sub-regional insulation performances and the individual insulation performances of dash pass-throughs. The weak paths of dash and floor are checked one by one by using the window method and sound intensity maps. Simulation models are developed based on the above experimental results, by which the insulation performance of each system could be predicted precisely. Finally, design studies are performed using the simulation models for a successor vehicle development.
차량 대시구조 차음성능에 대한 실러 적용 효과의 시험 분석
채기상(Ki-Sang Chae),유지우(Ji WooYoo),이상우(Sang-woo Lee),이승(Seung Lee) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
Sound insulation performance of vehicle dash system is determined by a superposition of the performances of panel, sealer, vibration deadner, sound package, and pass-throughs. Up to now, the sealer treatments effects on insulation performance of dash are not clear. Therefore, it is difficult to include these effects in virtual development phase. In this paper, the sealer’s effects are experimentally studied in the viewpoint of Sound Transmission Loss (STL) of dash structure. A test structure of vehicle dash is prepared for the measurement of STL. The locations of sealer treatment are classified into a few characteristic regions, and STL measurements are performed under various conditions of sealer treatment. Additionally, experiments for vibration deadener effects are also performed and compared to the results of selaer treatement. The summary of the experiments are as following: 1) STL of dash structure without sealer treatment is lower as much as 9 dB in the high frequencies such as above 1kHz, compared to maximum sealer treatment. 2) For locations of sealer treatment, the compartment-side is more important compared to the engine room-side. 3) For the case of dash panel with a large flat reinforement, at which air gap exists between dash panel and reinforcement, the sealer treatment along the edge of the reinforcement could contribute to the enhancement in STL. 4) Compared to the application of sealer treament, application of vibration deadener has a small sensitivity in STL in the high frequencies.
채기상(Ki-Sang Chae),박철민(Chul-Min Park),이인직(In-Jik Yi),김상모(Sang-Mo Kim) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Vehicle interior noise above 500㎐ is usually controlled by sound package parts. The materials and geometries of sound package parts directly affect on this high frequency noise, so those effects should be simulated. In this study, Statistical Energy Analysis (SEA) is utilized to simulate the design change effects of sound package parts for a CUV vehicle. Using a commercial SEA simulation tool, a SEA vehicle model is built and validated for idealized acoustic excitations, and the validated model is used for wide open throttle (WOT) condition. Design changes of 7 sound package parts are considered, and their effects on Articulation Index (AI) are analyzed using a DOE approach, and optimal design alternatives are chosen. Finally, through several vehicle tests it is proved that AI can be improved with decrease of weight and cost with aid of SEA approach.
승용차량의 중주파수 대역 구조기인 소음예측을 위한 FE-SEA 하이브리드 모델 개발
유지우(Ji Woo Yoo),채기상(Ki-Sang Chae),A. Charpentier,임종윤(Jong Yun Lim) 한국소음진동공학회 2014 한국소음진동공학회 논문집 Vol.24 No.8
Vehicle simulation models for noise and vibration prediction have been developed so far generally in two schemes. One is FE models generally used for problems below 200 Hz such as booming noise, and the other is SEA models for high frequencies of more than 1 kHz, representatively related to sound packages. There have been many researches to develop a simulation model for 200~1000 Hz, so-called mid-frequency region, and this paper shows one practical result that covers the trimmed body of a sedan vehicle. The simulation model is developed based on an FE model, and then FE elements at some areas are substituted with SEA elements to reduce DOFs. SEA panels are described by modal density, radiation efficiency, stiffness and damping characteristics that are found from some numerical assessments. Sound packages are modeled similarly as a conventional SEA model. The results obtained from the hybrid model were compared to experimental results. Predicted pressure and vibrational velocity generally show a good agreement. The developed simulation model and related technology are successfully being used in vehicle development process.
1kHz 이하 구조기인 소음예측을 위한 트림바디 모델의 개발과 적용
유지우(Ji Woo Yoo),채기상(Ki-Sang Chae),A. Charpentier,임종윤(Jong Yun Lim) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.10
Vehicle CAE models for NVH predictions are largely developed in two schemes. One is FE models generally used for below 200 Hz problems such as booming noise, and the other is SEA models for high frequencies of more than 1 kHz, representatively related to sound packages. HMC has tried to develop a CAE model for 200-1000 Hz, so-called mid-frequency region, and this paper is one of the corresponding results. The CAE model is developed based on an FE model, and then FE elements at some areas are substituted with SEA elements to reduce DOFs. SEA panels are described by modal density, radiation efficiency, stiffness and damping characteristics that are found from some numerical assessments. Sound packages are modeled similarly as a conventional SEA model. The CAE model developed in this manner, the hybrid model, was compared to experimental results. Predicted pressure and vibrational velo city generally show a good agreement. The developed CAE model and related technology are successfully being used in vehicle development process.
시험에 의한 대시시스템의 소음특성 규명 및 시뮬레이션 신뢰성 연구
유지우(Ji Woo Yoo),채기상(Ki-Sang Chae),조진호(Jin Ho Cho) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.4
Low frequency noises (up to about 200 Hz) mainly occur due to particular modes, resulting in booming noises, and in general the solutions may be found based on mode controls where conventional methods such as FEM can be used. However, at higher frequencies between 0.3~ 1 kHz, as the number of modes rapidly increase, radiation characteristics from structures, performances of damping sheets and sound packages may be more crucial rather than particular modes, and consequently the conventional FEM may be less practical in dealing with this kinds of structure-borne problems. In this context, so-called ‘mid-frequency simulation model’ based on FE-SEA hybrid method is studied and validated. Energy Transmission loss (i.e. air borne noise) is also studied. A dash panel component is chosen for this study, which is an important path that transfers both structure-borne and air borne energies into the cavity. Design modifications including structural modifications, attachment of damping sheets and application of different sound packages are taken into account and the corresponding noise characteristics are experimentally identified. It is found that the dash member behaves as a noise path. The damping sheet or sound packages have similar influences on both sound radiation and transmission loss. The comparison between experiments and simulations shows that this model could be used to predict the tendency of noise improvement.