지하철 진동에 의한 구조음 실측치와 예측치 비교

이태호(Tae-Ho Lee),안용찬(Yong-Chan Ann),조정식(Jung-Sik Cho),이기륭(Ki-Ryung Lee) 한국소음진동공학회 2014 한국소음진동공학회 학술대회논문집 Vol.2014 No.10

지하철 인근 지역에서 차량 통과 시 차륜과 레일의 상호작용으로 인한 진동이 지반을 통하여 건물까지 전파되어 구조전달음이 발생하게 된다. 이러한 구조전달음이 발생하는 지하철 인근 지역에서 도로나 주거단지가 새롭게 조성될 예정인 경우, 완공 이후에 발생하는 구조전달음 영향을 사전에 평가하고 대책을 수립하는 것이 요구된다. 본 논문에서는 국내에 위치한 일부 역사에서의 구조전달음을 측정하고 국외의 예측식을 검토하여 구조전달음의 실측치와 예측치를 비교한다. 따라서 국내 지하철의 구조전달음 예측에 대하여 국외 예측식의 타당성을 검토함으로써 향후 건설될 지하구간 역사의 인근 주거지역에 대한 구조전달음을 예측하는데 기초 자료로 활용하고자 한다.

차체골격내 복합체 삽입을 이용한 구조기인 아이들 소음저감

김효식(Kim, Hyo-Sig),김중희(Kim, Joong-Hee) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.4

As a matter of fact, it has been not allowed to modify the shape of a vehicle body skeleton since the technical definition for the structure was fixed and the corresponding molds were developed. By the way, if it is available to apply an alternative to reinforce the skeleton without changing its mold, it must be much flexible to improve the performance qualities relevant to not only NVH(noise, vibration and harshness) but also crash and durability. Recently, a solution of so-called composite body becomes available for the need. We present a design method to insert the composite body inside a vehicle body skeleton in order to improve a structure-borne noise at the idle condition. The algorithms, topology optimization and design sensitivity analysis, are applied to mainly search the sensitive structural sections in the body skeleton and to extract the target stiffness of the sections. Inserting the composite bodies into the sensitive portions, it is predicted to achieve the countermeasures which can compromize the design availability in terms of the idle noise and weight. According to the validation result with test vehicles, the concerned noise transfer function is reduced and the idle booming noise is resultantly improved.

차량 가진원 유무에 따른 실내소음의 전달경로 분석에 대한 연구

박종호(Park Jongho),이상권(Lee Sangkwon) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.4

Structure-bone noise is an important aspect to consider during the design and development of a vehicle. Reduction of structure-bone noise of the compartment in a vehicle is an important task in automotive engineering. Many methods which analyze transfer path of noise have been used for structure-bone noise. The existing method to measure of frequency response function of transfer path has been tested by removing a source. This Paper presents an experimental analysis about Transfer Path Analysis of the vehicle interior noise according to Excitation or not. To identify these points of difference, experiment were conducted through an experimental test using simulation vehicle.

차량 배기 시스템 마운트 브라켓에서 중주파수 대역 트림바디 음향 민감도 해석의 정확도 개선을 위한 연구

정민규(Minkyu Jung),이상윤(Sangyun Lee),최진호(Jinho Choi) 한국자동차공학회 2019 한국자동차공학회 학술대회 및 전시회 Vol.2019 No.11

There are two types of noise in a vehicle. One is the structure-borne noise which results from the mechanical vibrations generated in a vehicle being transmitted through the mounting systems causing body panels to vibrate, and the other is the airborne noise which results from the radiated sound power being transmitted through the body panels to the interior or to the vehicle exterior. FEM (Finite Element Method) and BEM (Boundary Element Method) are generally used for the structure borne noise analysis in low frequency range under 200㎐, while SEA is used for the air borne noise analysis in high frequency range over 1㎑. Hybrid FE-SEA method could be used for noise analysis in mid frequency range and it had been studied to get reliability in the analysis. But the hybrid method takes long time in building a CAE model due to conversion SEA element through FE model as well as getting modal density, stiffness multiplier, radiation multiplier and coupling loss factor. In this paper, acoustic sensitivity analysis and design study have been performed based on FE method at exhaust mount bracket area in mid-frequency range. The proper contact model is proposed for improving the fidelity of the acoustic sensitivity analysis using FE method, and CAE results is compared with test results to verify the proposed method.

전달 경로 분석과 패널 기여도 분석을 이용한 휠로더의 실내소음 저감에 관한 연구

김보용(Kim, Bo-Yong),신창우(Shin, Chang-Woo),정원태(Jeong, Won-Tae),박성용(Park, Sung-Yong),장한기(Jang, Han-Kee),김성재(Kim, Seong-Jae),강연준(Kang, Yeong-June) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.8

Transfer path analysis(TPA) and panel contribution analysis(PCA) have been used widely to reduce interior noise of mechanical systems. TPA enables us to decompose interior noise into air-borne and structure-borne noises and estimate the path contribution of noise sources. PCA is also used to identify the noise contribution of each sub-panel in vibro-acoustic systems. In this paper, TPA and PCA are applied to wheel loader, one of the heavy construction equipments. Firstly, TPA for air-borne noise is conducted to estimate the contribution of air-borne sources using pressure transfer function. Thereafter, TPA for structure -borne noise is employed to verify the results of air-borne source quantification through the synthesis of two results. Secondly, PCA is performed by both TPA using pressure transfer function between panels inside the cabin and boundry element method(BEM) for the cabin of wheel loader with various boundary conditions. As a results, it was found that TPA conducted by experiments and PCA accomplished by both experiments and BEM are very effective methods in analyzing the path and contribution of the noises for reducing an interior noise level in the wheel loader system.

진동 파워흐름 측정을 통한 SUV용 엔진 마운트의 에너지 전달 기여도 분석에 관한 연구

김수곤(Kim, Su-Gon),이상권(Lee, Sang-Kwon),김성종(Kim, Sung-Jong) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.4

Reduction of structure-borne noise in the compartment of a car is an important task in automotive engineering. Many methods which analyze noise transfer path have been generally used for structure-borne noise. These methods are useful in solving particular problem but do not quantify the effectiveness of vibration isolation for each isolator of a vehicle. To quantify the effectiveness of vibration isolation, the vibrational power flow measurement has been used for a simple isolation system or a laboratory based isolation system. This paper identifies the transfer path of booming noise in a SUV. The powertrain used for test has a in-line 4cylinder engine and 5-shift auto-transmission. This powertrain is transversely supported by four isolators. We calculated the energy flow throughout four isolator by the measurement of power flow and the contribution of energy flow at each isolator.

구조기구조기인 아이들 소음 저감을 위한 차체 골격 내 복합체 삽입 최적설계

김효식(Hyosig Kim),윤성호(Seongho Yoon),김중희(Joonghee Kim) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5

As a matter of fact, it has been difficult to modify the shape of vehicle body skeletons since the technical definition for a global body structure was fixed and the corresponding molds were developed. By the way, if it is available to apply an alternative to reinforce the skeletons without changing their molds, it will be more flexible to improve the performance qualities relevant to crash, durability and NVH(Noise, Vibration and Harshness). Recently, a solution with the composite body becomes available for the purpose. We present an optimal design method to insert the composite bodies into a vehicle body skeleton in order to improve the structure-borne noise at the idle condition. The algorithms, topology optimization and gradient based optimization, are applied to mainly search the sensitive structural joints in the body skeleton and to extract the technical definition of composite body insertions. Inserting the composite bodies into the sensitive joints, it is predicted to achieve the countermeasure which can meet the design availability in terms of the idle noise and the weight. According to the validation result with test vehicles, the concerned noise transfer function is reduced and the idle booming noise is resultantly improved.

승용차 실내소음의 전달경로 해석

지태한,최윤봉 한국소음진동공학회 1999 소음 진동 Vol.9 No.1

Structure-borne noise is an important aspect to consider during the design and development of a vehicle. In this work. it was desired to identify the primary paths associated with structure-borne noise generated from the engine and front suspension. An experimental source-path-receiver model was used to characterize the system. A variety of primary sources such as engine. tires or exhaust system generate vibrations of the inner surfaces of the passenger compartment of a vehicle which subsequently radiate noise. The source was characterized by the force acting at the engine-to-body interface. and the path was characterized by pressure over force FRF's. The excitation forces were indirectly determined using dynamic stiffness of rubber mount or the system accelerance matrix. Through these analysis, path contribution diagram which is well expressed primary noise path is obtained.

방사소음 및 투과소음에 대한 승용차량 대시패널의 설계인자 별 영향도 분석

유지우(Yoo, Ji-Woo),채기상(Chae, Ki-Sang),박철민(Park, Chul-Min),서진관(Suh, Jin-Kwan),이기용(Lee, Ki-Yong) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.1

While a dash panel component, close to passengers, plays a very important role to protect heat and noise from a power train, it is also a main path that transfers vibration energy and eventually radiates acoustic noise into the cavity. Therefore, it is important to provide optimal design schemes incorporating sound packages such as a dash isolation pad and a floor carpet, as well as structures. The present study is the extension of the previous investigation how design variables affect sound radiation, which was carried out using the simple plate and framed system. A novel FE-SEA hybrid simulation model is used for this study. The system taken into account is a dash panel component of a sedan vehicle, which includes front pillars, front side members, a dash panel and corresponding sound packages. Design variables such as panel thicknesses and sound packages are investigated how they are related to two main NVH indexes, sound radiation power(i.e. structure-borne) and sound transmission loss(i.e. air borne). In the viewpoint of obtaining better NVH performance, it is shown that these two indexes do not always result in same tendencies of improvement, which suggests that they should be dealt with independently and are also dependent on frequency regions.

승용차량의 소음저감을 위한 시험과 시뮬레이션을 이용한 대시 시스템의 특성 연구

유지우(Yoo, Ji Woo),채기상(Chae, Ki-Sang),조진호(Cho, Jin Ho) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.11

Low frequency noises(up to about 200 Hz) such as booming are mainly caused by particular modes, 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 increases, 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 to reduce noise in this frequency region. 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 transmits 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 and 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.