전달손실 최대화를 위한 다층 흡음재-패널 배열 최적설계

김용진(Kim, Yong-Jin),이중석(Lee, Joong-Seok),강연준(Kang, Yeon-June),김윤영(Kim, Yoon-Young) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.12

Though multilayered foam-panel structures have been widely used to reduce sound transmission in various fields, most of the previous works to design them were conducted by repeated analyses or experiments based on initially given configurations or sequences. Therefore, it was difficult to obtain an optimal sequence of multilayered foam-panel structure yielding superior sound isolation capability. In this work, we propose a new design method to sequence a multi-panel structure lined with a poroelastic material having maximized sound transmission loss. Being formulated as a one-dimensional topology optimization problem fur a given target frequency, the optimal sequencing of panel-poroelastic layers is systematically carried out in an iterative manner. In this method, a panel layer is expressed as a limiting case of a poroelastic layer to facilitate the optimization process. This means that main material properties of a poroelastic material are treated as interpolated functions of design variable. The designed sequences of panel-poroelastic multilayer were shown to be significantly affected by the target frequencies; more panels were obtained at higher target frequency. The sound transmission loss of the system was calculated by the transfer matrix derived from Biot's theory.

원통형 임피던스 튜브 내 다중 미세천공 판의 음향투과

김현실,마평식,김봉기,이성현,서윤호 한국음향학회 2020 韓國音響學會誌 Vol.39 No.4

In this paper, sound transmission of Micro-Perforated Plates (MPPs) installed in an impedance tube with a circular cross-section is described using an analytic method. Vibration of the plates is expressed in terms of an infinite series of modal functions, where modal function in the radial direction is given by the Bessel function. Under the plane wave assumption, a low frequency approximation is derived, and a formula for the sound transmission coefficient of multi-layered MPPs is presented using the transfer matrix method. The Sound Transmission Losses (STLs) of single and double MPPs are computed using the proposed method and compared with those done by the Finite Element Method (FEM), which shows an excellent agreement. As the perforation increases, the STL is degraded, since the STL becomes dominated by the perforation ratio rather than by vibration of the plate. The STL shows dips at natural frequencies as well as at the mass-spring-mass resonance frequency. The proposed model for the STL prediction in this study can be applied to an arbitrary number of MPPs, where each MPP may or may not have a perforation. 본 논문은 원통형 임피던스 튜브내에 설치된 다중 미세천공판(Micro-Perforated Plate, MPP)의 음향투과를해석적으로 구하는 방법을 다루었다. 판의 진동을 무한 급수의 합으로 전개하였는데 반경방향으로는 Bessel 함수를포함한다. 평면파 가정하에서 저주파수 대역의 근사식을 유도하였으며 전달함수법을 이용하여 다중 MPP에 대한 음향투과율 공식을 제시하였다. 단일과 이중 MPP의 음향투과손실(Sound Transmission Loss, STL)을 본 논문에서 제안한 공식을 이용하여 계산하였으며 유한요소법(Finite Element Method, FEM)을 사용한 결과와 잘 일치 하였다. 천공율이 증가할수록 STL은 감소하는데 이는 판의 진동보다는 천공율이 더 큰 영향을 주기 때문이다. STL은 판의 공진주파수에서 골(dip)을 보이며 이중 MPP의 STL은 질량-스프링-질량 진동에 해당하는 공진주파수에서 골을 보인다. 본 연구에서 제안한 STL 예측 모델은 임의의 개수의 다중 MPP에 적용이 가능하며 각각의 판은 미세천공을 포함하거나 포함하지 않는 두 가지 경우가 모두 가능하다.

다입력/다출력관을 갖는 확장관의 투과손실 해석

박기춘,김양한 한국소음진동공학회 1998 소음 진동 Vol.8 No.5

Transmission loss of the simple expansion chamber with multiple inlet and outlet ports is obtained. Transfer matrices which represent the relation between the power variables(pressure and velocity) of inlets and outlets depend on the input relatons as well as the acoustic system parameters(i.e. geometry of the chamber, wall admittance, etc.). The analysis has been performed analytically, including the effects of higher order modes for the 2-inlet/1-outlet, 1-inlet/2-outlet and 2-inlet/2-outlet systems. This study yeilds that phase difference between the inlet ports can significantly increase the transmission loss in low frequency range.

전달경로의 차이를 이용한 차량용반능동형 머플러의 특성에 관한 연구

이종민,김경목,손동구,이장현,황요하 한국소음진동공학회 2001 소음 진동 Vol.11 No.3

Passive type mufflers installed on every car haute inherent problem of lowering engine power and fuel efficiency caused by backpressure which is byproduct of complex internal structure. Recent improvements like installing a calve to change exhaust gas path depending on power requirement and rpm have only marginally improved performance. Tremendous amount of recent research works on active exhaust noise control have failed to commercialize because of numerous physical and economical reasons. In this paper, a unique seal-active muffler using difference of transmission paths is presented. In this system exhaust pipe is divided into two and joined again downstream. Exhaust noise is reduced by destructive interference when two-divided noise join again with transmission paths'difference which is half of the wavelength of a main noise frequency. One divided path has a sliding mechanism to change length thereby transmission path length difference is adjusted to entwine rpm change. The proposed system has minimal backpressure and does not need a secondary sound source like a speaker so it can overcome many problems of failed active noise control methods. We have verified proposed system's superior performance by simulation and comparison experiment with passive mufflers.

승용차 자동변속기용 트랜스퍼 드라이브 기어 베어링의 효율개선 방법에 관한 연구

이인욱(In Wook Lee),한성길(Sung Gil Han),곽범섭(Beom-Seop Gwak),이호성(Ho Sung Lee),송철기(Chul Ki Song) 한국기계가공학회 2021 한국기계가공학회지 Vol.20 No.3

An automatic transmission of automobiles enables comfortable driving experience with lower transmission shifting jerks. However, the assembly structure is more complicated and requires additional components with lower efficiency than the manual transmission system. Extensive research has been conducted to improve the overall transmission efficiency by optimizing each component of the automatic transmission assembly. This study focuses on enhancing the friction torque of double angular contact ball bearings used in automatic transmission. The friction torque of the bearing varies with the operating conditions such as the operational load and rotating speed. Since reducing the friction torque of the bearing tends to deteriorate the durability of the bearing, it is necessary to design the bearing having a minimum required friction torque by determining the durability life of an automatic transmission assembly, In this study, the theoretical life and friction torque of conventional and newly-developed bearings are calculated. The difference in the friction torque between the new and existing bearings are also evaluated.

압력 손실을 고려한 소음기의 위상 최적화

이진우(Jin Woo Lee),장강원(Gang Won Jang) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

A topology optimization based design method is proposed to effectively obtain the internal optimal topologies of acoustic silencers for improving their acoustic attenuation performance without large pressure drop. To the end, topology optimization problems are formulated to increase the transmission loss of the silencers and decrease their pressure drop simultaneously. Finite element models are used for acoustical analysis and flow analysis of the silencers. One design variable assigned to each finite element is pushed to the limiting values, 0 or 1, during optimization process by carefully-selected interpolation functions When the design variable becomes 1, the associated element is filled with solid, which blocks flow and fully reflects an incident acoustic wave. In contrast, when the design variable becomes 0, fluid and incident acoustic wave freely passes the associated element. Several optimal topologies are obtained from the formulated topology optimization problems for given solid volumes.

복합시트의 구조가 흡,차음성에 미치는 영향

이병찬 ( Byung Chan Lee ),김성룡 ( Sung Ryong Kim ) 한국복합재료학회 2012 Composites research Vol.25 No.5

복합시트의 구조를 변화시켜 흡?차음성에 미치는 영향을 연구하였다. 폴리프로필렌 보드의 표면과 배면에 폴리에틸렌테레 프탈레이트 부직포를 핫 프레스로 융착하여 복합시트를 제조하였다. 면밀도가 0.64kg/m2인 부직포를 사용하여 제조한 복합시트의 흡음률은 0.1-0.2의 값을 나타내어 폴리프로필렌 보드의 흡음률에 비해 약 100~400%의 증가를 나타내었다. 폴리프로필렌 보드의 면밀도를 증가시키거나 복합시트 위에 반구형의 홈을 포함하는 경우에 복합시트의 투과손실이 증가하였다. 평판복합시트와 사인 파형을 가지는 복합시트의 구조를 변화시켜 만든 2가지 복합시트 구조에 따른 흡음률과 차음도의 변화를 조사하였다. The effect of structure on the sound absorption and sound transmission loss of composite sheet was investigated. A sheet of polypropylene was bonded by hot press with nonwoven fabric sheets of polyethylene terephthalate on the top side and the back side. Absorption coefficient of composite sheet using nonwoven fabric with surface density of 0.64kg/m2 was 0.1-0.2. It is 100-400% improvement compare to that of polypropylene sheet. The transmission loss of composite sheet was increased with surface density of polypropylene board and introduction of hemisphere hole on the surface of sheet. Two types of composite sheet were made using flat sheet and sine wave shaped sheet and the effect of sheet structure on the transmission loss was investigated.

변속기 외접 기어트레인의 마찰 및 쳐닝 동력 손실 예측

박기종(Kijong Park),강마루(Maru Kang),이승호(Seungho Lee),손우철(Woocheol Son),자니 하리안토(Jonny Harianto),아멧 칼만(Ahmet Kahraman) 한국자동차공학회 2017 한국자동차공학회 부문종합 학술대회 Vol.2017 No.5

주파수 가중함수를 적용한 흡기계의 강건설계 연구

이종규(Lee, J.K.),박영원(Park, Y.W.),채장범(Chai, J.B.) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.6

This paper introduces the robust design of an intake system using transmission loss and the frequency weighting function. First, transmission loss is measured to evaluate the performance of the noise reduction for the intake system. The robust design parameters of the intake system are extracted by adapting a cost function with the Taguchi method. Subsequently, the frequency weighting function is developed by the subjective evaluation in which 6 special engineers were participated. Finally, the comparison between the proposed frequency weighted optimal design and unweighted optimal design for the transmission loss as the part is performed. Here, the overall levels of the transmission loss according to the methods are presented to validate the effectiveness of the proposed methodology.

자동변속기유의 마찰 및 점도 특성이 연비향상에 미치는 영향에 대한 연구

유성춘(Sungchoon Yoo),차상엽(Sangyoup Cha) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

To reduce viscosity to be related to the flow resistance or to improve the friction property of automatic transmission fluid is one of the effective way to improve fuel economy of motor vehicle. This study shows that automatic transmission fluid to have a lower viscosity contribute to improve the fuel economy because reduce the torque loss and improve the transmittal efficiency, While Friction property did not help to improve the transmittal efficiency in the automatic transmission. Also, shows F/F type transmission is more affected by viscosity of ATF than F/R type transmission.