• 대한기계학회논문집A
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• 제33권11호
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• pp.1244-1248
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• 2009

Although rubber components are extensively used in mechanic parts. There are still a lot of difficulties in designing the rubber components applied in complex shapes and preloaded states because of the complicated material properties. One of the most important parameters for more detailed and accurate mechanical analysis during the development stages is the dynamic characteristics of the rubber components. It is well known that the dynamic properties of rubber are dependent on frequency as well as static preload. Consequently, a large number of experiments have to be conducted to identify the dynamic stiffness of a rubber bush considering the various applied conditions. In this paper, an efficient experimental method is suggested, which estimates the dynamic stiffness of a rubber bush using rubber material test and static stiffness of the bush. This method is capable of predicting the dynamic stiffness of a rubber bush under various load conditions from minimized test data.

• 한국소음진동공학회논문집
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• 제26권7호
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• pp.827-835
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• 2016

Ride comfort of a vehicle is often determined by rubber bushes in suspension system. If transmission forces versus deformations across the bushes are available under operational conditions, improvement of the ride comfort could be done with more ease. Recently, the transmission forces are measured using custom-made force transducers inside the links. This study presents a feasibility study on estimation of the rubber bush deformations using vibration signals on the rigid links. Linear variable displacement transducers as well as piezoelectric accelerometers are used to expand frequency range to very low frequency, which cannot be done with accelerometers only. How to estimate the bush deformation from the two vibration signals on the links are presented together with experimental results.

• 한국안전학회지
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• 제21권2호
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• pp.15-21
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• 2006

The railroad bogie's components experience repeated loading during service. Especially, oil damper bush has been fatigue fractured on the plane between rubber and steel stem during service, and which results in inferior of performance of the bogie. In this study, in order to offer a proper maintenance method of the bush, bubber bush used for the oil damper was fatigue tested and its damage fraction during service was estimated. Also, FEM analysis on the bush was conducted. When 1400, 1200, and 1000kgf of repeated loads were applied to the oil damper bush, final damage fraction exhibited 63.7%, 50% and 40%. From the results of FEM analysis, deformation energy density was found to be $0.5452kgf/mm^{2}$ at an applied load of 1400kgf and the location with maximum value coincided with the fractured location of the bush. Finally, it will be desirable to adopt the normalized damage fraction rather than absolute damage fraction in estimating remaining service lifetime of the bush.

• 한국소음진동공학회논문집
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• 제20권10호
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• pp.907-914
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• 2010

While rubber components are extensively used in automobile vehicle, there are still a lot of difficulties in designing the rubber components applied in complex shapes and preloaded states because of the complicated material properties. In this paper, an efficient experimental method is suggested, which estimates the dynamic stiffness of a rubber component using rubber material test and static stiffness of the bush. And it is verified by comparing with FEM predictions and experimental results. This method is capable of predicting the dynamic stiffness of a rubber bush under various load conditions from minimized test data. Also it estimates dynamic characteristics of a rubber component using rubber material test and FEM calculation.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.490-498
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• 2010

K사의 방진고무 사출성형에 있어서 애로사항인 토크로드부시(torque rod bush)의 캐비티 가장자리(edge) 구간에서의 에어트랩(air-trap) 발생 및 다이내믹 댐퍼(dynamic damper)에 있어서 사출시 미성형(short shot) 발생 등의 문제점을 해결하기 위하여, 상용 CAE 프로그램인 MOLDFLOW(Ver. 5.2)를 이용한 전산모사를 수행하여 적정금형설계를 도출하고 적정작업조건을 구축하였다. 그 결과 방진고무 중에서 토크로드부시의 사출성형에서의 에어트랩 발생 등의 공정문제를 최적 캐비티 가장자리 경사각 및 게이트 수를 조절함으로써 캐비티 가장자리에서의 유동선단(flow-front)의 유동정체를 방지하고 유동을 원활하게 하여 해결하였다. 한편 다이내믹 댐퍼의 사출시 충전(filling) 단계에서의 캐비티 비충전으로 인한 미성형 불량은 에어벤트(air-vent) 구를 에어트랩 발생 빈도가 매우 높은 유동선단 상향류와 하향류의 두 흐름이 만나는 지점에 설치함으로써 미성형 불량을 해결하였다. 또한 게이트 위치를 댐퍼 상단에서 중단으로 변경하거나 게이트 수를 증가시킨 경우에 미성형 불량이 K사의 경우보다 개선되었다.

• Composites Research
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• 제13권5호
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• pp.10-17
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• 2000

계면상 조건과 단섬유 함유량 증가에 따른 강화고무의 피로특성에 대해 실험적 고찰을 하였다. 피로시험 후 기지고무의 스프링 상수는 약 21% 감소하였고, 강화고무는 반대로 증가하였다. 강화고무의 스프링 상수 변화율은 섬유함유량 증가에 따라 감소하였고, 계면상 조건이 우수할수록 변화율이 적었다. 피로시험 후 기지고무의 온도는 2.5배, 강화고무는 1.7∼2.0배 증가하였다. 강화고무의 온도 변화율은 섬유 함유량 증가에 따라 감소하였고, 동일한 섬유 함유량에서 계면상 조건이 우수할수록 변화율이 적었다. 이번 연구에서 접착제 402와 고무용액을 2번씩 도포한 경우가 가장 우수한 계면상 모델(C)이 되었다. 그리고 이러한 강화고무를 자동차의 Engine Mount Rubber, Bush 그리고 Stopper등의 적용을 검토하였다.

• 전산구조공학
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• 제28권4호
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• pp.16-20
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• 2015

• Journal of Mechanical Science and Technology
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• 제19권6호
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• pp.1229-1242
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• 2005

When natural rubber is used for a long period of time, it becomes aged; it usually becomes hardened and loses its damping capability. This aging process affects not only the material property but also the (fatigue) life of natural rubber. In this paper the aging effects on the material property and the fatigue life were experimentally investigated. In addition, several fatigue life prediction equations for natural rubber were proposed. In order to investigate the aging effects on the material property, the load-stretch ratio curves were plotted from the results of the tensile test, the compression test and the simple shear test for virgin and heat-aged rubber specimens. Rubber specimens were heat-aged in an oven at a temperature ranging from $50^{\circ}C$ to $90^{\circ}C$ for a period ranging from 2 days to 16 days. In order to investigate the aging effects on the fatigue life, fatigue tests were conducted for differently heat-aged hourglass-shaped and simple shear specimens. Moreover, finite element simulations were conducted for the specimens to calculate physical quantities occurring in the specimens such as the maximum value of the effective stress, the strain energy density, the first invariant of the Cauchy-Green deformation tensor and the maximum principal nominal strain. Then, four fatigue life prediction equations based on one of the physical quantities could be obtained by fitting the equations to the test data. Finally, the fatigue life of a rubber bush used in an automobile was predicted by using the prediction equations, and it was compared with the test data of the bush to evaluate the reliability of those equations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.69-74
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• 2006

It is known that the various noise sources which are engine, transmission, tire, intake system, etc exist at vehicle driving status. Specially noises which cannot be expected by a driver induce unpleasantness to all passengers. These noises are difficult to distinguish noise sources or specifications because of too many vehicle parts. Therefore in this paper, study on abnormal noise of bush on suspension system is performed by the measurement and analysis of the noises of bushings that are generated artificially. The measured noises are analyzed by two points-view of spectrum and sound quality. Finally, it is shown that the noise sources of bushings on the suspension system which are the pillow ball joint bush of a control arm and the rubber bush of a lower arm could be distinguished by the spectrum distribution and a index value based on tonality.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.453-458
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• 2008

Under driving condition, A vehicle experiences various kinds of loads, which brings on the buckling and fracture of suspension systems. Lower control arm (LCA), which consists of 2 bush joints and 1 ball joint connection, is the one of the most important parts in the suspension system. The bush joints absorb the impact load and reduce the vibration from the road. When analyzing the LCA behavior, it is important to understand the material properties and boundary conditions of bushing systems correctly, because of the nonlinearity characteristics of the rubber. In this paper, in order to predict the large scale deformation of the LCA more precisely, three factors are newly suggested, that is, coupling of bush stiffness between translation and rotation, bush extraction force and maximum rotation angle of ball joint. LCA stiffness is estimated by CAE and component test. Analysis and test results are almost same and the validity of considering three factors in LCA analysis is verified.