• Smart Structures and Systems
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• 제21권3호
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• pp.349-358
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• 2018

This paper investigates the free vibration analysis of double-beam system coupled by a two-degree-of-freedom mass-spring system. In order to generalize the model, the main beams are assumed to be elastically restrained against translation and rotation at one end and free at the other. Furthermore, the mass-spring system is elastically connected to the beams at adjustable positions by means of four translational and rotational springs. The governing differential equations of the beams and the mass-spring system are derived and analytically solved by using the Fourier transform method. Moreover, as a second way, a finite element solution is derived. The frequency parameters and mode shapes of some diverse cases are obtained using both methods. Comparison of obtained results by two methods shows the accuracy of both solutions. The influence of system parameters on the free vibration response of the studied mechanical system is examined.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.319-322
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• 2003

For the analysis of leveling process by the 3-dimensional elastic-plastic finite element method, a finite element analysis program modeling large deformation of shell has been developed. This program fur analyzing large deformation of sheet during leveling includes spring-back analysis as well as efficient contact treatment between sheet and rolls of leveler. This is verified by the simple leveling experiment with 5 rolls at laboratory. Besides the leveling examples, problems within the category of large strain and rotation, such as 3-dimensional roll-up and gutter occurrence at continuous bending-unbending process are also tested for verification of the program. The residual curvatures of strip predicted by finite element analysis are within 20% error range of the experiment. The formation and direction of anticlastic curvature or gutter during bending-unbending under tension is predicted and this agrees with the experimental results.

• 한국정밀공학회지
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• 제20권10호
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• pp.199-207
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• 2003

The Timoshenko beam model has been known as the most accurate model for representing beam structures. However, the Timoshenko beam model may give rise to a significant error when it is applied to multi-stepped beam structures. This paper is intended to demonstrate the modeling error of Timoshenko beam based finite element model for multi-stepped beam structures and to suggest a new modeling method to improve the accuracy. A tentative bending spring is introduced into the stepped section to represent the softening effect due to the presence of step. This paper also proposes a finite element modeling method in the light with the tentative bending spring model for the step softening effect. The proposed method rigorously adapts computation results from a commercial finite element code. The validity of the proposed method is demonstrated through a series of simulation and experiment.

• 한국기계가공학회지
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• 제12권1호
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• pp.77-83
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• 2013

This paper presents the feasibility on the application of composite coil spring, which has great interest in the automobile industry. In order to obtain much lighter weight of the composite spring, it will be necessary to optimize the design variables such as fiber angles and diameter of coil, etc. First of all, mechanical properties were measured to consider the effects of FVR and ply angles for carbon fiber composite material. And the shear modulus with respect to ply angles were derived based on twisting angles calculated by torsional beam model. Next we determined the design parameters of composite coil spring, which has equivalent spring rate to the steel coil spring. In order to assess the proposed method, finite element model of the composite spring was developed and analysed to obtain the spring constant. The results showed that static spring rate of the composite spring was in a good agreement with that of steel spring.

• International Journal of Railway
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• 제1권3호
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• pp.122-127
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• 2008

Rubber components are widely used in many application such as vibration isolators, damping, ride quality. Rubber spring is used in primary suspension system for railway vehicle. Characteristics and useful life prediction of rubber spring was very important in design procedure to assure the safety and reliability. Non-linear properties of rubber material which are described as strain energy function are important parameter to design and evaluate of rubber spring. These are determined by physical tests which are uniaxial tension, equi-biaxial tension and pure shear test. The computer simulation was executed to predict and evaluate the load capacity and stiffness for rubber spring. In order to investigate the useful life, the acceleration test were carried out. Acceleration test results changes as the threshold are used for assessment of the useful life and time to threshold value were plotted against reciprocal of absolute temperature to give the Arrhenius plot. By using the acceleration test, several useful life prediction for rubber spring were proposed.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권1호
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• pp.9-15
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• 2003

This Paper deals with the design of Moving Magnet type Linear Oscillatory Actuator(MM-LOA) using spring damper based on the design procedure and the characteristic analysis. MM-LOA is applied to variable load such as vaccum pump and compressor, The structure of piston type is selected to reduce a noise. MM-LOA has over-displacement in starting state because of the low inertia of mover To improve the starting characteristic, spring damper is used. The optimum spring constant of spring damper is detected and in consideration of spring damper, MM-LOA redesigned. The parameter is calculated by Finite Element Method(FEM). For the dynamic characteristic analysis, time differential method composed of voltage and kinetic equation is used. The propriety of the improved model is verified through the experimental results.

• 한국자동차공학회논문집
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• 제6권6호
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• pp.1-6
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• 1998

A leaf spring plays an important role in a passenger bus. Since characteristic of a leaf spring has a hysteresis behaviour, modeling technique for a leaf spring is an important issue for passenger bus analysis. In this paper, modeling technique for a leaf spring is presented. First, non-linear FEM model of a leaf spring is constructed then it is used to make an approximated model to be used in dynamic analysis. The modeling procedure is ex-plained in step by step approach. Then, this model is applied to dynamic analysis of a mini-bus with flexible body and non-linear dynamic force element. The results are compared with test data.

• 한국전산구조공학회논문집
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• 제24권1호
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• pp.33-41
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• 2011

본 연구에서는 비부착형 포스트텐션 시스템의 해석에 적용할 수 있는 모델링기법을 제시하였다. 모델링은 유한요소 해석 프로그램을 이용하였으며, tube-to-tube contact 요소를 도입하여 강연선의 물리적 형상을 직접적으로 모델링하는 방법과 실제의 강연선 외에 가상의 강연선을 콘크리트에 매입하고, 두 개의 강연선을 스프링으로 연결하여 간접적으로 모델링하는 방법을 동시에 제시하고 비교하였다. 콘크리트의 인장경화 현상을 무시하였을때 두 모델링기법에서는 거의 동일한 결과를 제공하지만 콘크리트의 인장경화를 고려한 경우에는 스프링을 이용한 간접적인 모델링기법을 통해서만 결과를 얻을 수 있었으며, 결과 또한 콘크리트의 경화현상을 고려하지 않은 경우와 다소 상이하였다. 비교를 통하여 비부착형 포스트텐션 시스템의 모델링기법으로 스프링을 이용한 모델링기법을 최종적으로 선정하고 기존의 실험적 연구에서 인용한 실험결과와 해석결과를 비교, 검증하였으며 또한 파라미터 스터디를 통해서 모델링의 적절성을 확인하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제21권1호
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• pp.59-66
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• 2017

이 논문에서는 원자력발전소나 각종 플랜트 시설물에서 배관을 보호하기 위하여 마찰방식을 이용한 댐퍼를 개발하여 성능을 분석하는 연구를 수행하였다. 마찰방식댐퍼는 MER-Spring에 압축력을 가하여 베어링과 샤프트에 마찰력을 발생시켜 진동을 감쇠시키는 장치이다. 댐퍼의 성능을 분석하기 위하여 MER-Spring과 마찰재의 재료특성을 분석하고, 마찰의 영향에 대한 연구를 수행하였으며, 이에 대한 거동 방정식을 수립하였다. 또한 재료의 변형 여부를 판단 및 수립된 거동방정식의 신뢰성 검토를 위하여 시작품을 제작하였고 시편으로 제작된 댐퍼의 성능 시험과 유한요소 해석을 통하여 이를 분석하였다. 그 결과, 재료의 신뢰성이 확인되었고 마찰계수는 속도에 따른 보정이 필요하며, 반복재하 실험 및 유한요소해석 결과 우수한 결과를 나타냄을 확인하였다. 또한, 추후에 동적하중에 대한 검토가 수행되어 이 연구의 성과가 더 넓은 범위에 적용되었으면 한다.

• Steel and Composite Structures
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• 제25권1호
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• pp.117-126
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• 2017

The component method is an analytical approach for investigating the moment-rotation relationship of steel connections. In this study, the component method was improved from two aspects: (i) load analysis of mechanical model; and (ii) combination of spring elements. An optimized component method with more reasonable component models, spring arrangement position, and boundary conditions was developed using finite element analysis. An experimental testing program in two major-axis and two minor-axis connections under symmetrically loading was carried out to verify this method. The initial rotational stiffness obtained from the optimized component method was consistent with the experimental results. It can be concluded that (i) The coupling stiffness between column and beam flanges significantly affects the effective height of the tensile-column web. (ii) The mechanical properties of the bending components were obtained using an equivalent t-stub model considering the bending capacity of bolts. (iii) Using the optimized mechanical components, the initial rotational stiffness was accurately calculated using the spring system. (iv) The characteristics of moment-rotation relationship for beam to column connections were effectively expressed by the SPRING element analysis model using ABAQUS. The calculations are simpler, and the results are accurate.