• Computational Structural Engineering
• /
• v.3 no.2
• /
• pp.67-75
• /
• 1990

A stepped beam with immovable ends under the free and forced vibrations with large amplitude is investigated by using the finite element method to show the effects of longitudinal displacement, shear deformation and rotary inertia. A modified harmonic force matrix is introduced for analysis of finite amplitude vibration of the stepped beam under uniform harmonic loading and a beam under nonuniform harmonic loading. Numerical examples are analysed for deflections and natural frequencies of stepped beam under various support conditions. Results show that the proposed method is valid and efficient.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.12
• /
• pp.301-306
• /
• 2016

In bridge performance assessments, a new load carrying capacity evaluation model of simple bridges was proposed, which is based on the developed simple support impact factor spectrum. In this paper, a conservative assumption that the inner span with the both ends fixed boundary condition is ideal for applying the impact factor response spectrum for continuous bridges. The impact factor response spectrum has been proposed based on this assumption. The response spectrum by comparing the numerical analysis result and actual measurement data verified the applicability. The analysis was loading the moving load of DB-24 in a six-span continuous bridge, which was the same as the actual measurement data, the dynamic response was measured in the fourth span. The frequency of the bridge was obtained by FFT on the acceleration response and the span-frequency of sample bridge was calculated by the frequency. The impact factor of the sample bridge was determined by applying the span-frequency of the bridge to the proposed response spectrum; it was similar to the result of comparing the actual measured impact factor. Therefore, the method using the impact factor response spectrum based on the frequency response of both ends-fixed beam was found to be applicable to an actual continuous bridge.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.6
• /
• pp.1799-1806
• /
• 1991

The effect of an elastic intermediate support on the vibration characteristics of a fluid conveying pipe system modeled as simply-simply supported and fixed-fixed supported pipes has been investigated. The approach is based on solving the closed form equation of the 4th order polynomials. The change of natural frequency and critical velocity are also investigated with the fluid density, the fluid velocity, the position and stiffness of the elastic intermediate support varied. The results show that the vibration characteristics of pipe system could be controled by changing the position and/or stiffness of the elastic intermediate support.

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.7
• /
• pp.585-591
• /
• 2003

In this paper, fiber optic sensor using Fabry-Perot interferometer which had benefit of minimize and light-weight was used. The sensor head has 1cm in length, total length of fiber is 9.5 chi and the sensor supported at both ends, simply. To analyze the acoustic characteristic non-directional speaker is used as a sound source. Acoustic applied in lateral direction and detected two signals were compared each other. Below 1㎑ fiber optic sensor has more sensitive than microphone, but in 2㎑ fiber optic sensor has less sensitive than microphone. This characteristic varies to the supporting system of fiber optic sensor. It was confirmed that the Fabry-Perot interferometric sensor detected acoustic signal, effectively. This kind of sensor can be applied to the structural health monitoring field of intellectual structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1995.04a
• /
• pp.334-339
• /
• 1995

COSINE 급수를 이용한 유한 길이 원통형 셀의 유체 영향계수에 대한 해석결과를 양단 단순지지 조건(Simply-supported condition)을 갖는 해석모델에서 이용한 SINE 급수를 적용한 해석 결과와 비교, 검토한 결과 유사한 경향을 보이고 있으며, 무차원 파수 ka 값이 커질수록 Reactance는 0으로 접근하고 Resistance는 .rho.c 값으로 접근하는 경향을 가지고 있어 타당한 해석방법임을 알 수 있었다. 따라서 양단에 끝막이 판을 갖고 있는 원통형 셀에 대한 음압복사 현상을 해석하는데 COSINE 급수를 이용하는 것이 가능함을 본 연구를 통하여 확인하였다. 또한 본 연구에서 유도한 Z$_{mm}$값을 이용하면 양단에 끝막이 판을 갖고 있는 원통형 셀에서의 유체 효과를 용이하게 해석할 수 있다.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1998.06e
• /
• pp.103-106
• /
• 1998

본 논문은 상용 FEM-BEM 프로그램을 사용하여 점-조화 가진(harmonic point excitation)에 의한 자유지지 경계 조건을 갖는 원통 셸(cylindrical shell)의 방사 효율(radiation efficiency) 실험의 결과와 비교하였다. 우선 충격 해머 실험(impact hammer test)을 통한 모드 시험(modal testing)으로 원통 셸의 공진 주파수(natural frequency)와 모드 형상(mode shape)의 특징을 살펴보고 다음으로 점-조화 가진에 의한 원통 셸의 방사 효율을 SYSNOISE와 ANSYS로 해석해 보았다. 동시에 음향 세기 실험을 통한 방사 효율을 측정하여 전산 해석의 결과와 실험의 결과를 비교해 보았다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05d
• /
• pp.306-311
• /
• 1996

CANFLEX 연료봉 다발을 구성하는 우라늄 펠릿이 장전된 핵연료봉의 공기중 진동특성을 진동 실험과 유한요소 해석을 통하여 구하였다. 유한요소 해석 시에는 우라늄 펠릿의 강성은 무시하고 질량은 지르칼로이 튜브에 부가하며, 연료봉 양단의 용접부위를 단순 지지보로 처리하는 모델을 제시하였다. 이 모델로부터 얻은 해석결과를 진동실험에서 구한 측정값과 비교하였다.

• Journal of Korean Society of Steel Construction
• /
• v.17 no.4 s.77
• /
• pp.459-467
• /
• 2005

This study focuses on the development of a new method of H-shaped beam-to-square column connection with an outer diaphragm and a field welding. The specific type of beam-to-column connection with an external stiffener, using field welding, is proposed. The structural behavior of this connection was examined experimentally. Two loading type tests were conducted under the experimental parameters given as details. First described was the symmetrical loading test, which supported both ends or a beam simply and applied a load from the column to the pend (What does this mean?) to investigate a fundamental characteristic of this connection. Further described was the anti-symmetrical loading test, which carried out simple support of the column'stop end and the column base, and applied a load from both ends of a beam to investigate the structural performance of this connection. From the results, it is clear that the external- stiffener-type connection proposed in this paper is the reliable connection method.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.12 no.5
• /
• pp.1003-1015
• /
• 1988

Damping information is required to analyse heat exchangers for flow-induced vibration. The most important energy dissipation mechanisms in heat exchanger tubes are related to the dynamic interaction between tube and support. In liquids, squeeze-film damping is dominat. Simple experiments were carried out of a two-span tube with one intermediate support to investigate the effects of tube-support parameters, such as: tube-support thickness, diametral clearance, tube eccentricity, tube span length, location of tube-support, and nature of dynamic interaction between tube and tube-support. The results show that squeeze-film damping is much larger for lateral-type motion than for rocking-type motion at the support. Eccentricity was found to be very important. Diametral clearance, support thickness and frequency are also very relevant. The effects of these parameters on squeeze-film damping are formulated and proposed in a semi-empirical expression.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.753-756
• /
• 2002

In this study, it is attempted to obtain the optimum size of holes in 15 square plate models where a hole exists on every quadrant of a plate, and to get eigenvalues by performing free vibration analysis far each model. Moreover, the specimen is produced from optimized square plate and eigenvalue of each plate is measured through the shocking load. And then the result is compared with that of finite element analysis. For free vibration analysis of the square plate, the boundary condition of finite element analysis and experiment is assumed as both ends support. From the results of this study, it is known that more stable structures can be designed by changing the natural frequency which is dependent on the location of holes and further studies are considered to be necessary for the basic design information.