• 한국구조물진단유지관리공학회 논문집
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• 제18권3호
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• pp.10-19
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• 2014

파형강판은 제형, 정현형 등의 형상으로 얇은 강판을 주름지게 가공한 것으로 두꺼운 평판을 대신하여 사용하여도 높은 면외방향의 강성을 확보할 수 있다. 또한, 아코디언효과로 축방향 강성이 거의 없어 플레이트거더의 웨브에 적용할 경우 웨브가 전단력만을 부담하는 방법으로 쉽게 설계할 수 있다. 그러나 파형강판의 전단좌굴은 평판과는 달리 국부좌굴과 전체좌굴 외에도 이들의 연성에 의해서도 좌굴이 발생하는 매우 복잡한 특성이 있으며, 이러한 연성좌굴에 대한 원인과 특성의 규명은 정현형의 경우 제형보다 연구결과가 부족한 실정이다. 따라서 본 연구에서는 정현형 파형강판의 전단좌굴 특성과 연성좌굴이 발생하는 경향에 대해서 연구하였다. 전단좌굴강도를 계산하기 위해서는 유한요소프로그램을 이용하였고 해석결과를 정해와 비교하였다. 또한, 주름의 두께와 형상 파라메타에 따른 좌굴응력 변화의 특성과 좌굴모드형상의 변화를 분석하였으며, 이들의 결과를 이론식의 결과와 비교하여 좌굴양상의 변화시점에 대해서 분석하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.791-791
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• 2009

Hybrid air-foil magnetic bearing combines two oil free bearing technologies to take advantage of the strengths of each bearing with minimizing each other weaknesses. This paper presents bending mode vibration control of a flexible shaft supported by the hybrid air-foil magnetic bearing. An experiment set-up of a flexible shaft supported by the hybrid air-foil magnetic bearing is built. In order to verify the effectiveness of the hybrid bearing, unbalance responses of the flexible shaft supported by three different bearings: air-foil, magnetic and hybrid bearings are compared. Effect of load sharing between air-foil and magnetic bearings are investigated through changing control gain and offset displacements of magnetic bearing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.853-861
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• 2007

To understand the concept of dynamic motion in two degree nonlinear coupled system, free vibration not including damping and excitation is investigated with the concept of nonlinear normal mode. Stability analysis of a coupled system is conducted, and the theoretical analysis performed for the bifurcation phenomenon in the system. Bifurcation point is estimated using harmonic balance method. When the bifurcation occurs, the saddle point is always found on Poincare's map. Nonlinear phenomenon result in amplitude modulation near the saddle point and the internal resonance in the system making continuous interchange of energy. If the bifurcation in the normal mode is local, the motion remains stable for a long time even when the total energy is increased in the system. On the other hand, if the bifurcation is global, the motion in the normal mode disappears into the chaos range as the range becomes gradually large.

• 한국소음진동공학회논문집
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• 제19권10호
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• pp.1092-1098
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• 2009

The squeal propensity of an automotive disc brake system is studied in the theoretical and computational manner. The rotating disc is in contact with two stationary pads and the nonlinear friction is engaged on the contact surface. The friction-coupled equations of motion are derived in the finite element(FE) of the actual brake disc and pad. From the general definition of friction force, the rotation and in-plane mode effects can be included properly in the brake squeal model. The eigenvalue sensitivity analysis and the mode shape visualization at squeal frequencies are also conducted for the detailed investigation. It is found that the squeal propensity is strongly influenced by rotation effect and the in-plane mode can be involved in squeal generation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.63-70
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• 2008

In this paper, we propose a bearing redundant coordinates and decoupled PD controller for 5-axes active magnetic bearing system, which consists of two bearing parts such as three-pole hybrid active magnetic bearing for stabilize the radial direction and ring-type permanent magnetic bearing stabilizing in axial and tilting motion. Based on derived system equation with decoupled control scheme, we conduct the modal analysis and measure of modal controllability and observability.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.556-561
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• 2001

In order to investigate the vibration characteristics of fluid-structure interaction problem, we modeled two rectangular identical plates coupled with bounded fluid. The fixed boundary condition along the plate edges and an ideal fluid were assumed. An experimental modal analysis in order to extract the modal parameters of the system was performed. Finite element analysis was performed using ANSYS to verify modal parameters and analytic results were compared with experimental results. As a result, comparison of experiment and FEM showed good agreement and the transverse vibration modes, in-phase and out of-phase, were observed alternately in the fluid-coupled system. The effect of distance between two rectangular plates on the fluid-coupled natural frequency was investigated.

• 한국지진공학회논문집
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• 제5권5호
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• pp.63-72
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• 2001

본 논문에서는 구조물의 안전성과 경제성을 함께 도모하도록 하기 위하여 모드 해석법을 이용하여 비틀림 거동을 하는 구조물의 동적 거동을 정적 하중으로 치환할 경우에 대한 횡하중 중심점을 가정하고, 횡하중 중심점과 구조물의 강도 중심을 일치시키도록 구조물의 설계 편심을 조절하는 방법을 제안한다. 그리고 제안된 방법에 의해 구조물을 설계하였을 경우, 다른 내진 기준에 의해 설계된 구조물과 비교하여 지나친 추가 연성도를 요구하지 않는다는 것을 보여준다.

• 소음진동
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• 제8권3호
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• pp.477-484
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• 1998

An analytical procedure on the base of the substructure synthesis and assumed modes method is developed to investigate the flexibility effect of bladed disk assembly on vibrational modes of flexible rotor system. In modeling the system, Coriolis forces, gyroscopic moments, and centrifugal stiffening effects are taken into account. The coupled vibrations between the shaft and bladed disk are then extensively investigated through the numerical simulation of simplified models, with varying the shaft rotational speed and the prewist and stagger angles of the blade. It is found that the Coriolis and inertia forces and the inertia torque, which are induced by the one nodal diameter modes of the bladed disk and vary depending upon the stagger and prewist angles, lead to the coupled motions of the shaft and the bladed disk.

• 한국소음진동공학회논문집
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• 제13권1호
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• pp.33-39
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• 2003

Interior parts of a vehicle are getting important to reduce interior noise. Therefore, prior analysis of cabin noise related with interior parts are necessary at first design stage. Recently, Statistical Energy Analysis(SEA) has been suggested as a possible way for high frequency range noise analysis of interior parts. The validity of noise analysis with SEA to interior parts has been preyed by comparing with experimental result, and the developed method with SEA has been applied in finding optimized interior parts package.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.792-798
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• 2012

This study shows the vibration characteristics of an actuator with six wire-suspensions, used in optical pickups of optical disc drives (ODDs). In this paper, the vibration characteristics of this beam structure is induced mathematically. To obtain vibration modes of focusing direction, the vibration analysis is achieved in lateral and longitudinal directions of the structure. The accuracy of induced vibration characteristics is proved by comparing mode frequencies with a finite element analysis. Finally, it is shown that mode shapes can be modified by changing design parameters in mathematical expressions.