• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.435-440
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• 2002

The free vibration of partially embedded piles is investigated. The pile model is based on the Bernoulli-Euler beam theory and the soil is idealized as a Winkler model for mathematical simplicity. The governing differential equation for the free vibrations of such members is solved numerically The piles with one typical end constraint (clamped/hinged/free) and the other hinged end with rotational spring are applied in numerical examples. The lowest three natural frequencies are calculated over a range of non-dimensional system parameters: the rotational spring parameter, the relative stiffness and the embedded ratio.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.369-374
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• 2001

This paper deals with the buckling loads of column with rotation end restricted by rotational spring. The ordinary differential equations governing the buckling loads of such column is derived as nondimensional forms, and also its boundary conditions are derived. The buckled column model is based on the classical Bemoulli-Euler beam theory. The Runge-Kutta method and Regula-Falsi method are used to perform the integration of the differential equations and to determine the eigenvalue. The numerical methods developed herein for the buckling loads of the such column are found to be efficient and reliable. It is expected that the results obtained herein can be practically utilized in the structural engineering field.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1000-1004
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• 2001

This study explores the free vibrations of tapered column with hinged end restricted by rotational spring. The ordinary differential equation governing the free vibration of such column is derived as nondimensional form in which three kinds of cross-sectional shape are considered. In order to obtain the natural frequencies of column, the governing differential equation is solved by numerical procedures. Numerical results are compared with existing solutions by other methods. It is expected that the results obtained herein can be practically utilized in the structural and the vibration control fields.

• Structural Engineering and Mechanics
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• 제16권5호
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• pp.533-556
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• 2003

The flutter and buckling analysis of a beam structure subjected to a static follower force is completely studied in the paper. The beam is fixed in the transverse direction and constrained by a rotational spring at one end, and by a translational spring and a rotational spring at the other end. The co-existence of flutter and buckling in this beam due to the presence of the follower force is an interesting and important phenomenon. The results from this theoretical analysis will be useful for the stability design of structures in engineering applications, such as the potential of flutter control of aircrafts by smart materials. The transition-curve surface for differentiating the two distinct instability regions of the beam is first obtained with respect to the variations of the stiffness of the springs at the two ends. Second, the capacity of the follower force is derived for flutter and buckling of the beam as a function of the stiffness of the springs by observing the variation of the first two frequencies obtained from dynamic analysis of the beam. The research in the paper may be used as a benchmark for the flutter and buckling analysis of beams.

• 전력전자학회논문지
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• 제22권5호
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• pp.390-396
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• 2017

In this paper, an exact mathematical model is derived for an exhaust gas recirculation (EGR) valve actuator driven by an H-bridge converter. Particularly, a spring torque model of the EGR valve is proposed. The spring torque model is proposed by converting spring force and Coulomb frictional force in linear motion into a rotational torque. Moreover, a mechanical end-stop model was proposed by the valve mechanism. The accuracy of the proposed model is verified by comparing the experimental results with the simulated results.

• 대한기계학회논문집
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• 제9권5호
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• pp.606-612
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• 1985

본 논문에서는 전보의 연속으로서 말단질량이 부착된 기둥의 자유단에 압축 종동력이 작용하는 비보존적 탄성계의 불완전 고정단에 나타나는 스프링 특성의 영향 을 연구하였다. 고정단은 병진스프링과 회전스프링으로 구속되었고, 이들 스프링 상 수의 여러 값이 말단질량과 연성(coupling)되어 기둥의 안정성에 미치는 영향을 연구 하였다. 기둥의 전단변형과 회전관성의 영향을 고려하였으며, Hamilton's principle 로서 계의 운동방정식과 경계조건의 식을 유도하여 수치해석하였다.

• Structural Engineering and Mechanics
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• 제52권5호
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• pp.971-995
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• 2014

The parts of semi-rigid connected and partially embedded piles in elastic soil, above the soil and embedded in the soil are called the first region and second region, respectively. The upper end of the pile in the first region is supported by linear-elastic rotational spring. The forth order differential equations of both region for critical buckling load of partially embedded and semi-rigid connected pile with shear deformation are established using small-displacement theory and Winkler hypothesis. These differential equations are solved by differential transform method (DTM) and analytical method and critical buckling loads of semirigid connected and partially embedded pile are obtained, results are given in tables and graphs are presented for investigating the effects of relative stiffness of the pile and flexibility of rotational spring.

• Smart Structures and Systems
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• 제30권2호
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• pp.173-181
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• 2022

The current paper presents a technique to detect crack in non-uniform cantilever-type pipe beams, that have step changes in the properties of their cross sections, restrained by a translational and rotational spring with a tip mass at the free end. An equation for estimating the natural frequencies for the non-uniform beams is derived using the boundary and continuity conditions, and an equivalent bending stiffness for cracked beam is applied to calculate the natural frequencies of the cracked beam. An experimental study for a step-changed non-uniform cantilever-type pipe beam restrained by bolts with a tip mass is carried out to verify the proposed method. The translational and rotational spring constants are updated using the neural network technique to the results of the experiment for intact case in order to establish a baseline model for the subsequent crack detection. Then, several numerical simulations for the specimen are carried out using the derived equation for estimating the natural frequencies of the cracked beam to construct a set of training patterns of a neural network. The crack locations and sizes are identified using the trained neural network for the 5 damage cases. It is found that the crack locations and sizes are reasonably well estimated from a practical point of view. And it is considered that the usefulness of the proposed method for structural health monitoring of the step-changed non-uniform cantilever-type pipe beam-like structures elastically restrained in the ground and have a tip mass at the free end could be verified.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.493-500
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• 2001

The purpose of this paper is to investigate the natural frequencies and mode shapes of tapered beams with general boundary condition(translational and rotational elastic support) at one end and carrying a tip mass with translational elastic support at the other end. The beam model is based on the classical Bernoulli-Euler beam theory which neglects the effects of rotatory inertia and shear deformation. The governing differential equation for the free vibrations of linearly tapered beams is solved numerically using the corresponding boundary conditions. Numerical results are compared with existing solutions by other methods for cases in which they are available. The lowest three natural frequencies and the corresponding mode shapes are calculated over a wide range of section ratio, dimensionless spring constant, and mass ratio.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.832-835
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• 2005

본 연구는 지반에 근입된 변단면 말뚝의 자유진동에 관한 연구이다. 이 논문에서는 말뚝이 근입된 지반을 Winkler형으로 이상화하여 변단면 말뚝의 자유진동을 지배하는 상미분방정식을 무차원형으로 표현하였으며, 이를 수치해석하여 대상구조의 고유진동수를 산출하였다. 수치해석 예에서는 상단이 자유, 하단이 회전지점과 회전스프링으로 이루어진 말뚝을 대상으로 회전스프링상수, 근입비, 지반계수, 접촉면의 폭비에 따른 고유진동수를 산출하고 그 결과를 고찰하였다.