• Title/Summary/Keyword: dynamic tension

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An Asymptotic Solution and the Green's Function for the Transverse Vibration of Beams with Variable Properties

  • Kim, Yong-Chul
    • Journal of Ocean Engineering and Technology
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    • v.24 no.1
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    • pp.34-38
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    • 2010
  • An analytical solution procedure for the dynamic response of beams with variable properties is developed by using an asymptotic solution and the Green's function. This asymptotic closed form solution is derived for the transverse vibration of beams under the assumption of slowly varying properties, such as mass, cross-section, tension etc., along the beam length. However, this solution is still found to be very accurate even in the case of large variation, such as step change in cross-section, mass, and tension. Therefore, this derived asymptotic closed form solution and the Green's function can be easily applied to find dynamic responses for various kind of beam vibration problems.

A Dynamic Response Analysis of Tension Leg Platforms in Waves (I) (인장계규식 해양구조물의 동적응답해석(I))

  • 구자삼;김진하;이창호
    • Journal of Ocean Engineering and Technology
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    • v.9 no.1
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    • pp.161-172
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    • 1995
  • A numerical procedure is described fro predicting the motion and structural responses of tension leg platforms(TLPs) in waves. The developed numerical approach is based on a combination of a three dimensional source distribution method and the dynamic response analysis method, in which the superstructure of TLPs is assumed flexible instead of the rigid body assumption used in tow-step analysis method. Both the hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural whole structure are formulated using element-fixed coordinate systems which have the origin at the node of the each hull element and move parallel to a space-fixed coordinate system. Numerical results are compared with the experimental and numerical ones, which are obtained in the literature, concerning the motion and structural responses of a TLP in waves. The results of comparison confirmed the validity of the proposed approach.

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Wave induced motion of a triangular tension leg platforms in deep waters

  • Abou-Rayan, A.M.;El-Gamal, Amr R.
    • Ocean Systems Engineering
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    • v.3 no.2
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    • pp.149-165
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    • 2013
  • Tension leg platforms (TLP's) are highly nonlinear due to large structural displacements and fluid motion-structure interaction. Therefore, the nonlinear dynamic response of TLP's under hydrodynamic wave loading is necessary to determine their deformations and dynamic characteristics. In this paper, a numerical study using modified Morison Equation was carried out in the time domain to investigate the influence of nonlinearities due to hydrodynamic forces and the coupling effect between all degrees of freedom on the dynamic behavior of a TLP. The stiffness of the TLP was derived from a combination of hydrostatic restoring forces and restoring forces due to cables and the nonlinear equations of motion were solved utilizing Newmark's beta integration scheme. The effect of wave characteristics was considered.

Nonlinear Vibration Analysis of Porous Thin Plate with Wire Impact Damping (와이어 충돌감쇠를 갖는 다공성 박판의 비선형 진동 해석)

  • 김성대;김원진;이부윤;이종원
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2001.11a
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    • pp.341-348
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    • 2001
  • In this study, nonlinear vibration analysis of the cylindrical orthotropic porous thin plate under V-shaped tension distribution with wire impact damping is considered. We make dynamic model of the plate under the tension using commercial FEM code and reduce the number of its degrees of freedom using dynamic condensation. The dynamic model of wire is obtained as lumped mass model from string equation. And then we analyze the nonlinear vibration of the plate including the impact phenomenon between the plate and the wire using the reduced mass and stiffness matrices of the plate and lumped model of the wire. The contact phenomenon between them can be described by impact contact elements composed of contact stiffness coefficients from Hertzian contact theory and contact damping coefficients from restitution coefficient between them. And we discussed the results of nonlinear vibration analysis for variations of their design parameters.

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Development of a Dynamic Response Analysis Method of Tension Leg Platforms in Waves (인장 계류식 해양구조물의 동적응답 해석법의 개발)

  • 구자삼;이창호;홍봉기
    • Journal of Ocean Engineering and Technology
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    • v.7 no.1
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    • pp.133-146
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    • 1993
  • A numerical procedure is described for predicting the motion and structural responses of tension leg platforms (TLPs) in waves. The developed numerical approach is based on combination of a three dimensional source distribution method and the dynamic response analysis method, in which the superstructure of TLPs is assumed flexible instead of the rigid body assumption used in usual two-step analysis method, proposed by Yoshida et. al. .The hydrodynamic interactions among TLP members, such as columms and pontoons, are included in the motion and structural analyses. Numerical results are compared with the experimental and numerical ones, which are obtained in the literature, of the motion and structural responses of a TLP in waves. The results of comparison confirmed the validity of the proposed approach.

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Testing of rubber bearings for the dynamic damper of seismic isolated buildings

  • Melkumyan, Mikayel;Hakobyan, Alexander
    • Smart Structures and Systems
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    • v.2 no.4
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    • pp.321-328
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    • 2006
  • The paper describes the testing facilities and the methodology on testing of laminated rubber bearings envisaged for application in the system of Dynamic Damper (DD) of seismic isolated buildings, as well as the obtained results. For the first time in Armenia laminated rubber bearings were tested simultaneously under the action of horizontal shear force and vertical tension force. The test results have proven the possibility of using rubber bearings as elements subjected to tension due to action of the mass of DD. Also it was confirmed that the suggested structural concept of DD for reducing the displacements and shear forces of seismic isolation systems will have reliable behavior during the design level earthquakes.

A STUDY ON NUMERICAL SIMULATION OF TOWED LOW-TENSION CABLE WITH NONUNIFORM CHARACTERISTICS (불균일 단면을 갖는 저장력 예인케이블에 관한 수치해석적 연구)

  • Jung, Dong-Ho;Park, Han-Il
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2002.05a
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    • pp.161-166
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    • 2002
  • Low-tension cables have been increasingly used in recent years due to deep-sea developments and the advent of synthetic cables. In the case of low-tension cables, large displacements may happen due to relatively small restoring forces of tension and thus the effects of fluid and geometric non-linearities become predominant. In this study, three-dimensional (3-D) dynamic behavior of a towed low-tension cable with non-uniform characteristics is numerically analyzed by considering fluid and geometric non-linearities and bending stiffness. A Fortran program is developed by employing a finite difference method. In the algorithm, an implicit time integration and Newton-Raphson iteration are adopted. For the calculation of huge size of matrices, block tri-diagonal matrix method is applied, which is much faster than the well-known Gauss-Jordan method in two point boundary value problems. Some case studies are carried out and the results of numerical simulations are compared with a in-house program of WHOI Cable with good agreements.

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Hybrid Tension/Mobile Control of working Robot for installed Troy Cable (트로이선 가설 작업 로봇의 장력 및 이동 제어에 관한 연구)

  • Hong, Jeng-Pyo;Won, Tae-Hyun;Kim, Mun-Soo;Hong, Soon-Ill
    • Proceedings of the KIPE Conference
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    • 2007.07a
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    • pp.455-457
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    • 2007
  • The objective of this study is development of a installed working robot for a troy cable with mobile and tension system. In this paper, an approach to designing controllers for dynamic hybrid Tension/Mobile control of a installed robot for a troy wire cable is presented. Mobile control system of robot is designed based on equation of dc motor and motion for moving robot and tension control system is designed based on equation of ac servomotor for generating torque and dynamic equation of a wire cable. The control parameters is determined by simulation in independence operation of two system.

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An analysis on dynamic behaviour of a towing cable for maneuver of marine survey instruments (해양탐사장비 운용을 위한 예인케이블의 거동해석)

  • JUNG D.H.;KIM H.J.;MOON D.S.;SHIN P.K.;CHOI H.S.;PARK H.I.
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2004.05a
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    • pp.55-60
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    • 2004
  • In this study, the configuration and tension of a towing cable for side-scan sonar are predicted in an ambient flow and at an unsteady towing condition. The governing equation of three-dimensional dynamic analysis for a flexible cable is solved using a finite difference method. We successfully predict the configuration and tension of a side-scan sonar and designed the towing system. It is found in static analyses that the side-scan sonar must be towed to keep a its stable depth at a reasonable speed. The study also reveals in the transient analyses that the dominant component affecting the top tension is the tangential drag force for the larger towing speed than the critical speed, and the self weight of a towed instrument for the smaller towing speed than. It should be maneuvered for a towing vessel with good consideration for the impact effect in a cable due to tension peak when a towing speed is suddenly increase. The developed program can be applicable for three-dimensional dynamic analysis of a towing system for various marine survey instruments.

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A Study on Three-dimensional Dynamic Analysis of a Towing Cable for Marine Survey Instruments (해양탐사장비 예인케이블의 3차원 동적해석에 관한 연구)

  • 정동호;김종규;박한일
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.8 no.2
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    • pp.203-209
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    • 2003
  • In this study, the configuration and tension of a towing cable for side-scan sonar are predicted in an ambient flow and at an unsteady towing condition. The governing equation of three-dimensional dynamic analysis for a flexible cable is solved using a finite difference method. We successfully predict the configuration and tension of a side-scan sonar and designed the towing system. It is found in static analyses that the side-scan sonar must be towed to keep a its stable depth at a reasonable speed. The study also reveals in the transient analyses that the dominant component affecting the top tension is the tangential drag force for the larger towing speed than the critical speed, and the soft weight of a towed instrument for the smaller towing speed than. It should be maneuvered for a towing vessel with good consideration for the impact effect in a cable due to tension peak when a towing speed is suddenly increase. The developed program can be applicable for three-dimensional dynamic analysis of a towing system for various marine survey instruments.