• Title/Summary/Keyword: nonlinear elastic coupling

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Torsional Vibration Analysis for Engine Shafting of Fishing Vessel with PTO System and Nonlinear Elastic Coupling (PTO시스템과 비선형 탄성커플링을 갖는 어선용 기관축계의 비틀림 진동해석)

  • Choi, Myung-Soo;Kim, Won-Rae;Moon, Deok-Hong
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.40 no.3
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    • pp.232-243
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    • 2004
  • After studying the composition about the torsional shafting of main engine for fishing vessel with Power Take Off (PTO) System, the authors made a computer program using the transfer stiffness coefficient method (TSCM) for analyzing torsional vibration about the shafting with PTO system and nonlinear elastic coupling. The torsional shafting of main engine was separated by 3 types according to the connecting. The torsional shafting of main engine was separated by 3 types according to the connecting condition of main engine with propeller or the PTO system or both of them. In this paper, the change of natural frequencies and natural modes according to connecting condition of torsional shafting and nonlinear elastic coupling were analyzed. The accuracy of the TSCM was confirmed by comparing with the computational results of the Finite Element Method.

Rigid block coupled with a 2 d.o.f. system: Numerical and experimental investigation

  • Pagliaro, Stefano;Aloisio, Angelo;Alaggio, Rocco;Di Egidio, Angelo
    • Coupled systems mechanics
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    • v.9 no.6
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    • pp.539-562
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    • 2020
  • In this paper the linear elastic coupling between a 2 degree of freedom shear-type frame system and a rigid block is analytically and experimentally investigated. As demonstrated by some of the authors in previous papers, it is possible to choose a coupling system able to guarantee advantages, whatever the mechanical characteristics of the frame. The main purpose of the investigation is to validate the analytical model. The nonlinear equations of motion of the coupled system are obtained by a Lagrangian approach and successively numerically integrated under harmonic and seismic excitation. The results, in terms of gain graphs, maps and spectra, represent the ratio between the maximum displacements or drifts of the coupled and uncoupled systems as a function of the system's parameters. Numerical investigations show the effectiveness of the nonlinear coupling for a large set of parameters. Thus experimental tests are carried out to verify the analytical results. An electro-dynamic long-stroke shaker sinusoidally and seismically forces a shear-type 2 d.o.f frame coupled with a rigid aluminium block. The experimental investigations confirm the effectiveness of the coupling as predicted by the analytical model.

Seismic performance evaluation of coupled core walls with concrete and steel coupling beams

  • Fortney, Patrick J.;Shahrooz, Bahram M.;Rassati, Gian A.
    • Steel and Composite Structures
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    • v.7 no.4
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    • pp.279-301
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    • 2007
  • When coupling beams are proportioned appropriately in coupled core wall (CCW) systems, the input energy from ground motions is dissipated primarily through inelastic deformations in plastic hinge regions at the ends of the coupling beams. It is desirable that the plastic hinges form at the beam ends while the base wall piers remain elastic. The strength and stiffness of the coupling beams are, therefore, crucial if the desired global behavior of the CCW system is to be achieved. This paper presents the results of nonlinear response history analysis of two 20-story CCW buildings. Both buildings have the same geometric dimensions, and the components of the buildings are designed based on the equivalent lateral force procedure. However, one building is fitted with steel coupling beams while the other is fitted with diagonally reinforced concrete coupling beams. The force-deflection relationships of both beams are based on experimental data, while the moment-curvature and axial load-moment relationships of the wall piers are analytically generated from cross-sectional fiber analyses. Using the aforementioned beam and wall properties, nonlinear response history analyses are performed. Superiority of the steel coupling beams is demonstrated through detailed evaluations of local and global responses computed for a number of recorded and artificially generated ground motions.

Nonlinear analysis of finite beam resting on Winkler foundation with consideration of beam-soil interface resistance effect

  • Zhang, L.;Zhao, M.H.;Xiao, Y.;Ma, B.H.
    • Structural Engineering and Mechanics
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    • v.38 no.5
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    • pp.573-592
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    • 2011
  • Comprehensive and accurate analysis of a finite foundation beam is a challenging engineering problem and an important subject in foundation design. One of the limitation of the traditional Winkler elastic foundation model is that the model neglects the effect of the interface resistance between the beam and the underneath foundation soil. By taking the beam-soil interface resistance into account, a deformation governing differential equation for a finite beam resting on the Winkler elastic foundation is developed. The coupling effect between vertical and horizontal displacements is also considered in the presented method. Using Galerkin method, semi-analytical solutions for vertical and horizontal displacements, axial force, shear force and bending moment of the beam under symmetric loads are presented. The influences of the interface resistance on the behavior of foundation beam are also investigated.

Dynamic response of a linear two d.o.f system visco-elastically coupled with a rigid block

  • Di Egidio, Angelo;Pagliaro, Stefano;Fabrizio, Cristiano;de Leo, Andrea M.
    • Coupled systems mechanics
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    • v.8 no.4
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    • pp.351-375
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    • 2019
  • The present work investigates the use of a rigid rocking block as a tool to reduce vibrations in a frame structure. The study is based on a simplified model composed by a 2-DOF linear system, meant to represent a general M-DOF frame structure, coupled with a rocking rigid block through a linear visco-elastic device, which connects only the lower part of the 2-DOF system. The possibility to restrain the block directly to the ground, by means of a second visco-elastic device, is investigated as well. The dynamic response of the model under an harmonic base excitation is then analysed in order to evaluate the effectiveness of the coupling in reducing the displacements and the drift of the 2-DOF system. The nonlinear equations of motion of the coupled assemblage 2-DOF-block are obtained by a Lagrangian approach and then numerically integrated considering some reference mechanical and geometrical quantities as variable parameters. It follows an extensive parametric analysis, whose results are summarized through behaviour maps, which portray the ratio between the maximum displacements and drifts of the system, with and without the coupling with the rigid block, for several combinations of system's parameters. When the ratio of the displacements is less than unity, the coupling is considered effective. Results show that the presence of the rocking rigid block improves the dynamics of the system in large ranges of the characterizing parameters.

Nonlinear Coupling Factor in Dynamic Model of Flexible Manipulator (유연 매니퓰레이터 동역학 모델링의 비선형 커플링 요소)

  • Lee Jin-Ho;Rhim Sung-Soo;Lee Soon-Geul
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.10a
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    • pp.404-408
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    • 2005
  • Having flexibility in a manipulator will degrade trajectory tracking control and manipulator tip positioning. In practice, however, constraints imposed by various operating requirements, will render the presence of such flexibility unavoidable. The dynamic analysis of the flexible manipulator is essential in designing proper control systems. A flexible manipulator consists of infinite number of elastic modes and the modes are usually coupled to each other. For the practicality, however, it is usually assumed that the flexible system consists of finite number of elastic modes and the modes are decoupled. These assumptions result in a linear and decoupled mathematical model of the flexible manipulator and simplify the analysis of the dynamic behavior and the design of the control system. The decoupling and linearization of the flexible link, however, has been assumed without in depth analysis. This paper focuses on the analysis of the significance of the non-linear coupling factors.

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Numerical simulations of interactions between solitary waves and elastic seawalls on rubble mound breakwaters

  • Lou, Yun-Feng;Luo, Chuan;Jin, Xian-Long
    • Structural Engineering and Mechanics
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    • v.53 no.3
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    • pp.393-410
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    • 2015
  • Two dimensional numerical models and physical models have been developed to study the highly nonlinear interactions between waves and breakwaters, but several of these models consider the effects of the structural dynamic responses and the shape of the breakwater axis on the wave pressures. In this study, a multi-material Arbitrary Lagrangian Eulerian (ALE) method is developed to simulate the nonlinear interactions between nonlinear waves and elastic seawalls on a coastal rubble mound breakwater, and is validated experimentally. In the experiment, a solitary wave is generated and used with a physical breakwater model. The wave impact is validated computationally using a breakwater - flume coupling model that replicates the physical model. The computational results, including those for the wave pressure and the water-on-deck, are in good agreement with the experimental results. A local breakwater model is used to discuss the effects of the structural dynamic response and different design parameters of the breakwater on wave loads, together with pressure distribution up the seawall. A large-scale breakwater model is used to numerically study the large-scale wave impact problem and the horizontal distribution of the wave pressures on the seawalls.

Viscous fluid induced vibration and instability of FG-CNT-reinforced cylindrical shells integrated with piezoelectric layers

  • Bidgoli, Mahmood Rabani;Karimi, Mohammad Saeed;Arani, Ali Ghorbanpour
    • Steel and Composite Structures
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    • v.19 no.3
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    • pp.713-733
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    • 2015
  • In this paper, viscous fluid induced nonlinear free vibration and instability analysis of a functionally graded carbon nanotube-reinforced composite (CNTRC) cylindrical shell integrated with two uniformly distributed piezoelectric layers on the top and bottom surfaces of the cylindrical shell are presented. Single-walled carbon nanotubes (SWCNTs) are selected as reinforcement and effective material properties of FG-CNTRC cylindrical shell are assumed to be graded through the thickness direction and are estimated through the rule of mixture. The elastic foundation is modeled by temperature-dependent orthotropic Pasternak medium. Considering coupling of mechanical and electrical fields, Mindlin shell theory and Hamilton's principle, the motion equations are derived. Nonlinear frequency and critical fluid velocity of sandwich structure are calculated based on differential quadrature method (DQM). The effects of different parameters such as distribution type of SWCNTs, volume fractions of SWCNTs, elastic medium and temperature gradient are discussed on the vibration and instability behavior of the sandwich structure. Results indicate that considering elastic foundation increases frequency and critical fluid velocity of system.

Advanced analysis for planar steel frames with semi-rigid connections using plastic-zone method

  • Nguyen, Phu-Cuong;Kim, Seung-Eock
    • Steel and Composite Structures
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    • v.21 no.5
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    • pp.1121-1144
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    • 2016
  • This paper presents a displacement-based finite element procedure for second-order distributed plasticity analysis of planar steel frames with semi-rigid beam-to-column connections under static loadings. A partially strain-hardening elastic-plastic beam-column element, which directly takes into account geometric nonlinearity, gradual yielding of material, and flexibility of semi-rigid connections, is proposed. The second-order effects and distributed plasticity are considered by dividing the member into several sub-elements and meshing the cross-section into several fibers. A new nonlinear solution procedure based on the combination of the Newton-Raphson equilibrium iterative algorithm and the constant work method for adjusting the incremental load factor is proposed for solving nonlinear equilibrium equations. The nonlinear inelastic behavior predicted by the proposed program compares well with previous studies. Coupling effects of three primary sources of nonlinearity, geometric imperfections, and residual stress are investigated and discussed in this paper.

Analysis of Nonlinear Vibration for Hybrid Composite Plates (혼합적층판에 대한 비선형 진동해석)

  • 이영신;김영완
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.12
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    • pp.2306-2314
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    • 1992
  • Using the Lagrangian equation, nonlinear vibration analysis of laminated hybrid composite plates is carried out. The effects of stacking sequences, aspect ratios, number of modes, number of layers and various elastic properties on nonlinear vibration are investigated. The presence of bending-extension coupling in antisymmetric plates yields a second power term in addition to a cubic nonlinear term in governing differential equation of motion. In the other symmetric case, this second term vanishes. The fundamental frequency of analytic results are compared with that of ABAQUS FEM analysis. For nonlinear vibration of antisymmetric unimaterial plate, the result of reference is presented for comparison with this result.