Optimal Cable Configurations for Passive Dynamic Control of Compliant Towers

1984 ◽  
Vol 106 (4) ◽  
pp. 311-318 ◽  
Author(s):  
J. F. Wilson ◽  
G. Orgill
Keyword(s):  
Dynamic Response ◽  
Optimization Algorithm ◽  
Nonlinear Dynamic ◽  
Wind Wave ◽  
Dynamic Control ◽  
Nonlinear Dynamic Model ◽  
Human Comfort ◽  
Compatible System ◽  
Compliant Tower ◽  
The Ideal

Whether in storm or normal seas, the ideal offshore cable-stayed compliant tower moves in harmony with the wind and waves. A properly tuned cable configuration is the key to controlled dynamic response. Formulated here are a nonlinear dynamic model involving wind, wave, current, tower, and cable interactions and a cable optimization algorithm. The objective function, the rms tower rotation, is minimized subject to appropriate constraints involving compatible system geometries and loads, as well as bounds on the platform level accelerations needed for human comfort. Tower motion is limited to a plane.

Nonlinear Dynamic Response of a Compliant Tower Under the Effect of Steady and Unsteady Sea States

2017 ◽  
Author(s):  
Konstantinos Chatziioannou ◽  
Vanessa Katsardi ◽  
Apostolos Koukouselis ◽  
Euripidis Mistakidis
Keyword(s):  
Structural Analysis ◽  
Dynamic Response ◽  
Deep Water ◽  
Nonlinear Dynamic ◽  
Wave Theory ◽  
Random Wave ◽  
Wave Loading ◽  
Nonlinear Dynamic Response ◽  
Steady Wave ◽  
Compliant Tower

The purpose of this work is to highlight the importance of considering the actual nonlinear dynamic response for the analysis and design of fixed deep water platforms. The paper highlights the necessity of applying dynamic analysis through the comparison with the results obtained by the authors by applying static nonlinear analysis on the structure under examination. The example treated in the context of the present paper is a compliant tower, set-up in deep water. Nonlinearities are considered both for the calculation of the wave loadings and the structural analysis. The wave loading is based on linear random wave theory and comparisons are provided with the steady wave theories, Airy and Stokes 5th. The former solution is based on the most probable shape of a large linear wave on a given sea-state; the auto-correlation function of the underlying spectrum. On the other hand, in the field of structural analysis, two cases are considered for comparison, static analysis and time history dynamic analysis. For both types of analysis, two sub-cases are considered, a case in which geometric nonlinearity and nonlinearities related to the modelling of the soil are considered and a case in which the corresponding linear theories are employed (reference cases). The structural calculations were performed using the well-known structural analysis software SAP2000, which was enhanced by a special programming interface that was developed to calculate the wave loading and to directly apply the generated loads on the structural members. The results show that the consideration of the particle velocities associated with the linear random wave theory in the wave loading lead to significant differences with respect to the steady wave theories in terms of the displacements and stresses of the structure. Moreover, irrespectively of the adopted wave theory, the nonlinear analyses lead to significant discrepancies with respect to the linear ones. This is mainly associated with the nonlinear properties of the soil. Another source of discrepancies between the results of static and dynamic analyses stems from the change of the effective natural frequency of the structure when nonlinearities are considered.

Nonlinear Dynamic Characteristics of PZT/Polymer Gripper

2018 ◽  
Vol 26 (1) ◽  
pp. 79-84
Author(s):  
Jia Xu ◽  
Yi-Ran Li ◽  
Hai-Bo Wang ◽  
Zhi-Wen Zhu
Keyword(s):  
Dynamic Response ◽  
Nonlinear Dynamic ◽  
Noise Intensity ◽  
Resonance Phenomenon ◽  
Dynamical Response ◽  
Stochastic Noise ◽  
Nonlinear Dynamic Model ◽  
Bounded Noise ◽  
Response Range ◽  
Nonlinear Dynamic Characteristics

A kind of PZT/polymer gripper is proposed in this paper and its nonlinear dynamic response in bounded noise is described. In this paper, a polymer piezoelectric material is applied in gripper to substitute the traditional PZT to improve the response range. Nonlinear differential items are introduced to interpret the hysteretic phenomena of the PZT/polymer piezoelectric composites material, and the nonlinear dynamic model of the PZT/polymer gripper in bounded noise is developed. The dynamic response of the system is obtained, and the bifurcation characteristics of the system are analyzed. The results of numerical simulation and experiments show that the stochastic noise intensity has important influence on the system's dynamical response, and the stochastic resonance phenomenon occurs with the stochastic noise intensity variety.

scholarly journals Nonlinear Dynamics and Analysis of a Planar Multilink Complex Mechanism with Clearance

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Xiulong Chen ◽  
Shuai Jiang ◽  
Yu Deng ◽  
Qing Wang
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamic Response ◽  
Phase Diagrams ◽  
Dynamic Model ◽  
Dynamic Behavior ◽  
Nonlinear Dynamic ◽  
Lagrange Equation ◽  
Nonlinear Dynamic Model ◽  
Planar Mechanism ◽  
Driving Speed

In order to understand the nonlinear dynamic behavior of a planar mechanism with clearance, the nonlinear dynamic model of the 2-DOF nine-bar mechanism with a revolute clearance is proposed; the dynamic response, phase diagrams, Poincaré portraits, and largest Lyapunov exponents (LLEs) of mechanism are investigated. The nonlinear dynamic model of 2-DOF nine-bar mechanism containing a revolute clearance is established by using the Lagrange equation. Dynamic response of the slider’s kinematics characteristic, contact force, driving torque, shaft center trajectory, and the penetration depth for 2-DOF nine-bar mechanism are all analyzed. Chaos phenomenon existed in the mechanism has been identified by using the phase diagrams, the Poincaré portraits, and LLEs. The effects of the different clearance sizes, different friction coefficients, and different driving speeds on dynamic behavior are studied. Bifurcation diagrams with changing clearance value, friction coefficient, and driving speed are drawn. The research could provide important technical support and theoretical basis for the further study of the nonlinear dynamics of planar mechanism.

Involute spline couplings in aero-engine: Predicting nonlinear dynamic response with mass eccentricity

2021 ◽  
Vol 235 (1) ◽  
pp. 75-92
Author(s):  
Xiangzhen Xue ◽  
Qixin Huo ◽  
Karl D Dearn ◽  
Jian Liu ◽  
Jipeng Jia
Keyword(s):  
Dynamic Response ◽  
Nonlinear Dynamic ◽  
Power Transmission ◽  
Reference Model ◽  
Nonlinear Dynamic Model ◽  
Nonlinear Dynamic Response ◽  
Mass Eccentricity ◽  
Spline Coupling ◽  
Aero Engines ◽  
Involute Spline

This work presents a nonlinear dynamic model considering the multi-tooth meshing behaviour and mass eccentricity of an involute spline coupling to tackle the serious problem of involute spline failure, in aviation power transmission systems. The dynamic meshing force is calculated for the same. Based on this, the influence of different mass eccentricities on the nonlinear dynamic response of the spline coupling was investigated in aero-engines. The results show that when the mass eccentricity is small, its impact on the system is insignificant. When the eccentricity reaches a certain value, the quasi-periodic and chaotic state appears alternately. Meanwhile, it can be concluded that the acceleration-frequency spectrum during the multi-periodic phase is an approximation of the working frequency with the accuracy affected by multiple teeth engagements. This was validated by the vibration experiments of the involute spline coupling. The proposed model, which considers the multi-tooth meshing behaviour and the mass eccentricity provides a reference model for the dynamic analysis of similar structures. The nonlinear dynamic response results attained lay a good theoretical foundation for fretting damage analysis and precise designs for involute spline couplings.

Study on Nonlinear Dynamic Response of the Gear-Shaft-Housing Coupling System

2010 ◽  
Vol 26-28 ◽  
pp. 805-808 ◽  
Author(s):  
Wen Zeng ◽  
X.Z. Zhu ◽  
Z.J. Wei
Keyword(s):  
Dynamic Response ◽  
Nonlinear Dynamic ◽  
Gear Tooth ◽  
Vibration Response ◽  
Housing System ◽  
Vibration Velocity ◽  
Nonlinear Dynamic Model ◽  
Nonlinear Dynamic Response ◽  
Meshing Stiffness ◽  
Coupling System

The nonlinear dynamic model of a gear-shaft-housing system is established by using finite element method (FEM). The nonlinear dynamic response of the coupling system under gear tooth time-varying stiffness, manufacturing error and other internal excitations is analyzed. Displacement, velocity and acceleration response of the coupling system and meshing stiffness and bearing support stiffness influences on vibration response of the coupling system are studied. The results show that the vibration amplitude near housing bearing seat is largest, secondly is the top of the housing and the vibration response at the sides and bottom of the housing are the smallest. As meshing stiffness and bearing support stiffness increase, vibration velocity and acceleration of the housing increase gradually. But bearing stiffness influence on the vibration response of the coupling system is significantly larger than that of meshing stiffness.

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