Maxwell–Voigt and Maxwell Ladder Models for Multi-Degree-of-Freedom Elastomeric Isolation Systems

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Sudhir Kaul
Keyword(s):  
Degree Of Freedom ◽  
Isolation System ◽  
Practical Applications ◽  
Geometrical Properties ◽  
Analysis And Design ◽  
Proposed Model ◽  
Elastomeric Isolator ◽  
Isolation Systems ◽  
Three Degree Of Freedom ◽  
Ladder Models

This paper presents a model for an elastomeric isolation system consisting of a three degree-of-freedom (DOF) rigid body assembled to a frame through multiple isolators. Each elastomeric isolator is either represented by a Maxwell–Voigt (MV) model consisting of two Maxwell elements or by a Maxwell ladder (ML) model consisting of three Maxwell elements. The MV models and the ML models are characterized by using experimental data that are collected at multiple excitation frequencies. The characterized models are evaluated and used to simulate the performance of the isolation system. The models developed in this paper are capable of representing frequency-dependent behavior that is exhibited by elastomeric isolators and the overall isolation system. Furthermore, the proposed model is capable of directly associating the behavior of the isolation system with physical and geometrical properties of each isolator. The proposed model is expected to be a useful tool for the analysis and design optimization of elastomeric isolation systems. Most of the isolation systems in practical applications exhibit multiple DOF, this model will be particularly useful in such applications since it does not constrain motion to translation only. This is a shortcoming of the models in the current literature that the proposed model attempts to overcome.

scholarly journals Analysis and design of the power law damping based on the nonlinear vessel isolation system

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881719 ◽  
Author(s):  
You Wang ◽  
Xinghua Zhu ◽  
Rong Zheng ◽  
Zhe Tang ◽  
Bingbing Chen
Keyword(s):  
Resonant Frequency ◽  
Working Conditions ◽  
Power Law ◽  
Nonlinear Damping ◽  
Frequency Region ◽  
Isolation System ◽  
Analysis And Design ◽  
Force Transmissibility ◽  
Isolation Systems ◽  
Isolation Performance

In this study, the applications of the cubic power law damping in vessel isolation systems are investigated. The isolation performance is assessed using the force transmissibility of the vessel isolation system, which is simplified as a multiple-degree-of-freedom system with two parallel freedoms. The force transmissibilities of different working conditions faced in practice are discussed by applying the cubic power law damping on different positions of the vessel isolation system. Numerical results indicate that by adding the cubic power law damping to an appropriate position, the isolation system can not only suppress the force transmissibility over the resonant frequency region but also keep the force transmissibility unaffected at the nonresonant frequency region. Moreover, the design of the nonlinear vessel isolation system is discussed by finding the optimal nonlinear damping of the isolation system.

Real-Time Smart Abstract Shape Identifiers

2012 ◽  
Vol 83 ◽  
pp. 144-150
Author(s):  
Maguid H.M. Hassan
Keyword(s):  
Neural Network ◽  
Real Time ◽  
Degree Of Freedom ◽  
Rule Base ◽  
Structural System ◽  
Inference System ◽  
Geometrical Properties ◽  
Earthquake Records ◽  
Abstract Shape ◽  
Three Degree Of Freedom

Smart structural systems are emerging as a vehicle for implementing semi active control algorithms. Sensors, processors and actuators are the generic basic components of any smart structural system. Sensors are employed in gathering information that could be used by a smart shape identifier in order to define a real-time abstract deformed shape of the system at any given point in time. This information could be employed in proposing a suitable smart control algorithm to suppress the vibration of a given structural system. In this paper, a generic framework for abstract shape identification is developed. The proposed framework employs predefined potential deformed patterns, for a given structural system, in training and/or designing the smart shape identifier. Two applications were developed which employ neural network and fuzzy logic as two potential smart technologies. Both models are capable of indentifying and/or classifying the abstract deformed shape of a three degree-of-freedom structural system in real-time. The neural network model was developed and trained by a single earthquake record then tested using five unseen earthquake records. The fuzzy inference system employed a rule-base that was developed to capture all potential combinations of inter-story deformations then tested using all six earthquake records. The performance of both models was measured by the statistical and geometrical properties of a linear compliance graph. The developed systems were initially designed and tested to model a three-degree-of-freedom system and are now being expanded to model a multi-degree-of-freedom system.

scholarly journals Displacement amplification ratio modeling of bridge-type nano-positioners with input displacement loss

2019 ◽  
Vol 10 (1) ◽  
pp. 299-307
Author(s):  
Jinyin Li ◽  
Peng Yan ◽  
Jianming Li
Keyword(s):  
Experimental Testing ◽  
Elastic Beam ◽  
Beam Theory ◽  
Element Analysis ◽  
Compliance Matrix ◽  
Amplification Ratio ◽  
Practical Applications ◽  
Analysis And Design ◽  
Proposed Model ◽  
Bridge Type

Abstract. This paper presents an improved modeling method for bridge-type mechanism by taking the input displacement loss into consideration, and establishes an amplification ratio model of bridge-type mechanism according to compliance matrix method and elastic beam theory. Moreover, the amplification ratio of the designed bridge-type nano-positioner is obtained by taking the guiding mechanism as the external load of bridge-type mechanism. Comparing with existing methods, the proposed model is more accurate, which is further verified by finite element analysis(FEA) and experimental test. The consistency of the results obtained from theoretical model, FEA and experimental testing indicates that the proposed model can accurately predict the amplification characteristics of nano-positioners, which helps the analysis and design of bridge-type nano-positioners in practical applications.

Passage Through Resonance in a Vibration Isolation System (Effects of Rate of Increasing the Voltage Applied to D.C. Motor)

2007 ◽  
Author(s):  
Tomohiko Tange ◽  
Ryo Kawana ◽  
Tetsuro Tokoyoda ◽  
Masatsugu Yoshizawa ◽  
Toshihiko Sugiura
Keyword(s):  
Rigid Body ◽  
Internal Resonance ◽  
Vibration Isolation ◽  
Transient Behavior ◽  
Degree Of Freedom ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Rotational Vibration ◽  
Three Degree Of Freedom ◽  
Driving Torque

This paper deals with transient nonlinear vibration of a rigid body suspended on a foundation by elastic springs and constrained in a plane. In such a three degree-of-freedom vibration isolation system, we assume that ‘2-1-1’ internal resonance exists between the vertical and horizontal vibrations of the rigid body and the rotational vibration about its center of gravity. Our main purpose is to examine theoretically the transient behavior passing through resonance under the condition that the D.C. motor directly drives the unbalanced rotor. Numerical simulation was carried out to clarify effects of rate of increasing V(t) on the peak amplitude of the vibration of the rigid body and on the driving torque of the D.C. motor. Moreover, experiment was conducted with a physical model of a three degree-of-freedom vibration isolation system, and the transient behavior passing through resonance was observed and compared with theoretical results in a typical case with internal resonance.

A Modular-Type Three-Axis Vibration Isolation System Using Negative Stiffness

2010 ◽  
Author(s):  
Md. Emdadul Hoque ◽  
Takeshi Mizuno ◽  
Yuji Ishino ◽  
Masaya Takasaki
Keyword(s):  
Vibration Isolation ◽  
Degree Of Freedom ◽  
Experimental Results ◽  
Negative Stiffness ◽  
Isolation System ◽  
Single Degree Of Freedom ◽  
Vibration Isolation System ◽  
Single Degree ◽  
In Series ◽  
Isolation Systems

A vibration isolation system is presented in this paper which is developed by the combination of multiple vibration isolation modules. Each module is fabricated by connecting a positive stiffness suspension in series with a negative stiffness suspension. Each vibration isolation module can be considered as a self-sufficient single-degree-of-freedom vibration isolation system. 3-DOF vibration isolation system can be developed by combining three modules. As the number of motions to be controlled and the number of actuators are equal, there is no redundancy in actuators in such vibration isolation systems. Experimental results are presented to verify the proposed concept of the development of MDOF vibration isolation system using vibration isolation modules.

Nonlinear Dynamic Analysis for the New Whole-Spacecraft Passive Vibration Isolator

2013 ◽  
Vol 300-301 ◽  
pp. 1231-1234 ◽  
Author(s):  
Li Jun Tan ◽  
Bo Fang ◽  
Jie Jie Zhang ◽  
Wen Hu Huang
Keyword(s):  
Vibration Isolation ◽  
Research Work ◽  
Influence Factors ◽  
Nonlinear Dynamic Analysis ◽  
Vibration Isolator ◽  
Isolation System ◽  
Practical Applications ◽  
Analysis And Design ◽  
Nonlinear Motion ◽  
Wide Range

The nonlinear vibration analysis related to viscoelastic damper is investigated for the new whole-spacecraft passive vibration isolator. The stepped sinusoidal sweep test is performed and the results reveal the nonlinearity of the system. The nonlinear motion equation is developed. The frequency response equation is derived by the method of harmonic balance. The experiment of various excitation levels are carried out contrasting with numerical simulations. The nonlinear influence factors to the vibration isolation system are argued and the identification results explain the effect parameters on the performance of the vibration isolator. The research work is of significant implications for the analysis and design of passive vibration isolator for a wide range of practical applications.

Passage Through Resonance in a Three Degree-of-Freedom Vibration Isolation System

2005 ◽  
Author(s):  
Ryo Kawana ◽  
Tetsuro Tokoyoda ◽  
Kazushige Sato ◽  
Masatsugu Yoshizawa ◽  
Toshihiko Sugiura
Keyword(s):  
Rigid Body ◽  
Vibration Isolation ◽  
Transient Behavior ◽  
Degree Of Freedom ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Unbalanced Rotor ◽  
Rotational Vibration ◽  
Three Degree Of Freedom ◽  
Theoretical Results

This paper deals with transient nonlinear vibration of a rigid body suspended on a foundation by elastic springs and constrained in a plane. In such a three degree-of-freedom vibration isolation system, we assume that ‘2-1-1’ internal resonance exists between the vertical and horizontal vibrations of the rigid body and the rotational vibration about its center of gravity. Next, the vibration of the rigid body is captured into or passes through resonance when the rotation speed of an unbalanced rotor equipped with the rigid body is increased. We theoretically examined the transient behavior of passage through resonance under the condition that a DC motor directly drives the unbalanced rotor with a limited electric current. Moreover, the experiment was conducted with a physical model of such a system, and transient oscillations through resonance were observed and compared with theoretical results in a few cases of limited currents.

Analysis and Design of Manipulators With Decoupled and Configuration-Invariant Inertia Tensors Using Remote Actuation

1992 ◽  
Vol 114 (2) ◽  
pp. 204-212 ◽  
Author(s):  
K. Youcef-Toumi
Keyword(s):  
High Speed ◽  
Dynamic Properties ◽  
Sufficient Conditions ◽  
Kinematic Chain ◽  
Degree Of Freedom ◽  
Direct Drive ◽  
Analysis And Design ◽  
Remote Actuation ◽  
Three Degree Of Freedom ◽  
Necessary And Sufficient

The dynamics of manipulators with diagonal and/or constant inertia tensors are described by simple differential equations. This feature greatly simplifies the control of high speed manipulators. This paper presents design methods, which incorporate selection of arm structure and link inertial properties, to achieve simplified manipulator dynamics. First the concept of remote actuation is described. A model is then developed in order to analyze the effects of remote actuation on the manipulator kinematics and dynamics. The modeling is based on Kane’s partial rates along with a set notation to concisely express the system’s dynamics. Second, necessary and sufficient conditions for achieving such dynamic properties for open and closed kinematic chain linkages are derived. These techniques are then applied in the design of three degree-of-freedom planar manipulator and the three degree-of-freedom spatial M. I. T direct-drive manipulator. The mass distribution conditions for which the arm inertia tensors are diagonal and configuration-invariant are derived. The resultant dynamic equations of these manipulators are shown to be very simple.

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