On the Displacement Transmissibility of a Base Excited Viscously Damped Nonlinear Vibration Isolator

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Zarko Milovanovic ◽  
Ivana Kovacic ◽  
Michael J. Brennan
Keyword(s):  
Nonlinear Systems ◽  
Nonlinear Vibration ◽  
Performance Characteristics ◽  
Vibration Isolator ◽  
Base Excitation ◽  
Vibration Isolators ◽  
System Parameters ◽  
Beneficial Effects ◽  
Absolute Displacement ◽  
Stiffness And Damping

In this article vibration isolators having linear and cubic nonlinearities in stiffness and damping terms are considered under base excitation. The influence of the system parameters on the relative and absolute displacement transmissibility is investigated. The performance characteristics of the nonlinear isolators are evaluated and compared with the performance characteristics of the linear isolators to highlight the beneficial effects in the nonlinear systems considered.

Sensitivity of Jump Avoidance Condition of Piecewise Linear Vibration Isolator to Dynamical Parameters

2005 ◽  
Author(s):  
Sagar Deshpande ◽  
Sudhir Mehta ◽  
G. Nakhaie Jazar
Keyword(s):  
Piecewise Linear ◽  
System Response ◽  
Structural Constraints ◽  
Vibration Isolator ◽  
Linear Vibration ◽  
Vibration Isolators ◽  
Non Linear ◽  
Dynamical Parameters ◽  
Non Linear System ◽  
Stiffness And Damping

An adapted averaging method is employed to obtain an implicit function for frequency response of a bilinear vibration isolator system under steady state. This function is examined for jump-avoidance and a condition is derived which when met ensures that the undesirable phenomenon of ‘Jump’ does not occur and the system response is functional and unique. The jump avoidance and sensitivity of the condition are examined and investigated as the dynamic parameters vary. The results of this investigation can be directly employed in design of effective piecewise linear vibration isolators. A linear vibration system is defined as one in which the quantities of mass (or inertia), stiffness, and damping are linear in behavior and do not vary with time [1]. Although mathematical models employing a linear ordinary differential equation with constant coefficients portray a simple and manageable system for analytical scrutiny, in most cases they are an incomplete representation simplified for the sake of study. Most real physical vibration systems are more accurately depicted by non-linear governing equations, in which the non-linearity may stem from structural constraints causing a change in stiffness and damping characteristics, or from inherent non-linear behavior of internal springs and dampers. This paper focuses on a general form of such a non-linear system. This study of piecewise-linear systems will allow hazardous system behavior over operating frequency ranges to be gauged and controlled in order to avoid premature fatigue damage, and prolong the life of the system.

Design of a piecewise linear vibration isolator for jump avoidance

2007 ◽  
Vol 221 (3) ◽  
pp. 441-449 ◽  
Author(s):  
G N Jazar ◽  
M Mahinfalah ◽  
S Deshpande
Keyword(s):  
Piecewise Linear ◽  
Harmonic Excitation ◽  
System Response ◽  
Structural Constraints ◽  
Vibration Isolator ◽  
Linear Vibration ◽  
Vibration Isolators ◽  
Non Linear ◽  
Non Linear System ◽  
Stiffness And Damping

Piecewise linear isolators are smart passive vibration isolators that provide effective isolation for high frequency/low amplitude excitation. This can be done by introducing a soft primary suspension and a relatively damped secondary suspension. Such a piecewise isolator prevents the system from a high relative displacement in low frequency/high amplitude excitation. By employed an averaging method it is possible to obtain an implicit function for frequency response of a symmetric bilinear vibration isolator system under steady-state harmonic excitation. This function is examined for jump avoidance. A condition is derived which when met ensures that the undesirable phenomenon of ‘jump’ does not occur and the system response is functional. The jump avoidance and sensitivity of the condition are examined and investigated as the dynamic parameters vary. The results of this investigation can be directly employed in design of effective piecewise linear vibration isolators. A linear vibration system is defined as one in which the quantities of mass (or inertia), stiffness, and damping are linear in behaviour and do not vary with time [1]. Although mathematical models employing a linear ordinary differential equation with constant coefficients portray a simple and manageable system for analytical study, in most cases they are an incomplete representation simplified for the sake of analysis. Most real physical vibration systems are more accurately depicted by non-linear governing equations, in which the non-linearity may stem from structural constraints causing a change in stiffness and damping characteristics, or from inherent non-linear behaviour of internal springs and dampers. This paper focuses on a general form of such a non-linear system. This study of piecewise-linear systems will allow hazardous system behaviour over operating frequency ranges to be gauged and controlled in order to avoid premature fatigue damage, and prolong the life of the system.

Application of Tuned Mass Dampers and Lever Type Vibration Isolator to the Quarter-Car Model in Order to Increase Ride Comfort

2010 ◽  
Author(s):  
Go¨ksu Aydan ◽  
Ender Cig˘erog˘lu ◽  
S. C¸ag˘lar Bas¸lamıs¸lı
Keyword(s):  
Ride Comfort ◽  
Small Mass ◽  
Vibration Isolator ◽  
Tuned Mass Dampers ◽  
Suspension Spring ◽  
Vibration Isolators ◽  
Quarter Car Model ◽  
Suspension Systems ◽  
In Series ◽  
Stiffness And Damping

In this paper, performance of passive vibration isolators, namely rotational / linear tuned mass dampers (TMD) and lever type vibration isolators (LVI), are investigated under different configurations for optimal ride comfort. TMDs reduce vibration levels by absorbing the energy of the system, especially around natural frequencies with the help of viscous dampers. Two types of TMDs, rotational and linear, are investigated in this study. Although linear TMDs can be more easily implemented on suspension systems, rotational TMDs show better performance in reducing vibration levels. The reason is that, the inertia effect of rotational TMDs is higher than linear TMDs. In order to obtain better results with TMDs, a study on different possible configurations is conducted. A plate, with very small mass, is added between sprung and unsprung masses without changing the original suspension spring stiffness and damping coefficients and acts as a support for in-series TMD applications. Finally, LVIs are implemented to reduce sprung mass acceleration and more satisfactory results are obtained especially around body bounce frequency.

Vibration Isolator System for Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 182-183
Author(s):  
K. Ohi ◽  
M. Mizuno ◽  
T. Kasai ◽  
Y. Ohkura ◽  
K. Mizuno ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Magnetic Fields ◽  
Environmental Conditions ◽  
Vibration Isolator ◽  
Air Conditioners ◽  
Vibration Isolators ◽  
Large Size ◽  
Electron Microscopes

In recent years, with electron microscopes coming into wider use, their installation environments do not necessarily give their performance full play. Their environmental conditions include air-conditioners, magnetic fields, and vibrations. We report a jointly developed entirely new vibration isolator which is effective against the vibrations transmitted from the floor.Conventionally, large-sized vibration isolators which need the digging of a pit have been used. These vibration isolators, however, are large present problems of installation and maintenance because of their large-size.Thus, we intended to make a vibration isolator which1) eliminates the need for changing the installation room2) eliminates the need of maintenance and3) are compact in size and easily installable.

Vibration control of an unbalanced system using a quasi-zero stiffness vibration isolator with fluidic actuators and composite material: An experimental study

2022 ◽  
pp. 107754632110514
Author(s):  
Sivakumar Solaiachari ◽  
Jayakumar Lakshmipathy
Keyword(s):  
Composite Material ◽  
Nonlinear Vibration ◽  
Vibration Isolation ◽  
Basalt Fiber ◽  
Experimental Investigations ◽  
Vibration Isolator ◽  
Coil Spring ◽  
Linear Type ◽  
Fluidic Actuators ◽  
Isolation Performance

In this study, a new type of vibration isolator based on fluidic actuators and a composite slab was tested experimentally with an unbalanced disturbance. Quasi-zero stiffness vibration isolation techniques are advanced and provide effective isolation performance for non-nominal loads. The isolation performance of the proposed isolator was compared to that of a nonlinear vibration isolator equipped with fluidic actuators and a mechanical coil spring (NLVIFA). The NLVIFA system is better suited to non-nominal loads; however, the mechanical spring axial deflection leads to limited amplitude reduction in the system. To address this issue, a cross buckled slab was developed to replace a mechanical coil spring for absorbing vertical deflection by transverse bending, which is made of a specially developed composite material of Basalt fiber reinforced with epoxy resin and enhanced with graphene nano pellets. This current study was concerned with the theoretical analysis and experimental investigations of the proposed nonlinear vibration isolator with fluidic actuators and composite material (NLVIFA-CM), which performs under quasi-zero stiffness characteristics. Because of its reduced axial deflection, the theoretical and experimental results show that the NLVIFA-CM system outperforms the NLVIFA system and other linear type vibration isolators in terms of isolation performance. Furthermore, the proposed vibration isolator makes a significant contribution to low-frequency vibration.

Dynamic Analysis of a Protein-Ligand Molecular Chain Attached to an Atomic Force Microscope

2004 ◽  
Vol 126 (4) ◽  
pp. 496-513 ◽  
Author(s):  
Deman Tang ◽  
Earl H. Dowell
Keyword(s):  
Nonlinear Systems ◽  
Atomic Force Microscope ◽  
Reduced Order Model ◽  
Molecular Chain ◽  
Static Equilibrium ◽  
Reduced Order Models ◽  
Base Excitation ◽  
Order Model ◽  
Reduced Order ◽  
Atomic Force

Dynamic numerical simulation of a protein-ligand molecular chain connected to a moving atomic force microscope (AFM) has been studied. A sinusoidal base excitation of the cantilevered beam of the AFM is considered in some detail. A comparison between results for a single molecule and those for multiple molecules has been made. For a small number of molecules, multiple stable static equilibrium positions are observed and chaotic behavior may be generated via a period-doubling cascade for harmonic base excitation of the AFM. For many molecules in the chain, only a single static equilibrium position exists. To enable these calculations, reduced-order (dynamic) models are constructed for fully linear, combined linear/nonlinear and fully nonlinear systems. Several distinct reduced-order models have been developed that offer the option of increased computational efficiency at the price of greater effort to construct the particular reduced-order model. The agreement between the original and reduced-order models (ROM) is very good even when only one mode is included in the ROM for either the fully linear or combined linear/nonlinear systems provided the excitation frequency is lower than the fundamental natural frequency of the linear system. The computational advantage of the reduced-order model is clear from the results presented.

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