scholarly journals About the weight and size parameters of electromagnetic stiffness correctors

2021 ◽  
Vol 2131 (5) ◽  
pp. 052003
Author(s):  
V Y Gross ◽  
A V Zharov ◽  
A M Baranovskiy ◽  
S N Reutov
Keyword(s):  
Relative Position ◽  
Elastic Element ◽  
Relative Displacement ◽  
Negative Stiffness ◽  
Stiffness Coefficient ◽  
Power Characteristic ◽  
Negative Coefficient ◽  
Static Stiffness ◽  
Vibration Isolators ◽  
Mathematical Expressions

Abstract A significant reduction in the levels of general ship vibrations can be achieved by using vibration isolators with a “floating” section of zero stiffness in vibration protection suspensions. In such devices, in parallel to the main elastic element, the so-called stiffness corrector (compensator) is switched on - a device with a negative coefficient of static stiffness, equipped with a restructuring system that ensures the retention of the corrector elements when the relative position of the vibrating and protected objects, caused by a change in static forces acting on these objects. One of the variants of the corrector is an electromagnetic stiffness corrector, in which the power characteristic with a negative stiffness coefficient is provided by two electromagnets with a common armature turned on in opposite directions. The disadvantage of such correctors is the dependence of their overall dimensions on the value of the permissible relative displacement of the vibrating and protected objects. The article deduced mathematical expressions that approximately determine the dependence of the overall dimensions of the stiffness corrector electromagnets on the value of the calculated relative displacement of the vibrating and protected objects, the possible field of application of vibration isolators Xwith electromagnetic stiffness correctors is determined.

Features of the Power Characteristics of the Vibration Isolators

2014 ◽  
Vol 1040 ◽  
pp. 678-681 ◽  
Author(s):  
Elena G. Gurova ◽  
Michail G. Gurov ◽  
Stanislav V. Makarov ◽  
Andrey Sergeev
Keyword(s):  
Elastic Element ◽  
Three Dimensional ◽  
Specific Area ◽  
Vibration Isolator ◽  
Power Characteristic ◽  
One Dimensional ◽  
Vibration Isolators ◽  
Power Characteristics ◽  
Negative Effect ◽  
Engineering Vibration

In this article the development of the perspective vibration protection device is described. The theory suggests the development of 3D-vibration isolator devices, which have power characteristics with zero stiffness area. A spatial vibroisolator is presented as an elastic element and stiffness compensator in-parallel of this element to obtain this specific area on power characteristic. This methodology allows us to make three-dimensional (3D) vibration isolator with electromagnetic stiffness compensator. This isolator allows to delete the vibration fluctuations in all three axes of space simultaneously. A spatial vibroisolated device consists of an elastic element and parallel 3D-electromagnetic stiffness compensator. An electromagnetic stiffness compensator is a two counter-mounted electromagnetic disks. Each disk is made as six electromagnetic or magnetic disconnected coils, and they are located two by two along three axes of space. The construction of one-dimensional vibration isolator with an electromagnetic stiffness compensator is presented in this article. Three-dimensional vibration isolator can be used in any area of mechanic, engineering, vibration dumping technique, which has a negative effect on human health and devices performance.

Frequency Response Analysis of Piecewise Nonlinear Vibration Isolator

2005 ◽  
Author(s):  
Patrick Stahl ◽  
G. Nakhaie Jazar
Keyword(s):  
Low Frequency ◽  
High Amplitude ◽  
Relative Displacement ◽  
Response Analysis ◽  
Frequency Response Analysis ◽  
State Behavior ◽  
Vibration Isolators ◽  
Short Period ◽  
Secondary Suspension ◽  
Low Amplitude

Non-smooth piecewise functional isolators are smart passive vibration isolators that can provide effective isolation for high frequency/low amplitude excitation by introducing a soft primary suspension, and by preventing a high relative displacement in low frequency/high amplitude excitation by introducing a relatively damped secondary suspension. In this investigation a linear secondary suspension is attached to a nonlinear primary suspension. The primary is assumed to be nonlinear to model the inherent nonlinearities involved in real suspensions. However, the secondary suspension comes into action only during a short period of time, and in mall domain around resonance. Therefore, a linear assumption for the secondary suspension is reasonable. The dynamic behavior of the system subject to a harmonic base excitation has been analyzed utilizing the analytic results derived by applying the averaging method. The analytic results match very well in the transition between the two suspensions. A sensitivity analysis has shown the effect of varying dynamic parameters in the steady state behavior of the system.

Shock isolation characteristics of a bistable vibration isolator with tunable magnetic controlled stiffness

2021 ◽  
pp. 1-28
Author(s):  
Bo Yan ◽  
Peng Ling ◽  
Yanlin Zhou ◽  
Chuan-yu Wu ◽  
Wen-Ming Zhang
Keyword(s):  
Damping Ratio ◽  
Excitation Amplitude ◽  
Relative Displacement ◽  
Vibration Isolator ◽  
Maximum Acceleration ◽  
Vibration Isolators ◽  
Displacement Ratio ◽  
Shock Isolation ◽  
Maximum Relative Displacement ◽  
Isolation Performance

Abstract This paper investigates the shock isolation characteristics of an electromagnetic bistable vibration isolator (BVI) with tunable magnetic controlled stiffness. The theoretical model of the BVI is established. The maximum acceleration ratio (MAR), maximum absolute displacement ratio (MADR) and maximum relative displacement ratio (MRDR) are introduced to evaluate the shock isolation performance of the BVI. The kinetic and potential energy are observed to further explore the performance of the BVI. The effects of the potential barrier, shape of potential well, damping ratio on the BVI are discussed compared to the linear vibration isolators (LVI). The results demonstrate that the intrawell oscillations and snap-through oscillations are determined by the excitation amplitude and duration time of main pulse. MADR and MRDR of the BVI are smaller than those of the LVI. The maximum acceleration peak amplitude of the BVI is far below that of the LVI, especially when the snap-through oscillation occurs. In brief, the proposed BVI has a better shock isolation performance than the LVI and has the potential to suppress the shock of space structures during the launch and on-orbit deploying process.

scholarly journals Improving Low Frequency Isolation Performance of Optical Platforms Using Electromagnetic Active-Negative-Stiffness Method

2020 ◽  
Vol 10 (20) ◽  
pp. 7342
Author(s):  
Yamin Zhao ◽  
Junning Cui ◽  
Junchao Zhao ◽  
Xingyuan Bian ◽  
Limin Zou
Keyword(s):  
Root Mean Square ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Laser Interferometry ◽  
Relative Displacement ◽  
Negative Stiffness ◽  
Mean Square ◽  
Electromagnetic Actuators ◽  
Micro Vibration ◽  
Isolation Performance

To improve the low-frequency isolation performance of optical platforms, an electromagnetic active-negative-stiffness generator (EANSG) was proposed, using nano-resolution laser interferometry sensors to monitor the micro-vibration of an optical platform, and precision electromagnetic actuators integrated with a relative displacement feedback strategy to counteract the positive stiffness of pneumatic springs within a micro-vibration stroke, thereby producing high-static-low-dynamic stiffness characteristics. The effectiveness of the method was verified by both theoretical and experimental analyses. The experimental results show that the vertical natural frequency of the optical platform was reduced from 2.00 to 1.37 Hz, the root mean square of displacement was reduced from 1.28 to 0.69 μm, and the root mean square of velocity was reduced from 14.60 to 9.33 μm/s, proving that the proposed method can effectively enhance the low frequency isolation performance of optical platforms.

scholarly journals Dynamically variable negative stiffness structures

2016 ◽  
Vol 2 (2) ◽  
pp. e1500778 ◽  
Author(s):  
Christopher B. Churchill ◽  
David W. Shahan ◽  
Sloan P. Smith ◽  
Andrew C. Keefe ◽  
Geoffrey P. McKnight
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Variable Stiffness ◽  
Negative Stiffness ◽  
Load Bearing ◽  
Vibration Isolators ◽  
Wide Range ◽  
Engineered Systems ◽  
Tunable Stiffness

Variable stiffness structures that enable a wide range of efficient load-bearing and dexterous activity are ubiquitous in mammalian musculoskeletal systems but are rare in engineered systems because of their complexity, power, and cost. We present a new negative stiffness–based load-bearing structure with dynamically tunable stiffness. Negative stiffness, traditionally used to achieve novel response from passive structures, is a powerful tool to achieve dynamic stiffness changes when configured with an active component. Using relatively simple hardware and low-power, low-frequency actuation, we show an assembly capable of fast (<10 ms) and useful (>100×) dynamic stiffness control. This approach mitigates limitations of conventional tunable stiffness structures that exhibit either small (<30%) stiffness change, high friction, poor load/torque transmission at low stiffness, or high power active control at the frequencies of interest. We experimentally demonstrate actively tunable vibration isolation and stiffness tuning independent of supported loads, enhancing applications such as humanoid robotic limbs and lightweight adaptive vibration isolators.

Optimal design of passenger vehicle seat with the use of negative stiffness elements

2019 ◽  
Vol 234 (2-3) ◽  
pp. 610-629 ◽  
Author(s):  
Georgios Papaioannou ◽  
Artemios Voutsinas ◽  
Dimitrios Koulocheris
Keyword(s):  
Vibration Isolation ◽  
Ride Comfort ◽  
Negative Stiffness ◽  
Vibration Isolators ◽  
Seat Suspension ◽  
Suspension Systems ◽  
Dynamic Factors ◽  
Safety And Health ◽  
The Common ◽  
Vehicle Seat

A seat that provides good vibration isolation is of prime importance for passenger’s safety and health. The main conflict in seat suspensions implies that the increasing initial deformation of the system (increase in “static discomfort”) leads to better isolation of accelerations (increase in “dynamic comfort”). Many researchers have focused on overcoming or at least suppressing this conflict between load support capacity and vibration isolation by modeling new suspension systems, such as the so-called negative suspension systems. However, apart from the modeling of new suspension systems, optimization is an important part in designing a seat and finding the best compromise between these two objectives. Thus, in this work, four types of seat suspension systems with embedded negative stiffness elements are implemented and optimized in order to be benchmarked. Three of them have already been tested either in passenger or in an off-road vehicle seat. All the vibration isolators are optimized with genetic algorithms in respect to static and dynamic factors of ride comfort by applying constraints oriented to the objectives and the design of the structure. The optimization is implemented for two excitations, which correspond to a vehicle driving over road profiles of Classes A and B, and the common solutions are outlined.

scholarly journals ENHANCED DAMPING CHARACTERISTICS OF TIMOSHENKO BEAM ON ELASTIC AND METAMATERIAL FOUNDATIONS

2020 ◽  
Vol 14 (1) ◽  
pp. 52-62
Author(s):  
A. O. Oyelade ◽  
O. M. Sadiq
Keyword(s):  
Timoshenko Beam ◽  
Damping Ratio ◽  
Reference Beam ◽  
Negative Stiffness ◽  
Flexural Wave ◽  
Flexural Waves ◽  
Static Stiffness ◽  
Damping Characteristics ◽  
Simulation Results ◽  
Flexural Wave Propagation

An analytical model is developed for the flexural wave propagation of a continuous Timoshenko beam resting on elastic and metamaterial foundations. The metamaterial foundation consists of positive and negative springs with a damper. This added negative stiffness component is constructed in such a way to provide the same static stiffness and the same damping component with the equivalent reference beam on elastic foundation. Numerical examples are used to investigate the effect of the shear on wavenumber and damping for beam with elastic and metamaterial foundations. The effects of engineering safety, damping coefficient and resonating mass on the dissipative property of the beam is investigated analytically. The simulation results provide indication of an enhanced damping characteristics for the damping ratio of the flexural waves propagating within the beam.

scholarly journals Magnetic spring effect on the force characteristics of the electromechanical magnetic liquid damper

Vestnik IGEU ◽  
2019 ◽  
pp. 32-40
Author(s):  
S.A. Nesterov ◽  
N.A. Morozov ◽  
Yu.B. Kazakov
Keyword(s):  
Magnetic Fluid ◽  
Compressive Force ◽  
Relative Displacement ◽  
Resistance Force ◽  
Vibration Frequencies ◽  
Power Characteristic ◽  
Power Characteristics ◽  
Magnetic Spring ◽  
Magnetorheological Suspension ◽  
Fluid Dampers

The effect of a magnetic spring is observed in electromechanical devices with limited pole sizes. Simultane-ous changing of the system magnetic conductivity after a relative displacement of the poles causes mag-netic tension forces. These forces in electromechanical magnetic fluid dampers have their own specific characteristics which have not been studied before. All this requires studying the effect of a magnetic spring on the damper power characteristics, estimating the effect of the properties of a magnetorheological suspension on the magnetic spring strength, nature of its change and combination of the action of magnetic forces and viscosity resistance to the piston movement. To do that, it is important to analyze the effect of a magnetic spring in statics, at a slow movement of the piston and its dynamic oscillations. The studies were based on the theory of natural experiment and methods of processing experimental results. We have obtained and analyzed dependences of the resistance force of the electromechanical magnetic fluid damper for different vibration frequencies and magnetic inductions. The effect of magnetic spring forces on the damper power characteristic has been investigated. It has been found how the damper resistance force is affected by the magnetic and hydrodynamic components. The use of a damper with alternating elements with high and low magnetic conductivities makes it possible to change the strength characteristic of electromechanical magnetic fluid dampers. The proportion of the force controlled by the magnetic field reaches 75 % of the total effort. The use of the magnetic spring effect allows increasing the damping efficiency at small amplitudes and vibration frequencies. Increasing the magnetic properties of a magnetorheological suspension enhances the effect of a magnetic spring if the piston is non-magnetic, and weakens it if it is a magnetic one. When the magnetic induction rises, the effect of the magnetic spring increases. By changing the initial piston position, it is possible to obtain an asymmetrical power characteristic, for example, without using valves and spools, to increase the rebound force and to reduce the compressive force. If there are no moving parts, the damper reliability increases.

THE INFLUENCE OF THE LENGTHS OF THE LINKS OF THE HINGED FOUR-LINK ON THE ANGLE OF HEIGHT, RETURN ANGLE AND RELATIVE DISPLACEMENT OF LINKS CONNECTED BY THE ELASTIC ELEMENT DURING THE OUTPUT LINK STABILITY

2020 ◽  
Author(s):  
Tat'yana Balabina ◽  
Mariya Karelina ◽  
Aleksey Mamaev
Keyword(s):  
Elastic Element ◽  
Variable Structure ◽  
Relative Displacement ◽  
Technological Equipment ◽  
Output Link ◽  
Periodic Rotation ◽  
Link Stability ◽  
Wide Possibility ◽  
The One ◽  
Automatic Action

Toothed-lever and cam-toothed-lever mechanisms are widely used in technological equipment of automatic and semi-automatic action to convert the one-way rotational motion of the input link into one-way rotary motion of the output link with periodic stops. To ensure periodic rotation with a precise fixed length, an elastic element with a preload of two-sided action is introduced into the mechanism, as a result of which the mechanism has a variable structure. Compared to other mechanisms of periodic rotation, in gear-link mechanisms there is a wide possibility of influencing the function of the position of the output link, the angle of reverse rotation and the relative displacements of the links connected to each other by an elastic element by changing the lengths of the links of the basic hinged four-link

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