Parametric Studies of the Vibration Control Effects of a Nonlinear Damper System under Multi-Axis Excitations

2013 ◽  
Vol 712-715 ◽  
pp. 1682-1685
Author(s):  
Zheng Lu
Keyword(s):  
Numerical Simulations ◽  
Vibration Control ◽  
Primary Structure ◽  
Coefficient Of Restitution ◽  
Primary System ◽  
Mass Ratio ◽  
System Parameters ◽  
Shaped Container ◽  
Weight Penalty ◽  
Parametric Studies

This paper studies the influence of system parameters to the vibration control effects of a nonlinear damper system under multi-axis excitations. The nonlinear damper system is composed of a particle damper and a primary structure. Based on numerical simulations, it is shown that: increasing the mass ratio can improve the dampers effectiveness, but only up to a certain level; applying particles with a high value of the coefficient of restitution can result in a broader range of acceptable response levels; a lightly-damped primary system can achieve a considerable reduction in its response with a small weight penalty; and that a cylindrically-shaped container provides a higher level of effectiveness than a rectangularly-shaped one.

Shock Isolation in Finite-Length Dimer Chains With Linear, Cubic, and Hertzian Spring Interactions

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Eric Smith ◽  
Aldo Ferri
Keyword(s):  
Numerical Simulations ◽  
Finite Length ◽  
Hertzian Contact ◽  
Mass Ratio ◽  
Transmitted Force ◽  
Parametric Studies ◽  
Shock Isolation ◽  
Isolation Systems ◽  
Chain Lengths ◽  
Isolation Performance

This paper investigates the use of finite 1:1 dimer chains to mitigate the transmission of shock disturbances. Dimer chains consist of alternating light and heavy masses with interconnecting compliance. Changing the mass ratio has provided interesting results in previous research. In particular, in the case of Hertzian contacts with zero-preload, certain mass ratios have revealed minimal levels of transmitted force. This paper examines this phenomenon from the perspective of utilizing it in practical isolation systems. The zero-preload Hertzian contact case is contrasted with chains connected by linear or cubic springs. Through numerical simulations, tradeoffs are examined between displacement and transmitted force. Parametric studies are conducted to examine how isolation performance changes with mass ratio, stiffness, and different chain lengths.

Active Parameter Control of Nonlinear Vibrating Structures

1989 ◽  
Vol 56 (3) ◽  
pp. 658-666 ◽  
Author(s):  
S. F. Masri ◽  
R. K. Miller ◽  
T. J. Dehghanyar ◽  
T. K. Caughey
Keyword(s):  
Vibration Control ◽  
Primary Structure ◽  
Control Method ◽  
Direct Method ◽  
Primary System ◽  
System A ◽  
On Line ◽  
Reliability And Robustness ◽  
Related Paper ◽  
Active Control Method

A simple, yet efficient method is presented for the on-line vibration control of nonlinear, multidegree-of-freedom systems responding to arbitrary dynamic environments. The procedure uses nonlinear auxiliary mass dampers with adjustable motion-limiting stops located at selected positions throughout a given nonlinear system. A mathematical model of the system to be controlled is not needed for implementing the control algorithm. The degree of the primary structure oscillation near each vibration damper determines the damper’s actively-controlled gap size and activation time. By using control energy to adjust the damper parameters instead of directly attenuating the motion of the primary system, a significant improvement is achieved in the total amount of energy expended to accomplish a given level of vibration control. In a related paper, the direct method of Lyapunov is used to establish that the response of the controlled nonlinear primary structure is Lagrange stable. Numerical simulation studies of several example systems, as well as an experimental study with a mechanical model, demonstrate the feasibility, reliability, and robustness of the proposed semi-active control method.

On Vibration Control Using a Bistable Snap Through Absorber From a Force Balance Perspective

2013 ◽  
Author(s):  
David R. Johnson ◽  
R. L. Harne ◽  
K. W. Wang
Keyword(s):  
Vibration Control ◽  
Primary Structure ◽  
Vibration Suppression ◽  
External Disturbance ◽  
Harmonic Balance Method ◽  
Harmonic Excitation ◽  
Force Balance ◽  
Single Frequency ◽  
System Response ◽  
Primary System

One approach to vibration control is to apply a force to a primary structure which opposes excitation, effectively canceling the external disturbance. A familiar passive example of this approach is the linear tuned mass absorber. In this spirit, the utility of a bistable attachment for attenuating vibrations, especially in terms of the high-orbit, snap through dynamic, is investigated using the harmonic balance method and experiments. Analyses demonstrate the fundamental harmonic snap through dynamic, having commensurate frequency with the single-frequency harmonic excitation, may yield displacements either substantially in-phase or out-of-phase with the primary structure. During in-phase snap through, forces are generated by the bistable oscillator which reinforce the applied loading, resulting in dramatic amplification of primary system response. During out-of-phase snap through, forces are generated which are only partially opposed to the input, leading to a measure of host structure attenuation. The experiments verify the analytical findings and also uncover nonlinear dynamics not predicted by the analysis that have slightly favorable vibration suppression performance when compared with the out-of-phase, fundamental harmonic snap through action.

scholarly journals Investigation On The Optimal Tunable Bi-Stable Clustered Energy Conversion Inspired Dynamic Vibration Absorbers: A Theoretical Study

2021 ◽  
Author(s):  
Xingbao Huang ◽  
Xiao Zhang ◽  
Bintang Yang
Keyword(s):  
Energy Conversion ◽  
Vibration Control ◽  
Conversion Efficiency ◽  
Energy Conversion Efficiency ◽  
Vibration Absorbers ◽  
Input Energy ◽  
Mass Ratio ◽  
Vibration Absorption ◽  
Dynamic Vibration Absorbers ◽  
Conversion Performance

Abstract This paper introduces an energy conversion inspired vibration control methodology and presents a representative prototype of tunable bi-stable energy converters. This work is concerned on improving the vibration absorption and energy conversion performance of tunable bi-stable clustered energy conversion inspired dynamic vibration absorbers (EC-DVAs). The deterministic parametric analysis of the energy transfer performance of clustered EC-DVAs is conducted. Firstly, nonlinear vibration behaviors including transient energy transfer and snap-through motions are studied, and then effects of EC-DVA number on vibration control is investigated. Furthermore, the optimal computation based on adjusting the length ratio (namely bi-stable potential barrier height) is developed to obtain the maximum energy conversion efficiency of clustered EC-DVAs and the minimum residual kinetic energy of the primary system considering different number of clustered EC-DVAs. Moreover, the optimal calculation based on optimal EC-DVA number is also developed to achieve the most excellent vibration absorption and energy conversion performance. Finally, the optimal calculation based on optimal mass ratio is conducted. Numerical simulations show that when the total mass ratio is constant the snap-through motions of each EC-DVA depend remarkably on EC-DVA number; the energy conversion efficiency and residual kinetic energy after dynamic length ratio optimization is independent on ambient input energy and EC-DVA number; The energy conversion efficiency and vibration absorption performance based on optimal EC-DVA number maintain high efficiency and stable when the ambient input energy or the potential energy of clustered EC-DVAs varies. The optimal mass ratio is large when the system’s potential barrier is too large and the ambient input energy is small. Therefore, the presented tunable bi-stable system of clustered EC-DVAs with appropriate bi-stable potential function and proposed optimization strategies is a potential alternative for vibration control of mechanical components exposed to varying impulses.

Transient Response of MDOF Systems With Inerters to Nonstationary Stochastic Excitation

2017 ◽  
Vol 84 (10) ◽  
Author(s):  
Sami F. Masri ◽  
John P. Caffrey ◽  
Hui Li
Keyword(s):  
Degrees Of Freedom ◽  
Broad Band ◽  
Primary System ◽  
Mean Square ◽  
Stochastic Excitation ◽  
Mass Ratio ◽  
Tuning Parameters ◽  
Mdof Systems ◽  
Mean Square Response ◽  
Arbitrary Location

Explicit, closed-form, exact analytical expressions are derived for the covariance kernels of a multi degrees-of-freedom (MDOF) system with arbitrary amounts of viscous damping (not necessarily proportional-type), that is equipped with one or more auxiliary mass damper-inerters placed at arbitrary location(s) within the system. The “inerter” is a device that imparts additional inertia to the vibration damper, hence magnifying its effectiveness without a significant damper mass addition. The MDOF system is subjected to nonstationary stochastic excitation consisting of modulated white noise. Results of the analysis are used to determine the dependence of the time-varying mean-square response of the primary MDOF system on the key system parameters such as primary system damping, auxiliary damper mass ratio, location of the damper-inerter, inerter mass ratio, inerter node choices, tuning of the coupling between the damper-inerter and the primary system, and the excitation envelope function. Results of the analysis are used to determine the dependence of the peak transient mean-square response of the system on the damper/inerter tuning parameters, and the shape of the deterministic intensity function. It is shown that, under favorable dynamic environments, a properly designed auxiliary damper, encompassing an inerter with a sizable mass ratio, can significantly attenuate the response of the primary system to broad band excitations; however, the dimensionless “rise-time” of the nonstationary excitation substantially reduces the effectiveness of such a class of devices (even when optimally tuned) in attenuating the peak dynamic response of the primary system.

scholarly journals The structure of the co-orbital stable regions as a function of the mass ratio

2020 ◽  
Vol 496 (3) ◽  
pp. 3700-3707
Author(s):  
L Liberato ◽  
O C Winter
Keyword(s):  
Angular Distance ◽  
Stable Region ◽  
Polynomial Functions ◽  
Mass Ratio ◽  
Three Body Problem ◽  
System Parameters ◽  
Wide Range ◽  
Value Range ◽  
Three Body ◽  
Orbital Region

ABSTRACT Although the search for extrasolar co-orbital bodies has not had success so far, it is believed that they must be as common as they are in the Solar system. Co-orbital systems have been widely studied, and there are several works on stability and even on formation. However, for the size and location of the stable regions, authors usually describe their results but do not provide a way to find them without numerical simulations, and, in most cases, the mass ratio value range is small. In this work, we study the structure of co-orbital stable regions for a wide range of mass ratio systems and build empirical equations to describe them. It allows estimating the size and location of co-orbital stable regions from a few system parameters. Thousands of massless particles were distributed in the co-orbital region of a massive secondary body and numerically simulated for a wide range of mass ratios (μ) adopting the planar circular restricted three-body problem. The results show that the upper limit of horseshoe regions is between 9.539 × 10−4 < μ < 1.192 × 10−3, which corresponds to a minimum angular distance from the secondary body to the separatrix of between 27.239º and 27.802º. We also found that the limit to existence of stability in the co-orbital region is about μ = 2.3313 × 10−2, much smaller than the value predicted by the linear theory. Polynomial functions to describe the stable region parameters were found, and they represent estimates of the angular and radial widths of the co-orbital stable regions for any system with 9.547 × 10−5 ≤ μ ≤ 2.331 × 10−2.

scholarly journals Experimental Active Vibration Control in Truss Structures Considering Uncertainties in System Parameters

2008 ◽  
Vol 2008 ◽  
pp. 1-14 ◽  
Author(s):  
Douglas Domingues Bueno ◽  
Clayton Rodrigo Marqui ◽  
Rodrigo Borges Santos ◽  
Camilo Mesquita Neto ◽  
Vicente Lopes
Keyword(s):  
Vibration Control ◽  
Dynamic Model ◽  
Electromechanical Coupling ◽  
Active Vibration Control ◽  
Experimental Methodology ◽  
Truss Structures ◽  
Linear Matrix ◽  
System Parameters ◽  
Identification Method ◽  
Active Vibration

This paper deals with the study of algorithms for robust active vibration control in flexible structures considering uncertainties in system parameters. It became an area of enormous interest, mainly due to the countless demands of optimal performance in mechanical systems as aircraft, aerospace, and automotive structures. An important and difficult problem for designing active vibration control is to get a representative dynamic model. Generally, this model can be obtained using finite element method (FEM) or an identification method using experimental data. Actuators and sensors may affect the dynamics properties of the structure, for instance, electromechanical coupling of piezoelectric material must be considered in FEM formulation for flexible and lightly damping structure. The nonlinearities and uncertainties involved in these structures make it a difficult task, mainly for complex structures as spatial truss structures. On the other hand, by using an identification method, it is possible to obtain the dynamic model represented through a state space realization considering this coupling. This paper proposes an experimental methodology for vibration control in a 3D truss structure using PZT wafer stacks and a robust control algorithm solved by linear matrix inequalities.

Linear Analysis of Uniformly Stressed, Orthotropic Cylindrical Shells

1986 ◽  
Vol 53 (2) ◽  
pp. 249-256 ◽  
Author(s):  
J. F. Wilson ◽  
G. Orgill
Keyword(s):  
Internal Pressure ◽  
Load Carrying Capacity ◽  
Uniform Load ◽  
Classical Elasticity ◽  
Proper Selection ◽  
System Parameters ◽  
Load Carrying ◽  
Parametric Studies ◽  
Deformation Patterns ◽  
Selection Of

Within the framework of classical elasticity, the nonbuckled deformations are calculated for orthotropic, right circular, thin-walled cylinders under uniform load conditions. The principle direction of orthotropy follows parallel constant angle helices. Nondimensional system parameters involving four material constants and three loading conditions (internal pressure, longitudinal load, and pure torque) are identified. Through parametric studies deformation patterns are calculated that are unique to orthotropy. Numerical examples illustrate that the proper selection of cylinder orthotropy can lead to designs with optimal deformations or load-carrying capacity. Results may be used for the design of robotic actuators driven by internal pressure.

Fractal Basin Boundaries and Chaotic Motions in Spring-Pendulum System

2003 ◽  
Author(s):  
Aria Alasty ◽  
Rasool Shabani
Keyword(s):  
Numerical Simulations ◽  
Multiple Scales ◽  
Basins Of Attraction ◽  
Chaotic Attractors ◽  
Global Behavior ◽  
Chaotic Motions ◽  
Pendulum System ◽  
Fractal Basin Boundaries ◽  
System Parameters ◽  
Basin Boundaries

This study investigates chaotic response in the spring-pendulum system. In this system beside of strange attractors, multiple regular attractors may coexist for some values of system parameters, where it is important to study the global behavior of the system using the basin boundaries of the attractors. Multiple scales method is used to distinguish the regions of stable and unstable attractors. In unstable regions, bifurcation diagram and poincare´ maps are used to study the existence of quasi-periodic and chaotic attractors. Results show that the jumping phenomena may occur when multiple regular attractors exist and for this case fractal basins of attraction are developed using numerical simulations.

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