SOME POSSIBILITIES OF DYNAMICAL VIBRATION DAMPING IN SYSTEMS WITH SEVERAL DEGREES OF FREEDOM

A method of dynamic vibration damping in mechanical oscillatory systems with several degrees of freedom is offered. The mathematical model of the system is represented in the form of structural scheme the equivalent in a dynamic relation to the automatic control system. The system contains device for con-verting the motion in the form of lever mechanisms containing focused additional masses. The possibilities of changing the dynamic properties of the system by using lever mechanisms and the additional ties in the form of gear connections of the elements system are shown. A method of constructing mathematical models and technology analysis of dynamic properties at kinematic excitation of system is proposed. The system of evaluation of the dynamic properties of the system in regimes of dynamic vibration damping simultaneously on two coordinates based on the use of transfer functions and analysis of structural scheme is offered. The results of computational modeling are given, confirming the manifestation the effects of dynamic blocking of external influences.

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DYNAMIC PROPERTIES OF THE ELECTROMECHANICAL SYSTEM DAMPED BY AN IMPACT ELEMENT WITH SOFT STOPS

International Journal of Applied Mechanics ◽

10.1142/s1758825114500161 ◽

2014 ◽

Vol 06 (02) ◽

pp. 1450016 ◽

Cited By ~ 6

Author(s):

MAREK LAMPART ◽

JAROSLAV ZAPOMĚL

Keyword(s):

Degrees Of Freedom ◽

Dynamic Properties ◽

Electric Circuit ◽

Response Characteristic ◽

Electromechanical System ◽

Frequency Response Characteristic ◽

Impact Element ◽

The Impact ◽

The Mathematical Model ◽

Three Degrees Of Freedom

The main aim of this paper is to focus on analysis of the dynamic properties of the electromechanical system with an impact element. This model is constructed with three degrees of freedom in the mechanical oscillating part, two translational and one rotational, and is completed with an electric circuit. The mathematical model of the system is represented by three mutually coupled second-order ordinary differential equations. Here, the most important nonlinearities are: stiffness of the support spring elements and internal impacts. Several important results were obtained by means of computational simulations. The impacts considerably increase the number of resonance peaks of the frequency response characteristic. Character of the system motion strongly depends on the width of clearances between the impact body and the rotor frame and changes from simple periodic to close to chaotic or to periodic with a large number of ultraharmonic components. For a suitably chosen system parameters, a significant damping effect of the impact element was observed.

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Modal Control for Active Vibration Damping of Cable-Driven Parallel Robots

Journal of Mechanisms and Robotics ◽

10.1115/1.4046434 ◽

2020 ◽

Vol 12 (5) ◽

Cited By ~ 1

Author(s):

Loïc Cuvillon ◽

Xavier Weber ◽

Jacques Gangloff

Keyword(s):

Degrees Of Freedom ◽

Transfer Functions ◽

Parallel Robot ◽

Vibration Damping ◽

Parallel Robots ◽

Robot Dynamics ◽

End Effector ◽

Active Vibration Damping ◽

Active Vibration ◽

High Dynamics

Abstract Cable-driven parallel robots are well suited for applications that require a very large workspace. Thanks to their lightweight moving parts, they can achieve high dynamics while remaining pretty safe for nearby human workers. Furthermore, their size depends only on the length of the cables; thus, their scale is almost totally decoupled from their cost. However, due to the cables, the stiffness is very low with respect to rigid link robots, inducing slowly damped oscillations of the end effector. Previous works have shown that those vibrations can be effectively damped by the winch actuators thanks to active vibration damping techniques. In this paper, a gain scheduling approach is proposed based on a linearized model of the robot dynamics. This model is projected in the modal space yielding six decoupled transfer functions for six degrees-of-freedom (DoFs) of a cable-driven parallel robot using thin cables. The stability of the proposed control law is analyzed for a static and a moving end effector. The proposed control algorithm is validated experimentally on an eight-cable suspended robot prototype.

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DIRECTIONS OF IMPROVING THE EFFICIENCY OF VIBRATION TECHNOLOGICAL MACHINES

Vibrations in engineering and technology ◽

10.37128/2306-8744-2020-4-6 ◽

2020 ◽

pp. 49-58

Author(s):

Oleg Omelyanov ◽

Mykhailo Zamriі

Keyword(s):

Mathematical Modeling ◽

Degrees Of Freedom ◽

Dynamic Properties ◽

New Technology ◽

Oscillatory System ◽

Simultaneous Action ◽

Oscillatory Systems ◽

Technical Developments ◽

Vibration Field ◽

Working Bodies

The article considers the directions of increasing the efficiency of vibrating technological machines. The processing of information on the development of vibration technologies is quite diverse and is represented by numerous scientific and technical developments related to improving the efficiency of vibration machines and ensuring the reliability of their work. The analytical basis for previous research in the creation of new technology are mathematical models that reflect the properties of mechanical oscillatory systems with several degrees of freedom, which perform small oscillations under the action of a system of periodic external perturbations that create vibration fields of one configuration. The dynamic properties of the working bodies of machines in a detailed form are revealed as the distribution of the amplitudes of oscillations of the points of the working bodies. In many cases, this distribution is linear, which is due to the manifestations of the properties of the simplest movements of the working bodies. Approaches are proposed in which the possible structural mathematical modeling is realized on the idea that a linear mechanical oscillatory system with concentrated parameters and several degrees of freedom can be compared with the structural scheme of the automatic control system. Particular attention is paid to the study and evaluation of the possibility of new dynamic effects associated with the simultaneous action of several working bodies of machines, as well as - modes of dynamic damping of oscillations. An important role in ensuring such developments is played by areas of research focused on the development of methods of mathematical modeling. Based on the research it is shown that the vibration field of the vibrating technological machine is formed under the influence of several factors, which are determined by the simultaneous action of several force perturbations, asymmetry of inertial and elastic properties of the mechanical system, the presence of additional connections. The introduction of additional links in the structure of the mechanical oscillating system of the vibrating machine, can significantly affect the structure of the vibration field, providing the choice of conditions for rational organization of the technological process of vibration processing, such as vibration hardening, crushing, transportation, screening.

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Electro Magneto Elastic Actuator for Nanoscience

Advances in Nanoscience and Nanotechnology ◽

10.33140/ann.03.01.05 ◽

2019 ◽

Vol 3 (1) ◽

Keyword(s):

Mathematical Model ◽

Transfer Function ◽

External Load ◽

Transfer Functions ◽

Physical Parameters ◽

Structural Scheme ◽

Matrix Transfer Function ◽

The Matrix ◽

The Mathematical Model

The mathematical model, the structural scheme, the matrix transfer function, the characteristics of the electro magneto elastic actuator is obtained. The transfer functions of the magneto elastic actuator are described the characteristics of the actuator with regard to its physical parameters and external load.

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Structural-parametric model of an electroelastic actuator for nanomechanics

10.36652/0042-4633-2020-8-3-11 ◽

2020 ◽

pp. 3-11

Author(s):

S.M. Afonin

Keyword(s):

Transfer Function ◽

Piezoelectric Actuator ◽

Transfer Functions ◽

Piezoelectric Effect ◽

Parametric Model ◽

Elastic Compliance ◽

Parametric Models ◽

Piezo Actuator ◽

Structural Scheme ◽

Model Transfer

Structural-parametric models, structural schemes are constructed and the transfer functions of electro-elastic actuators for nanomechanics are determined. The transfer functions of the piezoelectric actuator with the generalized piezoelectric effect are obtained. The changes in the elastic compliance and rigidity of the piezoactuator are determined taking into account the type of control. Keywords electro-elastic actuator, piezo actuator, structural-parametric model, transfer function, parametric structural scheme

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Design, Fabrication, and Testing of a Novel 3D 3-Fingered Electrothermal Microgripper with Multiple Degrees of Freedom

Micromachines ◽

10.3390/mi12040444 ◽

2021 ◽

Vol 12 (4) ◽

pp. 444

Author(s):

Guoning Si ◽

Liangying Sun ◽

Zhuo Zhang ◽

Xuping Zhang

Keyword(s):

Degrees Of Freedom ◽

Dynamic Properties ◽

Three Dimensional ◽

Polyimide Film ◽

Zebrafish Embryos ◽

Multiple Degrees Of Freedom ◽

Electrothermal Actuator ◽

3D Space ◽

Pick And Place

This paper presents the design, fabrication, and testing of a novel three-dimensional (3D) three-fingered electrothermal microgripper with multiple degrees of freedom (multi DOFs). Each finger of the microgripper is composed of a V-shaped electrothermal actuator providing one DOF, and a 3D U-shaped electrothermal actuator offering two DOFs in the plane perpendicular to the movement of the V-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with the polyimide film. The durability of the polyimide film is tested under different voltages. The static and dynamic properties of the finger are also tested. Experiments show that not only can the microgripper pick and place microobjects, such as micro balls and even highly deformable zebrafish embryos, but can also rotate them in 3D space.

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A New Approach of Soft Joint Based on a Cable-Driven Parallel Mechanism for Robotic Applications

Mathematics ◽

10.3390/math9131468 ◽

2021 ◽

Vol 9 (13) ◽

pp. 1468

Author(s):

Luis Nagua ◽

Carlos Relaño ◽

Concepción A. Monje ◽

Carlos Balaguer

Keyword(s):

Parallel Mechanism ◽

Degrees Of Freedom ◽

Kinematic Model ◽

Experimental Tests ◽

Humanoid Robots ◽

Inverse Kinematic ◽

Element Analysis ◽

New Approach ◽

Flexible Polymer ◽

The Mathematical Model

A soft joint has been designed and modeled to perform as a robotic joint with 2 Degrees of Freedom (DOF) (inclination and orientation). The joint actuation is based on a Cable-Driven Parallel Mechanism (CDPM). To study its performance in more detail, a test platform has been developed using components that can be manufactured in a 3D printer using a flexible polymer. The mathematical model of the kinematics of the soft joint is developed, which includes a blocking mechanism and the morphology workspace. The model is validated using Finite Element Analysis (FEA) (CAD software). Experimental tests are performed to validate the inverse kinematic model and to show the potential use of the prototype in robotic platforms such as manipulators and humanoid robots.

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Designing of Drive Systems in the Aspect of the Desired Spectrum of Operation

Energies ◽

10.3390/en14092562 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2562

Author(s):

Tomasz Dzitkowski ◽

Andrzej Dymarek ◽

Jerzy Margielewicz ◽

Damian Gąska ◽

Lukasz Orzech ◽

...

Keyword(s):

Degrees Of Freedom ◽

Dynamic Properties ◽

Dynamic Parameters ◽

Synthesis Algorithm ◽

Moments Of Inertia ◽

Driving System ◽

Six Degrees Of Freedom ◽

Resonance Frequencies ◽

Drive Systems ◽

Power Component

A method for selecting dynamic parameters and structures of drive systems using the synthesis algorithm is presented. The dynamic parameters of the system with six degrees of freedom, consisting of a power component (motor) and a two-speed gearbox, were determined, based on a formalized methodology. The required gearbox is to work in specific resonance zones, i.e., meet the required dynamic properties such as the required resonance frequencies. In the result of the tests, a series of parameters of the drive system, defining the required dynamic properties such as the resonance and anti-resonance frequencies were recorded. Mass moments of inertia of the wheels and elastic components, contained in the required structure of the driving system, were determined for the selected parameters obtained during the synthesis.

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Nonlinear Behavior of a Magnetic Bearing System

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2814135 ◽

1995 ◽

Vol 117 (3) ◽

pp. 582-588 ◽

Cited By ~ 29

Author(s):

L. N. Virgin ◽

T. F. Walsh ◽

J. D. Knight

Keyword(s):

Degrees Of Freedom ◽

Initial Conditions ◽

Nonlinear Behavior ◽

Analytical Techniques ◽

Magnetic Bearing ◽

Forced Response ◽

The Mathematical Model ◽

Two Degree Of Freedom ◽

Sensitivity To Initial Conditions ◽

Bearing System

This paper describes the results of a study into the dynamic behavior of a magnetic bearing system. The research focuses attention on the influence of nonlinearities on the forced response of a two-degree-of-freedom rotating mass suspended by magnetic bearings and subject to rotating unbalance and feedback control. Geometric coupling between the degrees of freedom leads to a pair of nonlinear ordinary differential equations, which are then solved using both numerical simulation and approximate analytical techniques. The system exhibits a variety of interesting and somewhat unexpected phenomena including various amplitude driven bifurcational events, sensitivity to initial conditions, and the complete loss of stability associated with the escape from the potential well in which the system can be thought to be oscillating. An approximate criterion to avoid this last possibility is developed based on concepts of limiting the response of the system. The present paper may be considered as an extension to an earlier study by the same authors, which described the practical context of the work, free vibration, control aspects, and derivation of the mathematical model.

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Carbon Nanotube Composites for Vibration Damping

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.47-50.817 ◽

2008 ◽

Vol 47-50 ◽

pp. 817-820 ◽

Cited By ~ 3

Author(s):

R.L. Dai ◽

W.H. Liao

Keyword(s):

Carbon Nanotube ◽

Epoxy Resin ◽

Dynamic Properties ◽

Element Model ◽

Vibration Damping ◽

Segment Length ◽

Pure Epoxy ◽

Nanotube Composites ◽

Carbon Nanotube Composites ◽

Set Up

It has been found that the composites of carbon nanotubes (CNTs) and epoxy resin could greatly enhance damping ability while the stiffness is kept high. In this paper, carbon nanotube enhanced epoxy resin is fabricated. A testing apparatus for obtaining composite dynamic properties is set up. In particular, the loss factors are measured. Experimental results show that CNT additive can provide the composite with several times higher damping as compared with pure epoxy. A finite element model is built to simulate the composite damping. CNT diameter and segment length are investigated using the developed model. Results show that composite damping is insensitive to CNT segment length while the effect of CNT diameter on composite damping is significant.

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