scholarly journals Oscillations Control of Rocking-Block-Type Buildings by the Addition of a Tuned Pendulum

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Luca Collini ◽  
Rinaldo Garziera ◽  
Kseniia Riabova ◽  
Mariya Munitsyna ◽  
Alessandro Tasora
Keyword(s):  
Numerical Simulations ◽  
Approximation Method ◽  
Dry Friction ◽  
Mechanical Model ◽  
Horizontal Plane ◽  
Galerkin Approximation ◽  
Block Type ◽  
Theoretical Part ◽  
Lagrange Formulation ◽  
Rocking Block

This study deals with the dynamical evolutions exhibited by a simple mechanical model of building, comprising a parallelepiped standing on a horizontal plane. The main goal is the introduction of a pendulum in order to reduce oscillations. The theoretical part of the work consists of a Lagrange formulation and Galerkin approximation method, and dry friction has also been considered. From the analytical/numerical simulations, we derive some important conclusions, providing us with the tools suitable for the design of absorbers in practical cases.

The Stick Motion of a Harmonically Excited, Friction-Induced Oscillator on a Sinusoidally Traveling Surface

2006 ◽  
Author(s):  
Albert C. J. Luo ◽  
Brandon C. Gegg ◽  
Steve S. Suh
Keyword(s):  
Dynamical Systems ◽  
Numerical Simulations ◽  
Dry Friction ◽  
The Other ◽  
Linear Oscillator ◽  
Analytical Prediction ◽  
Nonlinear Friction ◽  
Friction Forces

In this paper, the methodology is presented through investigation of a periodically, forced linear oscillator with dry friction, resting on a traveling surface varying with time. The switching conditions for stick motions in non-smooth dynamical systems are obtained. From defined generic mappings, the corresponding criteria for the stick motions are presented through the force product conditions. The analytical prediction of the onset and vanishing of the stick motions is illustrated. Finally, numerical simulations of stick motions are carried out to verify the analytical prediction. The achieved force criteria can be applied to the other dynamical systems with nonlinear friction forces possessing a CO - discontinuity.

Analysis of Motion of the Impact-Dry-Friction Pair of Bodies and its Application to the Investigation of the Impact Dampers Dynamics

1999 ◽  
Author(s):  
František Peterka
Keyword(s):  
Analytical Solution ◽  
Numerical Simulations ◽  
Mechanical System ◽  
Relative Motion ◽  
Dry Friction ◽  
Friction Pair ◽  
Strong Nonlinearity ◽  
Friction Forces ◽  
The Impact ◽  
Analysis Of Motion

Abstract The motion with impacts and dry friction forces appears in some mechanical systems as mechanisms with clearances, (e.g., in gearings, pins, slots, guides, valve gears etc.), impact dampers, relays, forming and mailing machines, power pics etc. Such mechanisms include one or more pairs of impacting bodies, which introduce the strong nonlinearity into the system motion. The motion of the general pair of bodies with the both-sides impacts and dry friction forces is assumed (Fig.1). It can be the part of a more complex chain of masses in the mechanical system. Dead zones in the relative motion of bodies can be caused by assumed nonlinearities. The mathematical conditions controlling the numerical simulations or analytical solution of the motion are introduced. The application of this method is explained by the study of the influence of dry friction force on amplitude-frequency characteristics of four types of dynamical and impact dampers with optimised parameters.

scholarly journals Convective cooling of tandem heated triangular cylinders placed in a channel

2010 ◽  
Vol 14 (1) ◽  
pp. 183-197 ◽  
Author(s):  
Afshin Mohsenzadeh ◽  
Mousa Farhadi ◽  
Kurosh Sedighi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Numerical Simulations ◽  
Incompressible Flow ◽  
Horizontal Plane ◽  
Plane Channel ◽  
Reynolds Numbers ◽  
Convective Cooling ◽  
Wall Proximity ◽  
Fluid Characteristics

Numerical simulations of forced convective incompressible flow in a horizontal plane channel with adiabatic walls over two isothermal tandem triangular cylinders of equal size are presented to investigate the effect of wall proximity of obstacles, gap space (i.e. gap between two squares), and Reynolds number. Computations have been carried out for Reynolds numbers of (based on triangle width) 100, 250, and 350. Results show that, wall proximity has different effect on first and second triangle in fluid characteristics especially in lower gap spaced, while for heat transfer a fairly same behavior was seen.

On Motion of Chaplygin Sleigh on a Horizontal Plane with Dry Friction

2019 ◽  
Vol 54 (5) ◽  
pp. 632-637
Author(s):  
A. V. Karapetyan ◽  
A. Yu. Shamin
Keyword(s):  
Dry Friction ◽  
Horizontal Plane ◽  
Chaplygin Sleigh

Hysteretic effects of dry friction: modelling and experimental studies

2007 ◽  
Vol 366 (1866) ◽  
pp. 747-765 ◽  
Author(s):  
Jerzy Wojewoda ◽  
Andrzej Stefański ◽  
Marian Wiercigroch ◽  
Tomasz Kapitaniak
Keyword(s):  
Numerical Simulations ◽  
Dry Friction ◽  
Experimental Studies ◽  
Friction Model ◽  
Hysteretic Effect ◽  
Motion Characteristic ◽  
Friction Models ◽  
Theoretical Analyses ◽  
Friction Modelling

In this paper, the phenomena of hysteretic behaviour of friction force observed during experiments are discussed. On the basis of experimental and theoretical analyses, we argue that such behaviour can be considered as a representation of the system dynamics. According to this approach, a classification of friction models, with respect to their sensitivity on the system motion characteristic, is introduced. General friction modelling of the phenomena accompanying dry friction and a simple yet effective approach to capture the hysteretic effect are proposed. Finally, the experimental results are compared with the numerical simulations for the proposed friction model.

A General Model for Two-Point Contact Dry-Friction Whip and Whirl

2012 ◽  
Author(s):  
Jason C. Wilkes
Keyword(s):  
Numerical Simulations ◽  
Analytical Model ◽  
General Model ◽  
Dry Friction ◽  
Point Contact ◽  
Current Work ◽  
Equipment Failure ◽  
Air Bearings ◽  
Single Location ◽  
Arbitrary Phase

Numerous papers have investigated the behavior of dry-friction whip and whirl; most of them consider contact between a rotor and stator at a single location. For rotors running on multiple magnetic bearings, air bearings, or bushings, equipment failure may result in rub at more than one location. For these cases, it is important to have an analytical model that characterizes possible regions of two-point contact dry-friction whip and whirl. Until a recent publication by Childs and Kumar in 2011, there were no attempts to analytically describe the behavior of dry-friction whip and whirl at more than one location. In their work, they assume that forces at the two rotor/stator contacts are either in-phase, or out-of phase. The current work presents a method that is more general, allowing for an arbitrary phase between contact locations. In theory this method can be applied to more than two contact locations; however, a two-point contact example case is developed and compared to numerical simulations in the current work.

scholarly journals Study of the Planar Rocking-Block Dynamics With Coulomb Friction: Critical Kinetic Angles

2012 ◽  
Vol 8 (2) ◽  
Author(s):  
Hongjian Zhang ◽  
Bernard Brogliato ◽  
Caishan Liu
Keyword(s):  
Numerical Simulations ◽  
Coulomb Friction ◽  
Numerical Scheme ◽  
Numerical Results ◽  
Experimental Results ◽  
Restitution Coefficient ◽  
Rocking Block ◽  
Kinetic Angle ◽  
Multiple Impact ◽  
Impact With Friction

The objective of this paper is to show, through the planar rocking block example, that kinetic angles play a fundamental role in multiple impact with friction. Even in the presence of Coulomb friction, a critical kinetic angle θcr is exhibited that allows one to split the blocks into two main classes: slender blocks with a kinetic angle larger than θcr, and flat blocks with a kinetic angle smaller than θcr. The value of θcr varies with the friction value, but it is independent of the restitution coefficient (normal dissipation). Numerical results are obtained using a multiple impact law recently introduced by the authors. Some comparisons between numerical and experimental results that validate the used model and numerical scheme are presented. However, this paper is mainly based on numerical simulations.

scholarly journals Self-Excited Lateral Vibrations of Rolling Tires

2015 ◽  
Author(s):  
Dénes Takács ◽  
Gábor Stépan
Keyword(s):  
Numerical Simulations ◽  
Mechanical Model ◽  
Critical Parameter ◽  
Lateral Deformation ◽  
Contact Patch ◽  
Lateral Vibrations ◽  
Low Degree ◽  
Minimum Number ◽  
Lateral Mode ◽  
Parameter Ranges

In this study, a low degree-of-freedom mechanical model of a rolling tire is constructed, in which the lateral deformation of the contact patch and tire carcass is considered. The so-called delayed contact patch model is implemented and combined with a simple tire carcass model. The interaction between the contact patch and the carcass together with the lateral mode of the attached suspension system is modeled by means of minimum number of relevant parameters in a simplified way in order to construct analytical results. Critical parameter ranges of self-excited vibrations are determined against the longitudinal speed of the tire. The intricate shapes of the corresponding tire deformations are presented by means of numerical simulations.

scholarly journals Specification of estimation of a passenger car ride smoothness under various exploitation conditions

2021 ◽  
Vol 23 (4) ◽  
pp. 719-725
Author(s):  
Gediminas Vaičiūnas ◽  
Stasys Steišūnas ◽  
Gintautas Bureika
Keyword(s):  
Field Experiment ◽  
Numerical Simulations ◽  
Horizontal Plane ◽  
Operating Conditions ◽  
Rolling Stock ◽  
Lateral Direction ◽  
Passenger Car ◽  
Comfort Index ◽  
Index Variation ◽  
The Stability

The stability and smoothness of rolling stock running could be defined accurately by universal Sperling's comfort index. The divergences of variation of Sperling's comfort index of a passenger car under specific operating conditions of running gear are examining in this paper. Numerical simulations of a passenger car running with independently rotating wheels under various conditions have been performing. Gained results showed that divergences of the Sperling's comfort index variation are particularly significant due to running gear component oscillations in the horizontal plane (lateral direction). A field experiment of a passenger car with a solid (traditional) wheelset with a flat running surface proved this hypothesis. The obtained results of this experiment confirmed this assumption. Therefore, the study of the regularities of lateral oscillations of a passenger car is the logical direction of further research.

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