Vibration Analysis of a Brake Mechanism: Modeling, Simulation and Experimental Results

2005 ◽  
Author(s):  
Mihaela A. Dupac ◽  
P. K. Raju
Keyword(s):  
Vibration Analysis ◽  
Relative Velocity ◽  
System Behavior ◽  
Linear Dynamics ◽  
System Parameters ◽  
Modeling Simulation ◽  
Dynamic Friction Coefficient ◽  
Mechanism Modeling ◽  
Dynamics Method ◽  
Good Agreement

In this paper, an approach for identifying a model capable of representing the dynamics of the brake mechanism is presented. Experimentally acquired in-plane vibrations of the pad were analyzed using the non-linear dynamics method of Lyapunov exponents in order to characterize the system behavior. Friction-induced vibrations were then studied via the associated 4 DOF theoretical model of the brake system. Numerical simulations demonstrated that for a set of system parameters, a certain value of the slope of the mathematical characteristic between the dynamic friction coefficient and relative velocity, triggers the exponential growth of instability with an envelope in good agreement with that approximated from the experimental data. The results obtained from this study provide new insights into brake dynamics and the associated instability mechanisms.

VIBRATION ANALYSIS OF A GRAPHENE NANORIBBON UNDER HARMONIC LORENTZ FORCE USING A HYBRID MODAL-MOLECULAR DYNAMICS METHOD

2014 ◽  
Vol 14 (02) ◽  
pp. 1350057 ◽  
Author(s):  
R. D. FIROUZ-ABADI ◽  
H. MOHAMMADKHANI ◽  
H. AMINI
Keyword(s):  
Molecular Dynamics ◽  
Vibration Analysis ◽  
Large Scale ◽  
Nonlinear Vibrations ◽  
Graphene Nanoribbon ◽  
Molecular Dynamics Method ◽  
Dynamic Simulations ◽  
Resonance Frequencies ◽  
Dynamics Method ◽  
Good Agreement

An efficient hybrid modal-molecular dynamics method is developed for the vibration analysis of large scale nanostructures. Using the reduced order method, presented in this paper, linear and nonlinear vibrations of a suspended graphene nanoribbon (GNR) carrying an electric current in a harmonic magnetic field are investigated. The resonance frequencies as well as the nonlinear vibration response obtained by the present technique and direct molecular dynamic simulations are in very good agreement. Also, the obtained results illustrate the hardening behavior of nonlinear vibrations which is diminished by stretching the GNR.

Stick-Slip Vibration Between Two Large Concentric Circular Discs in Rotational Contact With Multiple Point Loads

2003 ◽  
Vol 125 (4) ◽  
pp. 786-792
Author(s):  
M. Baleri ◽  
F. Sassani ◽  
P. L. Ko
Keyword(s):  
Robotic Manipulators ◽  
Integral Model ◽  
Mathematical Representation ◽  
Multiple Point ◽  
Rotating Platform ◽  
Stick Slip ◽  
System Parameters ◽  
Modeling Simulation ◽  
Contact Loads ◽  
Good Agreement

This paper presents a study of the stick-slip frictional phenomenon when large contact areas subjected to uneven contact loads, such as the rotating platform of excavators and large robotic manipulators, are involved. The objective of the investigation is to a gain better understanding of the phenomenon from experimental observations and to develop a mathematical representation that can be used for modeling, simulation and design purposes. A dynamic integral-model has been proposed and simulations have been carried out. The effects of various system parameters on the behavior of the system have been studied experimentally and analytically. The simulation results using the proposed integral-model are in good agreement with the experimental results. The latter also show that stick-slip vibrations can be influenced by the loading conditions.

Stick-Slip Vibration Between Two Large Concentric Circular Discs in Rotational Contact With Multiple Point Loads

2003 ◽  
Author(s):  
M. Baleri ◽  
F. Sassani ◽  
P. L. Ko
Keyword(s):  
Experimental Results ◽  
Integral Model ◽  
Mathematical Representation ◽  
Multiple Point ◽  
Stick Slip ◽  
System Parameters ◽  
Modeling Simulation ◽  
Contact Loads ◽  
Simulation Results ◽  
Good Agreement

This paper presents a study of the stick-slip frictional phenomenon when large contact areas subjected to uneven contact loads are involved. The objective of the investigation is to gain better understanding of the phenomenon from experimental observations and to develop a mathematical representation that can be used for modeling, simulation and design purposes. A dynamic integral-model has been proposed and simulations have been carried out. The effects of various system parameters on the behavior of the system have been studied experimentally and analytically. The simulation results using the proposed integral-model are in good agreement with the experimental results. The latter also show that stick-slip vibrations can be influenced by the loading conditions.

scholarly journals The frequency of Kozai–Lidov disc oscillation driven giant outbursts in Be/X-ray binaries

2019 ◽  
Vol 489 (2) ◽  
pp. 1797-1804 ◽  
Author(s):  
Rebecca G Martin ◽  
Alessia Franchini
Keyword(s):  
Orbital Period ◽  
Time Scale ◽  
Orbital Plane ◽  
Material Flows ◽  
X Ray ◽  
System Parameters ◽  
Be Star ◽  
Chaotic Nature ◽  
X Ray Binaries ◽  
Good Agreement

ABSTRACT Giant outbursts of Be/X-ray binaries may occur when a Be-star disc undergoes strong eccentricity growth due to the Kozai–Lidov (KL) mechanism. The KL effect acts on a disc that is highly inclined to the binary orbital plane provided that the disc aspect ratio is sufficiently small. The eccentric disc overflows its Roche lobe and material flows from the Be star disc over to the companion neutron star causing X-ray activity. With N-body simulations and steady state decretion disc models we explore system parameters for which a disc in the Be/X-ray binary 4U 0115+634 is KL unstable and the resulting time-scale for the oscillations. We find good agreement between predictions of the model and the observed giant outburst time-scale provided that the disc is not completely destroyed by the outburst. This allows the outer disc to be replenished between outbursts and a sufficiently short KL oscillation time-scale. An initially eccentric disc has a shorter KL oscillation time-scale compared to an initially circular orbit disc. We suggest that the chaotic nature of the outbursts is caused by the sensitivity of the mechanism to the distribution of material within the disc. The outbursts continue provided that the Be star supplies material that is sufficiently misaligned to the binary orbital plane. We generalize our results to Be/X-ray binaries with varying orbital period and find that if the Be star disc is flared, it is more likely to be unstable to KL oscillations in a smaller orbital period binary, in agreement with observations.

OPTIMAL VELOCITY MODEL WITH RELATIVE VELOCITY

2006 ◽  
Vol 17 (01) ◽  
pp. 65-73 ◽  
Author(s):  
SHIRO SAWADA
Keyword(s):  
Nonlinear Analysis ◽  
Relative Velocity ◽  
Velocity Model ◽  
Fundamental Diagram ◽  
Optimal Velocity ◽  
Traffic Jam ◽  
Optimal Velocity Model ◽  
Linear And Nonlinear ◽  
The Stability ◽  
Good Agreement

The optimal velocity model which depends not only on the headway but also on the relative velocity is analyzed in detail. We investigate the effect of considering the relative velocity based on the linear and nonlinear analysis of the model. The linear stability analysis shows that the improvement in the stability of the traffic flow is obtained by taking into account the relative velocity. From the nonlinear analysis, the relative velocity dependence of the propagating kink solution for traffic jam is obtained. The relation between the headway and the velocity and the fundamental diagram are examined by numerical simulation. We find that the results by the linear and nonlinear analysis of the model are in good agreement with the numerical results.

Hydrogen Storage in MgH2 Matrices: An Ab-Initio Study of Mg-MgH2 Interface

2008 ◽  
Vol 139 ◽  
pp. 23-28 ◽  
Author(s):  
Simone Giusepponi ◽  
Massimo Celino ◽  
Fabrizio Cleri ◽  
Amelia Montone
Keyword(s):  
Molecular Dynamics ◽  
Total Energy ◽  
Ab Initio ◽  
Atomic Hydrogen ◽  
Level Structure ◽  
Atomic Level ◽  
Work Of Adhesion ◽  
Ab Initio Study ◽  
Dynamics Method ◽  
Good Agreement

We studied the atomic-level structure of a model Mg-MgH2 interface by means of the Car-Parrinello molecular dynamics method (CPMD). The interface was characterized in terms of total energy calculations, and an estimate of the work of adhesion was given, in good agreement with experimental results on similar systems. Furthermore, the interface was studied in a range of temperatures of interest for the desorption of hydrogen. We determined the diffusivity of atomic hydrogen as a function of the temperature, and give an estimate of the desorption temperature.

Sequences of Global Bifurcations and the Related Outcomes after Crisis of the Resonant Attractor in a Nonlinear Oscillator

1997 ◽  
Vol 07 (11) ◽  
pp. 2437-2457 ◽  
Author(s):  
W. Szemplińska-Stupnicka ◽  
E. Tyrkiel
Keyword(s):  
Nonlinear Oscillator ◽  
Duffing Oscillator ◽  
Nonlinear Resonance ◽  
Basins Of Attraction ◽  
Global Bifurcations ◽  
System Behavior ◽  
Coexisting Attractors ◽  
System Parameters

The problem of the system behavior after annihilation of the resonant attractor in the region of the nonlinear resonance hysteresis is considered. The sequences of global bifurcations, in connection with the associated metamorphoses of basins of attraction of coexisting attractors, are examined. The study allows one to reveal the mechanism that governs the phenomenon of the post crisis ensuing transient trajectory to settle onto one or another remote attractor. The problem is studied in detail for the twin-well potential Duffing oscillator. The boundary which splits the considered region of system parameters into two subdomains, where the outcome is unique or the two outcomes are possible, is defined.

scholarly journals CAD/CAM System for Additive Manufacturing with a Robust and Efficient Topology Optimization Algorithm Based on the Function Representation

2021 ◽  
Vol 11 (16) ◽  
pp. 7409
Author(s):  
Dmitry Popov ◽  
Yulia Kuzminova ◽  
Evgenii Maltsev ◽  
Stanislav Evlashin ◽  
Alexander Safonov ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Additive Manufacturing ◽  
3D Modeling ◽  
Mechanical Tests ◽  
Simulation Data ◽  
Function Representation ◽  
Modeling Simulation ◽  
Cad Cam ◽  
Design Ideas ◽  
Good Agreement

Additive manufacturing erases the distance between design ideas and finished parts. However, designers must use several software tools to use these advantages. Moreover, these tools operate with different representations of geometry. This paper describes the architecture of a new CAD/CAM system that uses only the function representation of the geometry (FRep). It provides all widely used design operations and allows an engineer to employ robust and efficient topology optimization algorithms. The developed CAD/CAM system consists of 3D modeling, simulation, topology optimization, and direct manufacturing modules. We successfully printed designed parts and performed mechanical tests of printed parts. The results of tests show good agreement with simulation data. The system makes it possible to create structures with the desired properties in a fast and flexible way. The proposed approach significantly helps in designing additive manufacturing process and saves time for its users.

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