Some Aspects of the Dynamical Behavior of the Impact Damper

2005 ◽  
Vol 11 (4) ◽  
pp. 459-479 ◽  
Author(s):  
F. Peterka ◽  
B. Blazejczyk-Okolewska
Keyword(s):  
Vibration Amplitude ◽  
Degrees Of Freedom ◽  
Dynamical Behavior ◽  
Coefficient Of Restitution ◽  
Harmonic Force ◽  
Impact Damper ◽  
Motion Trajectories ◽  
The Impact ◽  
Impact Motion ◽  
External Harmonic Force

In this paper we show some aspects of the dynamical behavior of a two-degrees-of-freedom system forced with an external harmonic force, which impacts cause a reduction of the vibration amplitude of the basic system. The purpose of the presented investigations is to determine the coefficient of restitution and the damping coefficient of the fender that ensure the required degree of a reduction in these vibrations. The regions of existence bifurcation diagrams and motion trajectories of different kinds of impact motion are presented and analyzed. The impact damper of vibrations is compared with a linear damper. The investigations have been conducted by means of numerical simulations.

scholarly journals The Effect of the Contact Model on the Design of Mechanical Systems

2012 ◽  
Author(s):  
M. R. Brake ◽  
D. S. Aragon ◽  
D. J. VanGoethem ◽  
H. Sumali
Keyword(s):  
Constant Coefficient ◽  
Degrees Of Freedom ◽  
Mechanical Systems ◽  
Constitutive Models ◽  
Coefficient Of Restitution ◽  
Rigid Body Dynamics ◽  
Contact Model ◽  
Elastic Plastic ◽  
Contact Models ◽  
The Impact

Impact is a wide-spread phenomenon in mechanical systems that can have a significant effect on the system’s dynamics, stability, wear, and damage. The simulation of impact in complex, mechanical systems, however, is often too computationally intensive for high fidelity finite element analyses to be useful as design tools. As a result, rigid body dynamics and reduced order model simulations are often used, with the impact events modeled by ad hoc methods such as a constant coefficient of restitution or a penalty stiffness. The consequences of the choice of contact model are studied in this paper for a representative multiple-degrees of freedom mechanical system. Four contact models are considered in the analysis: a constant coefficient of restitution model, two similar elastic-plastic constitutive models, and one dissimilar elastic-plastic constitutive model. The predictions of wear, mechanical failure, and stability are assessed for each of the contact models, and the subsequent effect on the system design is investigated. These results emphasize the importance of choosing a realistic contact model when simulations are being used to drive the design of a system.

Impact damper for axial vibration of a continuous system

2015 ◽  
Vol 230 (13) ◽  
pp. 2145-2157
Author(s):  
SB Sanap ◽  
SY Bhave ◽  
PJ Awasare
Keyword(s):  
Vibration Amplitude ◽  
Damping Ratio ◽  
Continuous System ◽  
Axial Vibration ◽  
Lumped Mass ◽  
Impact Damper ◽  
Forcing Function ◽  
Repetitive Impact ◽  
Sinusoidal Functions ◽  
The Impact

Application of Impact damper for reduction of vibration amplitude through momentum transfer is now well established. However, no literature is available for the effect of an impact damper on axial vibration of a rod as a continuous system. The equation for axial vibratory displacement of the rod, fixed at one end and a lumped mass at the other end, is derived by considering steady state vibrations having a period equal to that of the forcing function at the free end. Structural damping is assumed to be modal with a damping ratio of 0.005. Taking this periodicity into account, the repetitive impact force is resolved in the sinusoidal functions through Fourier series analysis. The forcing function thus will have components with the frequency of the external force and the multiple harmonic forces resulting from impacts. Since an infinite series is involved, the solution is obtained for a truncated series using MATLAB. It is observed that the damper is most effective when the Impact distribution parameter is equal to 0.5. The results of the numerical analysis are supported by experiments and are found to be in good agreement with the theoretical results. The reduction of vibration amplitude is observed to be dependent on the clearance (travel of impacting mass), mass ratio of the impacting mass to the main system, frequency of excitation, and the location of the stop in addition to the impact distribution.

scholarly journals An Approach for the Impact Dynamic Modeling and Simulation of Planar Constrained Metamorphic Mechanism

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Yanyan Song ◽  
Boyan Chang ◽  
Guoguang Jin ◽  
Zhan Wei ◽  
Bo Li
Keyword(s):  
Rigid Body ◽  
Modeling And Simulation ◽  
Dynamic Modeling ◽  
Dynamic Models ◽  
Dynamic Theory ◽  
Coefficient Of Restitution ◽  
Body System ◽  
Metamorphic Mechanism ◽  
The Impact ◽  
Impact Motion

This paper studied the impact dynamic modeling of the planar constrained metamorphic mechanism (PCMM) during configuration transformation. Based on the dynamic theory of the multi-rigid-body system and the coefficient of restitution equation, a new method for dynamic modeling of PCMM considering impact motions generated by configuration transformation is presented, which can be treated as a theoretical foundation for performance design and dynamic control. Firstly, the topology theory based on the impact motion can be classified as the stable impact motion and the mobile impact motion, which is the prerequisite for dynamic modeling and simulation. Secondly, the stable and mobile impact dynamic models for PCMM are established according to the dynamic theory of the multi-rigid-body system. Then, using these models, the corresponding impulse solving models are deduced combining with the coefficient of restitution equation. Finally, the examples of the stable impact motion and the mobile impact motion are respectively given, and the configuration-complete dynamic simulations are carried out. By comparing with the dynamic models without considering the impact motion, the dynamic characteristics of PCMM are analyzed. The theory and method proposed in this paper can be also applied in general planar robotic systems to deal with the problem of internal collision dynamics.

Interval of restitution coefficient for chattering in impact damper

2021 ◽  
pp. 146134842110518
Author(s):  
Zongqi Li ◽  
Yanchen Du
Keyword(s):  
Frequency Ratio ◽  
Control Parameter ◽  
Coefficient Of Restitution ◽  
Restitution Coefficient ◽  
Mass Ratio ◽  
Collision System ◽  
Impact Damper ◽  
Periodic Movement ◽  
Movement Characteristics ◽  
The Impact

Based on the impact damper, a dynamic model of a non-fixed constrained collision system was established. The coefficient of restitution is used as the main control parameter to analyze the system’s periodic movement and its bifurcation region. The chattering movement characteristics of the system were revealed. The interval of restitution coefficient for the chattering of collision system under various mass ratio and frequency ratio was obtained. The results show that the chattering phenomenon occurs in the collision system when the coefficient of restitution is greater than 0.5; as the mass ratio decreases, the interval of restitution coefficient for chattering continues to expand; as the frequency increases, the interval of restitution coefficient for chattering narrows.

Stability of a Semi-Active Impact Damper: Part I—Global Behavior

1989 ◽  
Vol 56 (4) ◽  
pp. 926-929 ◽  
Author(s):  
M. P. Karyeaclis ◽  
T. K. Caughey
Keyword(s):  
Periodic Solutions ◽  
Vibration Amplitude ◽  
Torsional Oscillator ◽  
Global Behavior ◽  
Impact Damper ◽  
General Behavior ◽  
Clutch Engagement ◽  
All Solutions ◽  
The Impact ◽  
Amplitude Level

A study is made of the general behavior of a semi-active impact damper. The system consists of an undamped forced torsional oscillator, and a flywheel which can be locked to the oscillator through a clutch. The impact which results during clutch engagement is effective in reducing the vibration amplitude level of the oscillator when it is subjected to bounded excitation. All solutions of the system are shown to be bounded when the input is bounded. Periodic solutions are discussed in the following paper, Part II.

scholarly journals Effects of the impact angle on the coefficient of restitution based on a medium-scale laboratory test

2018 ◽  
Author(s):  
Yanhai Wang ◽  
Wei Jiang ◽  
Shengguo Cheng ◽  
Pengcheng Song ◽  
Cong Mao
Keyword(s):  
Laboratory Test ◽  
Impact Angle ◽  
Coefficient Of Restitution ◽  
Small Scale ◽  
Medium Scale ◽  
Motion Trajectories ◽  
Small Impact ◽  
General Rules ◽  
Highly Correlated ◽  
The Impact

Abstract. The reliability of a computer program simulating rockfall trajectory depends on the ascertainment of reasonable values for the coefficients of restitution, which typically vary with the kinematic parameters and terrain conditions. The effects of the impact angle on the coefficients of restitution have been identified and studied using laboratory experiments. However, the laboratory tests performed to date have largely been limited to a small scale. This paper presents the results of a medium-scale laboratory test on the coefficients of restitution for spherical polyhedrons impacting concrete slabs. The specimens were made of natural limestone, and the motion trajectories were recorded by a 3D motion capture system. The normal coefficient of restitution Rn and the impact angle α are highly correlated. Comparisons between the results of existing tests and our experiments demonstrate that certain general rules regarding the effect of the impact angle hold regardless of the test scales and conditions. Increasing the impact angle will induce reductions in the values of Rn and the energy coefficient of restitution RE, whereas it will have a significant impact on the tangential coefficient of restitution Rt. A small impact angle will likely cause the rebound angle to exceed the impact angle, which typically causes a higher Rn and lower RE. This phenomenon leads to extreme scatter in the measured data under the conditions of a small impact angle and hinders the prediction of the rockfall trajectory.

scholarly journals DYNAMICS OF A TWO DEGREE OF FREEDOM VIBRO-IMPACT SYSTEM WITH MULTIPLE MOTION LIMITING CONSTRAINTS

2004 ◽  
Vol 14 (01) ◽  
pp. 119-140 ◽  
Author(s):  
D. J. WAGG ◽  
S. R. BISHOP
Keyword(s):  
Degrees Of Freedom ◽  
Dynamical Behavior ◽  
Mathematical Formulation ◽  
Constrained Systems ◽  
Degree Of Freedom ◽  
Dimensional Parameter ◽  
Impact Oscillators ◽  
Single Mass ◽  
The Impact ◽  
Two Degree Of Freedom

We consider the dynamics of impact oscillators with multiple degrees of freedom subject to more than one motion limiting constraint or stop. A mathematical formulation for modeling such systems is developed using a modal approach including a modal form of the coefficient of restitution rule. The possible impact configurations for an N degree of freedom system are considered, along with definitions of the impact map for multiply constrained systems. We consider sticking motions that occur when a single mass in the system becomes stuck to an impact stop, and discuss the computational issues related to computing such solutions. Then using the example of a two degree of freedom system with two constraints we describe exact modal solutions for the free flight and sticking motions which occur in this system. Numerical examples of sticking orbits for this system are shown and we discuss identifying the region, S in phase space where these orbits exist. We use bifurcation diagrams to indicate differing regimes of vibro-impacting motion for two different cases; firstly when the stops are both equal and on the same side (i.e. the same sign) and secondly when the stops are unequal and of opposing sign. For these two different constraint configurations we observe qualitatively different dynamical behavior, which is interpreted using impact mappings and two-dimensional parameter space.

scholarly journals Energy dissipation of a particle colliding on a flat surface

2021 ◽  
Vol 249 ◽  
pp. 06007
Author(s):  
Fabricio Éric Fernández ◽  
Marcelo Fabián Piva ◽  
Román Gustavo Martino ◽  
María Alejandra Aguirre
Keyword(s):  
Kinetic Energy ◽  
Degrees Of Freedom ◽  
Flat Surface ◽  
Coefficient Of Restitution ◽  
Normal Direction ◽  
Normal Velocity ◽  
Factors Affecting ◽  
Different Types ◽  
Before And After ◽  
The Impact

To gain an understanding of the factors affecting the interaction of one grain with its environment as it reaches equilibrium, we study a particle bouncing off a flat surface. The bouncing of the particle leads to dissipation that is usually characterized with t, the coefficient of restitution, defined as the ratio between the velocity component that is normal to the contact surface just before impact (Vn) and the same component, but immediately after the collision (Vn’), i.e. related to a kinetic energy corresponding to motion in the normal direction. We will show how d is affected by energy stored in other degrees of freedom and transferred to kinetic energy that leads to an increase in normal velocity after the impact Vn’, and therefore to, ɛ >1. For this purpose, the evolution of potential, translational kinetic energy and rotational kinetic energy is analysed during the whole relaxation process and just before and after each collision for two different types of particle, a disk and a faceted particle.

Mechanically-Tunable Quantum Interference in Ferrocene-Based Single-Molecule Junctions

2020 ◽  
Author(s):  
María Camarasa-Gómez ◽  
Daniel Hernangómez-Pérez ◽  
Michael S. Inkpen ◽  
Giacomo Lovat ◽  
E-Dean Fung ◽  
...  
Keyword(s):  
Single Molecule ◽  
Quantum Interference ◽  
Degrees Of Freedom ◽  
Building Blocks ◽  
Ferrocene Derivative ◽  
Single Molecule Junctions ◽  
Molecule Junction ◽  
Single Molecule Junction ◽  
The Impact ◽  
D Orbitals

Ferrocenes are ubiquitous organometallic building blocks that comprise a Fe atom sandwiched between two cyclopentadienyl (Cp) rings that rotate freely at room temperature. Of widespread interest in fundamental studies and real-world applications, they have also attracted<br>some interest as functional elements of molecular-scale devices. Here we investigate the impact of<br>the configurational degrees of freedom of a ferrocene derivative on its single-molecule junction<br>conductance. Measurements indicate that the conductance of the ferrocene derivative, which is<br>suppressed by two orders of magnitude as compared to a fully conjugated analog, can be modulated<br>by altering the junction configuration. Ab initio transport calculations show that the low conductance is a consequence of destructive quantum interference effects that arise from the hybridization of metal-based d-orbitals and the ligand-based π-system. By rotating the Cp rings, the hybridization, and thus the quantum interference, can be mechanically controlled, resulting in a conductance modulation that is seen experimentally.<br>

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