A Novel Impact Damper Consisting of a Linear Chain of Particles

2012 ◽  
Author(s):  
Mohamed Gharib ◽  
Saud Ghani
Keyword(s):  
Kinetic Energy ◽  
Passive Control ◽  
Linear Chain ◽  
Control Device ◽  
Contact Forces ◽  
Primary System ◽  
Small Ball ◽  
Impact Damper ◽  
Particle Chain ◽  
The Impact

Passive control is preferred due to its simplicity and low power consumption. A common passive control device is the Impact Damper which consists of a freely moving mass constrained by two stops inside a container mounted on the primary system. Researchers attempted to develop the impact damper for many decades. Their objective was to decrease the high accelerations, contact forces and noise levels. In this paper, a novel type impact damper consisting of linear chain of different sizes spherical balls is introduced. The Linear Particle Chain (LPC) impact damper is based on dissipating the kinetic energy of the primary system by placing a small ball between each two large balls in the chain arrangement. The small ball will have numerous collisions with the larger balls when the primary system is excited. This behavior leads to dissipate part of the kinetic energy at each collision with the large balls. The LPC impact damper is validated by comparing its responses with the single unit conventional impact damper. The free vibration of a single degree of freedom system equipped with the damper is studied. It has been shown that the LPC impact damper is more efficient than the conventional impact damper. A parametric study is conducted to investigate the effective number of balls and the efficient geometry of the impact damper to be used in a specific available space in the primary system.

scholarly journals Optimization of the impact multi-mass vibration absorbers

2017 ◽  
Vol 26 (3) ◽  
pp. 394-400 ◽  
Author(s):  
Ivan Kernytskyy ◽  
Bohdan Diveyev ◽  
Mykhajlo Hlobchak ◽  
Orest Horbaj ◽  
Marta Kopytko ◽  
...  
Keyword(s):  
Passive Control ◽  
Vibration Mode ◽  
Control Device ◽  
Vibration Absorber ◽  
Vibration Absorbers ◽  
Dynamic Vibration Absorber ◽  
Impact Damper ◽  
Freely Moving ◽  
The Impact ◽  
Impact Mass

The problem of attaching dynamic vibration absorber (DVA) to a discrete multi-degree-of-freedom or continuous structure has been outlined in many papers and monographs. An impact damping system can overcome some limitations by impact as the damping medium and impact mass interaction as the damping mechanism. The paper contemplates the provision of DVA with the several of the impact masses. Such originally designed absorbers reduce vibration selectively in maximum vibration mode without introducing vibration in other modes. An impact damper is a passive control device which takes the form of a freely moving mass, constrained by stops attached to the structure under control, i.e. the primary structure. The damping results from the exchange of momentum during impacts between the mass and the stops as the structure vibrates. The paper contemplates the provision of the impact multi-mass DVA’s with masses collisions for additional damping. For some cases of DVA optimization such a design seems more effective than conventional multi-mass DVA with independent mass moving. A technique is developed to give the optimal DVA’s for the elimination of excessive vibration in harmonic stochastic and impact loaded systems.

Passive Multi-Degree-of-Freedom Structural Control Using LPC Impact Dampers

2015 ◽  
Author(s):  
Mohamed Gharib ◽  
Mansour Karkoub
Keyword(s):  
Structural Control ◽  
Flexible Structures ◽  
Tall Buildings ◽  
Degree Of Freedom ◽  
Frame Structure ◽  
Linear Arrangement ◽  
Impact Damper ◽  
Particle Chain ◽  
The Impact ◽  
Partial Damage

Excessive vibration is one of the main reasons leading to partial damage and in some cases collapse of tall buildings and structures. Impact dampers provide an effective, economical, and easy to install solution to the vibration problem in several applications. The latest developed type in the impact dampers family is the Linear Particle Chain (LPC) impact damper. It consists of a linear arrangement of two sizes of freely moving masses, constrained by two stops. This paper presents the results of an experimental investigation on the effectiveness of the LPC impact damper in damping the vibrations of a multi-degree-of-freedom system under different types of excitations. A prototype of the LPC impact dampers is fabricated and tested in our lab using a three-story frame structure. The experimental outcomes clearly show that the LPC impact damper can effectively attenuate the free and forced vibrations of flexible structures.

Shock-Based Experimental Investigation of the Linear Particle Chain Impact Damper

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Mohamed Gharib ◽  
Mansour Karkoub
Keyword(s):  
Frame Structure ◽  
Primary System ◽  
Mass Ratio ◽  
Linear Arrangement ◽  
Single Degree Of Freedom ◽  
Impact Damper ◽  
Single Degree ◽  
Particle Chain ◽  
The Common ◽  
Freely Moving

Impact dampers (IDs) provide an effective, economical, and retrofittable solution to the vibration problem in several engineering applications. An ID typically consists of a single or multiple masses constrained between two or more stops and attached to a primary system to be controlled. The latest developed type in the IDs family is the linear particle chain (LPC) ID. It consists of a linear arrangement of two sizes of freely moving masses, constrained by two stops. The high number of impacts among the damper masses leads to rapid energy dissipation compared to the common IDs. This paper presents an experimental study on the effectiveness of the LPC ID in reducing the vibrations of a single degree-of-freedom (SDOF) frame structure under different shock excitations. Prototypes of the LPC and conventional IDs with different geometric parameters are fabricated. The structure is excited by either an impact at the top floor or pulses at its base. The damping effect of the LPC ID is compared with that of conventional IDs. The experimental outcomes clearly show that the LPC ID can effectively reduce the response of simple structures under shock excitation. Additional investigations are conducted to examine the LPC ID sensitivity to the main damper parameters, such as the chain length, damper mass ratio, and damper clearance.

An Experimental Study of a Novel Impact Damper in Free Vibration of Structures

2014 ◽  
Author(s):  
Mohamed Gharib ◽  
Mansour Karkoub ◽  
Muhammad Tahir Bin Yousaf ◽  
Mohammad AlGammal
Keyword(s):  
Single Unit ◽  
Free Vibrations ◽  
Control Device ◽  
Experimental Investigations ◽  
Passive Vibration Control ◽  
Single Degree Of Freedom ◽  
Impact Damper ◽  
Single Degree ◽  
Particle Chain ◽  
Structure Vibration

A Linear Particle Chain (LPC) impact damper is a newly developed passive vibration control device. It is an extension for the commonly used conventional (single unit) impact damper. In this paper, experimental investigations are conducted to examine the efficacy of the LPC impact damper in attenuating the free vibrations of single degree of freedom structures. The experiments’ outcomes clearly indicate the significant effect of the LPC impact damper in suppressing the structure vibration compared to the conventional impact dampers.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

scholarly journals Simulation Verification of the Contact Parameter Influence on the Forces’ Course of Cereal Grain Impact against a Stiff Surface

2021 ◽  
Vol 11 (2) ◽  
pp. 466
Author(s):  
Włodzimierz Kęska ◽  
Jacek Marcinkiewicz ◽  
Łukasz Gierz ◽  
Żaneta Staszak ◽  
Jarosław Selech ◽  
...  
Keyword(s):  
Dynamic Properties ◽  
Decisive Role ◽  
Force Sensor ◽  
Contact Forces ◽  
Correct Selection ◽  
Contact Parameter ◽  
Cereal Grain ◽  
Wide Range ◽  
The Impact ◽  
Selection Of

The continuous development of computer technology has made it applicable in many scientific fields, including research into a wide range of processes in agricultural machines. It allows the simulation of very complex physical phenomena, including grain motion. A recently discovered discrete element method (DEM) is used for this purpose. It involves direct integration of equations of grain system motion under the action of various forces, the most important of which are contact forces. The method’s accuracy depends mainly on precisely developed mathematical models of contacts. The creation of such models requires empirical validation, an experiment that investigates the course of contact forces at the moment of the impact of the grains. To achieve this, specialised test stations equipped with force and speed sensors were developed. The correct selection of testing equipment and interpretation of results play a decisive role in this type of research. This paper focuses on the evaluation of the force sensor dynamic properties’ influence on the measurement accuracy of the course of the plant grain impact forces against a stiff surface. The issue was examined using the computer simulation method. A proprietary computer software with the main calculation module and data input procedures, which presents results in a graphic form, was used for calculations. From the simulation, graphs of the contact force and force signal from the sensor were obtained. This helped to clearly indicate the essence of the correct selection of parameters used in the tests of sensors, which should be characterised by high resonance frequency.

scholarly journals Uncontrolled Electric Vehicle Charging Impacts on Distribution Electric Power Systems with Primarily Residential, Commercial or Industrial Loads

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1688 ◽  
Author(s):  
C. Birk Jones ◽  
Matthew Lave ◽  
William Vining ◽  
Brooke Marshall Garcia
Keyword(s):  
Power Systems ◽  
Electric Power ◽  
Low Voltage ◽  
Peak Load ◽  
Electric Power Systems ◽  
Primary System ◽  
Maximum Increase ◽  
Actual Distribution ◽  
The Impact ◽  
Ev Charging

An increase in Electric Vehicles (EV) will result in higher demands on the distribution electric power systems (EPS) which may result in thermal line overloading and low voltage violations. To understand the impact, this work simulates two EV charging scenarios (home- and work-dominant) under potential 2030 EV adoption levels on 10 actual distribution feeders that support residential, commercial, and industrial loads. The simulations include actual driving patterns of existing (non-EV) vehicles taken from global positioning system (GPS) data. The GPS driving behaviors, which explain the spatial and temporal EV charging demands, provide information on each vehicles travel distance, dwell locations, and dwell durations. Then, the EPS simulations incorporate the EV charging demands to calculate the power flow across the feeder. Simulation results show that voltage impacts are modest (less than 0.01 p.u.), likely due to robust feeder designs and the models only represent the high-voltage (“primary”) system components. Line loading impacts are more noticeable, with a maximum increase of about 15%. Additionally, the feeder peak load times experience a slight shift for residential and mixed feeders (≈1 h), not at all for the industrial, and 8 h for the commercial feeder.

scholarly journals Dynamics of Multibody Systems With Spherical Clearance Joints

2005 ◽  
Author(s):  
P. Flores ◽  
J. Ambro´sio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Force Model ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Contact Force Model ◽  
Dynamics Of Multibody Systems ◽  
The Impact

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.

Seismic Control Effect for Nonlinear Benchmark Building Using Passive or Semi-Active Damper

2002 ◽  
Author(s):  
Akira Fukukita ◽  
Tomoo Saito ◽  
Keiji Shiba
Keyword(s):  
Active Control ◽  
Passive Control ◽  
Feedforward Control ◽  
Electrical Power ◽  
Control Device ◽  
Control Effect ◽  
Damping Force ◽  
Active Device ◽  
Seismic Control ◽  
Control Forces

We study the control effect for a 20-story benchmark building and apply passive or semi-active control devices to the building. First, the viscous damping wall is selected as a passive control device which consists of two outer plates and one inner plate, facing each other with a small gap filled with viscous fluid. The damping force depends on the interstory velocity, temperature and the shearing area. Next, the variable oil damper is selected as a semi-active control device which can produce the control forces by little electrical power. We propose a damper model in which the damping coefficient changes according to both the response of the damper and control forces based on an LQG feedback and feedforward control theory. It is demonstrated from the results of a series of simulations that the both passive device and semi-active device can effectively reduce the response of the structure in various earthquake motions.

Sign in / Sign up

Export Citation Format

Share Document