scholarly journals KNITTED MATERIALS CAPACITY FOR VIBRATION PROTECTION APPLICATIONS

2019 ◽  
Vol 2019 ◽  
pp. 6-9
Author(s):  
MIRELA BLAGA ◽  
Neculai-Eugen SEGHEDIN
Keyword(s):  
Vibration Isolation ◽  
Natural Frequencies ◽  
Structural Parameters ◽  
Free Vibrations ◽  
Knitted Fabrics ◽  
Vibration Absorption ◽  
Spacer Fabric ◽  
Sense Of Touch ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The present work is a synthesis of the author’s previous research on weft and warp knitted fabrics response under dynamic stress and their capacity of vibration damping. The main objective of this research is to experimentally investigate the vibration behaviour of these fabrics with an existing testing method, in order to understand how the fabric structural parameters affect their vibration isolation performance. The authors have focused their interest on the knitted fabrics characterization through their natural frequencies, which were determined by employing the free vibrations method. The natural frequency is the rate at which an object vibrates when it is not disturbed by an outside force. A comparative fabrics analysis of the measured natural frequencies is performed and the main parameters of influence are discussed. An ideal knitted spacer fabric developed for anti-vibration purposes, should have the capacity of absorb energy efficiently, still having sufficient stiffness to avoid its collapse and an acceptable thickness in order to maintain a sense of touch and dexterity to complete the tasks. The preliminary results confirmed that knitted fabrics can be engineered and exploited as structures with vibration absorption capabilities.

An experimental study on vibration isolation performance of weft-knitted spacer fabrics

2016 ◽  
Vol 86 (20) ◽  
pp. 2225-2235 ◽  
Author(s):  
Fuxing Chen ◽  
Yanping Liu ◽  
Hong Hu
Keyword(s):  
Experimental Study ◽  
Vibration Isolation ◽  
Nonlinear Behavior ◽  
Harmonic Excitation ◽  
Excitation Level ◽  
Spacer Fabric ◽  
Spacer Fabrics ◽  
Vibration Isolation Performance ◽  
Isolation Performance ◽  
Load Mass

This paper presents an experimental study on the vibration isolation performance of weft-knitted spacer fabrics under forced harmonic excitation. The weft-knitted spacer fabrics with two different thicknesses were first designed by varying the linking distance of the spacer monofilament and fabricated using an electronic flat knitting machine. Then, their vibration isolation performance was tested under forced vibration condition via sinusoidal sweeps from low to high frequencies. The typical acceleration transmissibility curve and effects of fabric thickness, load mass and excitation level were discussed in detail. The results obtained show that the thicker spacer fabric has a lower resonance frequency than the thinner fabric due to lower stiffness, and thus can isolate the vibration at a lower frequency level. The results also show that changing the load mass and excitation level changes the loading conditions of the fabric structure, and thus also changes fabric stiffness and vibration isolation performance due to nonlinear behavior of spacer fabrics. It is expected that this study could provide some useful information to promote the application of weft-knitted spacer fabrics for vibration isolation.

On vibration isolation of sandwich plate with periodic hollow tube core

2017 ◽  
Vol 21 (3) ◽  
pp. 1119-1132 ◽  
Author(s):  
Gui-Lan Yu ◽  
Hong-Wei Miao
Keyword(s):  
Vibration Isolation ◽  
Sandwich Plate ◽  
Experimental Studies ◽  
Low Frequency ◽  
Dispersion Relations ◽  
Frequency Responses ◽  
Vibration Attenuation ◽  
Potential Applications ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The vibration isolation performance of a PC sandwich plate with periodic hollow tube core is investigated experimentally and numerically. The experiment results reveal that there exist vibration attenuation zones in acceleration frequency responses which can be improved by increasing the number of periods or tuning some structure parameters. The presence of soft fillers shifts the attenuation zone to lower frequencies and enhances the capability of vibration isolation to some extent. Dispersion relations and acceleration frequency responses are calculated by finite element method using COMSOL MULTIPHYSICS. The attenuation zones obtained by experiments fit well with that by simulations, and both are consistent with the band gap in dispersion relations. The numerical and experimental studies in the present paper show that this PC sandwich plate exhibits a good performance on vibration isolation in low frequency ranges, which will provide some useful references for relevant research and potential applications in vibration propagation manipulations.

Vibration isolation performance of nonobstructive particle damping in a machine rack

2018 ◽  
Vol 25 (5) ◽  
pp. 1122-1130 ◽  
Author(s):  
Zhanpeng Zheng ◽  
Chengjun Wu ◽  
Hengliang Wu ◽  
Jianyong Wang ◽  
Xiaofei Lei
Keyword(s):  
Theoretical Model ◽  
Dynamic Response ◽  
Vibration Isolation ◽  
Passive Control ◽  
Vibration Energy ◽  
Damping Force ◽  
Damping Effect ◽  
Particle Damping ◽  
Vibration Isolation Performance ◽  
Isolation Performance

Nonobstructive particle damping (NOPD) is a novel passive control technology with strong nonlinear-damping. Many scholars put effort into the research on the internal mechanism of NOPD. In contrast, the application of NOPD to engineering has not received much research effort. A theoretical model based on the principle of gas–solid flows, which is employed to evaluate damping effect of NOPD and to predict dynamic response of a machine rack by a co-simulation approach, is established in this paper. In view of the difference between damping effect acting on the lateral and bottom of NOPD holes directly, total damping force is divided into lateral damping force and bottom damping force according to the Janssen theory of stress changed direction. Moreover, NOPD technology is applied to a machine rack for discussing its vibration isolation performance. The results indicate that NOPD technology can suppress the intense vibration, especially between 4000 Hz and 8000 Hz. It is noted that the theoretical model of NOPD can accurately predict the dynamic response of the machine rack with NOPD. The 1/3 Octave vibration energy spectrum indicates that NOPD technics can dissipate the vibration energy of the machine rack at full frequency, especially in 31.5 Hz, and attenuation up to 39.75 dB.

scholarly journals Vibration isolation performance of an elevator motor using Nitrile-Butadiene Rubber /Multi-Walled Carbon Nanotube composite machine mounts

2020 ◽  
Vol 318 ◽  
pp. 01050
Author(s):  
Konstantinos Tsongas ◽  
Gabriel Mansour
Keyword(s):  
Vibration Isolation ◽  
Element Model ◽  
Test System ◽  
Damping Capacity ◽  
Butadiene Rubber ◽  
Motor Test ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The objective of this paper is to evaluate the vibration isolation performance of an elevator motor mounted on elastomeric nanocomposite mounts. A series of conventional acrylonitrile-butadiene rubber (NBR) mounts have been reinforced with 20wt% concentration of multi-walled carbon nanotubes (MWCNTs). The vibration isolation capacity of the machine mounts was calculated through the transmissibility of an elevator motor test system. A Finite Element Model (FEM) was introduced and a harmonic analysis based on the ANSYS code has been utilized to investigate the modal behavior of the nanocomposite machine mount/elevator motor system and extract a representative model of the vibrational behavior. The cyclic compression results have revealed that the stiffness and damping capacity of the conventional elastomers can be modified by adjusting the proportion of MWCNTs. Elastomers’ vibration isolation performance of the motor was ameliorated with the inclusion of MWCNTs, signifying that the enhancement of the elastomers with MWCNTs was rather effective. The vibration level of the elevator motor was decreased to 90% by incorporating the optimal concentration of MWCNTs in NBR mounts.

Optimization of Vehicle Powertrain Mounting System and its Performance

2013 ◽  
Vol 441 ◽  
pp. 580-583
Author(s):  
Gong Yu Pan ◽  
Xin Yang ◽  
You Yan
Keyword(s):  
Vibration Isolation ◽  
Dynamics Model ◽  
Acceleration Response ◽  
Idle State ◽  
Decoupling Method ◽  
Before And After ◽  
Vibration Transmissibility ◽  
Six Degree Of Freedom ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In order to solve the vibration problem of diesel engine powertrain assembly at its idle state, a six degree-of-freedom dynamics model of the powertrain mounting system is established and a optimization based on Adams/View is applied to simulation and analysis on the powertrain mounting system with energy decoupling method. The results show that the optimized repositioning mounts installation position can effectively improve decoupling rate in main vibration directions of mounting system. Based on this, the vibration transmissibility and acceleration response before and after optimization are simulated. The results show that the optimized engine mounting system makes a great improvement of vibration isolation performance.

The Experimental Research of Vibration Isolation Performance of MR Isolator at High Temperature

2012 ◽  
Vol 184-185 ◽  
pp. 525-528 ◽  
Author(s):  
Hui Yan ◽  
Liang Chen ◽  
Hong Rui Ao ◽  
Hong Yuan Jiang
Keyword(s):  
Vibration Isolation ◽  
Evaluation Index ◽  
Structural Parameter ◽  
Sweep Frequency ◽  
Frequency Test ◽  
Metal Rubber ◽  
Performance Evaluation Index ◽  
Vibration Isolation Performance ◽  
Isolation Performance ◽  
Sine Sweep

Transmissibility is the main performance evaluation index of Metal Rubber (MR) isolator, which can be got by sine sweep frequency test. At different temperature, the sine sweep frequency test is done with different structural parameter MR isolator. The influence that relative density and pre-deformation have on transmissibility and natural frequency when temperature changed is analyzed. The changing regularity of MR isolator’s transmissibility at different temperature is explored. Research results provide the basis for designing MR isolator.

Vibration and Shock Isolation Performance of a Semi-Active “On-Off” Damper

1985 ◽  
Vol 107 (4) ◽  
pp. 398-403 ◽  
Author(s):  
S. Rakheja ◽  
S. Sankar
Keyword(s):  
Relative Position ◽  
Relative Velocity ◽  
Vibration Isolation ◽  
Performance Characteristics ◽  
Orifice Area ◽  
Hydraulic Damper ◽  
Control Scheme ◽  
Vibration Isolation Performance ◽  
Isolation Performance ◽  
Command Signal

The concept of an “on-off” damper employing the feedback signals from directly measurable variables is proposed. A control scheme utilizing the directly measurable relative position and relative velocity signals to produce the command signal is configured. The on-off damping mechanism can be achieved through the modulation of orifice area in a conventional hydraulic damper, using a two position on-off valve driven by the command signal. The shock and vibration isolation characteristics of the proposed on-off damper are evaluated through computer simulations. The shock and vibration isolation performance characteristics of the proposed damper are compared to the performance characteristics of a passive and an on-off damper utilizing the feedback from absolute and relative velocity signals.

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