scholarly journals Stiffness-based Spring Design Optimization using Taguchi Method to reduce Low-Frequency Vibration

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Ahmad Yusuf Ismail ◽  
Al Munawir ◽  
Noerpamoengkas A
Keyword(s):  
Taguchi Method ◽  
High Frequency ◽  
Vibration Isolation ◽  
Low Frequency ◽  
Stiffness Coefficient ◽  
Frequency Range ◽  
High Noise ◽  
Low Frequency Vibration ◽  
Optimization Variable ◽  
Vibration Transmissibility

Low-frequency vibration has been troublesome for a mechanical system. Despite the measurement difficulties, low-frequency vibration also creates several environmental effects such as high noise level that is harmful to the human body. One of the methods to reduce vibration is tuning the vibration isolation i.e. spring and damping coefficient. However, the latter method is found to be effective only for the mid-high frequency range. Therefore, this paper proposes an optimization of the spring a.k.a. stiffness coefficient in order to reduce the low-frequency vibration. The Taguchi method is used as an optimization tool since it offers simplicity yet powerful for any field of application, particularly in engineering. Two significant parameters in the spring geometry were selected as the optimization variable in the Taguchi method and evaluated using vibration transmissibility concept. The result shows that the Taguchi method has been successfully obtained the optimum value for the spring geometry purposely to reduce the vibration transmissibility.

scholarly journals Dynamic characterization of controlled multi-channel semi-active magnetorheological fluid mount

2021 ◽  
Vol 12 (2) ◽  
pp. 751-764
Author(s):  
Zhihong Lin ◽  
Mingzhong Wu
Keyword(s):  
High Frequency ◽  
Optimization Design ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Vehicle Model ◽  
Mr Fluid ◽  
Unbalanced Force ◽  
Low Frequency Vibration ◽  
Engine Mount

Abstract. In this paper, a novel structure of a controlled multi-channel semi-active magnetorheological (MR) fluid mount is proposed, including four controlled channels and one rate-dip channel. Firstly, the magnetic circuit analysis, rate-dip channel optimization design, and MR fluid mount damping analysis are given. Secondly, the mathematical model of the controlled multi-channel semi-active MR fluid mount is constructed. We analyze the effect of controlled multi-channel closing on the dynamic characteristics of the mounts and the effect of the presence or absence of the rate-dip channel on the low-frequency isolation of the mount. Finally, the controlled multi-channel semi-active MR fluid mount was applied to the 1/4 vehicle model (a model consisting of an engine, a single engine mount, a single suspension and a vehicle frame), with the transmissibility of the engine relative to the vehicle frame at low frequency and the transmissibility of the engine reciprocating unbalanced force to the vehicle frame magnitude at high frequency as the evaluation index. Numerical simulation shows the following points. (1) The controllable multi-channel semi-active MR fluid mount can achieve adjustable dynamic stiffness and damping with applied 2 A current to different channels. (2) With known external excitation source, applied currents to different controllable channels can achieve the minimum transmissibility and meet the mount wide-frequency vibration isolation requirement, while adding a rate-dip channel can improve the low-frequency vibration isolation performance of the MR fluid mount. (3) Switching and closing different controllable channels in the 1/4 vehicle model can achieve the minimum transmissibility of low-frequency engine vibrations relative to the vehicle frame and high-frequency engine vibrations reciprocating an unbalanced force to the vehicle frame. Therefore, the design of the controllable multi-channel semi-active MR fluid mount can meet the wide-frequency isolation.

Physical modeling and experimental verification of magneto-rheological damper under medium and high frequency excitation

2020 ◽  
pp. 146442072096600
Author(s):  
Fanghui Xu ◽  
Dawei Dong ◽  
Yan Huang ◽  
Shizhe Song ◽  
Bing Yan
Keyword(s):  
Physical Model ◽  
High Frequency ◽  
Vibration Isolation ◽  
Dynamic Performance ◽  
Low Frequency ◽  
Damping Force ◽  
Active Device ◽  
Low Frequency Vibration ◽  
Output Characteristics ◽  
Magneto Rheological

As a promising semi-active device, magneto-rheological damper has been widely used in low-frequency vibration isolation fields (within 20 Hz) such as bridge damping and building seismic resistance. Recently, the application of magneto-rheological damper has extended to medium and high frequency fields such as satellite and power engine vibration control, accompanied with an urgent need of detailed understanding of its output characteristics. In this paper, a comprehensive physical model is established to analyze dynamic performance of the magneto-rheological damper. The model, derived from both Poiseuille and Couette flow, aims to describe the relationship between the flow rate and pressure difference. The compressibility of the magneto-rheological fluid, the inertia of both the fluid and piston assembly, and the friction are involved to capture the medium and high frequency dynamics of the damping force. Theoretical calculation and simulation verification of magnetic circuit are conducted. Then the experiment based on a self-made prototype is carried out. The results show that the damping force calculated by proposed physical model matches well with the experimental results across the predefined range of frequency and coil current levels.

The Characteristic Analysis of Double Vibration Isolation Model Based on MRF and Piezoceramics

2012 ◽  
Vol 246-247 ◽  
pp. 1309-1313
Author(s):  
De Sheng Zhang ◽  
Guo Tian He ◽  
Ming Li ◽  
Li Song
Keyword(s):  
High Frequency ◽  
Shear Force ◽  
Vibration Isolation ◽  
Rapid Development ◽  
Low Frequency ◽  
Process Technology ◽  
Characteristic Analysis ◽  
Ultralow Frequency ◽  
Model Based ◽  
Low Frequency Vibration

with the rapid development of ultraprecise process technology, the precision of instrument is being improved fast. Then instruments are more sensitive to the vibration of environment. This paper took advantage of the controlled character of MRF’s shear force, using actuators made of PZT,and put forward the double vibration isolation model based on MRF and piezoceramics. Through the theoretical analysis we arrival at a conclusion that the model has a good Isolation effect on both high frequency vibration and low frequency vibration especially ultralow frequency vibration.

Assessment of ergonomically designed handle shapes for low-frequency vibration responses

2018 ◽  
Vol 233 (8) ◽  
pp. 1564-1573 ◽  
Author(s):  
B Jain AR Tony ◽  
MS Alphin
Keyword(s):  
Low Frequency ◽  
Human Hand ◽  
Frequency Range ◽  
Large Magnitude ◽  
Low Frequency Vibration ◽  
Hand Tool ◽  
Vibration Transmissibility ◽  
Vibration Responses ◽  
Subjective Measurements ◽  
The Mean

Hand-operated tool handles transmit a large magnitude of vibration to the hand-arm system during low-frequency operations. Therefore, the precise design of a hand tool is very important to overcome musculoskeletal disorders, hand-arm vibration, etc. This study was aimed at developing optimal tool handles with an increased contact area and to overcome the contact pressure, which causes discomfort and pain. Six different human hand-based optimal handles (handles B to G) and one optimal cylindrical handle (handle A) were designed and fabricated using 3D printing technology, in order to assess the effect of low-frequency vibrations. The effect of handle shapes was evaluated with objective and subjective measurements using 15 subjects. Objective measurements were performed to assess the vibration transmissibility by experimental study at the frequency range of 0–100 Hz, and subjective measurements were performed to rate the handles based on comfort descriptors and overall comfort of the handles. Root mean square vibration accelerations were recorded at the wrist, elbow, and shoulder of each subject and at the base of the handle fixture to evaluate the vibration transmissibility for each handle. The mean vibration transmissibility was found to be minimum for handle B and was rated to be more comfortable by the subjects. The results indicated that all the human hand-based handles transmit less vibration and were rated to be more comfortable than the optimal cylindrical handle.

scholarly journals Methods for Measuring the Dynamic Stiffness of Resilient Rail Fastenings for Low Frequency Vibration Isolation of Railways, Their Problems and Possible Solutions

2005 ◽  
Vol 24 (2) ◽  
pp. 107-115 ◽  
Author(s):  
Chris Morison ◽  
Anbin Wang ◽  
Oliver Bewes
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Inertial Force ◽  
Transport Systems ◽  
Frequency Range ◽  
Low Frequency Vibration ◽  
Urban Rail ◽  
Low Stiffness ◽  
European Standards

Low frequency ground or structure-borne sound and vibration emission from urban rail transport systems can be greatly reduced by reducing the stiffness of the rail fastening. Estimates and models of the efficacy of such systems require accurate measurements of their dynamic stiffness over the frequency range of interest, and European Standards make recommendations for such measurements. This paper describes these methods and their shortcomings when applied to modern complete assemblies with low stiffness, one problem of which is the contribution of inertial forces at frequencies approaching and above the natural resonance of the system. This paper suggests a method for correcting for this inertial force, and tests this correction with the driving point method of dynamic stiffness measurement when applied to the Pandrol VANGUARD resilient rail fastening. The preliminary tests effectively triple the frequency range of valid measurements, a result which could be improved when applied to stiffer systems or with further improvements to the test equipment.

Vibration Isolation on Lightweight Floor Structures

2002 ◽  
Vol 9 (4) ◽  
pp. 257-269 ◽  
Author(s):  
P Hammer ◽  
J Brunskog
Keyword(s):  
High Frequency ◽  
Vibration Isolation ◽  
Low Frequency ◽  
High Mobility ◽  
Frequency Range ◽  
Two Stage ◽  
One Stage ◽  
Straight Line ◽  
Floor Structure

A theoretical and experimental study of vibration isolation for a source on a lightweight floor structure is presented. The effectiveness of one-stage and two-stage isolator systems is studied. Approximate formulae are presented for both low and high frequency for the receiver, the floor structure. For the mobility, a comparison between approximate formulae, numerical exact results and experimental results are presented. The low frequency asymptote for the approximate mobility is valid up to l/λp ≈ 1/4. The high frequency asymptote is valid from l/λp ≈ 1/2. A straight line can be drawn between these two points for the intermediate range 1/4 < l/λp < 1/2. Finally, a case study is presented. A fan is mounted on a wooden joist floor. The effect of both one and two stage isolation is demonstrated. It is clearly seen that the high mobility situation for the receiver is increased by adding a rigid body to the mount. Hence, in the frequency range of interest, the ‘receiver’ acts more or less as a blocked termination. A two-stage isolator almost completely eliminates the structure borne sound and compared to a one-stage isolator it reduces the sound by 20 dB at the rpm for the fan.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

scholarly journals An Improved Time Integration Method Based on Galerkin Weak Form with Controllable Numerical Dissipation

2021 ◽  
Vol 11 (4) ◽  
pp. 1932
Author(s):  
Weixuan Wang ◽  
Qinyan Xing ◽  
Qinghao Yang
Keyword(s):  
High Frequency ◽  
Integration Method ◽  
Time Integration ◽  
Low Frequency ◽  
Weak Form ◽  
High Accuracy ◽  
Numerical Dissipation ◽  
Frequency Range ◽  
Time Integration Method ◽  
Numerical Damping

Based on the newly proposed generalized Galerkin weak form (GGW) method, a two-step time integration method with controllable numerical dissipation is presented. In the first sub-step, the GGW method is used, and in the second sub-step, a new parameter is introduced by using the idea of a trapezoidal integral. According to the numerical analysis, it can be concluded that this method is unconditionally stable and its numerical damping is controllable with the change in introduced parameters. Compared with the GGW method, this two-step scheme avoids the fast numerical dissipation in a low-frequency range. To highlight the performance of the proposed method, some numerical problems are presented and illustrated which show that this method possesses superior accuracy, stability and efficiency compared with conventional trapezoidal rule, the Wilson method, and the Bathe method. High accuracy in a low-frequency range and controllable numerical dissipation in a high-frequency range are both the merits of the method.

scholarly journals A Compact Four-Port Coplanar Antenna Based on an Excitation Switching Reconfigurable Mechanism for Cognitive Radio Applications

2019 ◽  
Vol 9 (15) ◽  
pp. 3157 ◽  
Author(s):  
O ◽  
Jin ◽  
Choi
Keyword(s):  
Cognitive Radio ◽  
High Frequency ◽  
Coplanar Waveguide ◽  
Low Frequency ◽  
Loop Antenna ◽  
Ultra Wideband ◽  
Frequency Range ◽  
Uwb Antenna ◽  
High Isolation ◽  
Loop Antennas

In this paper, we propose a compact four-port coplanar antenna for cognitive radio applications. The proposed antenna consists of a coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna and three inner rectangular loop antennas. The dimensions of the proposed antenna are 42 mm × 50 mm × 0.8 mm. The UWB antenna is used for spectrum sensing and fully covers the UWB spectrum of 3.1–10.6 GHz. The three loop antennas cover the UWB frequency band partially for communication purposes. The first loop antenna for the low frequency range operates from 2.96 GHz to 5.38 GHz. The second loop antenna is in charge of the mid band from 5.31 GHz to 8.62 GHz. The third antenna operates from 8.48 GHz to 11.02 GHz, which is the high-frequency range. A high isolation level (greater than 17.3 dB) is realized among the UWB antenna and three loop antennas without applying any additional decoupling structures. The realized gains of the UWB antenna and three loop antennas are greater than 2.7 dBi and 1.38 dBi, respectively.

Electromagnetic Property of La0.7Sr0.3MnO3/Ag Composite at High Frequency

2015 ◽  
Vol 655 ◽  
pp. 182-185
Author(s):  
Ke Lan Yan ◽  
Run Hua Fan ◽  
Min Chen ◽  
Kai Sun ◽  
Xu Ai Wang ◽  
...  
Keyword(s):  
High Frequency ◽  
Single Phase ◽  
Low Frequency ◽  
Electromagnetic Property ◽  
High Frequency Range ◽  
Frequency Range ◽  
Free Electron Concentration ◽  
Theoretical Simulation ◽  
Electrical And Magnetic Properties ◽  
Three Phase

The phase structure, and electrical and magnetic properties of La0.7Sr0.3MnO3(LSMO)-xAg (xis the mole ratio,x=0, 0.3, 0.5) composite were investigated. It is found that the sample withx=0 is single phase; the samples withx=0.3 and 0.5 present three phase composite structure of the manganese oxide and Ag. With the increasing of Ag content, the grain size of the samples increases and the grain boundaries transition from fully faceted to partially faceted. The permittivity of spectrum (10 MHz - 1 GHz) and the theoretical simulation reveal that the plasma frequencyfpincrease with Ag content, due to the increasing of free electron concentration, which is further supported by the enhancement of conductivity. While for the permeability (μr'), theμr'decrease with the increasing of Ag content at low frequency range (f< 20 MHz), while at the relative high frequency range (f> 300 MHz), theμr'increased with Ag content. Therefore, the introduction of elemental Ag resulted in a higherμr'at the relative high frequency range.

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