Environmental and sound divergence effects on the performance of rectangular sonic crystals with Helmholtz resonators

2017 ◽  
Vol 24 (12) ◽  
pp. 2483-2493 ◽  
Author(s):  
Hsiao Mun Lee ◽  
Kian Meng Lim ◽  
Heow Pueh Lee
Keyword(s):  
Resonant Frequency ◽  
Numerical Simulations ◽  
Insertion Loss ◽  
Noise Source ◽  
Experimental Methods ◽  
Experimental Results ◽  
Noise Attenuation ◽  
Helmholtz Resonators ◽  
Sonic Crystals ◽  
Indoor And Outdoor

Environmental and sound divergence effects on the noise attenuation performance of rectangular sonic crystals with Helmholtz resonators were investigated using experimental methods. The experiments were conducted under indoor, semi-indoor, and outdoor conditions. The positions of the noise source and receiver were rotated to different angles to study the sound divergence effects on the sonic crystals. For a full array of sonic crystals, performance of the sonic crystals at indoor and semi-indoor were similar and poorer than outdoor at all frequencies. The presence of Helmholtz resonators caused a significant amount of insertion loss at 1000 Hz for experiments that were indoors and outdoors. 1000 Hz was the designed resonant frequency produced by the Helmholtz resonators. The reduction of the number of columns of the sonic crystals resulted in greater negative insertion loss in all three environment conditions. The sound divergence effects on the sonic crystals were greater for frequencies above 800 Hz and they were less significant for frequencies below 800 Hz. The types of noises had noticeable effects on insertion loss obtained by the sonic crystals. Numerical simulations were performed to investigate the dispersion properties of the sonic crystals. Numerical results with and without Helmholtz resonators generally showed similar trends with the corresponding experimental results.

scholarly journals Geometry Effects on the Noise Reduction of Helmholtz Resonators

2012 ◽  
Author(s):  
M. Farooqui ◽  
A. Alhamoud ◽  
A. Aliuddin ◽  
S. Mekid
Keyword(s):  
Resonant Frequency ◽  
Noise Reduction ◽  
Degrees Of Freedom ◽  
Helmholtz Resonator ◽  
Shape Effect ◽  
Noise Attenuation ◽  
Two Degrees Of Freedom ◽  
Helmholtz Resonators ◽  
Geometry Effects

In this paper the effect of geometry shape of the Helmholtz resonator on its resonant frequency and on its noise attenuation capability is discussed. The theory of resonant frequency depending on the shape of the vessel of the resonator is verified analytical and numerically using COMSOL for one and two degrees of freedom. The simulation was validated experimentally and has shown very good agreements. Various shapes of the resonators were compared in arrays. A better understanding of the shape effect is shown through simulations.

Simulation of Noise Attenuation Using One and Two Degree of Freedom Helmholtz Resonators in Pipelines

2012 ◽  
Author(s):  
Maaz Farooqui ◽  
Samir Mekid
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Acoustic Wave ◽  
Degrees Of Freedom ◽  
Design Procedure ◽  
Experimental Results ◽  
Noise Attenuation ◽  
Acoustic Wave Propagation ◽  
Helmholtz Resonators ◽  
Two Degree Of Freedom

Helmholtz resonators are known to be efficient resonators for ducts if they are properly designed. A design procedure is suggested in this paper to identify the size of the resonators in one and two degrees of freedom. The procedure is supported by a through numerical simulation of acoustic wave propagation that is presented and is verified using published experimental results. The overall procedure shows achievable great attenuation of noise in pipeline.

An Assessment of the Value of Theory in Predicting Gas-Bearing Performance

1961 ◽  
Vol 83 (2) ◽  
pp. 195-200 ◽  
Author(s):  
S. Cooper
Keyword(s):  
Steady State ◽  
Slip Velocity ◽  
Reynolds Equation ◽  
Energy Equation ◽  
Experimental Methods ◽  
Experimental Results ◽  
Theoretical Investigations ◽  
Gas Bearing ◽  
Theoretical Results

The object of the paper is to indicate the value of theoretical investigations of hydrodynamic finite bearings under steady-state conditions. Methods of solution of Reynolds equation by both desk and digital computing, and methods of stabilizing the processes of solution, are described. The nondimensional data available from the solutions are stated. The outcome of an attempted solution of the energy equation is discussed. A comparison between some theoretical and experimental results is shown. Experimental methods employed and some difficulties encountered are discussed. Some theoretical results are given to indicate the effects of the inclusion of slip velocity, stabilizing slots, and a simple case of whirl.

Silica Nanochannel Surface Effect on Monosaccharide Transport

2010 ◽  
Author(s):  
Arturas Ziemys ◽  
Alessandro Grattoni ◽  
Jaskaran Gill ◽  
Mauro Ferrari
Keyword(s):  
Molecular Dynamics ◽  
Molecular Modeling ◽  
Surface Effect ◽  
Glucose Solution ◽  
Effective Diffusivity ◽  
Experimental Methods ◽  
Experimental Results ◽  
Monosaccharide Transport

The interface of silica nanochannel of 10 nm was studied by molecular modeling and experimental methods. Molecular Dynamics study on glucose solution revealed that 2–3 nm of interface solution to silica walls has reduced glucose diffusivity. That reduction affects the effective diffusivity of glucose in silica nanochannel. Experimental results show Fickian-like release of glucose through 13 nm nanochannel. Molecular modeling and experimental results suggest that glucose is not sufficiently confined to possess non-Fickian behavior.

Study on a Novel MEMS High G Acceleration Sensor

2012 ◽  
Vol 490-495 ◽  
pp. 499-503
Author(s):  
Ping Li ◽  
Yun Bo Shi ◽  
Jun Liu ◽  
Shi Qiao Gao
Keyword(s):  
Resonant Frequency ◽  
Natural Frequency ◽  
Impact Load ◽  
Hopkinson Bar ◽  
Experimental Results ◽  
Structure Parameters ◽  
Acceleration Sensor ◽  
Piezoresistive Effect ◽  
Sensor Structure ◽  
The Impact

This paper presents a novel MEMS high g acceleration sensor based on piezoresistive effect. For the designed sensor structure, the formula of stress, natural frequency and damping was derived in theory, and the resonant frequency can up to 500kHz. After the structure parameters were designed, the sensor was fabricated by the standard processing technology, and the sensitivity was tested by Hopkinson bar. According to the experimental results, the sensitivity of the high g acceleration sensor is 0.125μV/g at the impact load of 164,002g.

Additive manufacturing of pure copper: From numerical simulations to experimental results

2021 ◽  
Author(s):  
Hagen Kohl ◽  
Lisa Schade ◽  
Gabor Matthäus ◽  
Tobias Ullsperger ◽  
Burak Yürekli ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Numerical Simulations ◽  
Pure Copper ◽  
Experimental Results

Effect of Ramp Angle on the Anti-Loosening Ability of Wedge Self-Locking Nuts Under Vibration

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Jianhua Liu ◽  
Hao Gong ◽  
Xiaoyu Ding
Keyword(s):  
Finite Element ◽  
Numerical Simulations ◽  
Production Technology ◽  
Material Properties ◽  
Threshold Value ◽  
Commercial Production ◽  
Experimental Results ◽  
Fe Method ◽  
Transversal Vibration

Recently, the wedge self-locking nut, a special anti-loosening product, is receiving more attention because of its excellent reliability in preventing loosening failure under vibration conditions. The key characteristic of a wedge self-locking nut is the special wedge ramp at the root of the thread. In this work, the effect of ramp angle on the anti-loosening ability of wedge self-locking nuts was studied systematically based on numerical simulations and experiments. Wedge self-locking nuts with nine ramp angles (10 deg, 15 deg, 20 deg, 25 deg, 30 deg, 35 deg, 40 deg, 45 deg, and 50 deg) were modeled using a finite element (FE) method, and manufactured using commercial production technology. Their anti-loosening abilities under transversal vibration conditions were analyzed based on numerical and experimental results. It was found that there is a threshold value of the initial preload below which the wedge self-locking nuts would lose their anti-loosening ability. This threshold value of initial preload was then proposed for use as a criterion to evaluate the anti-loosening ability of wedge self-locking nuts quantitatively and to determine the optimal ramp angle. Based on this criterion, it was demonstrated, numerically and experimentally, that a 30 deg wedge ramp resulted in the best anti-loosening ability among nine ramp angles studied. The significance of this study is that it provides an effective method to evaluate the anti-loosening ability of wedge self-locking nuts quantitatively, and determined the optimal ramp angle in terms of anti-loosening ability. The proposed method can also be used to optimize other parameters, such as the material properties and other dimensions, to guarantee the best anti-loosening ability of wedge self-locking nuts.

scholarly journals Numerical Simulations of V-Shaped Plates Subjected to Blast Loadings: A Validation Study

2016 ◽  
Vol 10 (11) ◽  
pp. 203
Author(s):  
Mohd Zaid Othman ◽  
Qasim H. Shah ◽  
Muhammad Akram Muhammad Khan ◽  
Tan Kean Sheng ◽  
M. A. Yahaya ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Variable Mass ◽  
Blast Loading ◽  
Experimental Results ◽  
Average Difference ◽  
Simulation Results ◽  
Blast Loadings ◽  
Carrier Vehicle ◽  
Good Agreement

A series of numerical simulations utilizing LS-DYNA was performed to determine the mid-point deformations of V-shaped plates due to blast loading. The numerical simulation results were then compared with experimental results from published literature. The V-shaped plate is made of DOMEX 700 and is used underneath an armour personal carrier vehicle as an anti-tank mine to mitigate the effects of explosion from landmines in a battlefield. The performed numerical simulations of blast loading of V-shaped plates consisted of various angles i.e. 60°, 90°, 120°, 150° and 180°; variable mass of explosives located at the central mid-point of the V-shaped vertex with various stand-off distances. It could be seen that the numerical simulations produced good agreement with the experimental results where the average difference was about 26.6%.

Modal Simulation and Testing of a Micro-Manipulator

2004 ◽  
Vol 127 (3) ◽  
pp. 515-519 ◽  
Author(s):  
Yongjun Lai ◽  
Marek Kujath ◽  
Ted Hubbard
Keyword(s):  
Numerical Simulations ◽  
Degrees Of Freedom ◽  
Compliant Mechanism ◽  
Dynamic Properties ◽  
Experimental Results ◽  
Mass Model ◽  
Thermal Actuators ◽  
Micro Manipulator ◽  
Six Dof

A micro-machined manipulator with three kinematic degrees-of-freedom (DOF): x, y, and φ is presented. The manipulator is driven by three thermal actuators. A six DOF discrete spring-mass model of the compliant mechanism is developed which manifests the dynamic properties of the device. Numerical simulations are compared with experimental results.

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