scholarly journals Numerical Simulation and Experimental Study of Capacitive Imaging Technique as a Nondestructive Testing Method

2021 ◽  
Vol 11 (9) ◽  
pp. 3804
Author(s):  
Farima Abdollahi-Mamoudan ◽  
Sebastien Savard ◽  
Tobin Filleter ◽  
Clemente Ibarra-Castanedo ◽  
Xavier P. V. Maldague
Keyword(s):  
Numerical Simulation ◽  
Electric Field Distribution ◽  
Imaging Technique ◽  
Capacitive Sensor ◽  
Experimental Result ◽  
Inspection Method ◽  
Testing Method ◽  
Physical Experiments ◽  
Nondestructive Testing Method ◽  
Imaging Performance

It was recently demonstrated that a coplanar capacitive sensor could be applied to the evaluation of materials without the disadvantages associated with the other techniques. This technique effectively detects changes in the dielectric properties of the materials due to, for instance, imperfections or variations in the internal structure, by moving a set of simple electrodes on the surface of the specimen. An AC voltage is applied to one or more electrodes and signals are detected by others. This is a promising inspection method for imaging the interior structure of the numerous materials, without the necessity to be in contact with the surface of the sample. In this paper, finite element (FE) modeling was employed to simulate the electric field distribution from a coplanar capacitive sensor and the way it interacts with a nonconducting sample. Physical experiments with a prototype capacitive sensor were also performed on a Plexiglas sample with subsurface defects, to assess the imaging performance of the sensor. A good qualitative agreement was observed between the numerical simulation and experimental result.

scholarly journals Numerical Simulation and Experimental Study of Capacitive Imaging Technique as a Non-Destructive Testing Method

2021 ◽  
Author(s):  
Farima Abdollahi Mamoudan ◽  
Sebastien Savard ◽  
Tobin Filleter ◽  
Clemente Ibarra-Castanedo ◽  
Xavier Maldague
Keyword(s):  
Numerical Simulation ◽  
Surface Defects ◽  
Capacitive Sensor ◽  
Experimental Result ◽  
Destructive Testing ◽  
Fe Modelling ◽  
Inspection Method ◽  
Physical Experiments ◽  
Imaging Performance ◽  
Non Destructive

It was recently demonstrated that a co-planar capacitive sensor could be applied to the evaluation of materials without the disadvantages associated with the other techniques. This technique effectively detects changes in the dielectric properties of the materials due to, for instance, imperfections or variations in the internal structure, by moving a set of simple electrodes on the surface of the specimen. An AC voltage is applied to one or more electrodes and signals are detected by others. This is a promising inspection method for imaging the interior structure of the numerous materials, without the necessity to be in contact with the surface of the sample. In this paper, Finite Element (FE) modelling was employed to simulate the electric field distribution from a co-planar capacitive sensor and the way it interacts with a non-conducting sample. Physical experiments with a prototype capacitive sensor were also performed on a Plexiglas sample with sub-surface defects, to assess the imaging performance of the sensor. A good qualitative agreement was observed between the numerical simulation and experimental result.

Simulation and Analysis on the Best Range of Lift-Off Values in MFL Testing

2013 ◽  
Vol 321-324 ◽  
pp. 811-814 ◽  
Author(s):  
De Hui Wu ◽  
Zhong Yuan Zhang ◽  
Zhen Liang Liu ◽  
Xiao Hao Xia
Keyword(s):  
Mechanical Vibration ◽  
Fem Simulation ◽  
Near Surface ◽  
Testing Method ◽  
Surface Areas ◽  
Field Peak ◽  
Lift Off ◽  
Nondestructive Testing Method ◽  
Strength Of Excitation ◽  
Flux Leakage

As a nondestructive testing method, the magnetic flux leakage (MFL) testing technique is widely used for the testing of surface and near-surface areas in ferromagnetic materials. The MFL field is influenced by parameters of defects, strength of excitation, sensor lift-off value and electromagnetic noises etc. A 2-D finite element method (FEM) simulation model is established in this paper to analyze the influence of lift-off values under the condition of mechanical vibration and electromagnetic noises. The distribution of the MFL field peak for different lift-off values and different depth defects is presented. The defect quantization errors caused by the mechanical vibration and electromagnetic noises are introduced to analyze the influence of lift-off values and electromagnetic noises. The best range of lift-off values can be determined from the results of error analysis. It is effective to improve the measuring accuracy in practical MFL testing.

scholarly journals Numerical Study of Pressure Attenuation Effect on Tunnel Structures Subjected to Blast Loads

2021 ◽  
Vol 11 (12) ◽  
pp. 5646
Author(s):  
Cheng-Wei Hung ◽  
Ying-Kuan Tsai ◽  
Tai-An Chen ◽  
Hsin-Hung Lai ◽  
Pin-Wen Wu
Keyword(s):  
Numerical Simulation ◽  
Orifice Plate ◽  
Experimental Result ◽  
Scale Model ◽  
Pressure Reduction ◽  
Expansion Chamber ◽  
Pressure Relief ◽  
Attenuation Effect ◽  
The One ◽  
Better Than

This study used experimental and numerical simulation methods to discuss the attenuation mechanism of a blast inside a tunnel for different forms of a tunnel pressure reduction module under the condition of a tunnel near-field explosion. In terms of the experiment, a small-scale model was used for the explosion experiments of a tunnel pressure reduction module (expansion chamber, one-pressure relief orifice plate, double-pressure relief orifice plate). In the numerical simulation, the pressure transfer effect was evaluated using the ALE fluid–solid coupling and mapping technique. The findings showed that the pressure attenuation model changed the tunnel section to diffuse, reduce, or detour the pressure transfer, indicating the blast attenuation effect. In terms of the effect of blast attenuation, the double-pressure relief orifice plate was better than the one-pressure relief orifice plate, and the single-pressure relief orifice plate was better than the expansion chamber. The expansion chamber attenuated the blast by 30%, the one-pressure relief orifice plate attenuated the blast by 51%, and the double-pressure relief orifice plate attenuated the blast by 82%. The blast attenuation trend of the numerical simulation result generally matched that of the experimental result. The results of this study can provide a reference for future protective designs and reinforce the U.S. Force regulations.

Preliminary results of numerical simulation of submarine landslide-generated waves

2021 ◽  
Author(s):  
Ramtin Sabeti ◽  
Mohammad Heidarzadeh
Keyword(s):  
Numerical Simulation ◽  
Numerical Modelling ◽  
Numerical Solutions ◽  
Numerical Technique ◽  
Source Region ◽  
Three Dimensional ◽  
Terminal Velocity ◽  
Sensitivity Analyses ◽  
Physical Experiments ◽  
Set Up

<p>Landslide-generated waves have been major threats to coastal areas and have led to destruction and casualties. Their importance is undisputed, most recently demonstrated by the 2018 Anak Krakatau tsunami, causing several hundred fatalities. The accurate prediction of the maximum initial amplitude of landslide waves (<em>η<sub>max</sub></em>) around the source region is a vital hazard indicator for coastal impact assessment. Laboratory experiments, analytical solutions and numerical modelling are three major methods to investigate the (<em>η<sub>max</sub></em>). However, the numerical modelling approach provides a more flexible and cost- and time-efficient tool. This research presents a numerical simulation of tsunamis due to rigid landslides with consideration of submerged conditions. In particular, this simulation focuses on studying the effect of landslide parameters on <em>η<sub>max</sub>.</em> Results of simulations are compared with our conducted physical experiments at the Brunel University London (UK) to validate the numerical model.</p><p>We employ the fully three-dimensional computational fluid dynamics package, FLOW-3D Hydro for modelling the landslide-generated waves. This software benefit from the Volume of Fluid Method (VOF) as the numerical technique for tracking and locating the free surface. The geometry of the simulation is set up according to the wave tank of physical experiments (i.e. 0.26 m wide, 0.50 m deep and 4.0 m). In order to calibrate the simulation model based on the laboratory measurements, the friction coefficient between solid block and incline is changed to 0.41; likewise, the terminal velocity of the landslide is set to 0.87 m/s. Good agreement between the numerical solutions and the experimental results is found. Sensitivity analyses of landslide parameters (e.g. slide volume, water depth, etc.) on <em>η<sub>max </sub></em>are performed. Dimensionless parameters are employed to study the sensitivity of the initial landslide waves to various landslide parameters.</p>

Numerical Simulation Study of Metal Transfer in MIG Welding with Magnetic Control

2014 ◽  
Vol 532 ◽  
pp. 545-548 ◽  
Author(s):  
Chao Yang ◽  
Shu Yuan Jiang ◽  
Hai Bo Bi
Keyword(s):  
Fluid Dynamics ◽  
Numerical Simulation ◽  
Mathematical Model ◽  
Simulation Study ◽  
Electromagnetic Theory ◽  
Metal Transfer ◽  
Experimental Result ◽  
Magnetic Control ◽  
Mig Welding ◽  
Model Based

This paper simulate the mode of metal transfer in MIG magnetic control welding by using CFD software FLUENT, establishing mathematical model based on fluid dynamics and electromagnetic theory, and simulate the form, grow and drop process of metal transfer with and without magnetic. Meanwhile, do experiments to confirm the simulate result, and it is well consistent with the experimental result.

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