Numerical studies of wave propagation through concrete walls using effective material property technique and FDTD method

2003 ◽  
Author(s):  
Wen-Chin Lan ◽  
Hsi-Tseng Chou ◽  
Hsing-Yi Chen
Keyword(s):  
Wave Propagation ◽  
Material Property ◽  
Fdtd Method ◽  
Concrete Walls ◽  
Numerical Studies ◽  
Effective Material Property

The Behavior of Electromagnetic Wave Propagation in Photonic Crystals with or without a Defect

2021 ◽  
Vol 36 (6) ◽  
pp. 632-641
Author(s):  
Ayse Basmaci
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Photonic Crystal ◽  
Fundamental Frequency ◽  
Material Property ◽  
Finite Differences ◽  
Electromagnetic Wave Propagation ◽  
Fdtd Method ◽  
Propagation Equation ◽  
Finite Differences Method

In this study, the electromagnetic wave propagation behavior of two-dimensional photonic crystal plates with a defect is investigated. For this purpose, the partial differential equation for the electromagnetic wave propagation in various photonic crystal plates containing a defect or not is obtained by using Maxwell’s equations. The defect is also defined in the electromagnetic wave propagation equation appropriately. In order to solve the electromagnetic wave propagation equation, the finite differences method is used. The material property parameters of the photonic crystal plates are determined with respect to the defects. Accordingly, the effects of material property parameters on electromagnetic wave propagation frequencies, phase velocities, and group velocities are examined. The effects of the size and position of the defects on the electromagnetic wave propagation frequencies are also discussed. The highest electromagnetic wave propagation fundamental frequency value obtained from the analyses performed is 1.198 Hz. This fundamental frequency value is obtained for the electromagnetic wave propagation in the t-shaped photonic crystal plate. Electromagnetic field distribution maps for the fundamental frequencies of the photonic crystal plates whose electromagnetic wave propagation behaviors are examined are obtained with the ANSYS package program based on the finite differences time-domain (FDTD) method.

Prediction of Effective Material Property of Tailor Welded Blanks for Air Bending Process

2012 ◽  
Vol 472-475 ◽  
pp. 761-766
Author(s):  
Yong Chuan Duan ◽  
Ying Ping Guan ◽  
Xing Dong Ma
Keyword(s):  
Finite Element ◽  
Tensile Test ◽  
Finite Element Model ◽  
Material Property ◽  
Statistical Error ◽  
Element Model ◽  
Ann Model ◽  
Process Data ◽  
Tailor Welded Blanks ◽  
Effective Material Property

A method based on artificial neural network (ANN) for predicting the effective material property is put forward in this paper. The finite element model of tensile test specimen is modeled in LS-DYNA code, which has transverse weld at the middle of the specimen and conforms to the ASTM specification. A statistical error analysis model is used to include the random phenomenon in the result of tensile test finite element model and verify the accuracy of finite element model (FEM) simulation. In order to study the effect of the processing parameter with design of experiment is followed, the simulation trail is conducted in all the levels of parameters. It is assumed that Hollomon’s law is followed by tailor welded blanks. The results obtained from fitting the post-process data of FEM by least square method are used to train and develop ANN model, the prediction average error of ANN model is acceptable compared with simulation trail.

Investigation of Contact Conditions During Stamping of a Thin Plate

2020 ◽  
Author(s):  
Harshal Y. Shahare ◽  
Rohan Rajput ◽  
Puneet Tandon
Keyword(s):  
Wave Propagation ◽  
Material Properties ◽  
High Speed ◽  
Fdtd Method ◽  
Propagation Model ◽  
Transmitted Wave ◽  
Two Dimensional ◽  
Contact Conditions ◽  
Simulation Based ◽  
Difference Time

Abstract Stamping is one of the most used manufacturing processes, where real-time monitoring is quite difficult due to high speed of the mechanical press, which leads to deterioration of the accuracy of the products In the present work, a method is developed to model elastic waves propagation in solids to measure contact conditions between die and workpiece during stamping. A two-dimensional model is developed that reduces the wave propagation equations to two-dimensional equations. To simulate the wave propagation inside the die-workpiece model, the finite difference time domain (FDTD) method and modified Yee algorithm has been employed. The numerical stability of the wave propagation model is achieved through courant stability condition, i.e., Courant-Friedrichs-Lewy (CFL) number. Two cases, i.e., flat die-workpiece interface and inclined die-workpiece interface, are investigated in the present work. The elastic wave propagation is simulated with a two-dimension (2D) model of the die and workpiece using reflecting boundary conditions for different material properties. The experimental and simulation-based results of reflected and transmitted wave characteristics are compared for different materials in terms of reflected and transmitted wave height ratio and material properties such as acoustic impedance. It is found that the numerical simulation results are in good agreement with the experimental results.

scholarly journals EFFECTIVE MATERIAL PROPERTY EXTRACTION OF A METAMATERIAL BY TAKING BOUNDARY EFFECTS INTO ACCOUNT AT TE/TM POLARIZED INCIDENCE

2012 ◽  
Vol 36 ◽  
pp. 1-33 ◽  
Author(s):  
Sung Kim ◽  
Edward F. Kuester ◽  
Christopher L. Holloway ◽  
Aaron D. Scher ◽  
James R. Baker-Jarvis
Keyword(s):  
Material Property ◽  
Boundary Effects ◽  
Effective Material Property

Effects of the cancellous bone structure in the skull on ultrasonic wave propagation

2020 ◽  
Author(s):  
Itsuki Michimoto ◽  
Keita Yano ◽  
Yasuyo Kobayashi ◽  
Kozue Saito ◽  
Mami Matsukawa
Keyword(s):  
Wave Propagation ◽  
Temporal Bone ◽  
Elderly Women ◽  
Bone Structure ◽  
Cerebral Blood Flow Velocity ◽  
Fdtd Method ◽  
Maximum Amplitude ◽  
Arterial Stenosis ◽  
Skull Bone ◽  
Cancellous Bone Structure

Abstract The Transcranial Doppler method (TCD) enables the measurement of cerebral blood flow velocity and detection of emboli by applying the ultrasound probe to the temporal bone window, orbital, or greater occipital foramen. TCD is widely used for the evaluation of cerebral vasospasm after subarachnoid hemorrhage, early detection of patients with arterial stenosis and the check of brain death. However, measurements often become difficult in elderly women. Among various factors for this problem, we focused on the effect of the skull bone on the ultrasound penetration into the brain. Especially, the effect of the temporal bone structure was investigated. Using a 2D digital bone model, wave propagation through the skull bone was investigated by the Finite-Difference Time-Domain (FDTD) method. We create bone models which have different BV/TV (Bone Volume/Total Volume) in diploe. Around BV/TV about 60% (similar to elderly women), the observed maximum amplitude decrease due to multiple reflection and scattering. The results suggest that effects of osteoposis on the skull make TCD measurement difficult.

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