Engineering Commons^™

Exploring The Detection Performance Of Different Array Configurations For Multi-Electrode Resistivity Method Tomography Using A 2.5d Finite Element Method, Zhao Rongchun, Lyu Yuzeng, Zhang Zhi, Wei Liuye, Pan Hongxu

Coal Geology & Exploration

Multi-electrode resistivity method is equipped with various electrode array configurations. Due to their different electrode arrangements, various electrode array configurations tend to exhibit significantly varying detection effects under different survey environments. Hence, to achieve satisfactory detection effects using high-resolution electrical resistivity tomography, it is necessary to explore the strategy for choosing appropriate array configurations targeting different objects in practical work. Given the high applicability of the method, its forward and inversion calculations remain a critical task. Based on the differential equations to be satisfied by the point source potential in a three-dimensional structure, this study derived the variational problem to …

Thermal Behavior Of Plain And Fiber-Reinforced Rigid Concrete Airfield Runways, Arash Karimi Pour

Open Access Theses & Dissertations

The environmental condition and temperature gradient are important factors resulting in concrete airfield runways cracking during the time. Rigid concrete airfield runways experience different thermal gradients during the day and night due to changes in air temperature. Curling and thermal expansion stresses are the main consequences resulting in various types of cracking over the surface and thickness of concrete airfield runways and increasing maintenance costs. The curvature of concrete slabs increases with an increase in the temperature gradient which is amplified when runways open to traffic. Additionally, the combination of the curling and shrinkage stresses, in rare circumstances, can be …

Mathematical Modeling: Finite Element Analysis And Computations Arising In Fluid Dynamics And Biological Applications, Jorge Reyes

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is often the case when attempting to capture real word phenomena that the resulting mathematical model is too difficult and even not feasible to be solved analytically. As a result, a computational approach is required and there exists many different methods to numerically solve models described by systems of partial differential equations. The Finite Element Method is one of them and it was pursued herein.This dissertation focuses on the finite element analysis and corresponding numerical computations of several different models. The first part consists of a study on two different fluid flow models: the main governing model of fluid …

Forward Modeling Of Radio-Magnetotelluric Method Based On Julia Acceleration And Study On Effect Of Displacement Current, Mei Zhuxu, Yuan Yuan, Zhou Feng, Zhou Cong, Zhang Lincheng

Coal Geology & Exploration

Radio-magnetotelluric method (RMT) is one of the important tools for shallow surface electromagnetic exploration. Since the exploration frequency band is 10‒300 kHz, the propagation of electromagnetic fields is greatly affected by the dielectric permittivity of the earth. The electromagnetic response calculated with traditional quasi-static conditions severely restricts the accuracy of RMT forward modeling and further affects the resolution of the inversion imaging. In response to this problem, a numerical simulation method of full-current RMT electromagnetic response based on Julia parallel acceleration was proposed. Then, the calculation of each frequency point was sent through the distributed computing in Julia to different …

Implementation Of A Least Squares Method To A Navier-Stokes Solver, Jada P. Lytch, Taylor Boatwright, Ja'nya Breeden

Rose-Hulman Undergraduate Mathematics Journal

The Navier-Stokes equations are used to model fluid flow. Examples include fluid structure interactions in the heart, climate and weather modeling, and flow simulations in computer gaming and entertainment. The equations date back to the 1800s, but research and development of numerical approximation algorithms continues to be an active area. To numerically solve the Navier-Stokes equations we implement a least squares finite element algorithm based on work by Roland Glowinski and colleagues. We use the deal.II academic library , the C++ language, and the Linux operating system to implement the solver. We investigate convergence rates and apply the least squares …

A Hyperelastic Porous Media Framework For Ionic Polymer-Metal Composites And Characterization Of Transduction Phenomena Via Dimensional Analysis And Nonlinear Regression, Zakai J. Olsen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Ionic polymer-metal composites (IPMC) are smart materials that exhibit large deformation in response to small applied voltages, and conversely generate detectable electrical signals in response to mechanical deformations. The study of IPMC materials is a rich field of research, and an interesting intersection of material science, electrochemistry, continuum mechanics, and thermodynamics. Due to their electromechanical and mechanoelectrical transduction capabilities, IPMCs find many applications in robotics, soft robotics, artificial muscles, and biomimetics. This study aims to investigate the dominating physical phenomena that underly the actuation and sensing behavior of IPMC materials. This analysis is made possible by developing a new, hyperelastic …

Parallel Anisotropic Unstructured Grid Adaptation, Christos Tsolakis, Nikos Chrisochoides, Michael A. Park, Adrien Loseille, Todd Michal

Computer Science Faculty Publications

Computational fluid dynamics (CFD) has become critical to the design and analysis of aerospace vehicles. Parallel grid adaptation that resolves multiple scales with anisotropy is identified as one of the challenges in the CFD Vision 2030 Study to increase the capacity and capability of CFD simulation. The study also cautions that computer architectures are undergoing a radical change, and dramatic increases in algorithm concurrency will be required to exploit full performance. This paper reviews four different methods to parallel anisotropic grid adaptation. They cover both ends of the spectrum: 1) using existing state-of-the-art software optimized for a single core and …

Effect Of New Titanium Alloy On Biomechanical Behavior Of Dental Implant, Jiwu Zhang, Qiguo Rong

Journal of System Simulation

Abstract: Titanium alloy materials have excellent mechanical properties, chemical stability and biocompatibility, and have become the main raw materials for implants. However, the biomechanical compatibility of medical titanium alloys still needs to be improved in order to meet the long-term safety and functionality of patient's clinical treatment requirement. New medical titanium alloy materials with high strength and low modulus play an important role in reducing the loosening and shedding of implants caused by stress shielding. The effects of new medical titanium alloy materials and traditional medical titanium alloy materials on implant structure and stress distribution of jaw are compared and …

Research On Simulation Of Heat Source Model Based On Finite Element Method In Surface Grinding, Wang Yan, Jianhua Xie, Xiong Wei, Yang Lin, Zhang Sheng

Journal of System Simulation

Abstract: Considering the influence of cutting chip thickness on the heat flux distribution, the discrete loading method of heat source model and its effects on numerical calculation error were analyzed. A novel load method towards heat source model with a non-integral function distribution was put forward based on the discretizing idea of finite element method (FEM). On the basis of the new provided load method, simulations about typical grinding conditions were conducted using parabolic and Rayleigh distribution heat source model, to analyze the influence law of heat source model on grinding temperature field. Compared with the measured grinding temperature and …

Modeling And Simulation Of Nonlinear Ultrasonic Evaluation For Steel Damage By Finite Element Analysis, Yanyan Liu, Shiwei Ma

Journal of System Simulation

Abstract: A method was developed to theoretically determine the creep damage of steel by using the nonlinear ultrasonic technique. A two-dimensional finite element model was built to simulate the creep damage of the material and the ultrasonic wave propagation through the degraded material. The nonlinear phenomenon of wave distortion was due to the microstructural changes of the material, which caused distortion that accumulated with propagation distance. Based on the model, the nonlinear parameter of the second-harmonic wave increased with the increase of temperature, which gave some guidelines for the evaluation of the early stage of the degradation of mechanical properties …

Review On Finite Element Model For Anti-Riot Kinetic Projectile Thorax Blunt Impact, Wang Song, Renjun Zhan

Journal of System Simulation

Abstract: In order to promote the construction and verification of the finite element models of human thorax and non-lethal projectiles in the field of blunt ballistic impact, the detailed anatomical and analogous structures of the thorax finite element models are combed and five typical of them are compared and verified. The construction and verification methods of the typical non-lethal projectile models are refined and the impact injury assessment methods are summarized. The next research recommendations are given. In order to improve the accuracy and biological fidelity of the thorax model, it is necessary to establish the physical and finite …

Design And Simulation Of Cut Flat Boring Bar By Both Materials' Composite Structure, Xie Feng, Wenxuan Wang, Xiaobao Lei

Journal of System Simulation

Abstract: Because the stressed structure of the boring bar in machine tool is a cantilever beam, and it is very easy to produce vibration. To study the vibration problem of boring bar, the general structure of boring bar was improved into the built-in damping core boring bar structure composed of two materials, according to the principle of self-excited vibration's coupling flutter and forced vibration's dynamic damping. At the same time, according to the principle that reasonable arrangement of small stiffness of the boring bar could reduce vibration, the composite structure boring bar was cut flat expecting to reach optimal damping …

Analysis Of Finite Element Method On Dynamic Contact Of Corn Ear, Xinping Li, Ma Lei

Journal of System Simulation

Abstract: According to the arrangement law of corn ear kernels, the solid model and the finite element model of the corn ear were established. ANSYS LS-DYNA software was used to analyze the distribution and transmission of stress on the corn ear shocked by wedge impact head. The simulation shows that on the corn ear the Von Mises of the region which is shocked is bigger than other region. Initial phase of the impact head shocking the corn ear, the Von Mises concentrate on both sides of shocked corn kernels. With the falling of the impact head, the Von Mises transmit …

Research On Natural Gas Explosion Rules For Cuboid Obstacles In Offshore Oil Platform, Pengcheng Wang, Yuqing Sun

Journal of System Simulation

Abstract: Quantities and blockage ratios of equipment on the platform has a great effect on the peak overpressure and temperature. The loss caused by explosion can be reduced to the minimum through the reasonable distribution of equipment, and the finite element method has been widely used in the simulation of gas cloud explosion. Offshore oil platform models with different cuboid obstacles were established by the finite element method and cuboid obstacles were distributed in 15 different situations. Mathematical relationships between overpressure and cuboid obstacles' quantities and blockage ratios were obtained. The results show that with the increase of quantities and …

Monte Carlo Simulations Of Coupled Transient Seepage Flow And Compressive Stress In Levees, Fred Thomas Tracy, Ghada Ellithy, Jodi L. Ryder, Martin T. Schultz, Benjamin R. Breland, T. Chris Massey, Maureen K. Corcoran

Publications

The purpose of this research is to compare the results from two different computer programs of flow analyses of two levees at Port Arthur, Texas where rising water of a flood from Hurricane Ike occurred on the levees. The first program (Program 1) is a two-dimensional (2-D) transient finite element program that couples the conservation of mass flow equation with accompanying hydraulic boundary conditions with the conservation of force equations with accompanying x and y displacement and force boundary conditions, thus yielding total head, x displacement, and y displacement as unknowns at each finite element node. The second program (Program …

Numerical Analysis And Fluid Flow Modeling Of Incompressible Navier-Stokes Equations, Tahj Hill

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Navier-Stokes equations (NSE) are an essential set of partial differential equations for governing the motion of fluids. In this paper, we will study the NSE for an incompressible flow, one which density ρ = ρ0 is constant.

First, we will present the derivation of the NSE and discuss solutions and boundary conditions for the equations. We will then discuss the Reynolds number, a dimensionless number that is important in the observations of fluid flow patterns. We will study the NSE at various Reynolds numbers, and use the Reynolds number to write the NSE in a nondimensional form.

We will …

Structure Optimization Analysis Of Distillation Kettle Based On Elastic-Plastic Mechanics, Xiaodong Hu, Liu Ning, Xiangsong Qi, Jianpeng Wang

Journal of System Simulation

Abstract: Based on the analysis of structural strength by elastic mechanics, there is a large stress singularity due to the discontinuity of the equipment structure, which makes the calculation result not consistent with the actual stress of the equipment. According to the actual design and structure of a distillation reactor, based on the theory of elastic-plastic mechanics, through modeling, meshing, loading and constraint analysis, the stress distribution of distillation kettle is analyzed; and the wall thickness and stiffener structure are optimized. The results show that the calculation results are reliable and the design of wall thickness is smaller than the …

Asymmetry Investigation On Radial Tire Contact Pressure Distribution, Haibo Huang, Xudong Yu, Jinpeng Liu, Yao Zhen

Journal of System Simulation

Abstract: The asymmetric pressure distribution in tire contact patch has significant impact on the vehicle fuel economy, tire wear and tire dynamics. In this paper, a FEA model for 205/55R16 semi-steel radial tire was built and verified by static pressure experiments. The influences of tire structural parameters and vehicle driving parameters on asymmetry factor for exploring the asymmetry of the pressure distribution in contact patch were investigated in the steady-state rolling condition. The results show that the influence of the parameters ranging from +50% to -50% on the asymmetry factor of the contact pressure distribution is nonlinear. The impact order …

Numerical Simulation Of Moisture Diffusion Of Composite Solid Propellant, Yufeng Wang, Gaochun Li, Xudong Zhang, Qu Kai, Jinfei Li

Journal of System Simulation

Abstract: In order to elucidate the humidity aging mechanism of composite solid propellant, the diffusion and the distribution of moisture inside the composite solid propellant under humidity was evaluated through the hygroscopic test of propellant. The mathematical and the FE model of moisture diffusion were proposed. The FEM was employed to simulate the moisture diffusion inside propellant. Moreover, the factors that affect the moisture diffusion were analyzed. The results showed that the humidity FEM can be used to simulate the hygroscopic process inside propellant. The temperature can affect the moisture diffusion. The higher the temperature is, the greater the …

Full Field Computing For Elastic Pulse Dispersion In Inhomogeneous Bars, A. Berezovski, R. Kolman, M. Berezovski, D. Gabriel, V. Adamek

Publications

In the paper, the finite element method and the finite volume method are used in parallel for the simulation of a pulse propagation in periodically layered composites beyond the validity of homogenization methods. The direct numerical integration of a pulse propagation demonstrates dispersion effects and dynamic stress redistribution in physical space on example of a one-dimensional layered bar. Results of numerical simulations are compared with analytical solution constructed specifically for the considered problem. Analytical solution as well as numerical computations show the strong influence of the composition of constituents on the dispersion of a pulse in a heterogeneous bar and …

Experiments And Multi-Field Modeling Of Inelastic Soft Materials, Shuolun Wang

Dissertations

Soft dielectrics are electrically-insulating elastomeric materials, which are capable of large deformation and electrical polarization, and are used as smart transducers for converting between mechanical and electrical energy. While much theoretical and computational modeling effort has gone into describing the ideal, time-independent behavior of these materials, viscoelasticity is a crucial component of the observed mechanical response and hence has a significant effect on electromechanical actuation. This thesis reports on a constitutive theory and numerical modeling capability for dielectric viscoelastomers, able to describe electromechanical coupling, large- deformations, large-stretch chain-locking, and a time-dependent mechanical response. This approach is calibrated to the widely-used …

Optimum Design And Operation Analysis Of Permanent Magnet-Assisted Synchronous Reluctance Motor, Jamal Dehghani Ashkezari, Hassan Khajeroshanaee, Mohsen Niasati, Mohammad Jafar Mojibian

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents an optimum design process and operational analysis of a permanent magnet-assisted synchronous reluctance motor (PMASynRM) as a low-cost and highly efficient consumed magnet material machine. The motor's topology is based on inserting partial permanent magnetic materials into flux barriers of an original synchronous reluctance motor (SynRM) that implicitly increase the difference between the machine's inductances, thereby increasing output torque. The procedure of rotor design as the main contribution of this paper is carefully illustrated. The rectangular shape of the flux barriers was found to achieve cost reduction and improve productivity. The impact of the permanent magnet added …

A Spectral Element Method For The Solution Of Magnetostatic Fields, Ibrahim Mahariq, Atakan Erciyas

Turkish Journal of Electrical Engineering and Computer Sciences

Recently, we have seen good progress in our capability to simulate complex electromagnetic systems. However, still there exist many challenges that have to be tackled in order to push limits restricting the field of computational electromagnetics upward. One of these challenges is the limitations in the available computational resources. Over several decades, the traditional computational methods, such as finite difference, finite element, and finite volume methods, have been extensively applied in the field of electromagnetics. On the other hand, the spectral element method (SEM) has been recently utilized in some branches of electromagnetics as waveguides and photonic structures for the …

Designs And Reliability Evaluations Of A Scattered Light Measurement System, Kang-Min Lee

Graduate Theses - Physics and Optical Engineering

The purpose of my work was to develop an in-plane stray light measurement system having the advantage of being easily applicable in both motion control and optical configurations. First of all, mechanical designs were conducted based on both 3D modeling and structural analysis through a finite element method (FEM). Optical configurations for both the incident source and the detector were designed to achieve minimum observed source convergence angle of the system. The control panel and micro stepping system were programmed for automated measurement. Finally, the designed system was calibrated and aligned. In order to evaluate the system reliability for scatter …

Study Of Temperature Distribution In Light--Tissue Interaction Using The Fem, Ahmet Yasi̇n Çi̇tkaya, Şaban Seli̇m Şeker

Turkish Journal of Electrical Engineering and Computer Sciences

In this paper, the numerical modeling of interaction between light sources and living biological tissue is studied. One of the most important results of physical interactions of light with biological tissue are thermal changes, which are a consequence of absorption of light. The severity of the effects is dependent upon several factors, including exposure duration, wavelength of the beam, beam energy, tissue type, and the area that is exposed to the beam. The temperature response of tissue irradiation is governed by the extensively used Pennes bioheat equation in a 3-dimensional space. The Pennes equation is solved initially for a single-layer …

An Application Of Simulated Annealing To Optimal Transcranial Direct Current Stimulation Of The Human Brain, Raheleh Tavakoli, Hamed Sadjedi, Seyyed Mohammad Pourmir Firoozabadi

Turkish Journal of Electrical Engineering and Computer Sciences

Transcranial direct current stimulation (tDCS) is known as the most effective technique for stimulating deeper brain areas. The capability of tDCS, however, strongly depends on the number of electrodes, their positions, and the amount of injected currents. This paper intends to apply the simulated annealing algorithm for determining optimal stimulation parameters in a multiple electrode scheme. The objective of the presented approach is to maximize the current density delivered to the target area under safety constraints. In order for the skin under the electrodes to be protected against temperature rises that may be caused by the stimulation, current injections are …

Multiphysics Modeling To Enhance Understanding Of Microwave Heating Of Food In Domestic Ovens, Jiajia Chen

Department of Biological Systems Engineering: Dissertations and Theses

Nonuniform heating is the biggest issue in the microwave heating of prepared meals. Multiphysics based models are promising tools to improve microwave heating uniformity by properly designing the food product. However, limited availability of accurate temperature-dependent material properties, inadequate model prediction accuracy, and high computational power and complexity in model development are three gaps that greatly limited the application of these models in the food industry.

To fill in the gaps, firstly, we developed a multitemperature calibration protocol to measure temperature-dependent dielectric properties (dielectric constant and loss factor). The temperature-dependent dielectric and thermal (thermal conductivity and specific heat capacity) properties …

Sensitivity Analysis And Optimum Design For The Stator Of Synchronous Reluctance Machines Using The Coupled Finite Element And Taguchi Methods, Hossein Azizi, Abolfazl Vahedi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper presents an investigation of the effect and optimization of stator geometry design parameters on the performance of synchronous reluctance machines (SynRMs). The level of importance of the stator design variable on the characteristic of the SynRM is determined using both the Taguchi method and a parametric analysis. An optimum design parameter combination is obtained using sensitivity analysis along with signal-to-noise ratio results. The 2-dimensional finite element model (FEM) of a SynRM is used to perform a sensitivity analysis and construct a Taguchi design of the experiment. The FEM simulation results confirm that the performance of the SynRM can …

A Combined Quadtree/Delaunay Method For 2d Mesh Generation, Simon Tang

Masters Theses 1911 - February 2014

Unstructured simplicial mesh is an integral and critical part of many computational electromagnetics methods (CEM) such as the finite element method (FEM) and the boundary element method (BEM). Mesh quality and robustness have direct impact on the success of these CEM methods.

A combined quadtree/Delunay 2D mesh generator, based on the early work of Schroeder (1991, PhD), is presented. The method produces a triangulation that approximates the original geometric model but is also topologically consistent. The key advantages of the method are: (a) its robustness, (b) ability to create a-priori graded meshes, and (c) its guaranteed mesh quality.

The method …

Finite Element Modeling Of A Superconducting Fault Current Limiter, Lale Ergene, J. Keith Nelson, Raghunath Parthasarathi

Turkish Journal of Electrical Engineering and Computer Sciences

This paper summarizes the work done to show finite element modeling results on a high temperature superconductor fault current limiter (FCL). The paper also gives the small mock-up design of the matrix FCL and its finite element model (FEM). It also discusses the limitations of the FEM and explains how the results from the FEM compare with the experimental data derived for the configuration. A 3-dimensional FEM has been used because of the structure of the real geometry, which does not show any plane or axisymmetric features.