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Applied Mathematics

2016

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Full-Text Articles in Mechanical Engineering

Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook Dec 2016

Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook

Electronic Theses and Dissertations

This dissertation is concerned with the development of robust numerical solution procedures for the generalized micromechanical analysis of linear and nonlinear constitutive behavior in heterogeneous materials. Although the methods developed are applicable in many engineering, geological, and materials science fields, three main areas are explored in this work. First, a numerical methodology is presented for the thermomechanical analysis of heterogeneous materials with a special focus on real polycrystalline microstructures obtained using electron backscatter diffraction techniques. Asymptotic expansion homogenization and finite element analysis are employed for micromechanical analysis of polycrystalline materials. Effective thermoelastic properties of polycrystalline materials are determined and compared ...


Multi-Dome Forming Of A Ti–Al–Mn Alloy, Sergey Aksenov, Aleksey Kolesnikov, Ivan Zakhariev Oct 2016

Multi-Dome Forming Of A Ti–Al–Mn Alloy, Sergey Aksenov, Aleksey Kolesnikov, Ivan Zakhariev

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.


Multi-Disciplinary Hands-On Desktop Learning Modules And Modern Pedagogies, Bernard J. Van Wie, David B. Thiessen, Marc Compere, Ximena Toro, Jennifer C. Adam, Et Al. Sep 2016

Multi-Disciplinary Hands-On Desktop Learning Modules And Modern Pedagogies, Bernard J. Van Wie, David B. Thiessen, Marc Compere, Ximena Toro, Jennifer C. Adam, Et Al.

Marc Compere

Our team’s research focuses on fundamental problems in undergraduate education in terms of how to expand use of well researched, yet still “new”, teaching pedagogies of ‘sensing’ or ‘hands-on’, ‘active’ and ‘problem-based learning’ within engineering courses. It is now widely accepted that traditional lectures ARE NOT best for students – yet that is what the community almost universally does. To address this issue we are developing new Desktop Learning Modules (DLMs) that contain miniaturized processes with a uniquely expandable electronic system to contend with known sensor systems/removable cartridges, as well as, unknown expansions to the project. We have shown ...


Project Haiti 2012: Providing An Experiential Learning Experience Through The Design And Delivery Of A Water Purifier In Haiti, Yung Wong, Johnathon Camp, Shavin Pinto, Kyle Fennesy, Marc Compere, Yan Tang Sep 2016

Project Haiti 2012: Providing An Experiential Learning Experience Through The Design And Delivery Of A Water Purifier In Haiti, Yung Wong, Johnathon Camp, Shavin Pinto, Kyle Fennesy, Marc Compere, Yan Tang

Marc Compere

In this paper, we share our experiences and lessons learned from Project Haiti 2012, a project to design and install a water purification system serving 20,000 people per day in the largest tent city in Haiti. Project Haiti 2012 was the third and largest system we have built for Haitians and represents a huge success for all participants and stakeholders. This paper discusses the unique experiential learning opportunity involved in the design and delivery of the water purifier in a foreign developing country. Multiple positive educational, social, and economic outcomes were achieved including students applying knowledge gained from coursework ...


High Tech High Touch: Lessons Learned From Project Haiti 2011, Yan Tang, Marc Compere, Yung Lun Wong, Jared Anthony Coleman, Matthew Charles Selkirk Sep 2016

High Tech High Touch: Lessons Learned From Project Haiti 2011, Yan Tang, Marc Compere, Yung Lun Wong, Jared Anthony Coleman, Matthew Charles Selkirk

Marc Compere

In this paper, we will share our experiences and lessons learned from a design project for providing clean water to a Haitian orphanage (Project Haiti 2011). Supported by funds from a renewable energy company and the university president’s office, five engineering students and two faculty members from Embry-Riddle Aeronautical University successfully designed and installed a solar powered water purification system for an orphanage located in Chambellan, Haiti. This paper discusses the unique educational experiences gained from unusual design constraints, such as ambiguity of existing facilities due to limited communication, logistics of international construction at a remote village location, and ...


A Fast Model For The Simulation Of External Gear Pumps, Zechao Lu, Xinran Zhao, Andrea Vacca Aug 2016

A Fast Model For The Simulation Of External Gear Pumps, Zechao Lu, Xinran Zhao, Andrea Vacca

The Summer Undergraduate Research Fellowship (SURF) Symposium

External gear pump is an important category of positive displacement fluid machines used to perform the mechanical–hydraulic energy conversions in many fluid power applications. An efficient numerical simulation program is needed to simulate the system in order to provide a direction for design purpose. The model consists of a lumped parameter fluid dynamic model and a model that simulates the radial micro-motions of the gear’s axes of rotation. The system consists of a set of ordinary differential equations related to the conservation on mass of the internal control volumes of the pump, which are given by the tooth ...


Delay-Independent Stability Analysis Of Linear Time-Delay Systems Based On Frequency, Xianwei Li, Huijun Gao, Keqin Gu Aug 2016

Delay-Independent Stability Analysis Of Linear Time-Delay Systems Based On Frequency, Xianwei Li, Huijun Gao, Keqin Gu

SIUE Faculty Research, Scholarship, and Creative Activity

This paper studies strong delay-independent stability of linear time-invariant systems. It is known that delay-independent stability of time-delay systems is equivalent to some frequency-dependent linear matrix inequalities. To reduce or eliminate conservatism of stability criteria, the frequency domain is discretized into several sub-intervals, and piecewise constant Lyapunov matrices are employed to analyze the frequency-dependent stability condition. Applying the generalized Kalman–Yakubovich–Popov lemma, new necessary and sufficient criteria are then obtained for strong delay-independent stability of systems with a single delay. The effectiveness of the proposed method is illustrated by a numerical example.


Implementing And Testing A Panel-Based Method For Modeling Acoustic Scattering From Cfd Input, S. Hales Swift Aug 2016

Implementing And Testing A Panel-Based Method For Modeling Acoustic Scattering From Cfd Input, S. Hales Swift

Open Access Dissertations

Exposure of sailors to high levels of noise in the aircraft carrier deck environment is a problem that has serious human and economic consequences. A variety of approaches to quieting exhausting jets from high-performance aircraft are undergoing development. However, testing of noise abatement solutions at full-scale may be prohibitively costly when many possible nozzle treatments are under consideration. A relatively efficient and accurate means of predicting the noise levels resulting from engine-quieting technologies at personnel locations is needed. This is complicated by the need to model both the direct and the scattered sound field in order to determine the resultant ...


Cfd Model For Ventilation In Broiler Holding Sheds, Christian Heymsfield May 2016

Cfd Model For Ventilation In Broiler Holding Sheds, Christian Heymsfield

Biological and Agricultural Engineering Undergraduate Honors Theses

Broiler production in Arkansas was valued at over $3.6 billion in 2013 (University of Arkansas Extension of Agriculture). Consequently, improvement in any phase of the production process can have significant economic impact and animal welfare implications. From the time poultry leave the farm and until they are slaughtered, they can be exposed to harsh environmental conditions, both in winter and in summer. After road transportation, birds are left to wait in holding sheds once they arrive at the processing plant, for periods of approximately 30 minutes to two hours. This project was interested in this holding shed waiting time ...


On The Scattering Of An Acoustic Plane Wave By A Soft Prolate Spheroid, Joseph Michael Borromeo May 2016

On The Scattering Of An Acoustic Plane Wave By A Soft Prolate Spheroid, Joseph Michael Borromeo

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis solves the scattering problem in which an acoustic plane wave of propagation number K1 is scattered by a soft prolate spheroid. The interior field of the scatterer is characterized by a propagation number K2, while the field radiated by the scatterer is characterized by the propagation number K3. The three fields and their normal derivatives satisfy boundary conditions at the surface of the scatterer. These boundary conditions involve six complex parameters depending on the propagation numbers. The scattered wave also satisfies the Sommerfeld radiation condition at infinity. Through analytical methods, series representations are constructed for the interior field ...


Procesy Cieplne I Aparaty (Lab), Wojciech M. Budzianowski Jan 2016

Procesy Cieplne I Aparaty (Lab), Wojciech M. Budzianowski

Wojciech Budzianowski

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Inżynieria Chemiczna Lab., Wojciech M. Budzianowski Jan 2016

Inżynieria Chemiczna Lab., Wojciech M. Budzianowski

Wojciech Budzianowski

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Robust Identification Of Dynamically Distinct Regions In Stratified Turbulence, Gavin D. Portwood, Stephen M. De Bruyn Kops, J. R. Taylor, H. Salehipour, C. P. Caulfield Jan 2016

Robust Identification Of Dynamically Distinct Regions In Stratified Turbulence, Gavin D. Portwood, Stephen M. De Bruyn Kops, J. R. Taylor, H. Salehipour, C. P. Caulfield

Mechanical and Industrial Engineering Faculty Publication Series

we present a new robust method for identifying three dynamically distinct regions in a stratified turbulent flow, which we characterise as quiescent flow, intermittent layers, and turbulent patches. The method uses the cumulative filtered distribution function of the local density gradient to identify each region. We apply it to data from direct numerical simulations of homogeneous stratified turbulence, with unity Prandtl number, resolved on up to 8192x8192x4092 grid points. In addition to classifying regions consistently with contour plots of potential enstropy, our method identifies quiescent regions as regions where ∊ ⁄ νΝ2 ~ Ο(1), layers as regions where ∊ ⁄ νΝ2 ~ Ο ...


Curvature-Dependence Of Cut-Off Frequencies Of Guided Waves Propagating Through Curved Structures Obtained By A Semi-Analytical Finite Element Method, Kosuke Kanda, Toshihiko Sugiura Jan 2016

Curvature-Dependence Of Cut-Off Frequencies Of Guided Waves Propagating Through Curved Structures Obtained By A Semi-Analytical Finite Element Method, Kosuke Kanda, Toshihiko Sugiura

Review of Progress in Quantitative Nondestructive Evaluation

Non-destructive testing (NDT) and structural health monitoring (SHM) are engineering techniques for investigating defects without breaking structures. Guided wave ultrasonic modes propagating over long distances can be applied to NDT for long structures such as plates, rods and pipes. Guided waves have a dispersion property, which represents dependence of propagation velocities on frequencies. Therefore, for effective use of guided waves, we need to know this property, which is usually expressed as dispersion curves [1]~[3].

The goal of this paper is to numerically investigate effects of curvatures on the dispersion property of guided waves propagating in a helical structure and ...


Constitutive Damage Variable Measurement In Composites Using Guided Waves, Olivier Mesnil, Massmo Ruzzene Jan 2016

Constitutive Damage Variable Measurement In Composites Using Guided Waves, Olivier Mesnil, Massmo Ruzzene

Review of Progress in Quantitative Nondestructive Evaluation

Cohesive Zone Methods (CZMs) are numerical methods used to numerically simulate damage initiation and growth at the interfaces of composite materials under external loading. These techniques provide estimates of the residual properties of a damaged specimen such as residual strengths, fatigue life or stiffness losses. To run these simulations, it is necessary to measure material properties such as the strengths of the interfaces. To describe the state of the structure at a given time instant during the loading, CZMs define a damage variable D which is a constitutive variable of the structure assessing its current state of health. The literature ...


Finite Element Modeling Of Resonance In Polycrystalline Materials For Resonance Ultrasound Spectroscopy, T. J. Lesthaeghe, R. A. Adebisi, S. Sathish, R. Cherry, P. A. Shade, J. C. Aldrin Jan 2016

Finite Element Modeling Of Resonance In Polycrystalline Materials For Resonance Ultrasound Spectroscopy, T. J. Lesthaeghe, R. A. Adebisi, S. Sathish, R. Cherry, P. A. Shade, J. C. Aldrin

Review of Progress in Quantitative Nondestructive Evaluation

Validation of models that predict the performance of aerospace engine materials depends on the ability to obtain accurate single crystal elastic constants. Resonance Ultrasound Spectroscopy (RUS) is a nondestructive technique in which the natural resonances of a material are utilized to obtain these constants. Traditional RUS utilizes an analytic approach to determine the resonance frequencies of a specimen given an initial guess set of elastic constants. A nonlinear optimization process then fits the elastic constants to experimentally measured data. This approach is limited both in its ability to handle specimens with complex geometry and to handle polycrystalline materials. These more ...


Hybrid Ray-Fdtd Model For The Simulation Of The Ultrasonic Inspection Of Cfrp Parts, Pierre Calmon, Karim Jezzine, Damien Segur, Romain Ecault, Nicolas Dominguez Jan 2016

Hybrid Ray-Fdtd Model For The Simulation Of The Ultrasonic Inspection Of Cfrp Parts, Pierre Calmon, Karim Jezzine, Damien Segur, Romain Ecault, Nicolas Dominguez

Review of Progress in Quantitative Nondestructive Evaluation

Carbon Fiber Reinforced Polymers (CFRP) are commonly used in structural parts in the aeronautic industry, to reduce the weight of aircraft while maintaining high mechanical performances. Simulation of the ultrasonic inspections of these parts has to face the highly heterogeneous and anisotropic characteristics of these materials. To model the propagation of ultrasound in these composite structures, we propose two complementary approaches. The first one is based on a ray model predicting the propagation of the ultrasound in an anisotropic effective medium obtained from a homogenization of the material. The ray model is designed to deal with possibly curved parts and ...


Multimode Model Based Defect Characterization In Composites, R. Roberts, S. Holland Jan 2016

Multimode Model Based Defect Characterization In Composites, R. Roberts, S. Holland

Review of Progress in Quantitative Nondestructive Evaluation

This paper reports on work to explore model based defect characterization methods for NDE of CFRP composites. The work is examining defect responses obtained with ultrasound and thermography, for the purpose of classifying and characterizing the defect through combined analysis of the multiple-mode data. Analysis is premised on the availability of forward scattering models to predict NDE response to specified defects. The approach to defect characterization identifies a set of parameters describing the defect, then optimizes agreement between NDE measurements and measurement predictions through manipulation of defect descriptors, subject to ancillary measures of defect properties imposed to regularize an otherwise ...


Comparison Of Numerical Simulations And Analytical Theories For Elastic Wave Scattering Within Polycrystalline Materials, A. Van Pamel, G. Sha, S. I. Rokhlin, M. J. S. Lowe Jan 2016

Comparison Of Numerical Simulations And Analytical Theories For Elastic Wave Scattering Within Polycrystalline Materials, A. Van Pamel, G. Sha, S. I. Rokhlin, M. J. S. Lowe

Review of Progress in Quantitative Nondestructive Evaluation

Understanding the propagation and scattering of ultrasonic waves within polycrystalline materials is relevant to both material characterisation and flaw detection NDE. Validating analytical theories of scattering however has historically been hampered by the difficulty of obtaining sufficiently reliable experimental data where the statistical properties of the grains within the volume of the material are known well enough. Instead, this presentation exploits important recent progress in numerical modelling, which for the first time enables accurate three-dimensional simulations of wave propagation and scattering in polycrystals. The presentation reports work using such a model to compare and validate 3D numerical simulations of wave ...


Modeling For Ut Inspection Of Anisotropic Materials, Robert A. Roberts, Robert Grandin, Andrew Downs Jan 2016

Modeling For Ut Inspection Of Anisotropic Materials, Robert A. Roberts, Robert Grandin, Andrew Downs

Review of Progress in Quantitative Nondestructive Evaluation

This presentation reports on the extension of an established CNDE ultrasound beam transmission model to accommodate transmission in generally anisotropic materials. Using principles of elastodynamic reciprocity, the model expresses the internal wave field as a surface integral over the radiating transducer, employing the full Green function (point force response function) for the combined body under inspection and the coupling medium. The model evaluates the Green function asymptotically for short wavelength, and is therefore referred to as an asymptotic Green function model (AGF). The integrand of the transducer integral is projected on to a discretely orthogonal Gaussian basis, leading to a ...


Full Wave Modeling Of Ultrasonic Scattering Using Nystrom Method For Nde Applications, Praveen Gurrala, Kun Chen, Jiming Song, Ron Roberts Jan 2016

Full Wave Modeling Of Ultrasonic Scattering Using Nystrom Method For Nde Applications, Praveen Gurrala, Kun Chen, Jiming Song, Ron Roberts

Review of Progress in Quantitative Nondestructive Evaluation

Approximate methods for ultrasonic scattering like the Kirchhoff approximation and the geometrical theory of diffraction (GTD) can deliver fast solutions with relatively small computational resources compared to accurate numerical methods. However, these models are prone to inaccuracies in predicting scattered fields from defects that are not very large compared to wavelength. Furthermore, they do not take into account physical phenomena like multiple scattering and surface wave generation on defects. Numerical methods like the finite element method (FEM) and the boundary element method (BEM) can overcome these limitations of approximate models. Commercial softwares such as Abaqus FEA and PZFlex use FEM ...


Modeling Of Piezoelectric Traveling Wave Rotary Ultrasonic Motors With The Finite Volume Method, Ivan Arturo Renteria Marquez Jan 2016

Modeling Of Piezoelectric Traveling Wave Rotary Ultrasonic Motors With The Finite Volume Method, Ivan Arturo Renteria Marquez

Open Access Theses & Dissertations

In 1983 Toshiiku Sashida developed a new motor concept called Piezoelectric Traveling Wave Rotary Ultrasonic Motor (PTRUSM). The advantages of these motors include high torque at low speed, absence of a generated magnetic field, and high potential for miniaturization. Unfortunately PTRUSMs have some disadvantages that limit the areas of applications for these types of motors. The disadvantages are a short operating life (about 1000 hours), small output power, and the need of a complex motor controller.

On one hand, these motors have been used in satellites, mobile phones, photocopiers, robotic arms, telescopes, automobiles, and camera autofocusing. On the other hand ...


Methodology For Analyzing Epoxy-Cnt Phononic Crystals For Wave Attenuation And Guiding, Madhu Kolati Jan 2016

Methodology For Analyzing Epoxy-Cnt Phononic Crystals For Wave Attenuation And Guiding, Madhu Kolati

Dissertations, Master's Theses and Master's Reports

Phononic crystals (PhnCs) control, direct and manipulate sound waves to achieve wave guiding and attenuation. This dissertation presents methodology for analyzing nanotube materials based phononic crystals to achieve control over sound, vibration and stress mitigation. Much of the analytical work presented is in identifying frequency band gaps in which sound or vibration cannot propagate through these PhnCs. Wave attenuation and mitigation analysis is demonstrated using finite element simulation. Engineering principles from current research areas of solid mechanics, solid-state physics, elasto-dynamics, mechanical vibrations and acoustics are employed for the methodology. A considerable effort is put to show that these PhnCs can ...


Project Oasis: Optimizing Aquaponic Systems To Improve Sustainability, Siddharth Nigam, Paige Balcom Jan 2016

Project Oasis: Optimizing Aquaponic Systems To Improve Sustainability, Siddharth Nigam, Paige Balcom

Honors Theses and Capstones

Started in Fall 2015, Project OASIS (Optimizing Aquaponic Systems to Improve Sustainability) is an interdisciplinary capstone project with the goal of designing a sustainable and affordable small-scale aquaponic system for use in developing nations to tackle the problems of malnutrition and food insecurity. Aquaponics is a symbiotic relationship between fish and vegetables growing together in a recirculating system. The project’s goals were to minimize energy consumption and construction costs while using universally available materials. The computational fluid dynamics (CFD) software OpenFOAM was used to create transient and steady-state models of fish tanks to visualize velocity profiles, streamlines, and particle ...