Engineering Commons^™

Lidar Assessment To Monitor Bridge Response Under Live And Dead Loads, Daniel Watson

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Understanding how a bridge structure responds to various loads in a time and resource-efficient approach is vital in characterizing bridge health. Bridge health monitoring is an evaluation of the structural condition and performance, which optimizes limited transportation budgets by prioritizing the bridges that are in the most need for retrofit or replacement. Identifying and remedying issues will mitigate long-term problems and ensure that the bridge remains open to service for all legal loads. In contrast, health monitoring and load rating will determine if a bridge can only carry traffic up to a certain weight or speed, requiring a bridge load …

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 …

Hybrid Long-Range Mid-Infrared Hyperbolic Phonon Polariton Waveguide Using Hexagonal Boron Nitride, Di Xiong

Theses and Dissertations

For any photonic-on-chip applications long propagation waveguides are critical. The use of plasmon polaritons for near-infrared and optical networks has been extensively studied for the purpose of achieving long propagation lengths, however, due to plasmonic polariton effects being negligible in mid- to long-wave infrared (IR) applications, phonon polaritons are required. In recent years, extensive research has been carried out on hexagonal boron nitride (h-BN), and it has been found that h-BN has naturally occurring sub-range phonon volume-constrained hyperbolic phonon polaritons (HPhPs). The numerical results in this thesis show both the long-range and short-range phonon volume polaritons modes in h-BN. A …

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 …

Wrinkling Of Membrane And Thin Film Under Torsion, Tingting Chen

Dissertations and Theses

Membranes and thin film structures are widely used in modern technologies. Applications include solar sails and sunshields in space missions, biological membranes and flexible circuit boards. Wrinkling of membrane or a stiff film on a soft substrate may occur in either desired or unwanted patterns. This work tries to obtain some understanding on the wrinkling phenomenon and provide guidance in avoiding wrinkling or effectively controlling the wrinkle patterns.

Many works have been published about wrinkling in the thin sheets since the 20^th century. However, there is no simple analytical way to systematically characterize the wrinkling in these studies. In …

Mechanical Characterizations Of 3d-Printed Plla/Steel Particle Composites, Hozhabr Mozafari, Pengfei Dong, Haitham Hadidi, Michael P. Sealy, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

The objective of this study is to characterize the micromechanical properties of poly-L-lactic acid (PLLA) composites reinforced by grade 420 stainless steel (SS) particles with a specific focus on the interphase properties. The specimens were manufactured using 3D printing techniques due to its many benefits, including high accuracy, cost effectiveness and customized geometry. The adopted fused filament fabrication resulted in a thin interphase layer with an average thickness of 3 μm. The mechanical properties of each phase, as well as the interphase, were characterized by nanoindentation tests. The effect of matrix degradation, i.e., imperfect bonding, on the elastic modulus of …

A High Torque Density Halbach Rotor Coaxial Magnetic Gear, Ho Yin Wong, Jonathan Z. Bird, David Barnett, Wesley Williams

Electrical and Computer Engineering Faculty Publications and Presentations

This paper presents the design, analysis, and experimental testing results for a 5.67:1 Halbach rotor magnetic gearbox with a ferromagnetic back support. Using 3-D finite element analysis software the Halbach magnetic gearbox was calculated to achieve a volumetric torque density of 284N·m/L with only an active region outer diameter of 120mm. The experimental prototype obtained an active region volumetric torque density of 261.4N·m/L

Solving Galbrun’S Equation With A Discontinuous Galerkin Finite Element Method, Marcus Maeder, Andrew Peplow, Maximilian Meindl, Steffen Marburg

All Works

© S. Hirzel Verlag · EAA Over many years, scientists and engineers have developed a broad variety of mathematical formulations to investigate the propagation and interactions with flow of flow-induced noise in early-stage of product design and development. Beside established theories such as the linearized Euler equations (LEE), the linearized Navier–Stokes equations (LNSE) and the acoustic perturbation equations (APE) which are described in an Eulerian framework, Galbrun utilized a mixed Lagrange–Eulerian framework to reduce the number of unknowns by representing perturbations by means of particle displacement only. Despite the advantages of fewer degrees of freedom and the reduced effort to …