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Mississippi State University Department of Mechanical Engineering

Overview
Works: 74 works in 77 publications in 1 language and 78 library holdings
Genres: Academic theses  Handbooks and manuals 
Publication Timeline
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Most widely held works by Mississippi State University
Investigating nondestructive evaluation of carbon fiber reinforced polymer beams using embedded Terfenol-D particle sensors by Jonathan D Rudd( )

2 editions published in 2014 in English and held by 2 WorldCat member libraries worldwide

Reinforced fiber polymer composites are a class of materials that are composed of multiple constituents that work together to create a material specific for applications. By combining different fibers and matricies, laminates can be created that meet demands for high specific stiffness, damping specifications, and electrical resistance. However, their internal complexity subjects them to a number of internal failure modes that have the potential to fail the laminate. Those failure mechanisms are fiber breaking, microcracking in the matrix, debonding of the fibers from matrix, and delamination of ply layers. To assess these failures, nondestructive evaluation methods have been developed to detect internal damage before catastrophic failure occurs. This dissertation investigates an in-situ magnetostrictive based nondestructive method for monitoring delaminations in carbon fiber reinforced polymer laminates by using embedded Terfenol-D particles. The objective is to characterize how laminate ply count and delamination presence affect sensing through the mechanical and magnetic parameters that influence the induced voltage or sensing signal. In addition, the effect of magnetostriction on the formation and propagation of cracks on the sensor boundaries are also investigated. Methods used to characterize this behavior involve experimental testing, analytical, and numerical modeling. From the results, a threedimensional finite element analysis model reveals how the sensor interacts mechanically with the host structure through lower stresses in the delaminated region due to the absence of adhesive forces. The stress variation results in a local magnetic permeability change which influences the induced voltage. The experimental nondestructive testing show that the key parameter influencing the sensing signal for this setup was the particle density, which is controlled by fabrication process. An attempt to analytically model the experimental sensing signal with a first order differential equation using a multi-step process was successful, but there is poor correlation with the experimental results. Finally, analytical mechanics are developed to evaluate the interlaminar failure under a magnetostrictive stress of 55MPa, and was found to not cause interlaminar failure or delamination propagation in Section-A
Time-averaged surrogate modeling for small scale propellers based on high-fidelity CFD simulations by Joseph Ray Carroll( )

1 edition published in 2013 in English and held by 1 WorldCat member library worldwide

Many Small Unmanned Aerial Vehicles (SUAV) are driven by small scale, fixed blade propellers. The flow produced by the propeller, known as the propeller slipstream, can have significant impact on SUAV aerodynamics. In the design and analysis process for SUAVs, numerous Computational Fluid Dynamic (CFD) simulations of the coupled aircraft and propeller are often conducted which require a time-averaged, steady-state approximation of the propeller for computational efficiency. Most steady-state propeller models apply an actuator disk of momentum sources to model the thrust and swirl imparted to the flow field by a propeller. These momentum source models are based on simplified theories which lack accuracy. Currently, the most common momentum source models are based on blade element theory. Blade element theory discretizes the propeller blade into airfoil sections and assumes them to behave as two-dimensional (2D) airfoils. Blade element theory neglects many 3D flow effects that can greatly affect propeller performance limiting its accuracy and range of application. The research work in this dissertation uses a surrogate modeling method to develop a more accurate momentum source propeller model. Surrogate models for the time averaged thrust and swirl produced by each blade element are trained from a database of time-accurate, high-fidelity 3D CFD propeller simulations. Since the surrogate models are trained from these high-fidelity CFD simulations, various 3D effects on propellers are inherently accounted for such as tip loss, hub loss, post stall effect, and element interaction. These efficient polynomial response surface surrogate models are functions of local flow properties at the blade elements and are embedded into 3D CFD simulations as locally adaptive momentum source terms. Results of the radial distribution of thrust and swirl for the steady-state surrogate propeller model are compared to that of time-dependent, high-fidelity 3D CFD propeller simulations for various aircraft-propeller coupled situations. This surrogate propeller model which is dependent on local flow field properties simulates the time-averaged flow field produced by the propeller at a momentum source term level of detail. Due to the nature of the training cases, it also captures the accuracy of time-dependent 3D CFD propeller simulations but at a much lower cost
Fatigue behavior and modeling of polyether ether ketone (PEEK) under constant and variable amplitude loadings( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

<p>The fatigue behavior and cyclic deformation of polyether ether ketone (PEEK) subjected to various uniaxial cyclic loading conditions were experimentally investigated. These include constant amplitude and multi-block loading conditions at various frequencies with zero and non-zero mean strains. Under constant amplitude loading, increasing the test frequency generally resulted in longer fatigue lives for PEEK, while a minimal effect of tensile mean strain was observed. For all fatigue tests under fully- reversed multi-block loadings, pre-loading was found to have a significant beneficial effect on PEEK fatigue resistance irrespective to the load sequence. However, no obvious load history and sequence effect on fatigue behavior was observed for pulsating tension block loading tests. Additionally, three models; strain-based, strain-stress-based, and energy-based models, were correlated to the experimental data in this study. The energy approach was found to provide better fatigue life predictions for PEEK under constant and multi-block loadings with various strain ratios and frequencies.</p>
Laboratory manual for ME 1021 experimental orientation by D. M Eastland( Book )

1 edition published in 1981 in English and held by 1 WorldCat member library worldwide

Turbulent simulations of feline aortic flow under hypertrophic cardiomyopathy heart condition( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

<p>A computational fluid dynamics (CFD) model is developed for pulsatile flows and particle transport to evaluate the possible thrombus trajectory in the feline aorta for Hypertrophic Cardiomyopathy (HCM) heart conditions. An iterative target mass flow rate boundary condition is developed, and turbulent simulations with Lagrangian particle transport model are performed using up to 11M grids. The model is validated for human abdominal aorta flow, for which the results agree within 11.6% of the experimental data. The model is applied for flow predictions in a generalized feline aorta for healthy and HCM heart conditions. Results show that in the HCM case, the flow through the iliac arteries decreases by 50%, due to the large recirculation regions in the abdominal aorta compared to the healthy heart case. The flow recirculation also result in stronger vortices with slower decay, causing entrapment of particles in the thoracic aorta and trifurcation regions. </p>
Characterization of a test stand for evaluating performance and qualifying metal media filters under ASME AG-1 by John Andrew Wilson( )

1 edition published in 2013 in English and held by 1 WorldCat member library worldwide

The Institute of Clean Energy Technology (ICET) at Mississippi State University was awarded a contract by the DOE to design, fabricate, assemble, and characterize a research grade test stand to assist in the development of ASME AG-1 Section FI Metal Media Filters. The major barriers to completing the code section is development of a test stand for collecting data necessary to specify performance requirements for use and for filter qualification. Currently there is not a test stand capable of performing this testing. Performance criteria for the FI test stand were developed by the Section FI project team and ICET. These performance criteria were used to create a test stand to collect the data necessary to get Section FI balloted and approved
Multiscale modeling of multiphase polymers( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

<p>Accurately simulating material systems in a virtual environment requires the synthesis and utilization of all relevant information regarding performance mechanisms for the material occurring over a range of length and time scales. Multiscale modeling is the basis for the Integrated Computational Materials Engineering (ICME) Paradigm and is a powerful tool for accurate material simulations. However, while ICME has experienced adoption among those in the metals community, it has not gained traction in polymer research. This thesis seeks establish a hierarchical multiscale modeling methodology for simulating polymers containing secondary phases.</p> <p>The investigation laid out in the chapters below uses mesoscopic Finite Element Analysis (FEA) as a foundation to build a multiscale modeling methodology for polymer material systems. At the mesoscale a Design of Experiments (DOE) parametric study utilizing FEA of polymers containing defects compared the relative impacts of a selection of parameters on damage growth and coalescence in polymers. Of the parameters considered, the applied stress state proved to be the most crucial parameter affecting damage growth and coalescence.</p> <p>At the macroscale, the significant influence of the applied stress state on damage growth and coalescence in polymers (upscaled from the mesoscale) motivated an expansion of the Bouvard Internal State Variable (ISV) (Bouvard et al. 2013) polymer model stress state sensitivity. Deviatoric stress invariants were utilized to modify the Bouvard ISV model to account for asymmetry in polymer mechanical performance across different stress states (tension, compression, torsion).</p> <p>Lastly, this work implements a hierarchical multiscale modeling methodology to examine parametric effects of heterogeneities on Polymer/Clay Nanocomposites (PCNs) mechanical performance under uncertainty. A Virtual Composite Structure Generator (VCSG) built three-dimensional periodic Representative Volume Elements
Fatigue behavior of Ti-6Al-4V ELI including mean stress effects( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

<p>This study investigates the cyclic deformation, fatigue behavior, and failure mechanisms for Ti-6Al-4V ELI (extra low interstitial) with and without mean strain/stress. Mean stress effects on fatigue behavior were studied using four strain ratios. Fatigue data generated was used to assess mean stress fatigue life prediction approaches, including stress-based methods such as Goodman, Gerber, Morrow, Walker and Kwofie; as well as strain-based models, such as Morrow, Smith-Watson-Topper, Walker, Kwofie, Ince-Glinka and a modified version of the Smith-Watson-Topper. The stress-based models did not yield reasonable results and data scatter was observed. The strain-based models offered better results, specifically the Morrow approach which provided more accurate fatigue life predictions. Fractography analysis determined that the influence of material defects on fatigue life had no major differences across all the strain ratios considered. Overall observations indicate that inclusions near the surface had great influence on the fatigue behavior. </p>
Experimental characterization of compaction and sintering of nanocrystalline copper steel powder( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

<p>The effect of ball milling on the compaction and sintering of nanocrystalline FC-0205 powder was studied in this work. As-received micron-sized FC-0205 powder was subjected to High Energy Ball Milling (HEBM) in an argon atmosphere at different milling time of 0, 8, 16, 20 and 24 hours to obtain nanocrystalline structures. Unmilled, 8 and 16 hour milled powder were compacted using uniaxial die compression at a pressure ranging from 274 MPa to 775 MPa to obtain a relative density from 74% to 95%. The steel powder compacts were sintered at temperatures ranging from 400 °C (752 °F) to 1120 °C (2048 °F) in a controlled atmosphere. Microscopy analysis using Optical Microscope (OM), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) was performed on the milled powder, and on the green and sintered compacts to examine the grain size, morphology and agglomeration.</p>
Effect of microstructure on the fatigue behavior of type 304L stainless steel including mean strain and cyclic rate effects( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

<p>In this study, the effects of stress and strain rate on cyclic deformation, secondary hardening, martensitic phase transformation, crack initiation, and fatigue behavior of type 304L stainless steel are examined. A series of load and strain controlled uniaxial zero and non-zero mean strain fatigue tests were conducted with varying frequencies in order to investigate the effect of loading rate on fatigue behavior. The volume fraction of martensite was quantified for several tests using x-ray diffraction and electron backscatter diffraction. The loading rates were found to have a direct effect on the microstructure and fatigue behavior of the alloy investigated. Adiabatic heating from an increased rate of loading was found to effect martensite formation which is a major contributor to the secondary hardening phenomena associated with many austenitic stainless steels under cyclic loading. Also affected by the microstructural changes were cyclic deformation, crack initiation, microstructurally small crack growth, and fatigue behavior.</p>
Computational investigation and parametric study of lateral impact behavior of pressurized pipelines by Yangqing Dou( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

This thesis presents a computational study to examine lateral impact behavior of pressurized pipelines and to determine influence of internal pressure on the impact behaviors of pipelines. More than 300 numerical simulations were carried out on mild steel pipe models with different internal pressure levels and were struck at the mid-span and at the one quarter span positions. The computational results for the first time systematically revealed the effects of internal pressure, impact position, and outside diameter on the lateral impact behavior of the pipeline models. It inspects effects of important parameters such as the outside diameter and internal pressure. Quartic polynomial functions are applied to formulate the maximum crushing force (F), permanent displacement (W), and absorbed energy (E) of the pressurized pipelines during the impact problem. Response surfaces are plotted based on the generated quartic polynomial functions and the quality (accuracy) of those functions are verified through several techniques
An investigation into friction stir welding of copper niobium nanolamellar composites by Josef Benjamin Cobb( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

The workpiece materials used in this study are CuNb nano-layered composites (NLC) which are produced in bulk form by accumulative roll bonding (ARB). CuNb NLC panels are of interest because of their increase in strength and radiation damage tolerance when compared to either of their bulk constituents. These increased properties stem from the bi-metal interface, and the nanometer length-scale of the layers. However to be commercially viable, methods to successfully join the ARB NLC which retain the layered structure panels are needed. Friction stir welding is investigated in this study as a possible joining method that can join the material while maintaining its layered structure and hence its properties. Mechanical properties of the weld were measured at a macro level using tensile testing, and at a local level via nano-indentation. The post weld layer structure was analyzed to provide insight into the flow paths. The grain orientation of the resulting weld nugget was also analyzed using electron backscatter diffraction and transmission Kikuchi diffraction. Results from this study show that the nano-layered structure can be maintained in the CuNb NLC by control of the friction stir welding parameters. The resulting microstructure is dependent on the strain experienced during the joining process. A variation in layer thickness reduction is correlated with increasing shear strain. Above a critical level of shear strain, the NLC microstructure was observed to fragment into equiaxed grains with a higher hardness than the NLC panels. Results from this study are also used to further the understanding of the material flow and hot working conditions experienced during the friction stir welding process
Modified internal state variable models of plasticity using nonlocal integrals in damage and gradients in dislocation density by Fazle Rabbi Ahad( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

To enhance material performance at different length scales, this study strives to develop a reliable analytical and computational tool with the help of internal state variables spanning micro and macro-level behaviors. First, the practical relevance of a nonlocal damage integral added to an internal state variable (BCJ) model is studied to alleviate numerical instabilities associated within the post-bifurcation regime. The characteristic length scale in the nonlocal damage, which is mathematical in nature, can be calibrated using a series of notch tensile tests. Then the same length scale from the notch tests is used in solving the problem of a high-velocity (between 89 and 107 m/s) rigid projectile colliding against a 6061-T6 aluminum-disk. The investigation indicates that incorporating a characteristic length scale to the constitutive model eliminates the pathological mesh-dependency associated with material instabilities. In addition, the numerical calculations agree well with experimental data. Next, an effort is made rather to introduce a physically motivated length scale than to apply a mathematical-one in the deformation analysis. Along this line, a dislocation based plasticity model is developed where an intrinsic length scale is introduced in the forms of spatial gradients of mobile and immobile dislocation densities. The spatial gradients are naturally invoked from balance laws within a consistent kinematic and thermodynamic framework. An analytical solution of the model variables is derived at homogenous steady state using the linear stability and bifurcation analysis. The model qualitatively captures the formation of dislocation cell-structures through material instabilities at the microscopic level. Finally, the model satisfactorily predicts macroscopic mechanical behaviors - e.g., multi-strain rate uniaxial compression, simple shear, and stress relaxation - and validates experimental results
An investigation of the formability of ZEK100 Mg alloy using pneumatic bulge formability testing methods( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

<p>The current study investigates the formability of ZEK100, a rare-earth containing magnesium alloy, using an in-house developed technique of pneumatic bulge forming. The thesis pursued innovation of sample preparation, testing, and experimental data analysis in order to create several forming limit diagrams (FLDs) of critical importance for determining a methodology for Mg formability. Samples were bulged through elliptical and circular dies at room temperature, 150 C, and 250 C, in two orientations, rolling direction (RD) and transverse direction (TD), in order to determine temperature dependence and orientation characteristics. The current research concluded ZEK100 is not a suitable alloy for room temperature forming processes used in automotive industries. Little difference between safe and marginal, as well as marginal and failure strain ratios was seen for RD orientation testing, while greater resolution is evident for TD orientation testing. ZEK100 exhibits a temperature dependence in relation to limiting strain between RD and TD.</p>
A petroleum energy, greenhouse gas, and economic life cycle analysis of several automotive fuel options by Matthew Carter Doude( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

A vehicle fuel's life does not begin when that fuel is pumped into the tank or the battery is charged. Each kilowatt-hour of fuel that is used has a history traceable back to its original feedstock, be it crude oil, corn, solar energy, or others. In this thesis, a life cycle analysis is performed on E10, E85, B20, hydrogen, and electricity, with the well-to-pump fossil fuel energy use and greenhouse gas emissions compared. Results are presented in the form of either energy or mass per kilowatt of fuel at the plug or at the pump. An analysis of the economic viability of each fuel to the consumer is also demonstrated. E85 is found to have the best well-to-pump fossil fuel energy use at 722 Wh/kWh, while hydrogen demonstrates the best well-to-wheel greenhouse gas emissions with 123 g/km (CO2 equivalent) and electricity produces the lowest vehicle lifetime operating cost of dollars 0 .241/mile
Strategies for optimization of diesel-ignited propane dual fuel combustion in a heavy duty compression ignition engine by Chad Duane Carpenter( )

1 edition published in 2013 in English and held by 1 WorldCat member library worldwide

A 12.9 L heavy duty compression ignition engine was tested with strategies for dual fuel optimization. The effects of varied intake manifold pressure as well as split-injection strategies at a load of 5 bar BMEP and 85 PES were observed. These results were used to allow testing of split-injection strategies at a higher load of 10 bar BMEP at 70 PES that were void of MPRR above 2000 kPa/CAD. The split-injection strategies at 5 bar BMEP showed that lower BSNOx can be achieved with minimal drop in FCE. Varying intake manifold pressure revealed that combustion occurs earlier in a cycle with increasing intake manifold pressure and indirectly increasing FCE. A load of 10 bar BMEP at 70 PES should only use split-injection strategy to maintain load without high MPRR as efficiency drops with dependency on the second injection
Predictive capabilities of advanced turbulence models in the wake region of a wall mounted cube( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

This thesis seeks to investigate the predictive capabilities of Advanced turbulence models in the wake region of a wall-mounted cube. Dynamic Hybrid RANS/LES (DHRL), Hybrid RANS/LES (HRL) models, Nonlinear Explicit Algebraic Reynolds Stress Model (NEARSM), One- and Two-equation models, and numerical flux schemes will be compared against Direct Numerical Simulation (DNS) results to determine which model, or combination of models, produce the closest replication. The simulations were ran in Loci-Chem using both built-in features and modular code additions. The simulation results show the Shear Stress Transport (SST) model ran with NEARSM and Optimized Gradient REconstruction (OGRE) scheme gives better results than all other RANS and HRL models investigated herein. This result is matched only by SST with DHRL and OGRE. The best results were achieved using SST with NEARSM, DHRL, and OGRE. Thus, the NEARSM model shows potential to improve simulation results compared to simpler linear eddy-viscosity models
Structural analysis and design of seals for coal mine safety by Matthew S Holmer( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

This research shows that worst-case methane-air detonation loading on coal mine seals could be more severe than the design loads required by federal regulations, and therefore mine seals should be designed with sufficient ductility beyond the elastic regime. For this study, reinforced concrete mine seals were designed according to traditional protective structural design methods to meet the federal regulation requirements, and then the response to worst-case loads was analyzed in a single-degreeof-freedom model. Coal mine seals designed to resist the regulation loads elastically experienced support rotations up to 4.27 deg when analyzed with the worst-case loads. The analysis showed that coal mine seals designed to satisfy the federal regulations can survive worst-case methane-air detonations if they have sufficient ductility, but will undergo permanent, inelastic deformation
Microstructure and mechanical properties comparison of EBF3 and LENS deposits including the repair and upgrade of a LENS machine by Jacob Allen Coleman( )

1 edition published in 2013 in English and held by 1 WorldCat member library worldwide

Advancements in the area of additive manufacturing have led to the development of new methods with the purpose of optimizing component properties and expanding operating environments. In a comparative study, the influence of process parameters including beam and laser current, translation speed, and wire feed and deposition rate on 316L stainless steel deposits produced by both Laser Engineered Net Shaping (LENS®) and Electron Beam Freeform Fabrication (EBF3) processes are investigated. Tensile tests are used to obtain information on the mechanical properties of the specimens. A metallographic analysis is performed using optical microscopy and SEM to characterize solidification grain structure, porosity, secondary dendrite arm spacing, and possible modes of failure. This study highlights the distinct characteristics of both additive methods and how they lead to different microstructure and mechanical properties. Also included in this study is the upgrade and repair of the LENS machine at CAVS
The Doctor of philosophy program in mechanical engineering at Mississippi State University by Mississippi State University( Book )

1 edition published in 1986 in English and held by 1 WorldCat member library worldwide

 
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