Engineering Commons^™

Characterization Of Impact Toughness Of 304l Stainless Steel Fabricated Through Laser Powder Bed Fusion Process, Sreekar Karnati, Atoosa Khiabhani, Aaron Flood, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this research, the impact toughness of powder bed based additively manufactured 304L stainless steel was investigated. Charpy specimens were built in vertical, horizontal and inclined (45⁰) orientations to investigate the variation in toughness with build direction. These specimens were tested in as-built and machined conditions. A significant difference in toughness was observed with varying build directions. The lowest toughness values were recorded when the notch was oriented in line with the interlayer boundary. The highest toughness was recorded when the notch was perpendicular to the interlayer boundary. A significant scatter in toughness values was also observed. The variation and …

Digital Acoustic Modem Design For Narrowband Underwater Vehicle Communications, Ertan Uysal, Serhat Yılma, Murat Kuzlu

Journal of Marine Science and Technology–Taiwan

Underwater communication has become a crucial data transmission technology for commercial and military marine applications in the last few decades. However, most underwater communication applications still use analogue technologies. Recent advances in digital signal processing technology have enabled numerous applications in different fields, especially in underwater wireless communications. This paper presents a digital underwater communication system, which transmits and receives acoustic signals via hydrophones employed as acoustic transmitters and receiver units. In this study, coding and modulation methods were also implemented in the prototype through a series of simulations.

Micro Combustion Of Primary Reference Fuels In Narrow Heated Channels, Veerendra Naralasetti

LSU Master's Theses

Conventional fuel testing machines like CFR engines require large quantities of fuel. The current study seeks to overcome this limitation by introducing an alternative method using a microscale combustion reactor which consumes relatively small amounts of fuel (100-250 ml). For this reason, Primary Reference Fuels (PRF’s: volumetric mixtures of n-heptane and iso-octane) which are simple surrogates of gasoline are selected to test using micro reactor. The primary goal is to determine the effectiveness of using the micro reactor setup to differentiate fuels of different octane number. Experiments with stoichiometric PRF/air mixtures are performed inside a cylindrical quartz tube of 1mm …

Robust Engineering Of Dynamic Structures In Complex Networks, Walter Botongo Bomela

McKelvey School of Engineering Graduate Student Theses & Dissertations

Populations of nearly identical dynamical systems are ubiquitous in natural and engineered systems, in which each unit plays a crucial role in determining the functioning of the ensemble. Robust and optimal control of such large collections of dynamical units remains a grand challenge, especially, when these units interact and form a complex network. Motivated by compelling practical problems in power systems, neural engineering and quantum control, where individual units often have to work in tandem to achieve a desired dynamic behavior, e.g., maintaining synchronization of generators in a power grid or conveying information in a neuronal network; in this dissertation, …

Controlling The Oxygen Microenvironment: The Role Of Hif-1Α In Early Tumor Progression, Sandra Lam

McKelvey School of Engineering Graduate Student Theses & Dissertations

Cancer drug efficacy has remained a critical obstacle for researchers as it has one of the lowest probabilities of success compared to other diseases. One method to help improve this success rate is to create better tumor models on which to perform the drug testing. With growing interesting in microphysiological systems, scientists can create more advanced in vitro models of human organ systems as well as diseased states. These “organ-on-a-chip” platforms aim to improve drug response prediction for both efficacy and toxicity. One underappreciated characteristic of many disease states is that they are often at a lower oxygen tension that …

Aromatic Tolerance And Utilization Mechanisms Of Rhodococcus Opacus Pd630 To Produce Value-Added Products From Lignin, Wiliam Henson

McKelvey School of Engineering Graduate Student Theses & Dissertations

Lignocellulosic biomass is a potential renewable feedstock for the microbial production of fuels and chemicals. For microbial utilization, lignocellulosic biomass must undergo pretreatment (e.g., thermochemical and enzymatic processing) to release fermentable sugars.

Lignin comprises ~15-30% of lignocellulosic biomass, and lignin-derived aromatic compounds released during pretreatment can inhibit the microbial conversion of lignocellulosic sugars to bioproducts. Additionally, cost-effective separation of lignin and lignin by-products from lignocellulosic sugars remains a challenge, and current processes generate large waste streams that are typically burned or discarded. Thus, efforts are underway to improve microbial tolerance to lignin by-products and to develop approaches for valorizing waste …

Additive Manufacturing Of Liners For Shaped Charges, Jason Ho, Cody Lough, Phillip R. Mulligan, Edward C. Kinzel, Catherine E. Johnson

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

A Shaped Charge (SC) is an explosive device used to focus a detonation in a desired direction, and has applications in oil extraction, weaponry and demolition. The focusing relies on a void in the explosive mass, shaped by a metal liner that becomes a super-heated projectile during detonation. Additive Manufacturing (AM) allows greater design freedom and geometric complexity for the liner portion of the SC. Specifically, hierarchical structuring and functional grading can potentially provide greater velocity, directionality, and efficiency. In this work, Selective Laser Melting (SLM) is used to explore different geometries for an SC liner made out of SS …

Fabricating Functionally Graded Materials By Ceramic On-Demand Extrusion With Dynamic Mixing, Wenbin Li, Austin J. Martin, Benjamin Kroehler, Alexander M. Henderson, Tieshu Huang, Jeremy Lee Watts, Greg Hilmas, Ming-Chuan Leu

Materials Science and Engineering Faculty Research & Creative Works

Ceramic On-Demand Extrusion (CODE) is an extrusion-based additive manufacturing process recently developed for fabricating dense, functional ceramic components. Presented in this paper is a further development of this process focusing on fabrication of functionally graded materials (FGM). A dynamic mixing mechanism was developed for mixing constituent ceramic pastes, and an extrusion control scheme was developed for fabricating specimens with desired material compositions graded in real time. FGM specimens with compositions graded between Al₂O₃ and ZrO₂ were fabricated and ultimately densified by sintering to validate the effectiveness of the CODE process for FGM fabrication. Energy dispersive spectroscopy …

Effect Of Wall Thickness And Build Quality On The Compressive Properties Of 304l Thin-Walled Structures Fabricated By Slm, Myranda Spratt, Sudharshan Anandan, Rafid M. Hussein, Joseph William Newkirk, K. Chandrashekhara, Heath Misak, Michael Walker

Materials Science and Engineering Faculty Research & Creative Works

The specific strength of lightweight lattice structures built with SLM is of interest to the aerospace industry. Honeycombs were manufactured with increasing wall thicknesses (which increases density) and tested under compression. The optimal strength to density ratio was determined from the resulting data. The build quality was also evaluated to determine how/if the results were influenced by the specimen quality. Differences between the nominal and as-built geometry were identified, but considered to be minimal. Microstructural evaluation of the specimens revealed a possible dependence on the ‘border scan’ properties, as the thickness of the specimens was such that the board scan …

Fiber-Fed Printing Of Free-Form Free-Standing Glass Structures, John M. Hostetler, Jason E. Johnson, Jonathan T. Goldstein, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel

Materials Science and Engineering Faculty Research & Creative Works

Additive Manufacturing (AM) of low-profile 2.5D glass structures has been demonstrated using a fiber-fed laser-heated process. In this process, glass fibers with diameters 90-125 μm are supported as they are fed into the intersection of the workpiece and a CO₂ laser beam. The workpiece is positioned by a four-axis CNC stage with coordinated rotational/transitional kinematics. The laser energy at λ = 10.6 μm is coupled to phonon modes in the glass, locally heating it above its working point. The rapid heating and cooling process allows for the deposition of various glasses into free-standing three-dimensional structures such as trusses and …

Fast Prediction Of Thermal History In Large-Scale Parts Fabricated Via A Laser Metal Deposition Process, Lei Yan, Tan Pan, Joseph William Newkirk, Frank W. Liou, Eric E. Thomas, Andrew H. Baker, James B. Castle

Materials Science and Engineering Faculty Research & Creative Works

Laser metal deposition (LMD) has become a popular choice for the fabrication of near-net shape complex parts. Plastic deformation and residual stresses are common phenomena that are generated from the intrinsic large thermal gradients and high cooling rates in the process. Finite element analysis (FEA) is often used to predict the transient thermal cycle and optimize processing parameters; however, the process of predicting the thermal history in the LMD process with the FEA method is usually time-consuming, especially for large-scale parts. Herein, multiple 3D FEA models with simple assumptions on the heat source and its loading methods are compared and …

Mechanical Properties Evaluation Of Ti-6al-4v Thin-Wall Structure Produced By A Hybrid Manufacturing Process, Lei Yan, Wenyuan Cui, Joseph William Newkirk, Frank W. Liou, Eric E. Thomas, Andrew H. Baker, James B. Castle

Materials Science and Engineering Faculty Research & Creative Works

The hybrid manufacturing (HM) process combines the precision of computer numerical control (CNC) and the freeform capability of additive manufacturing to expand the versatility of advanced manufacturing. The intent of this paper is to explore the relationship between HM processing parameters and mechanical properties of the final parts manufactured by one type of HM process that combines laser metal deposition (LMD) and CNC milling. The design of experiment (DOE) is implemented to explore the Ti-6Al-4V thin-wall structure fabrication process with different HM build strategies. Vickers hardness, tensile test, and microstructure analyses are conducted to evaluate the mechanical property variance within …

Development Of An Engineering Diagram For Additively Manufactured Austenitic Stainless Steel Alloys, Zachary T. Hilton, Joseph William Newkirk, Ronald J. O'Malley

Materials Science and Engineering Faculty Research & Creative Works

Austenitic stainless steels are the most widely applied types of stainless steels, due to their good weldability and high corrosion resistance. A number of engineering diagrams exist for the purpose of providing insight into the behavior of these steels. Examples of these diagrams are constitution diagrams (aka Schaeffler Diagrams) which are used to approximate the solidification path of the alloy and the amount of retained ferrite in the solidified matrix. Other diagrams are the Suutala diagram, which approximates cracking susceptibility, and microstructural maps, which predict the solidification path by varying a processing parameter, such as cooling rate. By combining these …

Frequency Response Inspection Of Additively Manufactured Parts For Defect Identification, Kevin Johnson, Jason Blough, Andrew Barnard, Troy Hartwig, Ben Brown, David Soine, Tristan Collum, Edward C. Kinzel, Douglas A. Bristow, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The goal of this paper is to evaluate internal defects in AM parts using dynamic measurements. The natural frequencies of AM parts can be identified by measuring the response of the part(s) to a dynamic input. Different excitation methods such as a modal impact hammer or shakers can be used to excite the parts. Various methods exist to measure the parts' responses and find the natural frequencies. This paper will investigate the use of Doppler lasers, accelerometers and Digital Image Correlation (DIC). The parts evaluated in this work include sets of parts that are still attached to the AM build …

Noninvasive Multi-Modality Studies Of Cardiac Electrophysiology, Mechanics, And Anatomical Substrate In Healthy Adults, Arrhythmogenic Cardiomyopathy, And Heart Failure, Christopher Andrews

McKelvey School of Engineering Graduate Student Theses & Dissertations

Heart disease is a leading cause of death and disability and is a major contributor to healthcare costs. Many forms of heart disease are caused by abnormalities in the electrical function of heart muscle cells or the cardiac conduction system. Electrocardiographic Imaging (ECGI) is a noninvasive modality for imaging cardiac electrophysiology. By combining recordings of the voltage distribution on the torso surface with anatomical images of the heart-torso geometry, ECGI reconstructs voltages on the epicardium. This thesis applies ECGI to novel studies of human heart function and disease and explores new combinations of ECGI with additional imaging modalities.

ECGI was …

Lignin Conversion To Value-Added Products Via Heterogeneous Catalysts, Yu Gao

McKelvey School of Engineering Graduate Student Theses & Dissertations

Increasing world population has led to great demands for fuels, chemicals, and materials, and has raised concerns over the depletion of non-renewable resources and the environmental impacts of their processing and utilization. However, the biorefinery concept suggests lignocellulosic biomass can be used as an alternative resource for producing a range of fuels, chemicals and materials to fulfill these demands in a sustainable way. Hence, fermentation technologies are widely developed to efficiently utilize lignocellulosic carbohydrates. However, the non-carbohydrate fraction of biomass, lignin, is still considered as waste and is under-utilized as low-grade fuel, mainly for local heat and electricity production. Since …

Development And Application Of Hybrid Wray-Agarwal Turbulence Model And Large-Eddy Simulation, Xu Han

McKelvey School of Engineering Graduate Student Theses & Dissertations

Rapid development in computing power in past five decades along with the development and progress in building blocks of Computational Fluid Dynamics (CFD) technology has made CFD an indispensable tool for modern engineering analysis and design of fluid-based products and systems. For CFD analysis, Reynolds-Averaged Navier-Stokes (RANS) equations are currently the most widely used fluid equations in the industry. RANS methods require modeling of turbulence effect (i.e. turbulence modeling) based on empirical relations and therefore often produce low accuracy results for many flows. In recent years, the Large Eddy Simulation (LES) approach has been developed which has shown promise of …

Assessment And Diagnosis Of Human Ovarian And Colorectal Cancer Using Optical And Photoacoustic Imaging, Sreyankar Nandy

McKelvey School of Engineering Graduate Student Theses & Dissertations

Optical imaging modalities have the advantage of high resolution, label free, rapid, low cost imaging for both in vivo and ex vivo diagnosis of biological tissues. Optical scattering, which is the main contrast of optical coherence tomography (OCT), is related to elastic scattering components, mainly stromal collagen. Tissue elasticity has recently emerged as an important diagnostic parameter associated with tumor development and progression and is also related to the distribution of structural components such as tissue collagen. We have used an optical coherence tomography elastography (OCTE) system for characterizing the differences in the micro-mechanical properties of benign and malignant human …

Development And Application Of Quadratic Constitutive Relation And Transitional Crossflow Effects In The Wray-Agarwal Turbulence Model, Hakop Jack Nagapetyan

McKelvey School of Engineering Graduate Student Theses & Dissertations

Computational Fluid Dynamics (CFD) has now become an almost indispensable tool for modern engineering analysis of fluid flow over aircrafts, turbomachinery, automobiles, and many other industrial applications. Accurate prediction of turbulent flows remains a challenging problem. The most popular approach for simulating turbulent flows in complex industrial applications is based on the solution of the Reynolds-Averaged Navier-Stokes (RANS) equations. RANS equations introduce the so called “Reynolds or turbulent stresses” which are generally modeled using the Boussinesq approximation known as “Turbulence modeling.” Despite their development over a century, the turbulence models used with RANS equations still need much improvement. The first …

Analysis Of Power System Low Frequency Oscillation With Empirical Mode Decomposition, Chia-Liang Lu, Chia-Yu Hsu, Pei-Hwa Huang

Journal of Marine Science and Technology–Taiwan

The low frequency oscillation (LFO) in power systems often consists of composite responses of various oscillation modes. Thus a direct analysis of LFO for revealing system dynamic characteristics is not straightforward. The primary objective of this study is to utilize the method of empirical mode decomposition (EMD) to expand the LFO response under study into multiple intrinsic mode functions (IMFs) for detailed investigation of power system dynamics. Then time-frequency power information is explored using wavelet transform to obtain time-frequency power graph which is further resolved into a time-frequencypower diagram. Finally, information from the time-frequencypower diagram is further examined to determine …

Sensitivity Analysis Of Steep Wave Riser With Internal Flow, Zhen Liu, Haiyan Guo

Journal of Marine Science and Technology–Taiwan

Offshore fields, specifically, deepwater oil and gas reserves, have been receiving increasing attention with the increasing consumption of petroleum products. Marine risers are critical to the petroleum industry. The steep wave riser (SWR) is becoming increasingly popular as its use has provided a solution for oil and gas exploration in water depths where traditional rigid risers could not tolerate the environmental loads or would have become very costly. A numerical model of an SWR with internal flow is built based on the slender rod model and the finite element method. The Newton-Raphson and the Newmark- methods are used to solve …

Morphological Characteristics Of Tidal Inlets Subject To A Short Term Typhoon Event: A Case Study In Lanyan River Estuary, Hsing-Yu Wang, Hui-Ming Fang, Sung-Shan Hsiao

Journal of Marine Science and Technology–Taiwan

This study aims to investigate different sediment particle sizes subject to transport characteristics of bed-load and suspendedload caused by nonlinear interactions of wave-tide-river in a tidal-estuary. A two-dimensional hydrodynamic coupling to a morphological model is developed to study this issue. A case study of Lanyang River estuary in Taiwan is applied and analyzed. The models are verified against field data (i.e., hydrodynamics and morphological change) collected from Lanyang River estuary during the invasion of typhoon Saola in July, 2012. Fairly good agreements are given comparing to field data. In general, the simulation indicates that suspended load could be transported toward …

Weight Minimization Of Ship Chamber Structure In Vertical Ship Lift Design Based On Multi-Level Structural Optimization Method, Kai Li, Zhengyao Yi, Chuanhui Ling, Zhijiang Yuan, Xiaogang Jiang

Journal of Marine Science and Technology–Taiwan

Weight reduction of ship chamber is a main concern of ship lift design for improving the load capacity. The structure of ship chamber is typical of beam-plate structure. To deal with structural optimization problem of beam-plate structure, a multilevel structural optimization method was developed based on combining an improved bi-directional evolutionary structural optimization (BESO) method and surrogate model method, which covers three optimization levels, as dimension optimization, topology optimization and section optimization. The aim of the proposed optimization method is to determine global design parameters, integral structural topology, and locations and sectional parameters of structural members from an oversized ground …

Bending Mechanical Behavior Analysis Of Glass-Fiber Reinforced Thermoplastic Pipe Based On A Nonlinear Solid Element Model, Shuqing Wang, Lu Yao, Xiangjian Meng

Journal of Marine Science and Technology–Taiwan

In this paper, a comprehensive investigation on the bending mechanical behavior of glass-fiber reinforced thermoplastic pipe (RTP) is implemented by using a three-dimensional (3D) solid finite-element (FE) model. A major contribution of this paper is to present a UMAT based equivalence procedure for solid elements, which is capable of considering the material anisotropic nonlinearity of thermoplastic composite pipe (TCP) laminate. First, the linearity and nonlinearity of RTP’s material are incorporated into the numerical analysis and their effects on the bending performance are compared. Then, based on the material nonlinearities, the influences of initial ovality, volume ratio of glass fiber, diameter-to-thickness …

Rotational Inertia Force Effects In Circular Squeeze Films With A Non-Newtonian Ferrofluid, Jaw-Ren Lin, Li-Ming Chu, Long-Jin Liang, Shu-Ting Hu

Journal of Marine Science and Technology–Taiwan

This paper aims to investigate the effects of rotational inertia force on the squeeze film characteristics between two circular disks lubricated with a non-Newtonian ferrofluid. Based on the Shliomis ferromagnetic fluid model incorporating with the Stokes couple stress fluid model, we have derived a non-Newtonian ferromagnetic Reynolds equation including the rotational inertia force effects for the study of squeeze film performances. From the results, the effects of rotational inertia forces of the upper disk yield a lower load capacity and a shorter squeezing time as compared to the non-rotating case. In addition, the influences of the related parameters on the …

Fast Eigenvalue Analysis Of Critical Oscillation Mode For Shipboard Electric Power System, Chao-Chun Li, Pei-Hwa Huang

Journal of Marine Science and Technology–Taiwan

Frequency domain analysis has been widely adopted for the study of the small signal stability of the power system. The frequency domain approach includes the linearization of the system to obtain a linear model as well as the system matrix of which the eigenvalues can be calculated to determine the system stability. However, we often have high order of system matrix and thus it will be undesirable to calculate and analyze all the system eigenvalues. This paper is to explore the problem of small signal stability for the shipboard electric power system and the main purpose is to find out …

Nonlinear Dynamics And Controlling Chaos In A Magnetic Levitation System, Shun-Chang Chang, Jui-Feng Hu, Yeou-Feng Lue

Journal of Marine Science and Technology–Taiwan

This investigation verifies the chaos motion of a magnetic levitation system with a ferromagnetic ball suspended in a voltage-controlled magnetic field, and explains a system for chaotic control. Then, the detailed dynamic behaviors are numerically investigated by means of Poincaré maps, phase portraits, time responses, and frequency spectra. The results reveal that due to the realistic nonlinear characteristics of magnetic forces, perioddoubling bifurcation has been observed to lead to chaos. Chaotic behavior is verified using Lyapunov exponents and Lyapunov dimensions. Finally, we propose a state feedback control technique for the effective control of a chaotic magnetic levitation system. Some simulation …

Use Of Swir Imaging To Monitor Layer-To-Layer Part Quality During Slm Of 304l Stainless Steel, Cody S. Lough, Xin Wang, Christopher C. Smith, Olaseni Adeniji, Robert G. Landers, Douglas A. Bristow, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper evaluates using in-situ SWIR imaging to monitor part quality and identify potential defect locations introduced during Selective Laser Melting (SLM) of 304L stainless steel. The microstructure (porosity, grain size, and phase field) and engineering properties (density, modulus, and yield strength) depend on the thermal history during SLM manufacturing. Tensile test specimens have been built with a Renishaw AM250 using varied processing conditions to generate different thermal histories. SWIR imaging data is processed layer-to-layer to extract features in the thermal history for each process condition. The features in the thermal history are correlated with resulting part engineering properties, microstructure, …

In-Situ Optical Emission Spectroscopy During Slm Of 304l Stainless Steel, Cody S. Lough, Luis I. Escano, Minglei Qu, Christopher C. Smith, Robert G. Landers, Douglas A. Bristow, Lianyi Chen, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper demonstrates the potential of in-situ Optical Emission Spectroscopy (OES) to monitor the Selective Laser Melting (SLM) process. A spectrometer is split into the beam path of a home-built SLM system to collect visible light emitted from the melt pool and plume. The inline configuration allows signal collection regardless of the laser scan location. The spectral data can be used to calculate the temperature of the vapor plume and correlated with the melt-pool size. The effects of varying the atmosphere and pressure on the OES signal are also explored. These results demonstrate that OES can provide useful feedback to …

Method For The Destruction Of Endotoxin In Synthetic Spider Silk Proteins, Richard E. Decker, Thomas I. Harris, Dylan R. Memmott, Christopher J. Peterson, Randolph V. Lewis, Justin A. Jones

Biological Engineering Faculty Publications

Although synthetic spider silk has impressive potential as a biomaterial, endotoxin contamination of the spider silk proteins is a concern, regardless of the production method. The purpose of this research was to establish a standardized method to either remove or destroy the endotoxins present in synthetic spider silk proteins, such that the endotoxin level was consistently equal to or less than 0.25 EU/mL, the FDA limit for similar implant materials. Although dry heat is generally the preferred method for endotoxin destruction, heating the silk proteins to the necessary temperatures led to compromised mechanical properties in the resultant materials. In light …