Engineering Commons^™

Fiber-Fed Laser-Heated Process For Printing Transparent Glass, John M. Hostetler, Jonathan T. Goldstein, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents the Additive Manufacturing (AM) of glass using a fiber-fed process. Glass fiber with a diameter of 100 μm is fed into a laser generated melt pool. A CO₂ laser beam is focused on the intersection between the fiber and the work piece which is positioned on a four-axis computer controlled stage. The laser energy at λ=10.6 μm is directly absorbed by the silica and locally heats the glass above the working point. By carefully controlling the laser power, scan speed, and feed rate, bubble free shapes can be deposited including trusses and basic lenses. Issues unique …

Design, Analysis, And Verification Of An Open-Wheeled Formula-Style Race Car Suspension System, Joshua Beckerman

Renée Crown University Honors Thesis Projects - All

This honors thesis presents the design, measurement, and analysis of an open-wheeled formula racecar suspension system. This racecar is the second iteration of Syracuse University’s Citrus Racing team student competition vehicle. The race car’s suspension system features several designs that enable geometric adjustability to impact the vehicles dynamic performance. The purpose of this research is to find an analytic approach to verifying the correlation between suspension design tunings and their effect on vehicle handling and road holding capacity. This was done by analyzing measured data obtained from a system of damper-mounted travel sensors as the vehicle drives through numerous realistic …

Investigation Of Build Strategies For A Hybrid Manufacturing Process Progress On Ti-6al-4v, Lei Yan, Leon Hill, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The various processing parameters of a hybrid manufacturing process, including deposition and machining, is being investigated with a Design of Experiment (DoE). The intent was to explore the effect of different build strategies on the final part’s Vickers hardness, tensile test, fatigue life, and microstructure. From this experiment, the processing parameters can be linked to various mechanical properties. This will lead to the ability to create a combination of deposition and machining parameters, which will result in improved mechanical properties.

Studying Chromium And Nickel Equivalency To Identify Viable Additive Manufacturing Stainless Steel Chemistries, Zachary T. Hilton, Joseph William Newkirk, Ronald J. O'Malley

Materials Science and Engineering Faculty Research & Creative Works

Chromium and nickel equivalency modeling has long been used in welding to determine the weldability of steel chemistries. A study was conducted to determine the applicability of Cr-Ni modeling to the additive manufacturing process. Many AM methods involve rapid solidification of small melt pools, similar to welding. Chemistries with varying Cr/Ni ratios were selected for use in a selective laser melting process and modeled using known models. Initial results indicate that the standard "safe welding zone" may not directly apply to additive manufacturing. The capability to build with chemistries outside the weldability “safe zone” could result in improved and varied …

New Models For Interference And Broadcast Channels With Confidential Messages, Mohamed Nafea, Aylin Yener

Electrical and Computer Engineering Faculty Research & Creative Works

A new model for the interference channel with confidential messages (IC-CM) is introduced, where each receiver, besides his noisy observations, is provided with a fixed-length subset, of his choosing, of noiseless observations for the transmitted codewords of both users, making confidential communication more challenging than the previous such model. In addition, in the same spirit, a broadcast channel with confidential messages (BC-CM), where the receivers noiselessly tap into subsets of their choice of the transmitted codeword, is considered. Achievable strong secrecy rate regions for both models are derived. In both models, the size of the subset quantifies a secure rate …

Metallic Components Repair Strategies Using The Hybrid Manufacturing Process, Xinchang Zhang, Wenyuan Cui, Wei Li, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The hybrid manufacturing process which integrates additive manufacturing with subtractive machining is competitive and promising in component repair. To automate this process, detecting the missing volume and generating the deposition tracks is the key. In this study, strategies for repairing defects on flat and non-flat surfaces were investigated. A cost-effective reverse engineering tool was utilized to reconstruct STL models of damaged objects. Point data of the fracture surface on flat surfaces was obtained to generate the tool path for material building up. For defects on non-flat surfaces, the damaged model was best-fitted with the nominal model. Then both models were …

Defects Classification Of Laser Metal Deposition Using Acoustic Emission Sensor, Haythem Gaja, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser metal deposition (LMD) is an advanced additive manufacturing (AM) process used to build or repair metal parts layer by layer for a range of different applications. Any presence of deposition defects in the part produced causes change in the mechanical properties and might cause failure to the part. In this work, defects monitoring system was proposed to detect and classify defects in real time using an acoustic emission (AE) sensor and an unsupervised pattern recognition analysis. Time domain and frequency domain, and relevant descriptors were used in the classification process to improve the characterization and the discrimination of the …

Characterization Of Heat-Affected Powder Generated During Selective Laser Melting Of 304l Stainless Steel Powder, Austin T. Sutton, Caitlin S. Kriewall, Ming-Chuan Leu, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The selective laser melting (SLM) process is an Additive Manufacturing (AM) technique that uses a laser to fuse successive layers of powder into near fully dense components. Due to the large energy input from the laser during processing, vaporization and instabilities in the melt pool occur causing the formation of condensate and laser spatter, collectively known as heat-affected powder. Since heat-affected powder settles into the powder bed, the properties of the unconsolidated powder may be altered compromising its reusability. In this study, characterization of 304L heat-affected powder was performed through particle size distribution measurements, x-ray diffraction, metallography, energy-dispersive spectroscopy mapping, …

Influence Of Gage Length On Miniature Tensile Characterization Of Powder Bed Fabricated 304l Stainless Steel, Sreekar Karnati, Jack L. Hoerchler, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Miniature tensile specimens with varying aspect ratios were fabricated from 304L stainless steel (SS) made using powder bed additive manufacturing (AM) process. The tensile characteristics measured from these specimens were analyzed to assess the impact of gage length. The study found no impact upon varying gage length on yield and ultimate strength measurements. However, a significant impact was observed on strain measurements. This data was also used to perform Weibull statistics to estimate the stochastic performance of the material. Fractography was performed to visually identify the types of flaws. A comparative study with specimens fabricated from cold rolled annealed 304 …

Relating Processing Of Selective Laser Melted Structures To Their Material And Modal Properties, Nicholas E. Capps, James S. Urban, Brian M. West, Cody S. Lough, Adriane Repogle, Troy Hartwig, Ben Brown, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Selective Laser Melting (SLM) creates metal parts by fusing powder layer-by-layer. It provides significant design flexibility and the possibility of low-volume production. The engineering properties of the printed metal are a function of the local thermal history. This creates challenges for validating Additively Manufactured (AM) parts. This paper correlates the engineering properties (density, modulus, yield strength and ultimate strength) for tensile test specimens created with different process parameters with the resonant frequencies determined using modal testing. The paper shows that yield and ultimate strengths for these specimens can be determined using modal analysis.

Thermal Modeling Of 304l Stainless Steel Selective Laser Melting, Lan Li, Cody S. Lough, Adriane Repogle, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper describes the continuum thermal modeling of the Selective Laser Melting (SLM) process for 304L stainless steel using Abaqus. Temperature dependent thermal properties are obtained from literature and incorporated into the model capturing the change from powder to fully dense stainless steel. The thermal model predicts the temperature history for multi-track scans under different process parameters (laser power, effective scanning speed, hatch spacing) which is used to extract the melt-pool size, solidification rate, and temperature gradients. These are compared to experimental results obtained from a Renishaw AM250 in terms of the melt pool size, grain structure, and cell spacing. …

Review Of Am Simulation Validation Techniques, Aaron Flood, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Due to the complexity of Additive Manufacturing (AM), it can require many trial runs to obtain processing parameters which produce a quality build. Because of this trial and error process, the drive for simulations of AM has grown significantly. Simulations only become useful to researchers if it can be shown that they are true representations of the physical process being simulated. All simulations have different methods of validation to show that they are an accurate representations of the process. This paper explores the various methodologies for validation of laser based metal AM simulations, focusing mainly on the modeling of the …

Determination Of Recovery Time For A Simple Lifting Task Based On Weight, Frequency, And Duration Of The Lift, Milad Amini

LSU Master's Theses

Musculoskeletal disorders (MSDs) are a leading cause of injury in American workplaces which cost the economy billions of dollars each year. Extensive research has shown that job fatigue is one of the causes of MSDs. Allocating frequent and adequate rest break is suggested to be an effective method in mitigating the work overload and fatigue prevention. The objective of this research was to determine rest periods for lifting tasks based on the activity heart rate and by using a set of task variables. Twenty-four university male students took part in this study. The two response variables were perceived level of …

A Mixed Methods Study Of The Performance And Dynamics Of University Technology Transfer And Commercialization, Berk Dogan

LSU Master's Theses

The technology transfer and commercialization encompasses various activities involved in acquiring intellectual property rights for the inventions, marketing of the inventions, and diffusing into the public domain through commercialization. Although many scholars have studied technology transfer within the academic institutions' context, the process has been assumed to be sequential. The technology transfer process is a complex process to be generalized as a linear sequential process. A mixed methods approach has been used to triangulate the findings from the literature review and descriptive analyses to conceptualize an alternative model that reflects the actual process more accurately. It was found that the …

On The Ramberg-Osgood Stress-Strain Model And Large Deformations Of Cantilever Beams, Ronald J. Giardina Jr

LSU New Orleans Theses and Dissertations

In this thesis the Ramberg-Osgood nonlinear model for describing the behavior of many different materials is investigated. A brief overview of the model as it is currently used in the literature is undertaken and several misunderstandings and possible pitfalls in its application is pointed out, especially as it pertains to more recent approaches to finding solutions involving the model. There is an investigation of the displacement of a cantilever beam under a combined loading consisting of a distributed load across the entire length of the beam and a point load at its end and new solutions to this problem are …

Separation Of Vocal And Non-Vocal Components From Audio Clip Using Correlated Repeated Mask (Crm), Mohan Kumar Kanuri

LSU New Orleans Theses and Dissertations

Extraction of singing voice from music is one of the ongoing research topics in the field of speech recognition and audio analysis. In particular, this topic finds many applications in the music field, such as in determining music structure, lyrics recognition, and singer recognition. Although many studies have been conducted for the separation of voice from the background, there has been less study on singing voice in particular.

In this study, efforts were made to design a new methodology to improve the separation of vocal and non-vocal components in audio clips using REPET [14]. In the newly designed method, we …

Particulate Matter And Carbon Monoxide Emission Factors From Incense Burning, Abhinay Jilla Mr.

LSU New Orleans Theses and Dissertations

Indoor air quality is a growing concern in the world. People spend a considerable amount of time in indoor environments such as homes, workplaces, shopping malls, stores, and so on. Indoor sources like incense and candle burning, cooking contribute a significant amount of indoor air pollutants such as particulate matter, carbon monoxide (CO), volatile organic compounds. Exposure to these kinds of pollutants can result in adverse health effects.

The purpose of this research is to determine the particulate matter and carbon monoxide emission factors (EFs) from incense stick burning. A test chamber with a rectangular exhaust duct, a fan to …

Analysis Of Variable Insensitive Friction Stir Welding Parameters, Robert L. Marrero Jr

LSU New Orleans Theses and Dissertations

Friction Stir Welding (FSW) was used to perform a Design of Experiment (DOE) to determine the welding parameters effects on yielding consistent mechanical properties across the length of the weld. The travel speed was varied across set forge force and RPM conditions, to find a dataset that will yield consistent mechanical properties independent of the travel speed. Six different welds were completed on two different aluminum panels, the advancing side being Aluminum alloy 2195-T8 at a thickness of .350”, with the retreating side being Aluminum alloy 2219-T851 with a gauge thickness of .360”. A Left-hand Right-hand self-reacting pin tool was …

Distributed Emitter Detector Design Under Imperfect Communication Channel, Soumyadip Patra

LSU New Orleans Theses and Dissertations

We consider the distributed detection of an emitter using multiple sensors deployed at deterministic locations. The signal from the emitter follows a signal attenuation model dependent on the distance between the sensor and the emitter. The sensors transmit their decisions to the fusion center through a parallel access Binary Symmetric Channel (BSC) with a cross-over probability. We seek to optimize the detection performance under a prescribed false alarm at the sensor level and at the system level. We consider the triangular topology structure and using the least favorable emitter range study the impact of the BSC on the system level …

Influence Of Adsorbed And Nonadsorbed Polymer Additives On The Viscosity Of Magnesium Oxide Suspensions, Lisa R. Murray, Jason E Bice, Emily G. Soltys, Christopher Perge, Sebastien Manneville, Kendra Erk

School of Materials Engineering Faculty Publications

Adsorbed polymer additives have been employed to reduce water content and improve cement workability through lowering viscosity, but the influence of over-dosage and the presence of nonadsorbed chains have yet to be fully understood. Model magnesium oxide (MgO) suspensions were used to investigate the potential processing effect of “free” chain concentration on cementitious mixtures. The rheological impact of the free chains was measured through incorporation of nonadsorbing poly(ethylene glycol) (PEG) to suspensions stabilized with an adsorbed comb-polymer superplasticizer. Analyses of the rheological data, that showed viscosity-increases and viscosity-reduction due to free PEG concentrations revealed a transition from depletion flocculation to …

Effect Of Optimizing Particle Size In Laser Metal Deposition With Blown Pre-Mixed Powders, Wei Li, Jingwei Zhang, Xinchang Zhang, Sreekar Karnati, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Functionally Graded Material (FGM) is often fabricated by Laser metal deposition with pre-mixed multiple powders (PMM-powder). Since the supplied PMM-powder directly affects FGM’s composition, investigation on PMM-powder’s property is greatly needed. This paper employed experimental method to observe an important problem: PMM-powder separation in fabricating FGM. A novel particle size optimization method was introduced as solution to eliminate the powder separation. Pre-mixed pure Cu and 4047 Al powders were used to do two experiments. The first experiment result disclosed the existence of powder separation. By optimizing the particle size, the PMM-powder separation was effectively solved in the second experiment result.

Towards Defect Detection In Metal Slm Parts Using Modal Analysis "Fingerprinting", James Urban, Nick E. Capps, Brian M. West, Troy Hartwig, Ben Brown, Robert G. Landers, Douglas A. Bristow, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The validation of Additively Manufactured (AM) materials is a difficult and expensive process because the local engineering properties are a function of the thermal history. The thermal history varies with the process parameters, as well as the part geometry. This paper presents a case study using modal testing to identify defects in realistic AM parts. A setup consisting of a Scanning Laser Doppler Vibrometer (LDV) was used to identify the resonant frequencies for several geometrically identical parts on a build plate. Parts with suboptimal process parameters from purposely varying the process parameters, are identified by a shift in the mode …

Fabricating Zirconia Parts With Organic Support Material By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Andrew Scherff, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace 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. This paper presents a further development of this process and focuses on fabricating 3 mol% yttria-stabilized zirconia (3YSZ) components that cannot be fabricated without using support structures. The 3YSZ paste is deposited through the main nozzle, and a polycaprolactone (PCL) pellet feedstock is melted and deposited through an auxiliary nozzle to build support structures. After a green part is printed and dried, the support structures are removed by heating the part to ~70 ⁰C to melt the PCL. The part is then …

Development Of A Hybrid Manufacturing Process For Precision Metal Parts, Leon Hill, Todd E. Sparks, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper summarizes the research and development of a hybrid manufacturing process to produce fully dense metal parts with CNC-level precision. High performance metals, such as titanium alloys, nickel superalloys, tool steels, stainless steels, etc. can benefit from this process. Coupling the additive and the subtractive processes into a multi-axis workstation, the hybrid process, can produce and repair metal parts with accuracy. The surface quality of the final product is similar to the industrial milling capability. To achieve such a system, issues of the metal deposition process and the automated process planning of the hybrid manufacturing process will be discussed.

A Compact Energy-Independent Czt-Based Gamma Camera, Youngho Seo, Yonggang Cui, Paul O'Connor, Qiu Huang, Ralph B. James, Debasis Mitra, Hui Pan

Electrical Engineering and Computer Science Faculty Publications

Conventional gamma cameras are heavy and occupy large volume for all required hardware components. Direct-conversion solid-state detectors like cadmium zinc telluride (CZT) enable a compact design of gamma cameras. In addition, conventional gamma cameras require different collimators for different gamma-ray photon energies, and the change of collimators between studies sometimes disrupts the workflow. To ease this inconvenience (i.e., bulkiness and collimator change), we have recently developed a compact, CZT-based, energy-independent gamma camera that requires only one collimator to cover a broad range of photon energies. In this paper, we show our design parameters and system specifications as well as simulation …

A Two-Dimensional Simulation Of Grain Structure Growth Within Substrate And Fusion Zone During Direct Metal Deposition, Jingwei Zhang, Wei Li, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, a predictive model based on a cellular automaton (CA)-finite element (FE) method has been developed to simulate thermal history and microstructure evolution during metal solidification for a laser-based additive manufacturing process. The macroscopic FE calculation that is validated by thermocouple experiment is designed to update the temperature field and a high cooling rate. A cellular automata-finite element (CAFE) method is developed to describe grain growth in the fusion zone. In the mesoscopic CA model, heterogeneous nucleation sites, grain growth orientation and rate, epitaxial growth, remelting of preexisting grains, metal addition, grain competitive growth, and columnar to equiaxed …

A New Broadcast Wiretap Channel Model, Mohamed Nafea, Aylin Yener

Electrical and Computer Engineering Faculty Research & Creative Works

A new broadcast wiretap channel (B-WTC) with a wiretapper who noiselessly taps into a fixed-length subset of the transmitted symbols of her choice, and observes the remainder through a noisy channel, is studied. An achievable strong secrecy rate region which extends Marton's inner bound to the proposed setting, is derived. Strong secrecy capacity regions for two classes of the new B-WTC, namely the new B-WTC with deterministic receivers, and the new B-WTC with degraded receivers and noisier wiretapper, are identified. These results extend the recently proposed new wiretap channel model to the broadcast setting.

Design And Fabrication Of Functionally Graded Material From Ti To Γ-Tial By Laser Metal Deposition, Xueyang Chen, Lei Yan, Joseph William Newkirk, Frank W. Liou

Materials Science and Engineering Faculty Research & Creative Works

Functionally graded material (FGM) is one kind of advanced material characterized by a gradual change in properties as the position varies. The spatial variation of compositional and microstructure over volume is aimed to control corresponding functional properties. In this research, when 100% γ-TiAl was directly deposited on pure Ti substrate, cracks were formed within the γ-TiAl layer. Then a six-layer crack-free functionally graded material of Ti/TiAl was designed and fabricated by laser metal deposition (LMD) method, with composition changing from pure Ti on one side to 100% γ-TiAl on the other side. The fabricated FGM was characterized for material properties …

Mechanical Properties Of 304l Parts Made By Laser-Foil-Printing Technology, Chia-Hung Hung, Yiyu Shen, Ming-Chuan Leu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser-Foil-Printing (LFP) is a novel laminated object manufacturing process for metal additive manufacturing. It fabricates three-dimensional metal parts by using a dual-laser system to weld and cut metal foils layer by layer. A main advantage of LFP is the higher cooling rate compared to powder-based laser additive manufacturing processes due to the thermal conductivity difference between foil and powder. This study focuses on the mechanical properties of 304L stainless steel parts built by the LFP process. The experimental results indicate that the yield strength and ultimate tensile strength of LFP fabricated 304L SS parts are higher by 9% and 8% …

Construction Of Metallic Glass Structures By Laser-Foil-Printing Technology, Yiyu Shen, Yingqi Li, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Metallic glasses (MGs) have superior mechanical properties such as high tensile strength, hardness, and corrosion resistance, as compared to crystalline metals. Although newly developed MGs have significantly reduced critical cooling rates down to 10 K/s, products of MGs are still limited to simple geometries such as foils/plates or rods with thin section-thickness which is mainly caused by the decrease of thermal conductivities of the new MGs. Recently, we developed a new Laser-foil-printing (LFP) additive manufacturing technology which welds foils, layer by layer, to construct desired 3D structures. With the LFP and Zr-based amorphous foils, 3D, large amorphous structures with complex …