Mechanical Engineering Commons^™

Performance Of Dynamically Simulated Reference Patterns For Cross Correlation Ebsd, Brian Jackson, Jordan Christensen, Saransh Singh, Marc De Graef, David T. Fullwood, Eric Richards Homer, Robert Wagoner

Faculty Publications

High-resolution (or \cross-correlation") electron backscatter diffraction analysis (HR-EBSD) utilizes cross-correlation techniques to determine relative orientation and distortion of an experimental electron backscatter diffraction pattern (EBSP) with respect to a reference pattern. The integrity of absolute strain and tetragonality measurements of a standard Si/SiGe material have previously been analyzed using reference patterns produced by kinematical simulation. While the results were promising, the noise levels were significantly higher for kinematically produced patterns, compared to real patterns taken from the Si region of the sample. This paper applies HR-EBSD techniques to analyze lattice distortion in a Si/SiGe sample, using recently developed dynamically simulated …

A Novel Extrusion-Based Additive Manufacturing Process For Ceramic Parts, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An extrusion-based additive manufacturing process, called the Ceramic On-Demand Extrusion (CODE) process, for producing three-dimensional ceramic components with near theoretical density is introduced in this paper. In this process, an aqueous paste of ceramic particles with a very low binder content ( < 1 vol%) is extruded through a moving nozzle at room temperature. After a layer is deposited, it is surrounded by oil (to a level just below the top surface of most recent layer) to preclude non-uniform evaporation from the sides. Infrared radiation is then used to partially, and uniformly, dry the just-deposited layer so that the yield stress of the paste increases and the part maintains its shape. The same procedure is repeated for every layer until part fabrication is completed. Several sample parts for various applications were produced using this process and their properties were obtained. The results indicate that the proposed method enables fabrication of large, dense ceramic parts with complex geometries.

Effect Of Sparse-Build Internal Structure On Performance Of Fused Deposition Modeling Tools Under Pressure, S. Meng, L. Mason, Gregory Taylor, X. Wang, Ming-Chuan Leu, K. Chandrashekhara, Mike Matlack, James Castle

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Two different approaches to design a sparse-build tool for fabrication by the fused deposition modeling (FDM) process are compared. One approach uses a 2D lattice structure and the other approach is inspired by topology optimization. Ultem 9085 is used as the material, and the amount of material used to build the tool is kept constant to ensure a fair comparison. A solid tool is also included in the comparison. The performance of the tool under uniform pressure is simulated using finite element analysis (FEA) and the accuracy of the FEA results is verified by comparing them with experimentally measured data …

Novel Extrusion-Based Additive Manufacturing Process For Ceramic Parts, Amir Ghazanfari, Wenbin Li, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An extrusion-based additive manufacturing process, called the Ceramic On-Demand Extrusion (CODE) process, for producing three-dimensional ceramic components with near theoretical density is introduced in this paper. In this process, an aqueous paste of ceramic particles with a very low binder content (< 1 vol%) is extruded through a moving nozzle at room temperature. After a layer is deposited, it is surrounded by oil (to a level just below the top surface of most recent layer) to preclude non-uniform evaporation from the sides. Infrared radiation is then used to partially, and uniformly, dry the just-deposited layer so that the yield stress of the paste increases and the part maintains its shape. The same procedure is repeated for every layer until part fabrication is completed. Several sample parts for various applications were produced using this process and their properties were obtained. The results indicate that the proposed method enables fabrication of large, dense ceramic parts with complex geometries.

Modal Response As A Validation Technique For Metal Parts Fabricated With Selective Laser Melting, Joshua D. Pribe, Brian M. West, Michelle L. Gegel, Troy Hartwig, Toby Lunn, Ben Brown, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper investigates modal analysis as a validation technique for additively manufactured parts. The Frequency Response Function (FRF) is dependent on both the geometry and the material properties of the part as well as the presence of any defects. This allows the FRF to serve as a “fingerprint” for a given part of given quality. Once established, the FRF can be used to qualify subsequently printed parts. This approach is particularly attractive for metal parts, due to the lower damping as well as use in high-value applications where failure is unacceptable. To evaluate the efficacy of the technique, tensile specimens …

Elevated Temperature Microstructure Stability Of Slm 304l Stainless Steel, Tarak Amine, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

With time at temperature, changes in metallurgical structure can be expected for almost any steel or alloy. In stainless steels, the changes can be grain growth, carbide precipitation, ferrite decomposition, or embrittlement. These phenomena can significantly effect the properties of the steel and would potentially change the functionality of the component. Therefore, to determine component stability, the elevated temperature microstructure stability of additive manufacturing materials was studied. This work investigates the influence of different aging times of additive material stainless steels (304L) fabricated with the Selective Laser Melting (SLM) process on microstructure and mechanical properties. Microstructure and mechanical properties were …

Simulation Of Cooling Rate Effects On Ti-48al-2cr-2nb Crack Formation In Direct Laser Deposition, Lei Yan, Wei Li, Xueyang Chen, Yunlu Zhang, Joseph William Newkirk, Frank W. Liou, David Dietrich

Materials Science and Engineering Faculty Research & Creative Works

Transient temperature history is vital in direct laser deposition (DLD) because it reveals the cooling rate at specific temperatures, which directly relates to phase transformation and types of microstructure formed in deposit. FEA simulation was employed to study the transient temperature history and cooling rate at different experimental setups in Ti-48Al-2Cr-2Nb DLD process. In this paper, an innovative model was described, which combines a moving Gaussian distribution heat source and element birth and death technology in ANSYS, help to analysis cooling rate control method and guide crack-free deposits build process.

Designed Extrudate For Additive Manufacturing Of Zirconium Diboride By Ceramic On-Demand Extrusion, Devin Mcmillen, Wenbin Li, Ming-Chuan Leu, Greg Hilmas, Jeremy Lee Watts

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This work describes a process by which zirconium diboride (ZrB2) parts may be fabricated using the Ceramic On-Demand Extrusion (CODE) process. An oxide-carbide-nitride system consisting of ceramic powders and pre-ceramic organics, designed to yield ZrB₂ after reaction sintering, has been developed to produce an aqueous-based extrudate for subsequent processing in the CODE system. Pressurelessly sintered test specimens containing 1 wt% PVA binder achieve high relative density ≥ 99%. The viscoelastic response of the extrudate was characterized via spindle rheometry with a small sample adapter. Batches with 1 wt% PVA and 0.5 wt% Methocel show strong shear thinning characteristic, under …

Effects Of Build Parameters On Compression Properties For Ultem 9085 Parts By Fused Deposition Modeling, Krishna P. Motaparti, Gregory Taylor, Ming-Chuan Leu, K. Chandrashekhara, James Castle, Mike Matlack

Mechanical and Aerospace Engineering Faculty Research & Creative Works

It has been observed by various researchers that parts fabricated by the Fused Deposition Modeling (FDM) process have anisotropic properties. The research presented in the present paper was aimed to study the compression properties of FDM parts and to comprehend their dependence on build parameters. In this study Ultem 9085 was used as the material to fabricate both solid and sparse-build coupons with variations in build direction, raster angle and air gap. A full factorial experimental design was used to study the individual and combined effects of these build parameters on the mechanical properties of the coupons. The mechanical properties …

Proposed Hybrid Processes For Part Building Using Fusion Welding And Friction Stir Processing, Megan A. Gegesky, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

It has been shown that a hybrid laser additive manufacturing and friction stir processing can deposit components with forged-like structures. This paper reports a hybrid fusion welding and friction stir process to create parts with quality structures. Combining traditional fusion welding and friction stir processing techniques for non-weldable aluminum alloys could facilitate the joining of difficult geometries in manufactured parts. This research illustrates mechanical property changes for non-weldable and weldable aluminum alloys. The Vickers hardness, and microhardness in the case of AA5052-H32, tensile strength and corrosion resistance of four processing states: base material, fusion welded material, friction stir welded material, …

Mechanical Engineering News, Georgia Southern University

Mechanical Engineering: News & Publications (2013-2023)

• Dr. Xuchun Ren Awarded NSF Research Grant

• Mechanical Engineering Faculty Visit Robins AFB

Determining The Print Accuracy Of Four Three-Dimensional Printers, Kshiteej Dalal

Master of Technology Management Plan II Graduate Projects

Rapid prototyping [RP] or 3D printing [3DP] have existed for some time now. One of the major deficiencies of 3DP is the accuracy of the printed three dimensional parts. Even beyond that is the lack of studies that have been designed to measure the 3DP components. Measuring, verifying and determining the accuracy of 3DP parts is the focus of this study. As the accuracy is measured and approaches those of CNC machined parts, it will drive the development of additional additive manufacturing [AM] machinery. In this project a component is created in a solid modeling package. A solid model of …

Design Maps For Fracture Resistant Functionally Graded Materials, Muhammad Ridwan Murshed

Theses and Dissertations

The objective of this research is to generate design maps to identify functionally graded microstructures with enhanced fracture toughness. Several Functionally Graded Materials (FGMs) with an edge crack and membrane loading are considered and the resulting J-integral values are computed numerically using Finite Element Analysis. In order to capture the resulting stress fields accurately, Barsoum elements are used in the vicinity of the crack tip and the simulations are carried out for several crack lengths (a) and material contrasts (κ). The averages of the J-integral values are used to determine the normalized Stress Intensity Factors which are then benchmarked with …

Modeling Of A Roll-To-Roll Plasma Cvd System For Graphene, Yudong Chen, Majed A. Alrefae, Anurag Kumar, Timothy S. Fisher

The Summer Undergraduate Research Fellowship (SURF) Symposium

Graphene is a 2D carbon material that has extraordinary physical properties relevant to many industrial applications such as electronics, oxidation barrier and biosensors. Roll-to-roll plasma chemical vapor deposition (CVD) has been developed to manufacture graphene at large scale. In a plasma CVD chamber, graphene is grown on a copper foil as it passes through a high-temperature plasma region. The temperatures of the gas and the copper foil play important roles in the growth of graphene. Consequently, there is a need to understand the temperature and gas velocity distributions in the system. The heat generated in the plasma creates a thermal …

Dynamic Modeling And Validation Of Micro-Chp Systems, Apurva Badithela, Neera Jain, Austin Nash

The Summer Undergraduate Research Fellowship (SURF) Symposium

Micro-Combined Heat and Power (micro-CHP) units locally generate electricity to simultaneously provide power and heat for residential buildings. Apart from the potential benefits of reducing carbon emissions and increasing robustness to brownouts and blackouts, micro-CHP systems can be controlled to meet energy demands. Micro-CHP systems consist of a prime mover that generates electricity, such as a fuel cell, an internal combustion engine, or a Stirling engine, and a waste heat recovery system that enables utilization of heat generated as a byproduct of electricity generation. Often, a thermal energy storage system is integrated with micro-CHP systems, thereby decoupling, in time, the …

Fluid Flow Thermometry Using Thermographic Phosphors, Gabriel J. Fenoglio, Humberto J. Detrinidad, Aman Satija, Alex D. Casey, Robert P. Lucht, Terrence R. Meyer

The Summer Undergraduate Research Fellowship (SURF) Symposium

Phosphor thermometry is a non-intrusive thermometry technique that allows for spatially and temporally resolved surface temperature measurements. The thermographic method has been employed in a number of applications that include combustion, sprays, and gas flows. In the current work, we investigate the implementation of thermographic phosphors in liquid flows, which is of interest in a wide range of applications in heat transfer, fluid mechanics, and thermal systems. Zinc oxide doped with Zinc (ZnO:Zn) was the phosphor employed for experimentation due to its high emission intensity and insolubility. In order to explore this application, the phosphor powder was uniformly dispersed in …

Pore Scale Transport Of Miscible And Immiscible Fluids In Porous Media, Tolulope O. Odimayomi, Arezoo M. Ardekani

The Summer Undergraduate Research Fellowship (SURF) Symposium

The separation of harmful or valuable substances entrapped in porous media has applications in processes such as enhanced oil recovery, diffusion in tissue, and aquifer remediation. In this study the motion and removal rate of immiscible and miscible solutions have been analyzed to gain understanding of solvent effectiveness as it is diluted due to diffusion or mixing within porous materials. The extraction of oil using water, a surfactant solution of 4% CTAB in water, and a foam produced form the surfactant solution is observed using two dimensional flows between parallel slides containing cylindrical obstacles. The fluid motion is visualized. The …

Laser-Assisted Microchanneling On Pmma Substrate Utilizing Two-Pass Fabrication Method, Sijie Zhang, Yung C. Shin

The Summer Undergraduate Research Fellowship (SURF) Symposium

Microchannel is widely used in microfluidic devices for mixing, chemical reaction, detection, particle separation and etc. CO₂ laser-based microchanneling of PMMA as a low cost, rapid, noncontact fabrication method has attracted the attention of industry. However, the typical V-shape grooves fabricated by CO₂ laser microchanneling have limitations since the V-shape grooves will affect the flow behavior and heat transfer of the fluid, which are important to the performance of microfluidic devices. A two-pass fabrication method is proposed and investigated in this paper to improve the quality of the PMMA microchannel fabricated by CO₂ laser. It was found …

Development Of A Diode-Laser Absorption-Spectroscopy Sensor For Real-Time Control Of Combustion Systems, Rahul P. Balla, Christopher S. Goldenstein

The Summer Undergraduate Research Fellowship (SURF) Symposium

Tunable diode-laser absorption spectroscopy (TDLAS) sensors are widely used for measuring gas properties. These sensors offer several advantages including: small footprint, affordability, applicability to harsh environments, rapid time response, and calibration-free operation. As a result, diode-laser sensors can be integrated into control-systems and have previously been used to control gas-turbine combustors. In this study, high-frequency sine waves were generated continuously by a LabVIEW program to simultaneously scan and modulate the wavelength and intensity of a diode laser. The modulated laser light was transmitted 20 cm through the air and measured on a photodetector. Custom-built lock-in software was used to acquire …

Dynamic Modeling Of Contact-Mode Triboelectric Generators By Lagrange’S Equations, Sean M. Gauntt, James Gibert

The Summer Undergraduate Research Fellowship (SURF) Symposium

Electret based energy scavenging devices utilize electrostatic induction to convert mechanical energy into electrical energy. Uses for these devices include harvesting ambient energy in the environment and acting as sensors for a range of applications. These types of devices have been used in MEMS applications for over a decade. However, recently there is an interest in Triboelectric generators/harvesters, i.e., electret based harvesters that relies on triboelectrification as well as electrostatic induction. The literature is filled with a variety of designs for the latter devices, constructed from materials ranging from paper and thin films; rendering the generators lightweight, flexible and inexpensive. …

Effect Of Aggregation And Particle Size On The Thermal Conductivity Of Nickel-Epoxy Nanocomposites, Jacob M. Faulkner, Xiangyu Li, Xiulin Ruan Dr.

The Summer Undergraduate Research Fellowship (SURF) Symposium

Microprocessor advancements have been stunted in recent years by inadequate means of heat dissipation as power continues to grow and size continues to shrink. One way to increase thermal conductivity while maintaining electrical insulation is to add metal nanoparticles to a polymer matrix. This cheap material has become a popular thermal interface for this reason. However, optimization of the interface is dependent upon a number of factors including particle size, shape, orientation, and aggregation. Various theoretical models and numerical approximations have been developed to find the effective thermal conductivity of such nanocomposites, but none has been able to fully incorporate …

The Effect Of Honeycomb Cavity: Acoustic Performance Of A Double-Leaf Micro Perforated Panel, Yuxian Huang, Kai Ming Li

The Summer Undergraduate Research Fellowship (SURF) Symposium

A micro perforated panel (MPP) is a device consisting of a thin plate and submillimeter perforations for reducing low frequency noise. MPPs have many advantages compared to traditional sound absorption materials, such as durability and designability, and they can be used in a variety of places such as room interior designs, passenger and crew compartments of aircrafts and combustion engines. The models in this study were designed and fabricated with the latest 3-D printing technology. The transmission loss and sound absorption coefficient of the 3-D printed double-leaf MPPs with honeycomb cavities were studied. According to the established theory, MPPs work …

Laser Assisted Manufacturing: A Comparison Of Mechanical Properties Between Lam And Conventional Manufacturing Techniques, William Blakeslee, Neil S. Bailey, Kyung-Min Hong, Shunyu Liu, Yung C. Shin

The Summer Undergraduate Research Fellowship (SURF) Symposium

Laser assisted manufacturing methods, such as direct metal deposition (DMD) and laser beam welding (LBW), are promising methods because of their higher precision and greater productivity when compared to traditional manufacturing methods. Because these methods are relatively new, the mechanical properties of samples produced by laser assisted manufacturing are not well understood. In this study the mechanical properties of samples produced by laser assisted manufacturing methods are analyzed and compared with data obtained from traditional manufacturing methods. The DMD process used Fe-TiC and Ti-TiC metal matrix composites, while LBW used AISI 304 stainless steel. The results vary widely with the …

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 space volumes …

Relative Contributions Of Inelastic Phonon Scattering And Elastic Phonon Scattering To Thermal Boundary Conductance Across Solid Interfaces, Mengxi Zhao, Zexi Lu, Xiulin Ruan

The Summer Undergraduate Research Fellowship (SURF) Symposium

The knowledge of inelastic phonon scattering is crucial for the understanding of thermal boundary conductance across solid interfaces. Several traditional theoretical models such as the acoustic mismatch model (AMM) and the diffuse mismatch model (DMM) assume that the elastic phonon scattering drives the thermal transport across the interface. But there are experiments indicating that the inelastic phonon scattering plays an important part in the interfacial thermal energy conduction as well. We use nonequilibrium molecular dynamics (NEMD) to predict the inelastic phonon conductance across Cu/Si interface. Temperature distribution across Cu/Si interface has been obtained from the simulation results, and a temperature …

X-Ray And Laser Investigation Of High Pressure Sprays, Wilbert C. Slowman, Lane E. Shultz, Terence R. Meyer

The Summer Undergraduate Research Fellowship (SURF) Symposium

The diagnostics of multiphase flows is important to understand the correlation of parameters such as nozzle geometry, flow velocity, liquid breakup characteristics, atomization, and mass distribution. Investigation of each of these parameters can lead to various improvements on design and optimization, for example, of combustion in gas turbines and rocket engines. For this project, the X-ray and optical diagnostics of multiphase flows in propulsion is investigated for high pressures. Two x-ray tube sources are used to illuminate the spray, and the images are captured on phosphor plates coupled to high-speed cameras. Reconstruction of the mass distribution is accomplished using computer …

Dynamic Behavior Of A Clamped-Clamped Bi-Stable Laminate For Energy Harvesting, Ajay V. Kumar, Andres F. Arrieta Ph.D., Myungwon Hwang

The Summer Undergraduate Research Fellowship (SURF) Symposium

Multi-stable laminates have many applications in morphing structures, energy harvesting devices, and metamaterials due to the specific characteristics attributed to the exhibited stable states. Changes between stable states allow for large deflections, on-demand variation of the stiffness of compliant structures embedded within these elements, and control of effective dynamic properties in periodic lattices. These changes in state can be accessed via a snap-through instability triggered by introducing a well-defined activation energy. The resulting oscillations could enable broadband energy harvesting via piezoelectric transduction and resistive circuits. In this paper, a clamped-clamped bi-stable laminate is studied to understand the behavior of the …

Investigation Of Aluminum Foams And Graphite Fillers For Improving The Thermal Conductivity Of Paraffin Wax-Based Phase Change Materials, Javieradrian Ruiz, Amy Marconnet, Yash Ganatra, John Howarter, Alex Bruce

The Summer Undergraduate Research Fellowship (SURF) Symposium

Passive thermal management with phase change materials (PCMs) has become the one of the most promising methods to cool cell phone processors due to the relatively simple implementation and profound impact on processor temperatures. Enhancing the thermal properties of conventional PCMs, mainly thermal conductivity and latent heat storage, allows for an overall improved thermal management system. This study aims to improve the thermal conductivity of paraffin wax (a typical commercial PCM) by the introduction of an expanded graphite (EG) filler to form a paraffin wax composite, and then infiltration of the EG/paraffin composite into an aluminum foam matrix. The thermal …

High Strain Rate Experiments Of Energetic Material Binder, Roberto Rangel Mendoza, Michael Harr, Weinong Chen

The Summer Undergraduate Research Fellowship (SURF) Symposium

Energetic materials, in particular HMX, is widely used in many applications as polymer bonded explosives (PBX) and rocket propellant. However, when damaged, HMX is known to be an unstable substance which renders it a hazardous material and in some cases unreliable. Finding critical mechanical conditions at high rates that render various forms of energetic materials as unreliable would be vital to understand the effects that vibrations and compression forces have on energetic materials. A better understanding would enable the ability to develop improvements in the manufacturing of PBX and rocker propellant. The method utilized to evaluate the mechanical properties of …

Effects Of Internal Egr On Modern Diesel Engines Internal Equipped With Vva At Idle, Erik R. Santini, Dheeraj B. Gosala, Gregory M. Shaver

The Summer Undergraduate Research Fellowship (SURF) Symposium

Vehicle emissions regulations are continuing to grow more challenging requiring near-zero levels of pollutant emissions. Nitric oxide (NOx) emissions are heavily regulated with the emission limit expected to become 1/10^th of its present limit by 2021. In order to meet the new regulations, improvements in both the engine and the exhaust aftertreatment system are required. Exhaust gas recirculation (EGR) is used to reduce the NOx produced by the engine while the aftertreatment system converts most of the engine-out emissions to safer gases before releasing them to the atmosphere. One of the main challenges with the aftertreatment system is that …