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Full-Text Articles in Engineering

Anisotropy In Impact Toughness Of Powder Bed Fused Aisi 304l Stainless Steel, Sreekar Karnati, Atoosa Khiabhani, Aaron Flood, Frank W. Liou, Joseph William Newkirk Mar 2019

Anisotropy In Impact Toughness Of Powder Bed Fused Aisi 304l Stainless Steel, Sreekar Karnati, Atoosa Khiabhani, Aaron Flood, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The current effort involved investigation into the anisotropy of AISI 304L fabricated through laser powder bed fusion. Charpy V‐notch specimens made from material fabricated at three different build orientations were tested and analyzed. A statistically significant difference among the toughness values indicates the presence of anisotropy within the additively manufactured material. While the lowest toughness was found in vertically built specimens, the horizontal specimens were found to exhibit the highest toughness. From the fracture surfaces, an atypical mode of failure was observed. Exclusive crack propagation along the interlayer track boundaries was observed. The toughness variation correlated with the ease ...


On The Feasibility Of Tailoring Copper-Nickel Functionally Graded Materials Fabricated Through Laser Metal Deposition, Sreekar Karnati, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk Mar 2019

On The Feasibility Of Tailoring Copper-Nickel Functionally Graded Materials Fabricated Through Laser Metal Deposition, Sreekar Karnati, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this study, pulse‐width modulation of laser power was identified as a feasible means for varying the chemical gradient in copper—nickel‐graded materials. Graded material deposits of 70 wt. %. copper‐30 wt. %. nickel on 100 wt. %. nickel and vice versa were deposited and characterized. The 70/30 copper—nickel weight ratio in the feedstock powder was achieved through blending elemental copper and 96 wt. %. Ni—Delero‐22 alloy. At the dissimilar material interface over the course of four layers, the duty cycle of power was ramped down from a high value to optimized deposition conditions. This change was ...


Cutter Elements For Drill Bits And Methods For Fabricating Same, Guodong Zhan, Biju Pillai Kumar, Russell C. Gilleylen, Michael D. Hughes, Xinhua Liang Feb 2019

Cutter Elements For Drill Bits And Methods For Fabricating Same, Guodong Zhan, Biju Pillai Kumar, Russell C. Gilleylen, Michael D. Hughes, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

A method of fabricating a PCD cutter element including a diamond table including a plurality of coated diamond particles fabricated using an atomic layer deposition (ALD) process.


Substrate Support Ring For More Uniform Layer Thickness, Heng Pan, Lara Hawrylchak, Christopher S. Olsen Feb 2019

Substrate Support Ring For More Uniform Layer Thickness, Heng Pan, Lara Hawrylchak, Christopher S. Olsen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Embodiments of substrate support rings providing more uniform thickness of layers deposited or grown on a substrate are provided herein. In some embodiments, a substrate support ring includes: an inner ring with a centrally located support surface to support a substrate; and an outer ring extending radially outward from the support surface, wherein the outer ring comprises a reaction surface area disposed above and generally parallel to a support plane of the support surface, and wherein the reaction surface extends beyond the support surface by about 24 mm to about 45 mm.


A Framework For Process Inspection Of Metal Additive Manufacturing, Chih-Kun Cheng, Frank W. Liou, Yi-Chien Cheng, Sheng-Chih Shen Feb 2019

A Framework For Process Inspection Of Metal Additive Manufacturing, Chih-Kun Cheng, Frank W. Liou, Yi-Chien Cheng, Sheng-Chih Shen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we propose a process inspection framework for metal additive manufacturing (AM) processes. AM, also known as 3D printing, is the process of joining materials to make objects on the basis of 3D model data and is envisioned to play a strategic role in maintaining economic and scientific dominance. Different from conventional manufacturing methods, the AM process is a point-by-point and layer-by-layer manufacturing. Thus, there are many opportunities to generate a process error that can cause quality issues in an AM part. A systematic AM process inspection is needed to yield acceptable performance of the part. The critical ...


Multiphysics Prediction Model Of Microwave Curing For Thick Polymer Composites, Siva Dasari Jan 2019

Multiphysics Prediction Model Of Microwave Curing For Thick Polymer Composites, Siva Dasari

Masters Theses

"Microwave curing technologies have many advantages over the traditional thermal curing methods for the manufacturing of fiber reinforced polymers, especially the processing speed and energy efficiency. Energy can be instantaneously transferred through applied electromagnetic fields and heat is generated based on dipolar rotational interactions. Microwave curing processes have been used for glass fiber composites but there are significant challenges associated with microwave curing of carbon fiber composites. Efficient heating may be difficult due to high dielectric loss associated with carbon fibers. Laminate quality will be highly dependent on the uniformity of the electromagnetic field in the material. In this work ...


Near-Field Electrospinning Of A Polymer/Bioactive Glass Composite To Fabricate 3d Biomimetic Structures, Krishna C. R. Kolan, Jie Li, Sonya Roberts, Julie A. Semon, Jonghyun Park, D. E. Day, Ming-Chuan Leu Jan 2019

Near-Field Electrospinning Of A Polymer/Bioactive Glass Composite To Fabricate 3d Biomimetic Structures, Krishna C. R. Kolan, Jie Li, Sonya Roberts, Julie A. Semon, Jonghyun Park, D. E. Day, Ming-Chuan Leu

Biological Sciences Faculty Research & Creative Works

Bioactive glasses have recently gained attention in tissue engineering and three-dimensional (3D) bioprinting because of their ability to enhance angiogenesis. Some challenges for developing biological tissues with bioactive glasses include incorporation of glass particles and achieving a 3D architecture mimicking natural tissues. In this study, we investigate the fabrication of scaffolds with a polymer/bioactive glass composite using near-field electrospinning (NFES). An overall controlled 3D scaffold with pores, containing random fibers, is created and aimed to provide superior cell proliferation. Highly angiogenic borate bioactive glass (13-93B3) in 20 wt.% is added to polycaprolactone (PCL) to fabricate scaffolds using the NFES ...


Light Touch Based Virtual Cane For Balance Assistance During Standing, Sindhu Reddy Alluri Jan 2019

Light Touch Based Virtual Cane For Balance Assistance During Standing, Sindhu Reddy Alluri

Masters Theses

"Can additional information about one's body kinematics provided through hands improve human balance? Light-Touch (LT) through hands helps improve balance in a wide range of populations, both healthy and impaired. The force is too small to provide any meaningful mechanical assistance -- rather, it is suggested that the additional sensory information through hands helps the body improve balance.

To investigate the potential for improving human balance through biofeedback through hands, we developed a Virtual Cane (VC) for balance assistance during standing. The VC mimics the physical cane's function of providing information about one's body in space. Balance experiments ...


Performance Evaluation Of Bmi Resin System For Thin-Ply Composites, Manoj Kumar Reddy Rangapuram Jan 2019

Performance Evaluation Of Bmi Resin System For Thin-Ply Composites, Manoj Kumar Reddy Rangapuram

Masters Theses

"Composites materials are increasingly being used in aerospace applications over the past few years. The unique properties like high strength to weight ratio, thermal stability, fatigue and corrosion resistance set them apart from the conventional materials. Composite materials are well suited for the applications where weight is the primary concern in the design. Composites structures are vulnerable to mechanical as well as thermal loadings. Transverse micro-cracking and delamination are the most common type of failures in composite materials. The thickness of the ply being used play a key role dictating the properties of the resultant composite structure. As the ply ...


Time-Dependent Reliability Methodologies With Saddlepoint Approximation, Zhangli Hu Jan 2019

Time-Dependent Reliability Methodologies With Saddlepoint Approximation, Zhangli Hu

Doctoral Dissertations

"Engineers always encounter time-dependent uncertainties that ubiquitously exist, such as the random deterioration of material properties and time-variant loads. Therefore the reliability of engineering systems becomes time-dependent. It is crucial to predict the time-dependent reliability in the design stage, given possible catastrophic consequences of a failure. Although extensive research has been conducted on reliability analysis, estimating the reliability accurately and efficiently is still challenging. The objective of this work is to develop accurate and efficient reliability methodologies for engineering design. The basic idea is the integration of traditional reliability methods with saddlepoint approximation (SPA), which can accurately approximate the tail ...


Reliability Analysis For Systems With Outsourced Components, Zhengwei Hu Jan 2019

Reliability Analysis For Systems With Outsourced Components, Zhengwei Hu

Doctoral Dissertations

"The current business model for many industrial firms is to function as system integrators, depending on numerous outsourced components from outside component suppliers. This practice has resulted in tremendous cost savings; it makes system reliability analysis, however, more challenging due to the limited component information available to system designers. The component information is often proprietary to component suppliers. Motivated by the need of system reliability prediction with outsourced components, this work aims to explore feasible ways to accurately predict the system reliability during the system design stage. Four methods are proposed. The first method reconstructs component reliability functions using limited ...


Solvent-Free Additive Manufacturing Of Electrodes For Li-Ion Batteries, Brandon Joshua Ludwig Jan 2019

Solvent-Free Additive Manufacturing Of Electrodes For Li-Ion Batteries, Brandon Joshua Ludwig

Doctoral Dissertations

"A new Li-ion battery electrode manufacturing process using a solvent free additive manufacturing method has been developed. Li-ion battery electrodes consist of active material particles, a binder additive, and a conductive additive. Traditionally, Li-ion battery electrodes are manufacturing using the "slurry casting" technique. In this method, the electrode materials are mixed with a solvent to create a slurry. Electrodes fabricated in this method are readily implemented for small platforms, such as portable electronics. However, this method isn't as economically viable in large platforms due to high material and manufacturing costs. High material and manufacturing costs are mostly attributed to ...


Deep Understanding Of Degradation In Lithium Ion Batteries Through Experimental And First-Principles Study, Yufang He Jan 2019

Deep Understanding Of Degradation In Lithium Ion Batteries Through Experimental And First-Principles Study, Yufang He

Doctoral Dissertations

"The growing interests in Lithium-ion Batteries (LIBs) have significantly accelerated the development of active materials. However, the key challenge is that electrode materials suffer from degradation, which include transition metal dissolution, solid electrolyte interphase (SEI) layer formation, and mechanical fracture. To address these issues, applying an ultrathin coating onto active materials via Atomic Layer Deposition (ALD) is an efficient way. Although numerious works have been done for active material performance improvement via ALD technology, the fundamental enhancement mechanisms of ALD coating on battery performance improvement are not yet known. Therefore, this dissertation consists of four papers, which focused on the ...


Characterization Of The Surface Condition In Aa6061 Resulting From Deep Rolling As A Function Of Common Industrial Parameters, Andrew Kenneth Layer Jan 2019

Characterization Of The Surface Condition In Aa6061 Resulting From Deep Rolling As A Function Of Common Industrial Parameters, Andrew Kenneth Layer

Masters Theses

"Roller burnishing is widely used in industry to improve the surface finish and fatigue life of components. As weight reduction continues to grow in the automotive and transportation industries, deep rolling can help maintain product performance by mitigating the increase in component stresses resulting from lower weight systems. Deep rolling parameters such as tool, applied angle, feed rate, spindle speeds, and relative tool direction all affect cycle time, product performance, and appearance. The effects of common industrial parameters on the resultant surface roughness and residual stress profiles were studied in this investigation. The samples were manufactured on a CNC lathe ...


The Effect Of Cell Size And Surface Roughness On The Compressive Properties Of Abs Lattice Structures Fabricated By Fused Deposition Modeling, Leah Hope Mason Jan 2019

The Effect Of Cell Size And Surface Roughness On The Compressive Properties Of Abs Lattice Structures Fabricated By Fused Deposition Modeling, Leah Hope Mason

Masters Theses

"Postprocessing is an important step in many manufacturing methods, but it is especially important for additive manufacturing. Researchers looking to improve the surface roughness of acrylonitrile butadiene styrene (ABS) parts fabricated by fused deposition modeling (FDM) have determined that acetone smoothing not only achieves improved surface roughness but increases compressive strength as well. This could be very beneficial to lattice structures, which are known for already having an excellent strength to weight ratio. If the compressive strength of ABS lattice structures could be improved even further using acetone smoothing, it could expand the applications for plastic lattice structures and improve ...


Remanufacturing Of Precision Metal Components Using Additive Manufacturing Technology, Xinchang Zhang Jan 2019

Remanufacturing Of Precision Metal Components Using Additive Manufacturing Technology, Xinchang Zhang

Doctoral Dissertations

"Critical metallic components such as jet engine turbine blades and casting die/mold may be damaged after servicing for a period at harsh working environments such as elevated temperature and pressure, impact with foreign objects, wear, corrosion, and fatigue. Additive manufacturing has a promising application for the refurbishment of such high-costly parts by depositing materials at the damaged zone to restore the nominal geometry. However, several issues such as pre-processing of worn parts to assure the repairability, reconstructing the repair volume to generate a repair tool path for material deposition, and inspection of repaired parts are challenging. The current research ...


Improvements In Digital Image Correlation And Application In Material Mechanical Test, Yunlu Zhang Jan 2019

Improvements In Digital Image Correlation And Application In Material Mechanical Test, Yunlu Zhang

Doctoral Dissertations

"Digital image correlation (DIC) is a non-contact full-field optical measurement method. With the advantages of high accuracy, low cost, and simple implementation, it has been widely applied in the area of experimental mechanics. In this study, DIC algorithm has been improved in the aspects of the pixel-level searching method and reference frame update strategy. The feature matching based method is proposed to provide an initial guess for all points of interest with semi-subpixel level accuracy in cases with small or large translation, deformation, or rotation. The bisection searching strategy is presented to automatically adjust the frame step for varying practical ...


Freeform Extrusion Fabrication Of Advanced Ceramics And Ceramic-Based Composites, Wenbin Li Jan 2019

Freeform Extrusion Fabrication Of Advanced Ceramics And Ceramic-Based Composites, Wenbin Li

Doctoral Dissertations

"Ceramic On-Demand Extrusion (CODE) is a recently developed freeform extrusion fabrication process for producing dense ceramic components from single and multiple constituents. In this process, aqueous paste of ceramic particles with a very low binder content ( < 1 vol%) is extruded through a moving nozzle to print each layer sequentially. Once one layer is printed, it is surrounded by oil to prevent undesirable water evaporation from the perimeters of the part. The oil level is regulated just below the topmost layer of the part being fabricated. Infrared radiation is then applied to uniformly and partially dry the top layer so that the yield stress of the paste increases to avoid part deformation. By repeating the above steps, the part is printed in a layer-wise fashion, followed by post-processing. Paste extrusion precision of different extrusion mechanisms was compared and analyzed, with an auger extruder determined to be the most suitable paste extruder for the CODE system. A novel fabrication system was developed based on a motion gantry, auger extruders, and peripheral devices. Sample specimens were then produced from 3 mol% yttria stabilized zirconia using this fabrication system, and their properties, including density, flexural strength, Young's modulus, Weibull modulus, fracture toughness, and hardness were measured. The results indicated that superior mechanical properties were achieved by the CODE process among all the additive manufacturing processes. Further development was made on the CODE process to fabricate ceramic components that have external/internal features such as overhangs by using fugitive support material. Finally, ceramic composites with functionally graded materials (FGMs) were fabricated by the CODE process using a dynamic mixing device"--Abstract, page iv.


Laser Welding Of Metallic Glass To Crystalline Metal In Laser-Foil-Printing Additive Manufacturing, Yingqi Li Jan 2019

Laser Welding Of Metallic Glass To Crystalline Metal In Laser-Foil-Printing Additive Manufacturing, Yingqi Li

Doctoral Dissertations

"The application of metallic glasses has been traditionally limited to parts with small dimensions and simple geometries, due to the requirement of fast cooling during the conventional process of casting. In addition, joining metallic glass to crystalline metal is of interest for many applications that require locally tailored functions and properties, but it is challenging. This research describes a promising additive manufacturing technology, i.e., laser-foil-printing, to make high-quality metallic glass parts with large dimensions and complex geometries and to fabricate multi-material components from metallic glass and crystalline metal. In this research, Zr52.5Ti5Al10Ni ...


Enhanced Quantum Dots Spontaneous Emission With Metamaterial Perfect Absorbers, Wei Wang, Xiaodong Yang, Ting S. Luk, Jie Gao Jan 2019

Enhanced Quantum Dots Spontaneous Emission With Metamaterial Perfect Absorbers, Wei Wang, Xiaodong Yang, Ting S. Luk, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Metamaterial perfect absorbers (PAs) made of a hexagonal array of holes on Ag-SiO 2 -Ag thin films have been realized and utilized to enhance the spontaneous emission rate and photoluminescence intensity of CdSe/ZnS quantum dots (QDs) spin-coated on the absorber top surface. Perfect absorption of incoming light occurs at the wavelength where the impedance is matched to that of the free space. When QDs strongly excite both the electric and magnetic resonances at this perfect absorption wavelength, a significant Purcell effect on the spontaneous emission process and enhanced radiative outcoupling of photoluminescence intensity are expected. For perfect absorbers with ...


Fabrication Of Alcocrfeni High-Entropy Alloy Coating On An Aisi 304 Substrate Via A Cofe₂Ni Intermediate Layer, Wenyuan Cui, Sreekar Karnati, Xinchang Zhang, Elizabeth Burns, Frank W. Liou Jan 2019

Fabrication Of Alcocrfeni High-Entropy Alloy Coating On An Aisi 304 Substrate Via A Cofe₂Ni Intermediate Layer, Wenyuan Cui, Sreekar Karnati, Xinchang Zhang, Elizabeth Burns, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Through laser metal deposition, attempts were made to coat AlCoCrFeNi, a high-entropy alloy (HEA), on an AISI 304 stainless steel substrate to integrate their properties. However, the direct coating of the AlCoCrFeNi HEA on the AISI 304 substrate was found to be unviable due to cracks at the interface between these two materials. The difference in compositional change was suspected to be the source of the cracks. Therefore, a new transition route was performed by coating an intermediate layer of CoFe2Ni on the AISI 304 substrate. Investigations into the microstructure, phase composition, elemental composition and Vickers hardness were ...