Silk As A Biomaterial Paste For Biomimetic Composite,
2016
Washington University in St. Louis
Silk As A Biomaterial Paste For Biomimetic Composite, Sang Hyun Park
McKelvey School of Engineering Graduate Student Theses & Dissertations
Silk is a highly promising biomaterial with unique bio-physicochemical properties, such as excellent mechanical and optical properties, biocompatibility and programmable biodegradability. Among many different types, silk from domesticated silkworm, bombyx mori has received wide attention owing to its availability in virtually unlimited quantities and ease of extraction. In this study, we investigated silkworm silk as a protein glue to realize nacre-like composites. We have employed spin assisted layer-by-layer technique to fabricate ultrathin free-standing biocomposite films. Two different composites have been studied: (i) graphene oxide (GO)/silk and (ii) chitin/silk. From our prior work, it is known that the adsorption of amphiphilic …
Nonaffine Rearrangements Of Atoms In Deformed And Quiescent Binary Glasses,
2016
Wright State University - Main Campus
Nonaffine Rearrangements Of Atoms In Deformed And Quiescent Binary Glasses, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The influence of periodic shear deformation on nonaffine atomic displacements in an amorphous solid is examined via molecular dynamics simulations. We study the three-dimensional Kob-Andersen binary mixture model at a finite temperature. It is found that when the material is periodically strained, most of the atoms undergo repetitive nonaffine displacements with amplitudes that are broadly distributed. We show that particles with large amplitudes of nonaffine displacements are organized into compact clusters. With increasing strain amplitude, spatial correlations of nonaffine displacements become increasingly long-ranged, although they remain present even in a quiescent system due to thermal fluctuations.
Properties Of Partially Stabilized Zirconia Components Fabricated By The Ceramic On-Demand Extrusion Process,
2016
Missouri University of Science and Technology
Properties Of Partially Stabilized Zirconia Components Fabricated By The Ceramic On-Demand Extrusion Process, Wenbin Li, Amir Ghazanfari, Devin Mcmillen, Ming-Chuan Leu, Greg Hilmas, Jeremy Lee Watts
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Ceramic On-Demand Extrusion (CODE) process is a novel additive manufacturing process for fabricating dense ceramic components from aqueous pastes of high solids loading. In this study, 3 mol% Y2O3 stabilized tetragonal zirconia polycrystal (3Y-TZP) parts were fabricated using the CODE process. The parts were then dried in a humidity controlled environmental chamber and sintered under atmospheric pressure. Mechanical properties of the sintered parts were examined using ASTM standard test techniques, including density, Young’s modulus, flexural strength, Weibull modulus, fracture toughness and Vickers hardness. The microstructure was analyzed, and grain size was measured using scanning electron microscopy. …
3d Printing Of A Polymer Bioactive Glass Composite For Bone Repair,
2016
Missouri University of Science and Technology
3d Printing Of A Polymer Bioactive Glass Composite For Bone Repair, Caroline Murphy, Krishna C. R. Kolan, M. Long, Ming-Chuan Leu, Julie A. Semon, D. E. Day
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A major limitation of synthetic bone repair is insufficient vascularization of the interior region of the scaffold. In this study, we investigated the 3D printing of adipose derived mesenchymal stem cells (AD-MSCs) with polycaprolactone (PCL)/bioactive glass composite in a single process. This offered a three-dimensional environment for complex and dynamic interactions that govern the cell’s behavior in vivo. Borate based bioactive (13-93B3) glass of different concentrations (10 to 50 weight %) was added to a mixture of PCL and organic solvent to make an extrudable paste. AD-MSCs suspended in Matrigel was extruded as droplets using a second syringe. Scaffolds measuring …
Powders For Additive Manufacturing Processes: Characterization Techniques And Effects On Part Properties,
2016
Missouri University of Science and Technology
Powders For Additive Manufacturing Processes: Characterization Techniques And Effects On Part Properties, Austin T. Sutton, Caitlin S. Kriewall, Ming-Chuan Leu, Joseph William Newkirk
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Powder-bed based Additive Manufacturing is a class of Additive Manufacturing (AM) processes that bond successive layers of powder by laser melting to facilitate the creation of parts with complex geometries. As AM technology transitions from the fabrication of prototypes to end-use parts, the understanding of the powder properties needed to reliably produce parts of acceptable quality becomes critical. Consequently, this has led to the use of powder characterization techniques such as scanning electron microscopy (SEM), laser light diffraction, x-ray photoelectron spectroscopy (XPS), and differential thermal analysis (DTA) to both qualitatively and quantitatively study the effect of powder characteristics on part …
Designed Extrudate For Additive Manufacturing Of Zirconium Diboride By Ceramic On-Demand Extrusion,
2016
Missouri University of Science and Technology
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 …
A Novel Extrusion-Based Additive Manufacturing Process For Ceramic Parts,
2016
Missouri University of Science and Technology
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.
Simulation Of Cooling Rate Effects On Ti-48al-2cr-2nb Crack Formation In Direct Laser Deposition,
2016
Missouri University of Science and Technology
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.
Modeling And Experimental Investigation Of Pre-Mixed Multi-Powder Flow In Fabricating Functional Gradient Material By Laser Metal Deposition Process,
2016
Missouri University of Science and Technology
Modeling And Experimental Investigation Of Pre-Mixed Multi-Powder Flow In Fabricating Functional Gradient Material By Laser Metal Deposition Process, Wei Li, Jingwei Zhang, Sreekar Karnati, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk, Karen M. Brown Taminger, W. L. Seufzer
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser Metal Deposition (LMD) is an effective process to fabricate Functionally Graded Material (FGM) from pre-mixed powders. Since the supplied multi-powder directly affects the deposited FGM’s composition, investigation on Pre-Mixed Multi-Powder (PMMP) flow during LMD is greatly needed. This paper presents a comprehensive numerical PMMP flow model. By solving discrete particle force balance equations coupled with continuity equations and momentum equations for carrier gas, the dynamic behavior of PMMP flow through powder feeder tube and out of nozzle was calculated. With this model, the particle sizes of multi-powder were optimized to obtain considered FGM composition. To verify the modeling results, …
Elevated Temperature Microstructure Stability Of Slm 304l Stainless Steel,
2016
Missouri University of Science and Technology
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 …
Investigation Of Tensile Properties Of Bulk And Slm Fabricated 304l Stainless Steel Using Various Gage Length Specimens,
2016
Missouri University of Science and Technology
Investigation Of Tensile Properties Of Bulk And Slm Fabricated 304l Stainless Steel Using Various Gage Length Specimens, Sreekar Karnati, I. Axelsen, Frank W. Liou, Joseph William Newkirk
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The complex solidification dynamics and thermal cycling during Selective Laser Melting process is expected to result in non-equilibrium material characteristics. There is an essential need for characterization techniques which are critical towards the estimation of anisotropies. The current investigation is targeted towards establishing tensile testing methodologies and their relation to differing gage lengths. Dog-bone shaped specimen designs with gage lengths of 1”, 0.3” and 0.12” were employed in this research. The characterization was performed on hot rolled-annealed 304 stainless and SLM fabricated 304L stainless. It was theorized that smaller gage length specimens would be instrumental in mapping material property anisotropy …
Novel Extrusion-Based Additive Manufacturing Process For Ceramic Parts,
2016
Missouri University of Science and Technology
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.
Investigation Of Heat-Affected 304l Ss Powder And Its Effect On Built Parts In Selective Laser Melting,
2016
Missouri University of Science and Technology
Investigation Of Heat-Affected 304l Ss Powder And Its Effect On Built Parts In Selective Laser Melting, Caitlin S. Kriewall, Austin T. Sutton, Ming-Chuan Leu, Joseph William Newkirk, Ben Brown
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Selective laser melting (SLM) is a powder bed based additive manufacturing process in which a layer of powder is laid over the surface of a substrate and a laser with sufficient energy is employed to selectively melt particles to build a part layer by layer. During the SLM process, dark smoke was observed coming off of the powder bed surface where the laser was interacting with powder. This phenomenon resulted from heat-affected powder that was visibly different than the base powder. Since the concentration of the heat-affected powder differs throughout the build chamber as a result of the recirculating argon …
Effect Of Powder Particle Size On The Fabrication Of Ti-6al-4v Using Laser Metal Deposition From Elemental Powder Mixture,
2016
Missouri University of Science and Technology
Effect Of Powder Particle Size On The Fabrication Of Ti-6al-4v Using Laser Metal Deposition From Elemental Powder Mixture, Xueyang Chen, Lei Yan, Wei Li, Frank W. Liou, Joseph William Newkirk
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Direct Laser Metal Deposition (LMD) was used to fabricate thin-wall Ti-6Al-4V using the powder mixture of Ti-6 wt.%Al-4 wt.%V. Scanning electron microscopy (SEM), optical microscopy (OM) and energy dispersive spectroscopy (EDS) were employed to examine the chemical composition and microstructure of the as-deposited sections. Vickers hardness tests were then applied to characterize the mechanical properties of the deposit samples which were fabricated using pre-mixed elemental powders. The EDS line scans indicated that the chemical composition of the samples was homogenous across the deposit. X-ray diffraction (XRD) was used for the phase identification. After significant analysis, some differences were observed among …
Proposed Hybrid Processes For Part Building Using Fusion Welding And Friction Stir Processing,
2016
Missouri University of Science and Technology
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, …
Design Maps For Fracture Resistant Functionally Graded Materials,
2016
Rowan University
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 …
Amine-Thiol Solution Route Method For Fabricating Cdxzn1-Xs Thin Film Solar Cells,
2016
Purdue University
Amine-Thiol Solution Route Method For Fabricating Cdxzn1-Xs Thin Film Solar Cells, Preston D. Fernandez, Xianyi Hu, Carol Handwerker, Rakesh Agrawal
The Summer Undergraduate Research Fellowship (SURF) Symposium
Cadmium zinc sulfide, CdZnS, is a promising material for the buffer layer of thin film solar cells because the alloy is considerably more cost effective and more optimizable than pure cadmium sulfide, CdS, in terms of band gap. The current fabrication methods of the buffer layer often require expensive equipment or produce undesirable impurities in the alloy. This study investigates a cost effective and scalable solution route method to synthesize the CdZnS buffer layer. Molecular precursors of CdZnS were dissolved in varying molecular ratios of cadmium and zinc in a mixture of hexylamine and propanethiol. The resulting alloys produced were …
Radiation Tailored Polymers For Detectors, Adhesive-Coatings And Other Industrial Uses,
2016
Purdue University
Radiation Tailored Polymers For Detectors, Adhesive-Coatings And Other Industrial Uses, Anna M. Earley, Alex Bakken, Rusi P. Taleyarkhan
The Summer Undergraduate Research Fellowship (SURF) Symposium
The ever growing importance of humans to depend on renewable resources has shifted the focus of consumers, producers, and even politicians to more sustainable answers. Furthermore, pressure on the oil and natural gas industry has elevated the status of biopolymers in this regard. Polylactic acid (PLA) is unique polymer that offers unique abilities for tailored property derivation; thereby, enabling one to replace many engineered polymers and provide a sustainable solution as a nontoxic renewable resource. As a bioplastic, the tailoring of PLA under various conditions is important to the application and integration into current industry uses. After irradiating high molecular …
Study Of Oxidative-Crosslink Reaction In Polyphenyl Sulfide (Pps) / Carbon Fiber And Its Influence In Additive Manufacturing,
2016
Purdue University
Study Of Oxidative-Crosslink Reaction In Polyphenyl Sulfide (Pps) / Carbon Fiber And Its Influence In Additive Manufacturing, Dong Hee Kim, Eduardo Barocio, Bastian Brenken, Anthony Favaloro, Byron Pipes
The Summer Undergraduate Research Fellowship (SURF) Symposium
Ever since its development in 1980s, Fused Filament Fabrication (FFF) has been an attractive additive manufacturing technology due to its flexibility to create intricate shapes at lower costs and faster manufacturing process than subtractive techniques. These advantages make FFF suitable for printing molds for use in traditional composites manufacturing processes. Combining FFF with high-temperature thermoplastic composites enables producing molds that not only sustain autoclave conditions but also have low coefficient of thermal expansion (CTE). A semi-crystalline polymer, Poly-phenylene Sulfide (PPS), with 50% by weight of carbon fiber is used as feedstock material for FFF. Nonetheless, PPS is sensitive to undergo …
Wearable Piezotronic Devices For Heart Rate Monitoring,
2016
Purdue University
Wearable Piezotronic Devices For Heart Rate Monitoring, Adam J. Miller, Wenzhuo Wu Dr.
The Summer Undergraduate Research Fellowship (SURF) Symposium
Self-powered multifunctional wearable devices that are capable of human-device interfacing are highly desired. Piezotronic devices utilize piezoelectricity and semiconductor properties to enable devices to have seamless interaction between human and device. One important use for piezotronic devices is for pressure sensing. Pressure sensing devices have been employed in smart skins, biomonitoring, gesture recognition, and many more applications. This study aims to create a flexible piezotronic device, specifically for use in pressure sensing to monitor heart rate. ZnO nanowires are grown on a flexible polymer substrate so that they can be made into wearable devices. A p-n heterojunction is formed by …
