Master of Science, The Ohio State University, 2013, Industrial and Systems Engineering

Thermal fatigue is one of the most common causes leading to die failure in die casting. This thesis investigates and presents the results of thermal fatigue life in a bi-metallic H13-Copper die which can be manufactured using laser additive manufacturing technologies now commercially available. Using finite element method, computational models are developed to simulate the thermal fatigue tests of Wallace (Benedyk, Moracz, and Wallace 1970). Numerical solutions to the thermal-mechanical problem are obtained. The solutions include temperature, strain and stress distributions within the test sample. Solutions were obtained for varying amounts of copper in the test sample geometry. Results from the pure H13 sample computational model compared very well with experimental values obtained by Wallace (Benedyk, Moracz, and Wallace 1970). The maximum temperature reached by the test sample is shown to decrease with increasing amounts of copper. The fatigue life is calculated using the `method of universal slopes' which relates the calculated cyclic strain ranges to the number of cycles necessary for fatigue crack initiation. The specimen geometry consisting of a half thickness of Cu and the other half thickness of H13 at the thinnest point in the full cross-section of the wall thickness was shown to provide the best balance between thermal and fatigue life performance.

Committee: Jerald Brevick (Advisor) Subjects: Engineering; Industrial Engineering; Mechanical Engineering; Metallurgy

Doctor of Philosophy, The Ohio State University, 2003, Industrial and Systems Engineering

The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deformed from the part design specification, a better die design and eventually to more productivity and cost savings. This dissertation presents a technique that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface. In order to validate and verify the die casting machine model, experimental work was conducted. The contact forces between dies and platens, strain in tie bars and dies and die temperature were measured. The experiments were run on a 250 metric ton Buhler die casting machine available at the Ohio State University. A total of 68 sensors (35 load cells, 31 strain gauges and one thermocouple) were mounted on the machine. The readings from these sensors were compared to the similar simulation predictions.

Committee: Richard Miller (Advisor) Subjects: Engineering, Industrial

Master of Science, The Ohio State University, 2007, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, The Ohio State University, 2018, Materials Science and Engineering

The development of new magnesium alloys with improved mechanical properties is important for lightweighting applications, since the current high pressure die cast (HPDC) magnesium alloys, i.e. AM50/60 (Mg-5/6wt.%Al-0.2wt.%Mn) and AZ91 (Mg-9wt.%Al-1wt.%Zn), have limited mechanical properties. Two magnesium alloy systems, Mg-Al-Sn (AT) and Mg-Al-Sn-Si (ATS), were investigated for potential automotive applications. A CALPHAD (CALculation of PHAse Diagrams) approach was used in the development of AT and ATS alloys and to aid in the design of heat treatment schedules. Scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), and transmission electron microscopy (TEM) techniques were used to characterize the microstructure of the alloys in the as-cast and heat treated conditions. Mechanical testing was performed on cast specimens, as well as samples cut from thin-wall HPDC components to compare the strength and ductility of these alloys to currently used magnesium alloys. To expand the applications of HPDC components in the transportation industries, further development and optimization of the process is needed. The development of super vacuum die casting (SVDC) process for aluminum and magnesium thin-wall castings were explored using process simulation and experimental validation. Two experimental dies, i.e., a test specimen die and a fluidity die, were designed to evaluate the castability of several new aluminum alloys and optimize process parameters for these alloys. The process conditions were successfully validated in industrial castings such as an automotive door inner and a side impact beam.

Committee: Alan Luo (Advisor); Michael Mills (Committee Member); Glenn Daehn (Committee Member); Gary Kennedy (Committee Member) Subjects: Materials Science

Master of Science in Engineering, Youngstown State University, 2016, Department of Mechanical, Industrial and Manufacturing Engineering

Sand casting has long been known to be an effective manufacturing method for metal casting and especially for parts of large dimensions and low production volume. But, for increasing complexity, the conventional sand casting process does have its limitations; one of them mainly being the high cost of tooling to create molds and cores. With the advent of additive manufacturing (AM), these limitations can be overcome by the use of a 3D sand printer which offers the unique advantage of geometric freedom. Previous research shows the cost benefits of 3D sand printing molds and cores when compared to traditional mold and core making methods. The line of research presented in this thesis introduces the idea of additive manufacturing at different stages of the sand casting process and investigates the decision-making process as well as the cost-based effects. This will enable foundries and manufacturers to integrate the use of AM machines more smoothly into their production process without the need for completely re-engineering the existing production system. A critical part of this thesis is the tooling cost estimation using a casting cost model that is significantly accurate to industry standard quotes. Based on these considerations, this thesis outlines three approaches for achieving this goal apart from traditional mold and core making methods. The first approach integrates 3D Printing at the pattern making level where the patterns and core-boxes are “printed” on an FDM printer. This eliminates the tooling costs associated with a traditional sand casting method. The second approach integrates 3D Printing at the core-making level by “mixing” traditional mold-making process and 3D sand printing process for core-making. The third approach, the 3D sand printer is used to create both the molds and the cores, thereby eliminating the need for traditional methods. An initial hypothesis is created which states that, for a given production volume, with increased complexity of the (open full item for complete abstract)

Committee: Brett Conner PhD (Advisor); Darrell Wallace PhD (Committee Member); Eric MacDonald PhD (Committee Member) Subjects: Economics; Engineering; Mechanical Engineering

Master of Science in Engineering, Youngstown State University, 2015, Department of Mechanical, Industrial and Manufacturing Engineering

The additive manufacturing industry has the potential to transform nearly every sector of our lives and jumpstart the next Industrial Revolution. Engineers and designers have been using 3D printers for more than three decades but mostly to make prototypes quickly and cheaply before they embark on the expensive business of tooling up a factory to produce the real things. In sand casting industries, a growing number of companies have adopted 3D sand printing to produce final casts. Yet recent research suggests that the use of 3D sand printing has barely begun to achieve its potential market. It is not surprising that executives are having difficulty adopting additive manufacturing; the technology has many second - order effects on business operations and economics. One of the most important factors is the lack of awareness of additive manufacturing's applications and values in the sand casting manufacturing process. The lack of awareness is significantly slowing down the adoption rates. This research will help executives to optimize their adoption decision by answering the question of "At what level of part complexity should sand printing be used instead of the conventional process in molds and cores manufacturing?" Moreover, this thesis defines and analyzes the geometric attributes which influence the parts' complexity. As known in the conventional sand casting process, the high level of complexity leads to higher manufacturing cost. On the other hand, in the additive manufacturing process, the manufacturing cost is fairly constant regardless of the level of complexity. Therefore, 3D sand printing provides a unique advantage that the increasing in geometric complexity of the part has no impact on the molds and cores manufacturing cost or what is known as "complexity for free."

Committee: Brett Conner PhD (Advisor); Martin Cala PhD (Committee Member); Guha Manogharan PhD (Committee Member) Subjects: Industrial Engineering

PhD, University of Cincinnati, 2005, Engineering : Chemical Engineering

The dry-casting process and the wet-casting process are two typical phase inversion techniques for manufacturing synthetic polymeric membranes. Although extensive modeling studies have been done for both casting processes in order to achieve an optimization of a membrane recipe, all models developed heretofore allow for mass transfer only by diffusion. A proper model for membrane casting should incorporate both the diffusive and convective contributions to the mass transfer fluxes. Therefore, the objective of this thesis is the developments of a dry-casting model and a wet-casting model based on the fundamental and general approach to construct well-defined mass-transfer problems incorporating both convection and diffusion. This new more general approach produces well-defined description of wet- and dry-casting processes that are solvable with currently available PDE solvers and accurately describe the effects of density variation in the system. Non-equilibrium thermodynamics allows further generalization of this approach to multicomponent mass-transfer problems. The predictions of the dry-casting model developed with this general approach show much better agreement with experimental data in the literature for the CA/acetone/water system. The new wet-casting model predicts the presence of a metastable region in the casting solution depending on the initial thickness that is not predicted by model that incorporates only diffusive mass transfer. Low-gravity experiments using a newly developed membrane casting apparatus show that macrovoids are formed in the CA/acetone/water casting solution when a metastable region is predicted by the new wet-casting model. Furthermore, membrane casting experiments that incorporated surfactant in the precipitation bath reveal that macrovoid formation is strongly associated with the coalescence of microdoplets having a high surface energy in the metastable region of the casting solution. Therefore, both the experimental and modeling re (open full item for complete abstract)

Committee: Dr. William Krantz (Advisor) Subjects: Engineering, Chemical

Doctor of Philosophy, The Ohio State University, 2004, Industrial and Systems Engineering

The fraction of melt which solidifies in the shot sleeve before the metal is injected into the die cavity is referred to as externally solidified products (ESP). ESP may affect the melt fluidity, cavity fill, microstructure and mechanical properties of final castings. The objectives of this research are to conduct simulations to investigate the amount of ESP formed during shot sleeve pouring and shot delay time period, and its distribution in the shot sleeve; to examine what amount of ESP will travel into the die cavity, and the final location of the ESP in the casting; to understand the gains and the limitations of computer modeling for the ESP study; to obtain insights on how to minimize or eliminate cold flakes in castings. The modeling activities in this research are categorized into two related studies. First, a FLOW3D athermal shot sleeve model was developed, which can estimate the ESP formation during the shot sleeve pouring and shot delay time period. The athermal shot sleeve model was developed and verified via an experiment conducted at OSU. Subsequently, the athermal model was applied to Briggs & Stratton's tensile bar casting to examine the ESP formation for this specific die casting process. Second, an isothermal cavity fill modeling using the marker/particle feature was developed to investigate ESP final distribution in the tensile bar cavities.

Committee: Jerald Brevick (Advisor) Subjects:

Master of Science, The Ohio State University, 2008, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2008, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, The Ohio State University, 2024, Materials Science and Engineering

Aluminum is increasingly favored in the automotive sector for its favorable mechanical properties and good strength-to-weight ratio. Laser welding finds utility in electric vehicle battery assemblies, while high pressure die castings (HPDC) are used in vehicle body construction. Nonetheless, defects pose a risk to the mechanical robustness of aluminum welds and cast parts. These defects include hydrogen porosity, entrapped air, and externally solidified crystals (ESCs). In this study, defects in die-cast and welded aluminum were investigated to understand their formation mechanisms and to explore methods for their prevention. Laser welding of aluminum and copper is commonly used in the battery assemblies of electric vehicles. However, aluminum is prone to forming hydrogen porosity when welded. The investigation of hydrogen porosity in aluminum welds involved the utilization of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), microcomputed tomography (\textmu-CT), and LECO\textsuperscript{\textregistered} analysis. It was observed that the oxide layer on anodized aluminum served as heterogeneous nucleation sites for hydrogen porosity. Anodized aluminum can contribute to increased hydrogen content in the liquid phase. As liquid aluminum solidifies, hydrogen is forced into the melt, leading to a state of supersaturation in the liquid. This supersaturation prompts the nucleation and growth of hydrogen porosity. Additionally, a cellular automaton (CA) model was expanded to predict hydrogen porosity under different hydrogen concentrations, laser speeds, and powers. To mitigate hydrogen porosity, it is necessary to either improve the cleaning process of the anodized aluminum or utilize an alternative corrosion-resistant material. Die-cast aluminum is frequently employed to reduce vehicle weight. However, the turbulent flow inherent in the die casting process can easily entrap air, leading to gas porosity. The impact of vacuum on entrapped a (open full item for complete abstract)

Committee: Alan Luo (Advisor); Ahmet Selamet (Committee Member); Xun Liu (Committee Member); Glenn Daehn (Committee Member) Subjects: Materials Science

Doctor of Philosophy, The Ohio State University, 2024, Materials Science and Engineering

The transportation sector is responsible for a significant contribution of global carbon emissions. Recent efforts to reduce carbon emissions have been focused on reducing the weight of all types of vehicles to improve efficiency. Aluminum alloys are widely used due to a combination of low density and excellent mechanical and corrosion properties. However, aluminum alloys contain high embodied emissions due to the energy intensive refinement process from bauxite ore. Recycled aluminum, called secondary aluminum, only requires around 5% of the energy needed to produce aluminum from bauxite ore (primary aluminum). Current recycling practices result in significant amounts of elemental impurities in secondary aluminum alloys, significantly decreasing their mechanical properties and limiting their uses in the transportation industry. The control of impurities during solidification ultimately controls the achievable mechanical properties of casting alloys, which are the most widely used. Thermodynamic calculations using the CALPHAD (calculation of phase diagrams) method were used to predict the effect of common impurities during solidification of secondary aluminum alloys. CALPHAD was also used to predict the effect of potential modifying elements. Lab-scale casting experiments were performed to evaluate the thermodynamic predictions via microstructure observations using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM) techniques. Control methods for favorable microstructures were developed. From the results, a secondary structural alloy composition was chosen for production-scale experiments using high pressure die casting (HPDC). The results showed that Al-Si based alloys with Fe impurity can be effectively modified by Mn and Sr additions, and the effects of Mg and Cu impurities can be mitigated by Ce additions, leading to property improvements. The investigations also showed novel Al-Ce based alloys can (open full item for complete abstract)

Committee: Alan Luo (Advisor); Glenn Daehn (Committee Member); Jenifer Locke (Committee Member) Subjects: Materials Science

Doctor of Philosophy (PhD), Ohio University, 2024, Mass Communication (Communication)

This dissertation engages in an exploration of the intricate discourse surrounding the casting decisions in Black history films. The study addresses the perspectives of two pivotal demographic groups, namely African Americans and African immigrants, unraveling the multifaceted perspectives and overarching implications associated with casting choices in the realm of Black cinema. The theoretical framework for this research is rooted in the interdisciplinary and multifaceted domain of cultural studies, which facilitates a comprehensive exploration of the intricate intersections among film casting, race, identity, representation, and reception scholarship. Employing a mixed-method research design, the study integrates paratextual analysis, qualitative interviews, and focus group discussions, collectively capturing a diverse range of perspectives held by both African Americans and African immigrants. This methodological approach effectively illuminates how participants seamlessly integrate their unique lived experiences and cultural backgrounds when assessing casting decisions for historical roles, contributing to a nuanced and holistic understanding of their viewpoints. The analysis of the collected data has unveiled compelling thematic insights that provide a comprehensive understanding of the intricate dynamics within the context of casting iv choices in Black history films. These themes, including Diverse Conceptions of Blackness, Historical Perspectives of Actors on Blackness and Black Issues in the American Context, Challenges and Perceived Displacement, Unpacking Distorted Depictions of African American History, Gaps in Diversity within Black Narratives and Investment in Emerging African American Talent, Commercial Dimensions of Casting, and African-history Movies Produced in the United States as American Productions, collectively illuminate the interplay of representation, identity, and economic considerations within the film industry. A (open full item for complete abstract)

Committee: Steve Howard (Committee Chair); Eve Ng (Committee Member); Webster Smith (Other); Jatin Srivastava (Committee Member); Taylor Kirsten (Committee Member) Subjects: African American Studies; Black Studies; Ethnic Studies; Film Studies; Mass Media

Doctor of Philosophy, The Ohio State University, 2023, Materials Science and Engineering

Rising concerns related to fuel consumption and greenhouse emissions are being addressed by the automotive industry through vehicle lightweighting. Hence to meet the stringent requirements for lightweighting, conventional steel body parts are being replaced with Al alloys, Mg alloys and composite materials. However, the use of dissimilar materials together poses a serious threat of galvanic corrosion leading to accelerated degradation of galvanically coupled body parts. Aiming to develop the automotive closure panels using carbon fiber reinforced plastics (CFRP) inner and an outer aluminum alloy sheet to replace what is now an all-steel design, corrosion studies are performed to determine effective qualification of materials. In the first part of this project, CFRP materials of two types, named as twill and random, coupled with aluminum alloys (AA) 6111 and 6022 in all combinations, are subjected to a Ford laboratory accelerated cyclic corrosion test (CETP: 00.00-L-467) and on-road testing with the help of OSU campus buses for a year. The ability of the laboratory accelerated test to predict the on-road corrosion behavior is assessed by comparing the material volume loss determined using optical profilometer, microscopic images of corroded regions, and measurements of galvanic currents of the coupons exposed to the cyclic test. Analysis of the test results indicated that the coupon combination AA6111 and CFRP-random exhibits the highest corrosion susceptibility whereas AA6022 coupled with CFRP-twill is least susceptible to galvanic corrosion among the combinations used in this study. In the second part of the study, electrochemical behavioral differences between CFRP-twill and -random contributing to the differences in activities when coupled to AA6xxx are evaluated. For this, a copper deposition technique was developed to quantify the extent of electrochemical activity and identify the exact location of electrochemically active sites on the CFRP. Optimization (open full item for complete abstract)

Committee: Gerald S. Frankel Dr. (Advisor); Narasi Sridhar Dr. (Committee Member); Jenifer Locke Dr. (Committee Member) Subjects: Atmosphere; Conservation; Energy; Engineering; Materials Science; Sustainability; Transportation

MFA, Kent State University, 2023, College of the Arts / School of Art

I have mourned many people, most of whom are still alive. Forming and maintaining relationships has always been difficult for me. They blossom and die in unexpected ways. For the vast majority of my life, I have felt like an outsider, never quite fitting in with family, friends, or community. This has led to relationships ending in sudden and unexpected ways, and I carry an immense amount of grief with me. These experiences have led me to create a collection of mourning veils in which I explore my non-linear grieving process of interpersonal relationships. These pieces are heavily influenced by my identity as a fat, neurodivergent, genderqueer dyke. I find it impossible to separate my mourning process from my identities which often leave me alienated and on the outside of my communities. Through captured pearls, cast silver, linked steel chain, and laser cut acrylic, I create a structure for my grief to manifest. These wearable objects allow me to physically express the emotions I experience internally but struggle to appropriately display. The weight and/ or placement of the pieces make them impossible to ignore, much like the aching pangs of sorrow.

Committee: Andrew Kuebeck (Advisor) Subjects: Fine Arts

MFA, Kent State University, 2023, College of the Arts / School of Art

This paper has been produced in advance of my MFA Thesis exhibition to provide insight into the work contained therein. Mathematics and science are integral to my artistic process. This body of work explores complex kinetic movement found in sine curves, utilizing simple geometric structures and polygons as base components. I am investigating connections. I see the intersection of art and scientific principles as an avenue for creative voice in union with nature. The body of work in this exhibition displays dynamic movement utilizing both geometric and organic forms in congress with mechanical structures. The work is constructed primarily from glass with integrated metal components. I am inspired by the fundamental concepts of growth and form that are expressed in nature. From the opening bud of a flower to the rhythmic movement of the tides, various aspects of movement and development are explored. The conscious observer is invited to engage with multiple senses within the exhibition as sound, light, and kinetic function activate the gallery space. Vibration and frequency are responsible for the creation of light, sound, molecular structure, and in this case, art. Each of the works in this exhibition explore different aspects of creation. I am fascinated by the sine curve; the helixing structure that animates our solar system as well as our DNA. This work expresses the movement of wave forms, demonstrating the versatility and beauty of the natural world by employing science and mathematics as the primary language for expression.

Committee: Davin Ebanks (Advisor); Shana Reisig (Committee Member); Henry Halem (Committee Member); Eli Kessler (Committee Member) Subjects: Fine Arts

Doctor of Philosophy, The Ohio State University, 2022, Materials Science and Engineering

In the last 20 years, research in magnesium alloys has greatly expanded with demand for high-strength lightweight alloys in the transportation industry. Mg-RE (rare earth) alloys have been of particular interest due to the formation of two strengthening phase types: long period stacking order (LPSO) phases and β-series precipitates. This work focuses on the development of high-strength cast Mg-RE multicomponent alloys that combine LPSO and β-series phases using a CALPHAD (CALculation of PHAse Diagrams)-based design approach. This work began by using CALPHAD modeling to study the effects of maximizing the LPSO phase fractions. Experimental samples demonstrated there was a slight increase in mechanical properties with high LPSO volume fractions, but the properties were below those obtained through β' precipitation in the commercial alloy WE43 (Mg-4Y-3.4RE-0.7Zr, all in wt%). It was also found that the CALPHAD model was underpredicting the LPSO phase fractions by ~20 vol%. Improvements were made to the Pandat database to bring the predictions within ~5 vol% of experimental values. In the second stage of this work, small-angle scattering (SAS) was used to quantitatively explore the effects of micro-alloying in the Mg-Nd system on β-series precipitates. Two SAS techniques were used in addition to transmission electron microscopy (TEM) to study the effects of micro-alloying: small-angle neutron scattering (SANS) and small-angle x-ray scattering (SAXS). It was found SAXS was a better technique to quantify the change in precipitate size with micro-alloying and aging, but more understanding of the system is needed to extract phase fraction changes. In the final stage of this work, the LPSO and β-series strengthening mechanisms were combined in an attempt to produce an Mg-Y-Nd-Zn-Zr alloy with properties superior to WE43. Nd does not form any LPSO phase, so there is less competition between the phases during formation. CALPHAD modeling is used to tailor the phase fracti (open full item for complete abstract)

Committee: Alan Luo (Advisor); Steve Niezgoda (Committee Member); Jenifer Locke (Committee Member) Subjects: Engineering; Materials Science

Doctor of Philosophy in Materials Science and Engineering, Youngstown State University, 2022, Materials Science

Additive Manufacturing (i.e. 3D printing) is causing a sea-change in sand casting with binder jetting technology that can create sand molds with unmatched geometric complexity. Now 3D Sand Printing (3DSP) can be optimized for more complex castings with denser part arrangements in multi-cavity molds as well as mold geometries that can make post-processing less time-consuming. Recent work has provided a foundation for developing methodologies to produce repeatable increases in part yield for a given mold while decreasing post-processing effort. This work involved developing methods of placing sensors in the molds to obtain real-time, in-situ data of the pouring and solidification processes in a casting. These were used to develop and validate material properties used for simulating the process. CT scanning was also found to be a useful tool to inspect and qualify 3DSP molds before use. This dissertation covers the use of this past work to develop methodologies to leverage the capabilities of 3DSP molds to increase the part yield per volume of sand used while decreasing work related to part break-out and the subsequent post-processing to remove features required for casting but not needed on the part such as gates and feeders.

Committee: Eric MacDonald PhD (Advisor); Darrell Wallace PhD (Committee Member); Pedro Cortes PhD (Committee Member); Virgil Solomon PhD (Committee Member); Tim Wagner PhD (Committee Member) Subjects: Aerospace Materials; Materials Science; Mechanical Engineering