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- Member of: ASU Electronic Theses and Dissertations
Description
This dissertation aims at developing novel materials and processing routes using alkali activated aluminosilicate binders for porous (lightweight) geopolymer matrices and 3D-printing concrete applications. The major research objectives are executed in different stages. Stage 1 includes developing synthesis routes, microstructural characterization, and performance characterization of a family of economical, multifunctional porous ceramics developed through geopolymerization of an abundant volcanic tuff (aluminosilicate mineral) as the primary source material. Metakaolin, silica fume, alumina powder, and pure silicon powder are also used as additional ingredients when necessary and activated by potassium-based alkaline agents. In Stage 2, a processing route was developed to synthesize lightweight geopolymer matrices from fly ash through carbonate-based activation. Sodium carbonate (Na2CO3) was used in this study to produce controlled pores through the release of CO2 during the low-temperature decomposition of Na2CO3. Stage 3 focuses on 3D printing of binders using geopolymeric binders along with several OPC-based 3D printable binders. In Stage 4, synthesis and characterization of 3D-printable foamed fly ash-based geopolymer matrices for thermal insulation is the focus. A surfactant-based foaming process, multi-step mixing that ensures foam jamming transition and thus a dry foam, and microstructural packing to ensure adequate skeletal density are implemented to develop foamed suspensions amenable to 3D-printing. The last stage of this research develops 3D-printable alkali-activated ground granulated blast furnace slag mixture. Slag is used as the source of aluminosilicate and shows excellent mechanical properties when activated by highly alkaline activator (NaOH + sodium silicate solution). However, alkali activated slag sets and hardens rapidly which is undesirable for 3D printing. Thus, a novel mixing procedure is developed to significantly extend the setting time of slag activated with an alkaline activator to suit 3D printing applications without the use of any retarding admixtures. This dissertation, thus advances the field of sustainable and 3D-printable matrices and opens up a new avenue for faster and economical construction using specialized materials.
ContributorsAlghamdi, Hussam Suhail G (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Abbaszadegan, Morteza (Committee member) / Bhate, Dhruv (Committee member) / Arizona State University (Publisher)
Created2019
Description
Thermal management in modern devices has become increasingly challenging due to the higher heat output from advanced electronics. Effective cooling solutions are essential to enhance performance, extend operational life, and reduce device failure rates. For every 10℃ increase in ambient temperature, device lifespan decreases by 50%, underscoring the need for innovative cooling methods. Micro/minichannel heat sinks have emerged as a promising solution due to their compact size and low thermal resistance. Various mechanisms have been studied to enhance thermal performance, including novel geometries, tailored fluid properties, and the use of ultrasonic waves.Ultrasonic waves have gained attention for their potential to improve heat transfer by disrupting boundary layers and enhancing fluid mixing. This thesis explores whether ultrasound can enhance thermal system performance and investigates the influence of key fluid properties, material selection, and varying parameters such as flow rate, heat input, and ultrasound power on heat transfer and pressure drop.
Three experiments were conducted to evaluate the effects of ultrasonic vibrations on heat transfer and pressure drop across different systems. In the first experiment, ultrasonic vibrations enhanced heat transfer by 13.5% in a circular minichannel heat sink made of stainless steel, using water as the coolant. In the second experiment, using a rectangular minichannel heat sink with water and propylene glycol-water mixtures, ultrasound improved heat transfer, with the highest enhancement observed in deionized water, while the effectiveness decreased with higher propylene glycol concentrations. The third experiment, conducted in a horizontal copper tube, showed a 13.5% heat transfer improvement for water and 11.3% for an ionic liquid. Across all experiments, the effect of ultrasound diminished as flow rates increased, and higher viscosity fluids reduced its effectiveness. Additionally, ultrasound contributed to an increase in pressure drop in all cases.
Overall, these findings highlight the potential of ultrasonic vibrations as an effective technique for enhancing heat transfer. This thesis could provide a basis for future research into ultrasonic technology as a promising technique.
ContributorsAlenezi, Abdulmajeed (Author) / Phelan, Patrick (Thesis advisor) / Shuaib, Abdelrahman (Committee member) / Bhate, Dhruv (Committee member) / Kwon, Beomjin (Committee member) / Al-Mangour, Bandar (Committee member) / Arizona State University (Publisher)
Created2024
Description
The advancements in additive manufacturing have made it possible to bring life to designs
that would otherwise exist only on paper. An excellent example of such designs
are the Triply Periodic Minimal Surface (TPMS) structures like Schwarz D, Schwarz
P, Gyroid, etc. These structures are self-sustaining, i.e. they require minimal supports
or no supports at all when 3D printed. These structures exist in stable form in
nature, like butterfly wings are made of Gyroids. Automotive and aerospace industry
have a growing demand for strong and light structures, which can be solved using
TPMS models. In this research we will try and understand some of the properties of
these Triply Periodic Minimal Surface (TPMS) structures and see how they perform
in comparison to the conventional models. The research was concentrated on the
mechanical, thermal and fluid flow properties of the Schwarz D, Gyroid and Spherical
Gyroid Triply Periodic Minimal Surface (TPMS) models in particular, other Triply
Periodic Minimal Surface (TPMS) models were not considered. A detailed finite
element analysis was performed on the mechanical and thermal properties using ANSYS
19.2 and the flow properties were analyzed using ANSYS Fluent under different
conditions.
that would otherwise exist only on paper. An excellent example of such designs
are the Triply Periodic Minimal Surface (TPMS) structures like Schwarz D, Schwarz
P, Gyroid, etc. These structures are self-sustaining, i.e. they require minimal supports
or no supports at all when 3D printed. These structures exist in stable form in
nature, like butterfly wings are made of Gyroids. Automotive and aerospace industry
have a growing demand for strong and light structures, which can be solved using
TPMS models. In this research we will try and understand some of the properties of
these Triply Periodic Minimal Surface (TPMS) structures and see how they perform
in comparison to the conventional models. The research was concentrated on the
mechanical, thermal and fluid flow properties of the Schwarz D, Gyroid and Spherical
Gyroid Triply Periodic Minimal Surface (TPMS) models in particular, other Triply
Periodic Minimal Surface (TPMS) models were not considered. A detailed finite
element analysis was performed on the mechanical and thermal properties using ANSYS
19.2 and the flow properties were analyzed using ANSYS Fluent under different
conditions.
ContributorsRaja, Faisal (Author) / Phelan, Patrick (Thesis advisor) / Bhate, Dhruv (Committee member) / Rykaczewski, Konrad (Committee member) / Arizona State University (Publisher)
Created2019
Description
Thermal management is a critical aspect of microelectronics packaging and often centers around preventing central processing units (CPUs) and graphics processing units (GPUs) from overheating. As the need for power going into these processors increases, so too does the need for more effective thermal management strategies. One such strategy is to utilize additive manufacturing to fabricate heat sinks with bio-inspired and cellular structures and is the focus of this thesis. In this study, a process was developed for manufacturing the copper alloy CuNi2SiCr on the 100w Concept Laser Mlab laser powder bed fusion 3D printer to obtain parts that were 94% dense, while dealing with challenges of low absorptivity in copper and its high potential for oxidation. The developed process was then used to manufacture and test heat sinks with traditional pin and fin designs to establish a baseline cooling effect, as determined from tests conducted on a substrate, CPU and heat spreader assembly. Two additional heat sinks were designed, the first of these being bio-inspired and the second incorporating Triply Periodic Minimal Surface (TPMS) cellular structures, with the aim of trying to improve the cooling effect relative to commercial heat sinks. The results showed that the pure copper commercial pin-design heat sink outperformed the additive manufactured (AM) pin-design heat sink under both natural and forced convection conditions due to its approximately tenfold higher thermal conductivity, but that the gap in performance could be bridged using the bio-inspired and Schwarz-P heat sink designs developed in this work and is an encouraging indicator that further improvements could be obtained with improved alloys, heat treatments and even more innovative designs.
ContributorsYaple, Jordan Marie (Author) / Bhate, Dhruv (Thesis advisor) / Azeredo, Bruno (Committee member) / Phelan, Patrick (Committee member) / Arizona State University (Publisher)
Created2021
Description
The hexagonal honeycomb is a bio-inspired cellular structure with a high stiffness-to-weight ratio. It has contributed to its use in several engineering applications compared to solid bodies with identical volume and material properties. This characteristic behavior is mainly attributed to the effective nature of stress distribution through the honeycomb beams that manifests as bending, axial, and shear deformation mechanisms. Inspired by the presence of this feature in natural honeycomb, this work focuses on the influence of the corner radius on the mechanical properties of a honeycomb structure subjected to in-plane compression loading. First, the local response at the corner node interface is investigated with the help of finite element simulation of a periodic unit cell within the linear elastic domain and validated against the best available analytical models. Next, a parametric design of experiments (DOE) study with the unit cell is defined with design points of varying circularity and cell length ratios towards identifying the optimal combination of all geometric parameters that maximize stiffness per unit mass while minimizing the stresses induced at the corner nodes. The observed trends are then compared with compression tests of 3D printed Nylon 12 honeycomb specimens of varying corner radii and wall thicknesses. The study concluded that the presence of a corner radius has a mitigating effect on peak stresses but that these effects are dependent on thickness while also increasing specific stiffness in all cases. It also points towards an optimum combination of parameters that achieve both objectives simultaneously while shedding some light on the functional benefit of this radius in wasp and bee nests that employ a hexagonal cell.
ContributorsRajeev, Athul (Author) / Bhate, Dhruv (Thesis advisor) / Oswald, Jay (Committee member) / Marvi, Hamidreza (Committee member) / Arizona State University (Publisher)
Created2021
Description
The study aims to develop and evaluate failure prediction models that accurately predict crack initiation sites, fatigue life in additively manufactured Ti-6Al-4V, and burst pressure in relevant applications.The first part proposes a classification model to identify crack initiation sites in AM-built Ti-6Al-4V alloy. The model utilizes surface and pore-related parameters and achieves high accuracy (0.97) and robustness (F1 score of 0.98). Leveraging CT images for characterization and data extraction from the CT-images built STL files, the model effectively detects crack initiation sites while minimizing false positives and negatives. Data augmentation techniques, including SMOTE+Tomek Links, are employed to address imbalanced data distributions and improve model performance.
This study proposes the Probabilistic Physics-guided Neural Network 2.0 (PPgNN) for probabilistic fatigue life estimation. The presented approach overcomes the limitations of classical regression machine models commonly used to analyze fatigue data. One key advantage of the proposed method is incorporating known physics constraints, resulting in accurate and physically consistent predictions.
The efficacy of the model is demonstrated by training the model with multiple fatigue S-N curve data sets from open literature with relevant morphological data and tested using the data extracted from CT-built STL files. The results illustrate that PPgNN 2.0 is a flexible and robust model for predicting fatigue life and quantifying uncertainties by estimating the mean and standard deviation of the fatigue life. The loss function that trains the proposed model can capture the underlying distribution and reduce the prediction error.
A comparison study between the performance of neural network models highlights the benefits of physics-guided learning for fatigue data analysis. The proposed model demonstrates satisfactory learning capacity and generalization, providing accurate fatigue life predictions to unseen examples.
An elastic-plastic Finite Element Model (FEM) is developed in the second part to assess pipeline integrity, focusing on burst pressure estimation in high-pressure gas pipelines with interactive corrosion defects. The FEM accurately predicts burst pressure and evaluates the remaining useful life by considering the interaction between corrosion defects and neighboring pits. The FEM outperforms the well-known ASME-B31G method in handling interactive corrosion threats.
ContributorsBalamurugan, Rakesh (Author) / Liu, Yongming (Thesis advisor) / Zhuang, Houlong (Committee member) / Bhate, Dhruv (Committee member) / Arizona State University (Publisher)
Created2023
Description
Integrating advanced materials with innovative manufacturing techniques has propelled the field of additive manufacturing into new frontiers. This study explores the rapid 3D printing of reduced graphene oxide/polymer composites using Micro-Continuous Liquid Interface Production (μCLIP), a cutting-edge technology known for its speed and precision. A printable ink is formulated with reduced graphene oxide for μCLIP-based 3D printing. The research focuses on optimizing μCLIP parameters to fabricate reduced graphene composites efficiently. The study encompasses material synthesis, ink formulation and explores the resulting material's structural and electrical properties. The marriage of graphene's unique attributes with the rapid prototyping capabilities of μCLIP opens new avenues for scalable and rapid production in applications such as energy storage, sensors, and lightweight structural components. This work contributes to the evolving landscape of advanced materials and additive manufacturing, offering insights into the synthesis, characterization, and potential applications of 3D printed reduced graphene oxide/polymercomposites.
ContributorsRavishankar, Chayaank Bangalore (Author) / Chen, Xiangfan (Thesis advisor) / Bhate, Dhruv (Committee member) / Azeredo, Bruno (Committee member) / Arizona State University (Publisher)
Created2024
Description
Layer-wise extrusion of cement pastes, mortars, or concrete is the most commonly used technique in three-dimensional (3D) concrete printing. Understanding the behavior of the printed binder after placement is crucial for optimizing the properties of 3D-printed elements. This research, conducted in two stages, fresh and hardened state responses, elucidates the post-extrusion mechanics of cementitious binders to enhance print quality. In Stage-1, a novel technique for characterizing 3D printable mortar binders using the green compression test (GCT) is introduced. Equations based on GCT parameters were established to predict buildability, the maximum height that can be sustained without significant deformation or failure. These equations were able to predict buildability and failure mechanisms over time accurately. Stage-2 investigates the mechanical response of hardened 3D printed binders, focusing on inter-layer and inter-filament interfaces, mixture types, and fiber content. Variation in interface positioning and the addition of fibers (0.28% by volume) improved flexural response while maintaining comparable compression strength. However, it did not eliminate anisotropy in compression, and mechanical properties remained inferior to cast counterparts. Next, a numerical model was developed, using cohesive zone finite elements to represent joints and an orthotropic visco-elastic-visco-plastic material model for the bulk filament. This model effectively predicted the mechanical response of 3D printed elements, accurately capturing anisotropy under uniaxial compression. This highlighted the importance of properly characterizing joints and selecting material models. Finally, ultra-high performance 3D printable mixtures were developed using a low water-to-binder ratio mixture with a higher content of water-reducing agent, achieving compressive strengths exceeding 100 MPa at 28 days. This mixture resulted in reduced anisotropy while providing strengths comparable to mold-cast specimens. Incorporating high fiber volume (1.5% by volume) into this mixture significantly enhanced compression and flexural responses. Composite material sections, created by printing different mixtures in various layers, showed comparable mechanical responses while improving cost and environmental efficiency. The findings of this research contribute to precise failure prediction during printing, propose methods for better mechanical responses in printed products, and offer insights into cost-effective and environmentally efficient section design through composite material printing using 3D concrete printing.
ContributorsTripathi, Avinaya (Author) / Neithalath, Narayanan (Thesis advisor) / Mobasher, Barzin (Committee member) / Hoover, Christian (Committee member) / Bhate, Dhruv (Committee member) / Rajan, Subramaniam (Committee member) / Arizona State University (Publisher)
Created2024
Description
Additive manufacturing (AM) enables design freedom previously not attainable with traditional manufacturing techniques. By developing a method of integrating heat pipe geometry into printed parts as a monolithic structure, designers can potentially increase thermal performance in a wide variety of components such as radiators. Traditional manufacturing of high temperature radiators, for example, involves heat-pipe-to-fin interfaces which introduce contact resistances and thermal stresses arising from coefficient of thermal expansion (CTE) mismatches. A monolithic additively manufactured heat pipe radiator (HPR) could significantly reduce these detrimental effects to performance.The goal of this research is to develop and design AM heat pipes, characterize their performance, and integrate these heat pipes into a functional device, an AM Monolithic Heat Pipe Radiator (MHPR). These MHPR devices could potentially improve thermal management for applications such as nuclear spacecraft propulsion and hypersonics.
This thesis specifically explores AM produced Inconel 718 to produce functional wicking structures. During the study several design approaches for creating heat pipe wicks with AM processes were explored and proposed for the first time in three categories as structured, sintered, and rastered approaches. Several aspects of wick design were studied to understand their influence on fluid wicking performance including porosity, print parameter selection, surface oxidation, print orientation, working fluid interaction, permeability, capillary pressure, pore size, and performance ratio. Manufacturing defect modes for AM wicks were also studied.
This thesis identified the rastered wicking strategy, with high hatch spacings and printed in the vertical print orientation, as the design strategy with the highest overall performance for monolithic HPR applications. The sintered wicking strategy was found to perform well when designs had thin wick regions in the horizontal print orientation and was less prone to manufacturing defects. Oxidation of the Inconel wicks greatly improved the wettability of the wick surface when using water as a working fluid but was less influential with ethanol. This thesis uncovers the important role of both surface assisted wetting and geometry assisted transport channels for superior wick performance. Several monolithic HPR prototypes were produced using AM and successfully tested in space-like conditions.
ContributorsNoe, Cameron Scott (Author) / Bhate, Dhruv (Thesis advisor) / Phelan, Patrick (Committee member) / Kwon, Beomjin (Committee member) / Arizona State University (Publisher)
Created2024
Description
Since their invention in the 19th century, polymers have played an essential role, yet their full potential in biomedicine remains largely untapped. Biocompatible polymers, known for their flexibility, accessibility, and modifiability, hold promise in creating complex biomimetic structures for bioscaffolds and biosensors. 3D printing, an emerging manufacturing technique, enables on-demand production of intricate structures, offering significant potential for personalized medicine and advanced biomedical engineering. This thesis focuses on designing and developing polymer-based bioscaffolds and biosensors using 3D printing. Chapter 1 provides an all-round introduction to common 3D printing techniques and polymeric biomaterials, especially biodegradable polymers. In Chapter 2, a gill-mimicking thermoelectric generator (TEG) was created to harvest body temperature and monitor bio-signals without external power. The out-of-plane geometry is obtained with fused deposition modeling (FDM), which is crucial for effective contact with various curved surfaces. Further improvements in biocompatibility enable the material to be implanted in vivo. Chapter 3 discusses UV-facilitated DIW printing for pelvic organ prolapse (POP) tissue scaffolds, featuring crosslink strategies for native tissue-like mechanical behavior. The double network comprises thiol-ene UV-initiated chemical bonds and alkaline-induced crystal regions as physical crosslink nodes. The crosslink density affects the degradation rate of the scaffold, enabling a slow degradation behavior beneficial to the recovery of the injured tissue. Chapter 4 presents a novel artificial artery design with varying moduli and natural polymers for bypass surgeries. The inner and outer layers of the conduit were stretched successively under different strains, endowing the vessel with varying moduli. Natural polymers were utilized to achieve low cytotoxicity and promote adequate cell adhesion. Additionally, the gelation behavior and the ink composition suitable for extrusion with a DIW platform were thoroughly studied. Image analysis, finite element analysis, and machine learning were employed to substantiate the findings regarding mechanical properties, extrusion quality, and printing fidelity in Chapters 3 and 4. This combination of computer-assisted analysis with experimental results enhances the robustness of the studies. Lastly, Chapter 5 provides an outlook and perspectives on the applications of biocompatible polymeric materials manufactured by 3D printing in the field of health applications.
ContributorsZhu, Yuxiang (Author) / Li, Xiangjia (Thesis advisor) / Vernon, Brent (Committee member) / Bhate, Dhruv (Committee member) / Guo, Shenghan (Committee member) / Song, Kenan (Committee member) / Arizona State University (Publisher)
Created2024