- Browse by Author
Browsing by Author "Park, Hye-Yeong"
Now showing 1 - 9 of 9
Results Per Page
Sort Options
Item Atomistic Modeling of Anisotropic Mechanical Properties of Lanthanum Zirconate Nanocystal(Elsevier, 2021-02) Guo, Xingye; Zhang, Jian; Park, Hye-Yeong; Jung, Yeon-Gil; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and TechnologyLanthanum zirconate (La2Zr2O7, or LZ) has been widely recognized as a promising candidate material for thermal barrier coating (TBC) applications since it has low thermal conductivity, high-temperature phase stability, and low sintering activity. However, the mechanical properties of LZ crystal have not been fully understood, which hinders it from future applications. In this work, atomistic simulations were performed to study the anisotropic mechanical properties of LZ crystal. Using both the first principles and molecular dynamics (MD) calculations, uniaxial tensile tests of LZ crystal in [001], [011], and [111] directions were simulated. The stress-strain curves of the tensile tests were calculated, and the ultimate tensile strength and toughness were derived. The Young's moduli in [001], [011], and [111] directions were calculated using both the stress-strain curves and an analytical method for small deformation. Additionally, shear stress-strain curves in {111}<110> and {111}<112> directions were investigated using both the first principles calculations and the MD method. Results show that Young's modulus of LZ crystal is highly anisotropic. The crystal has the highest Young's modulus in [111] direction, and {111}<112> direction is the favorable slip system during shear deformations.Item Finite Element Modeling of Coating Thickness Using Heat Transfer Method(Elsevier, 2021-01) Li, Yafeng; Dhulipalla, Anvesh; Zhang, Jian; Park, Hye-Yeong; Jung, Yeon-Gil; Koo, Dan Daehyun; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and TechnologyA new heat transfer based finite element model is proposed to simulate coating thickness in the electron-beam physical vapor deposition (EB-PVD) process. The major advantage of the proposed model is that it is much computationally efficient than the traditional ray-tracing based model by about two orders of magnitude. This is because the Gaussian distribution heating source has the same profile as the cosine relation used in the ray-tracing method. Firstly, the model simulates the temperature profile of a metal substrate heated by a heating source with a Gaussian distribution. Then using a calibrated conversion process, the temperature profile is converted to corresponding coating thickness. The model is successfully demonstrated by three validation cases, including a stationary disk, a stationary cylinder, and a rotary three-pin component. The predicted coating thicknesses in the validation cases are in good agreement with either the ray-tracing based analytical solution or experimental data. After its validation, the model is applied to a rotary turbine blade to predict its coating thickness distribution. In summary, the model is capable to simulate coating thickness in complex shaped parts.Item Machine Learning in Additive Manufacturing: A Review(Springer, 2020) Meng, Lingbin; McWilliams, Brandon; Jarosinski, William; Park, Hye-Yeong; Jung, Yeon-Gil; Lee, Jehyun; Zhang, Jing; Engineering Technology, School of Engineering and TechnologyIn this review article, the latest applications of machine learning (ML) in the additive manufacturing (AM) field are reviewed. These applications, such as parameter optimization and anomaly detection, are classified into different types of ML tasks, including regression, classification, and clustering. The performance of various ML algorithms in these types of AM tasks are compared and evaluated. Finally, several future research directions are suggested.Item Microstructure and Phase Analysis of 3D-Printed Components Using Bronze Metal Filament(Springer, 2020-03) Lu, Zhe; Ayeni, Oyedotun Isaac; Yang, Xuehui; Park, Hye-Yeong; Jung, Yeon-Gil; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and TechnologyTypical metal 3D printing processes with powders require either a laser or electron beam as the heating source. In this work, an alternative non-expensive metal 3D printing process based on the fused deposition modeling process using metal filled filament is studied. Using bronze filament as a feedstock, the microstructures, phases, compositions of the filament, as-printed, and sintered specimens are analyzed. The 3D printing process basically does not modify the morphology and phases of the filament. Sintering temperature below 832 °C is recommended. Above 832 °C, there are substantial oxidation reactions leading to the formation of copper oxide and cassiterite shell structure around the bronze core. The mechanical properties of the 3D-printed sample are measured using the three-point bending test. The measured flexural strength is 27.9 MPa, and the modulus of elasticity is 1.2 GPa. This study provides important information for applying the bronze filament in future engineering applications.Item Modeling of Temperature Swing Effect in Silica Reinforced Porous Anodized Aluminum Based Thermal Barrier Coating(SAE International, 2021) Gulhane, Abhilash; Zhang, Jian; Yang, Xuehui; Lu, Zhe; Park, Hye-Yeong; Jung, Yeon-Gil; Li, Yafeng; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and TechnologyThis paper presents a finite element (FE) based model to simulate the temperature swing phenomenon of Silica Reinforced Porous Anodized Aluminum (SiRPA) thermal barrier coatings (TBCs). A realistic 3D SiRPA coating microstructure is constructed, based on the morphology of an experimentally grown coating structure, and the known relationship of geometry and anodization parameters. The coatings’ thermophysical properties are first computed using the FE model. The predicted thermal conductivity, thermal diffusivity, and bulk density are compared well with the experimental values. Also, transient thermal analysis is conducted to model the temperature swing effect of the coating by comparing the temperature fluctuation of SiRPA coating with conventional Yttria Stabilized Zirconia (YSZ) based TBCs. With the predicted thermophysical properties, the model is capable to predict the “temperature swing” effect of SiRPA by a transient thermal analysis. Temperature fluctuation of SiRPA is found greater compared to YSZ coating, suggesting its applicability in internal combustion engines. The porosity-dependent thermal conductivity of SiRPA coating is numerically derived. The thermal conductivity decreases linearly with increasing total porosity. The modeling data illustrate that the SiRPA coating shows a higher fluctuation compared to YSZ based TBCs, suggesting its applicability in internal combustion engines.Item Removal and repair techniques for thermal barrier coatings: a review(Taylor & Francis, 2020) Yang, Xuehui; Zhang, Jian; Lu, Zhe; Park, Hye-Yeong; Jung, Yeon-Gil; Park, Heesung; Koo, Dan Daehyun; Sinatra, Raymond; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and TechnologyA comprehensive literature review of the existing techniques for removing and repairing of damaged thermal barrier coatings is presented, with the focus on top ceramic coats. The advantages and disadvantages of each technique are compared and assessed. The review shows that there is not a universal method applicable to all coating systems. The selection of the coating removal and repair process must be specific to damaged coating systems, based on their composition, type of damages, and available resources. This review will provide some inside look at various approaches in an effort to meet the different coating repair needs.Item Synthesis and machining characteristics of novel TiC ceramic and MoS2 soft particulate reinforced aluminium alloy 7075 matrix composites(Elsevier, 2020-04) Dhulipalla, Anvesh; Kumar, Budireddy Uday; Akhil, Varupala; Zhang, Jian; Lu, Zhe; Park, Hye-Yeong; Jung, Yeon-Gil; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and TechnologyIn this work, the synthesis and machinability studies are presented for a new TiC ceramic and MoS2 soft particulate reinforced aluminium alloy 7075 (AA7075) matrix composite (AMCs). The results show that the AMCs have improved machinability compared with the base AA7075. The chip morphology is changed from continuous sheared chips in AA7075 to discontinuous chips in AMCs. The change is caused by the reduced ductility in AMCs due to reinforcement TiC and MoS2 microparticles. The surface roughness is increased for the AMCs when compared to that of base alloy due to hard TiC particles.Item Thermal properties of La2Zr2O7 double-layer thermal barrier coatings(Taylor & Francis, 2018) Guo, Xingye; Lu, Zhe; Park, Hye-Yeong; Li, Li; Knapp, James; Jung, Yeon-Gil; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and TechnologyLa2Zr2O7 is a promising thermal barrier coating (TBC) material. In this work, La2Zr2O7 and 8YSZ-layered TBC systems were fabricated. Thermal properties such as thermal conductivity and coefficient of thermal expansion were investigated. Furnace heat treatment and jet engine thermal shock (JETS) tests were also conducted. The thermal conductivities of porous La2Zr2O7 single-layer coatings are 0.50–0.66 W m−1 °C−1 at the temperature range from 100 to 900°C, which are 30–40% lower than the 8YSZ coatings. The coefficients of thermal expansion of La2Zr2O7 coatings are about 9–10 × 10−6 °C−1 at the temperature range from 200 to 1200°C, which are close to those of 8YSZ at low temperature range and about 10% lower than 8YSZ at high temperature range. Double-layer porous 8YSZ plus La2Zr2O7 coatings show a better performance in thermal cycling experiments. It is likely because porous 8YSZ serves as a buffer layer to release stress.Item Water surface reinforcement effect in 3D printed polymer derived SiOC ceramics(Springer, 2021-01) Yang, Xuehui; Zhang, Jian; Park, Hye-Yeong; Jung, Yeon-Gil; Jones, Alan; Zhang, Jing; Mechanical and Energy Engineering, School of Engineering and TechnologyIn this work, PDC SiOC porous structures were fabricated using the stereolithography (SLA) 3D printing method with preceramic resin methylsiloxane. The printed structures were then sintered at 1000 °C for 1 h. Water treatment can help prevent the shrinkage and remove the unreacted resin. From the XRD and FT-IR results, the sintered ceramic is amorphous SiOC. The microstructures show that the printed structures have high geometric accuracy. The water reinforcement process produces smoother surfaces on the printed structures.