Browsing by Subject "finite element method"
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Item 3D Transient Modeling of Bulk High Temperature Superconducting Material in Passive Magnetic Bearing Applications(0000-00-00) Pratap, S. B.; Hearn, C.Bulk high temperature superconductors (HTSC) are being considered for use in several engineering applications including passive magnetic bearings. These bearings besides being passive i.e. inherently stable also offer the promise of lower bearing losses thus they are being considered for use with flywheels for energy storage in applications related to frequency regulation and for correcting forecasting errors associated with renewable energy sources. The effort presented in this paper was undertaken to characterize the performance of these bearings such as longitudinal and transverse stiffness and loss characteristics. To this end, a finite element method using the T-Ω potentials was used for the formulation. The results of the finite element method (FEM) were verified with experiments. These experiments are described. This FEM tool was also used to guide the development of a reduced order model which could run faster and therefore could be used in larger system simulations. Some discussions about the run time on a desktop PC are also presented.Item Analytical and Experimental Characterization of Anisotropic Mechanical Behaviour of Infill Building Strategies for Fused Deposition Modelling Objects(University of Texas at Austin, 2017) Cunico, Marlon Wesley MachadoAs consequence of the 3d printing extraordinary rising along the last years, product development fields are facing new challenges. In addition, it is notary that low cost additive manufacturing, as such fused filament fabrication (FFF), result in objects with anisotropic mechanical behaviour. Nevertheless, there is still lacking studies that highlight a proper specification of those mechanical proprieties. For that reason, the main goal of this work is to present a mechanical characterization of anisotropic behaviour of FFF objects as a function of infill strategy using a finite element method. In this work, the main effect of building parameters were investigated in addition the identification of generalized elasticity and failure mode formulations. By the end, the general recommendation for objects building was sketched in order to support new strength based developments.Item A Computational and Experimental Investigation into Mechanical Characterizations of Strut-Based Lattice Structures(University of Texas at Austin, 2019) Sereshk, Mohammad Reza Vaziri; Triplett, Kevin; St. John, Christopher; Martin, Keith; Gorin, Shira; Avery, Alec; Byer, Eric; St Pierre, Conner; Soltani-Tehrani, Arash; Shamsaei, NimaStrut-based lattices are widely used in structural components for reducing weight. Additive manufacturing has provided a unique opportunity to fabricate such complex geometries. In addition to the unit cell type, the strut size and shape can significantly affect the mechanical properties achieved. Therefore, furnishing a lattice structure library may help in selecting the appropriate combination of lattice types and dimensions for targeted mechanical performance for a specific application. This study presents a method for determination of mechanical properties, including strength and stiffness, for lattice structures. Finite element (FE) simulations are used as the main tool and the results of which are to be verified by mechanical testing of samples fabricated using the laser beam powder bed fusion (LB-PBF) process. Proper lattices with the stiffness matched with associated bone were determined. However, the result indicated that lattices made from 316L SS are not strong enough for bone implants. The proposed procedure can be used for other unit cells of interest due to its generality.Item Correlations of Interlayer Time with Distortion of Large Ti-6Al-4V Components in Laser Metal Deposition with Wire(University of Texas at Austin, 2018) Lee, Y.S.; Bandari, Y.; Simunovic, S.; Richardson, B.; Kirka, M.M.Laser metal deposition with wire (LMD-w) is one of the emerging additive manufacturing (AM) technologies for large-scale aerospace components due to high deposition rates and material efficiency. However, it often results in undesired stresses and distortions due to non-uniform expansion and contraction of material during printing. Controlling inter-layer time, preheating, and clamping are the effective methods to mitigate the thermally induced stress and deformation. In this study, the effect of inter-layer cooling time on part distortion is investigated using a finite element method (FEM). The model accounts for actual tool paths, power, and cooling conditions. The results show that the model effectively captures the fluctuation of the Ti-6Al-4V plate during printing. Also, it shows an asymmetric distortion on the plate edges. Ultimately, the sequentially coupled thermal-stress simulation provided a quantitative understanding of the inter-layer cooling time on titanium plate distortion for the large-scale LMD-w process.Item Melt Pool Evolution Study in Selective Laser Melting(University of Texas at Austin, 2015) Cheng, Bo; Chou, KevinIn selective laser melting (SLM) additive manufacturing, the completion of the entire scanning cross-sectional area of each layer build is consisted of many smaller scanning patches. Hence, the scanning length in each path may be too short to reach the melt pool quasi-steady state, thus, affecting the melt pool geometry, which is also effected by the process parameters. It is also known that the melt pool size correlates with the build part microstructures and properties. In this study, temperature simulations, finite-element based, of SLM for In718 is applied to track the thermal response during scanning of an individual patch. The results show that the process parameters determine the melt pool evolution, which affects the actual molten pool size in the regions defined by the raster scanning length. Manipulating the scanning path length and process parameters, based on the melt pool evolution information, may help to achieve a desired melt pool size for part quality controls.Item Numerical Simulation Of Impact Effects On Multilayer Fabrics(2007-12) Fahrenthold, E.; Rabb, R.; Bohannan, A.; Fahrenthold, E.; Rabb, R.; Bohannan, A.High strength fabrics provide lightweight impact protection and are employed in a wide range of applications. Examples include body armor for law enforcement and military personnel and orbital debris shielding for the International Space Station. Numerical simulation of impact effects on fabric protection systems is difficult., due to the complex woven structure of the fabric layers and the typical application of fabrics in a multilayer configuration. Recent research has applied a new particle-element method to the simulation of impact effects on multilayer fabrics, applicable over a wide range of impact velocities, for use in body armor and orbital debris shielding design applications.Item Phase-Field Simulation and Design of a Ferroelectric Nano-Generator(2011-04) Krauss, M.; Muench, I.; Landis, C. M.; Wagner, W.; Landis, C. M.We study the behavior of ferroelectric material (BaTiO3) for the design of a nano-generator to convert mechanical into electrical energy. The investigations consider an electro-mechanical phase-field model with polarization as state variable. This widely accepted model has its origins in the work of and is fully developed by Landis and coworkers. We use a finite element model to simulate tetragonal regions of ferroelectric material sputtered on substrate. Different geometries as well as various mechanical and electrical boundary conditions are considered. The model parameters are normalized to achieve better computational conditions within the stiffness matrix. The major objective of this contribution is the fundamental understanding of domain switching caused by a cyclic electrical field. The corresponding hysteresis loops of the overall polarization cannot be achieved by using a two-dimensional model because the domain topologies evolve in three dimensions. The three-dimensional nature of the domain structure evolution is even true for flat regions or thin films. We show some examples of three-dimensional domain topologies, which are able to break energetically unfavorable symmetries. Finally, the computational model of a tetragonal nano-generator with dimensions 10 x 60 x 10 nm is presented. The specific ratio of height to width and the mounting on substrate is essential for its performance and principle of energy harvesting. We discuss the challenges and scopes of such a system.Item Prediction of the Elastic Response of TPMS Cellular Lattice Structures Using Finite Element Method(University of Texas at Austin, 2017) Karamooz-Ravari, M.R.; Taheri Andani, M.Cellular lattice structures are a group of porous materials in which the cells are regularly distributed. Since the morphology of the cells is complicated, the fabrication of them is challenging using conventional methods. However, with the advent of additive manufacturing technology, more attention is focused on these classes of materials because the regular geometry makes it possible to tailor the mechanical response of the structure. Among all kinds of cellular lattice structures, those based on triply periodic minimal surfaces are of great importance due to mechanical and biological properties. Since the fabrication of such structures is challenging and expensive, it is desirable to predict their mechanical response before fabrication. In this paper, finite element approach is employed to predict the elastic response of two well-known Schwarz minimal surfaces named P-Type and G-Type. To do so, first, the cloud points of the surfaces are generated using the implicit equation of the surface and are converted into solid finite element models. The results show that at the same value of porosity, the P-Type specimen provides a higher value of elastic modulus than G-Type one.