# Browsing by Subject "finite element analysis"

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Item Additive Manufactured Lightweight Vehicle Door Hinge with Hybrid Lattice Structure(University of Texas at Austin, 2019) Aydin, I.; Akarcay, E.; Gumus, O.F.; Yelek, H.; Engin, C.B.Show more Item Design Optimization of a Customized Dental Implant Manufactured via Electron Beam Melting®(University of Texas at Austin, 2009-09) Chahine, Gilbert; Atharifar, Hosein; Smith, Pauline; Kovacevic, RadovanShow more Finite Element Analysis (FEA) is a commonly used tool to evaluate biomechanics of traditional dental implants. Biomechanics help predict bone response and implant retention which strongly affects the longevity of the implant. The current research utilizes an analogues approach with FEA, to evaluate the biomechanics of a customized dental implant design built by Electron Beam Melting®, and to contribute towards the implant’s design optimization. The analysis consists of three distinct simulation models. The first model is established in order to get an insight of the biomechanics produced by a biting force of 400 N on a second human molar in the mandible, its corresponding superposed mate and the surrounding biomaterial. In the second model, the lower jaw molar is replaced by a Ti-6Al-4V customized dental implant with a solid surface at the root. In the third model, the customized dental implant has a modified outer-layer at the root with adjustable elasticity. By using a deterministic optimization technique in the FEA, an elasticity of the modified layer can be selected in a manner to minimize stress shielding from occurring.Show more Item Design Rules for Additively Manufactured Wrist Splints Created Using Design of Experiment Methods(University of Texas at Austin, 2018) Kelly, S.; Paterson, A.M.J.; Bibb, R.J.Show more Research has shown that wrist splints can be made using Additive Manufacturing (AM) with a similar or greater performance than splints created using traditional manufacturing methods. By using AM, many of the problems associated with traditional splinting such as poor aesthetics and poor ventilation could be mitigated. However, work to date typically reviews splints with singular pattern designs (e.g. Voronoi patterns), which have structural and safety implications if similar but untested patterns are created. Using Design of Experiments (DOE) design rules were to enable clinicians to confidently design splints alongside their patients. Design rules were created by investigating variables of cut out patterns using DOE methods. Finite Element Analysis (FEA) of various combinations of cut out variables was conducted.Show more Item Effect of Wall Thickness and Build Quality on the Compressive Properties of 304L Thin-Walled Structures Fabricated by SLM(University of Texas at Austin, 2018) Spratt, Myranda; Anandan, Sudharshan; Hussein, Rafid M.; Newkirk, Joseph W.; Chandrashekhara, K.; Misak, Heath; Walker, MichaelShow more The specific strength of lightweight lattice structures built with SLM is of interest to the aerospace industry. Honeycombs were manufactured with increasing wall thicknesses (which increases density) and tested under compression. The optimal strength to density ratio was determined from the resulting data. The build quality was also evaluated to determine how/if the results were influenced by the specimen quality. Differences between the nominal and as-built geometry were identified, but considered to be minimal. Microstructural evaluation of the specimens revealed a possible dependence on the ‘border scan’ properties, as the thickness of the specimens was such that the board scan made up most of the part. This work was used to validate the results of a finite element analysis of this geometry.Show more Item Fast Prediction of Thermal History in Large-Scale Parts Fabricated Via a Laser Metal Deposition Process(University of Texas at Austin, 2018) Yan, Lei; Pan, Tan; Newkirk, Joseph W.; Liou, Frank; Thomas, Eric E.; Baker, Andrew H.; Castle, James BShow more Laser metal deposition (LMD) has become a popular choice for the fabrication of near-net shape complex parts. Plastic deformation and residual stresses are common phenomena that are generated from the intrinsic large thermal gradients and high cooling rates in the process. Finite element analysis (FEA) is often used to predict the transient thermal cycle and optimize processing parameters; however, the process of predicting the thermal history in the LMD process with the FEA method is usually time-consuming, especially for large-scale parts. Herein, multiple 3D FEA models with simple assumptions on the heat source and its loading methods are compared and validated with experimental thermocouple data.Show more Item Methods for Enhancing the Speed of Numerical Calculations for the Prediction of the Mechanical Behavior of Parts Made Using Additive Manufacturing(University of Texas at Austin, 2013) Nikoukar, Mohammad; Patil, Nachiket; Pal, Deepankar; Stucker, BrentShow more Finite element modeling (FEM) is one of the most common methods for predicting the thermo-mechanical properties of 3D structures. Since FEM was developed primarily to analyze and optimize structures that would then be mass-produced, the time for modeling was small compared to the time required to produce the components. With the advent of Additive Manufacturing (AM) it is now possible to produce and test complex parts more quickly than FEM methods can predict their mechanical performance. As such, an enhanced numerical method for quickly solving for the mechanical behavior of components is needed to fully take advantage of the speed and versatility of this new manufacturing paradigm. In order to enhance the computational efficiency of FEM, a novel method was developed to adapt FEM for prediction of fundamental deformation responses of AM-produced parts. A general FEM strategy comprised of constructing the stiffness and external stimuli (such as laser power or pressure) as matrices and vectors respectively has been formulated. Thermo-mechanical response is calculated by obtaining the compliance matrix from the stiffness matrix and then multiplying the corresponding values of the compliance matrix with the external stimulus vector. Obtaining the compliance matrix from the stiffness matrix is accomplished, in most cases, using a well-known Cholesky algorithm which starts by transforming the stiffness matrix into a lower triangular matrix with zeros above its diagonal [1]. In this study, the Cholesky algorithm has been improved by identification of discrete sparse bands and by eliminating many zero multiplications in the lower triangular matrix to obtain the thermo-mechanical response much faster than currently available algorithms. In addition, the vector based storage strategy of the above-mentioned discrete sparse bands and multipliers have been used to save computer storage space, including free cache memory, resulting in faster computations. An example showing the time advantage of this new framework over previously used algorithms to obtain the deformation response of an additively manufactured axial beam is provided along with its theoretical background.Show more Item Modeling the Melt Pool of the Laser Sintered Ti6Al4V Layers with Goldak's Double-Ellipsoidal Heat Source(University of Texas at Austin, 2018) Soylemez, E.Show more Selective laser melting process has been widely studied to elucidate the effects of process parameters (laser speed, laser power, scan strategy, hatch distance, layer thickness, etc.) on the manufactured parts. Experimental and numerical modeling studies have been investigating the melt pool shapes of the laser sintered layers to correlate the melt pool geometry with the part quality. Although modeling results agree with the experiments, the melt pool cross-section may form key holing rather than semi-circular shape due to Marangoni effect, recoil pressure, and sudden evaporation for some process parameters combinations. To accurately model the melt pool depth, this study proposes a finite element analysis (FEA) model that simulates the laser source as the Goldak’s double-ellipsoidal heat power density model. Single bead experiments of Ti6Al4V were conducted within the processing range of laser sintering system with the 400 W laser, and these experimental results allowed to verify simulated FEA results.Show more Item A New Finite Element Solver using Numerical Eigen Modes for Fast Simulation of Additive Manufacturing Processes(University of Texas at Austin, 2013) Patil, Nachiket; Pal, Deepankar; Stucker, BrentShow more A new efficient numerical technique has been formulated for dimensional reduction and phenomenological multi-scale simulation of additive manufacturing processes using finite element analysis. This technique is demonstrated using prismatic build volumes to represent the Selective Laser Melting powder bed fusion additive manufacturing process. The Eigen modes determined as an outcome of implementation of this technique will help to reduce the time necessary for optimization of process parameters and closed loop control. In addition to thermal simulations of the Selective Laser Melting process, this technique is also applicable to the simulation of lattice structures, layered materials such as ultrasonically consolidated laminates, thin walled coatings and development of high fidelity beam and plate theories for parts made using additive manufacturing processes. A future integration of this method with analytical Eigen wavelets will provide infinite support compared to finite support provided by directional polynomial shape functions currently used for implementation of finite element strategies. The present Eigen modes will be also useful in analysis and optimization of mask projection based additive manufacturing processes.Show more Item Numerical Simulation And Analytical Solution For Plane Waves Focused By A Parabolic Reflector(2013-07) Tsai, Y. T.; Haberman, M. R.; Zhu, J.; Tsai, Y. T.; Haberman, M. R.; Zhu, J.Show more A transient analytical solution is presented to predict the pressure responses along the axis of a parabolic reflector for normally incident plane waves. The solution was derived using geometrical acoustics and the Kirchhoff-Helmholtz integral. Results of the analytical solution were compared to the numerical simulation results, and good agreements were obtained. The numerical simulation visualizes the wave field in air to give a better understanding of propagation of the reflected waves.Show more Item OPTIMIZATION OF COMPUTATIONAL TIME FOR DIGITAL TWIN DATABASE IN DIRECTED ENERGY DEPOSITION FOR RESIDUAL STRESSES(University of Texas at Austin, 2023) Tariq, Usman; Joy, Ranjit; Wu, Sung-Heng; Arif Mahmood, Muhammad; Woodworth, Michael M.; Liou, FrankShow more Metal Additive Manufacturing (MAM) has experienced rapid growth and demonstrated its cost-effectiveness in the production of high-quality products. However, MAM processes introduce significant thermal gradients that result in the formation of residual stresses and distortions in the final parts. Finite Element Analysis (FEA) is a valuable tool for predicting residual stresses, but it requires substantial computational power. This study aims to reduce computational time by incorporating a thermo-mechanical model specifically designed for the Directed Energy Deposition (DED) process using Ti6Al4V. This model predicts the thermal history and subsequent residual stresses in the deposited material. Various FEA methods, including “chunk”, layer, and conventional methods are examined, providing a comparative analysis of computational cost and numerical accuracy. These findings contribute towards the realization of a digital twin database, where the incorporation of efficient and accurate FEA models can optimize part quality and strength while reducing computational time.Show more Item Physical Modeling: Simulation of Micro-Void Development within Large Scale Polymer Composite Deposition Beads(University of Texas at Austin, 2021) Awenlimobor, Aigbe; Wang, Zhaogui; Smith, Douglas E.Show more Short carbon fiber composites are used in large-scale polymer deposition additive manufacturing due to their increased stiffness and strength and reduced thermal expansion and print distortion. While much attention has been given to interlayer properties, less is known about bead microstructure, including the effect that suspended fibers have on porosity. This paper develops a model for single fiber motion in a purely viscous flow that is simulated with a custom finite element fiber suspension analysis. Our fiber simulation is based on Jeffrey’s model assumptions where translational and rotational velocities which zero applied forces and moments are computed. Velocity gradients along streamlines within the flow of polymer melt through a large-scale polymer deposition additive manufacturing flow field serve as input. The pressure distribution around a fiber is computed along the flow path including the die swell expansion at the nozzle exit. The simulation provides insight into micro-void formation within printed beads.Show more Item Separation Force Analysis Based on Cohesive Delamination Model for Bottom-Up Stereolithography Using Finite Element Analysis(University of Texas at Austin, 2014) Liravi, Farzad; Das, Sonjoy; Zhou, ChiShow more Bottom-up (constrain-surface) Additive Manufacturing (AM) systems have been widely used in industry. Compared to traditional open-surface AM technology, properties like better vertical resolution, higher material filling rate, less production time, and less material waste make bottom-up AM technology a suitable candidate for fabrication of complex three dimensional materials with high accuracy. However during the pulling up stage, the substantial force generated between the formed part and the material container has high risk of breaking the part and therefore reduces the process reliability. In this paper, an optimization-based method is developed to model bottom-up AM process using finite element analysis (FEA). The FEA model is developed using ABAQUS to model the behavior of the cohesive delamination at the interface of the formed part and a hyper-elastic intermediate which has been used to reduce the pulling up force. An optimization model is also established to evaluate the cohesive stiffness parameters that cannot be calculated directly from closed formulas or mechanical tests. The results of this work will be used to develop an adaptive closed-loop mechanics-based system to control the pulling up process and achieve a reliable technology.Show more Item Simulation of Planar Deposition Polymer Melt Flow and Fiber Orientation in Fused Filament Fabrication(University of Texas at Austin, 2017) Heller, B.P.; Smith, D.E.; Jack, D.A.Show more Mechanical and thermal properties of a 3D printed part are improved by adding discrete carbon fibers to the Fused Filament Fabrication (FFF) polymer feedstock. The properties of the fiber-filled composite are significantly influenced by the orientation of the carbon fibers within the extruded bead where fiber orientation in the bead is affected by the nozzle internal flow geometry, extrudate swell, and the deposition flow during the FFF process. In this work, a 2D Stokes flow finite element analysis is performed to evaluate FFF extrusion for a large-scale deposition extruder where special attention is given to the deposition of polymer melt on the moving platform below the nozzle. The shape of the extruded polymer is computed using a free surface normal velocity minimization technique. Once the velocity field and flow boundary is computed for the bead deposition process, fiber orientation and the resulting mechanical properties of the solidified composite are computed within the printed bead.Show more Item Thermo-structural Finite Element Analysis of Direct Laser Metal Deposited Thin-Walled Structures(2005-08-26) Zekovic, Srdja; Dwivedi, Rajeev; Kovacevic, RadovanShow more Multilayer direct laser metal deposition is a fabrication process in which the parts are fabricated by creating a molten pool into which particles are injected. During fabrication, a complex thermal history is experienced in different regions of the build, depending on the process parameters and part geometry. The thermal history induces residual stress accumulation in the buildup, which is the main cause of cracking during the fabrication. The management of residual stress and the resulting distortion is a critical factor for the success of the process. A thermostructural finite element model (FEM) of the process is developed, and the analysis reveals different patterns of residual stress in the thin-walled structures depending on the deposition strategy and the geometry of the structures. The residual stress patterns obtained from finite element analysis (FEA) are in good agreement with the experimental results.Show more Item Using Design of Experiments in Finite Element Modeling to Identify Critical Variables for Laser Powder Bed Fusion(University of Texas at Austin, 2015) Ma, Li; Fong, Jeffrey; Lane, Brandon; Moylan, Shawn; Filliben, James; Heckert, Alan; Levine, LyleShow more Input of accurate material and simulation parameters is critical for accurate predictions in Laser Powder Bed Fusion (L-PBF) Finite Element Analysis (FEA). It is challenging and resource consuming to run experiments that measure and control all possible material properties and process parameters. In this research, we developed a 3-dimensional thermal L-PBF FEA model for a single track laser scan on one layer of metal powder above a solid metal substrate. We applied a design of experiments (DOE) approach which varies simulation parameters to identify critical variables in L-PBF. DOE is an exploratory tool for examining a large number of factors and alternative modeling approaches. It also determines which approaches can best predict L-PBF process performance.Show more