Browsing by Subject "thermal modeling"

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3D thermal-electrochemical lithium-ion battery computational modeling
(2009-08) Gerver, Rachel Ellen; Meyers, Jeremy P.; Ezekoye, Ofodike A.
The thesis presents a modeling framework for simulating three dimensional effects in lithium-ion batteries. This is particularly important for understanding the performance of large scale batteries used under high power conditions such as in hybrid electric vehicle applications. While 1D approximations may be sufficient for the smaller scale batteries used in cell phones and laptops, they are severely limited when scaled up to larger batteries, where significant 3D gradients can develop in concentration, current, temperature, and voltage. Understanding these 3D effects is critical for designing lithium-ion batteries for improved safety and long term durability, as well as for conducting effective design optimization studies. The model couples an electrochemical battery model with a thermal model to understand how thermal effects will influence electrochemical behavior and to determine temperature distributions throughout the battery. Several modeling example results are presented including thermal influences on current distribution, design optimization of current collector thickness and current collector tab placement, and investigation of lithium plating risk in three dimensions.
Experiment Based Superposition Thermal Modeling of Laser Powder Bed Fusion
(University of Texas at Austin, 2021) Lough, Cody S.; Landers, Robert G.; Bristow, Douglas A.; Drallmeier, James A.; Brown, Ben; Kinzel, Edward C.
This paper evaluates experiment-based superposition thermal modeling for Laser Powder Bed Fusion (LPBF) with a pulsed laser. An analytical pulsed laser thermal model establishes the modeling procedure. The framework inverts a powder bed’s single pulse temperature response from experimental spatiotemporal Short-Wave Infrared (SWIR) camera data. Superimposing this response along a scan path simulates multi-pulse LPBF. Results show the experimentally informed superposition model rapidly and accurately predicts a layer’s temperature history. The model has applications in correction of thermally driven LPBF errors and in-situ part qualification.
Material Issues in Layered Forming
(1993) Amon, Christina; Beuth, Jack; Kirchner, Helmut; Merz, Robert; Prinz, Fritz; Schmaltz, Kevin; Weiss, Lee
A brief overview of key issues in layered thermal processing is given. Incremental sintering and layered fusion ofpowder and molten droplets are discussed. The criteria for remelting the solid substrate are derivedfrom a one dimensional heat transfer model. Temperature gradients which occur during solidification and subsequent cooling. are responsible for the build up of internal stresses which can be estimated through establishing an elastic beam model. The difficulties as well as opportunities regarding the generation of multi-layer multi-material structures are also described in this article.
Melt Pool Geometry Simulations for Powder-Based Electron Beam Additive Manufacturing
(University of Texas at Austin, 2013-08-16) Cheng, Bo; Chou, Kevin
It is known that the melt pool geometry and dynamics strongly affect the build part properties in metal-based additive manufacturing (AM) processes. Thus, process temperature predictions may offer useful information of the melt pool evolution during the heating-cooling cycle. A transient thermal modeling for powder-based electron beam additive manufacturing (EBAM) process has been developed for process temperature simulations, considering temperature and porosity dependent thermal properties. In this study, the thermal model is applied to evaluate, for the case of Ti-6Al-4V in EBAM, the process parameter effects, such as the beam speed, on the temperature profile along the melt scan and the corresponding melt pool geometric characteristics such as the lengthdepth ratio and the cross-sectional area. The intent is to establish a process envelop for part quality control.
Thermal Modeling of 304L Stainless Steel Selective Laser Melting
(University of Texas at Austin, 2017) Li, Lan; Lough, Cody; Replogle, Adriane; Bristow, Doug; Landers, Robert; Kinzel, Edward
This paper describes the continuum thermal modeling of the Selective Laser Melting (SLM) process for 304L stainless steel using Abaqus. Temperature dependent thermal properties are obtained from literature and incorporated into the model capturing the change from powder to fully dense stainless steel. The thermal model predicts the temperature history for multi-track scans under different process parameters (laser power, effective scanning speed, hatch spacing) which is used to extract the melt-pool size, solidification rate, and temperature gradients. These are compared to experimental results obtained from a Renishaw AM250 in terms of the melt pool size, grain structure, and cell spacing. These experimental results are used to tune unknown simulation parameters required by the continuum model including the optical penetration depth and thermal conductivity multiplier for the molten region. This allows the model to yield predictive simulations of melt pool size and solidification structure of SLM 304L stainless steel.
Thermal Modeling of Fiber Optic Embedment in Metal Additive Manufacturing
(University of Texas at Austin, 2021) Snider, Elias; Gegel, Michelle; Holguin, Ryan; Dominguez, Cesar; Bernardin, John; Bristow, Douglas; Landers, Robert
Optical fibers are useful in many sensing applications, including temperature and radiation sensing as well as distributed strain measurements. These optical fibers may be consolidated within an additive manufacturing process to help diagnose and/or monitor the mechanical performance of a part. However, bonding optical fibers to metal parts using laser-based additive manufacturing requires processing temperatures dangerous to the fiber, posing challenges for fiber survival. To protect the fiber and allow bonding with the metal part, the fibers are plated with a nickel coating prior to embedment – a process that is costly to perform. These coatings may also have small internal defects that vary from one fiber to the next. Due to manufacturing cost and lack of repeatability, it is difficult to experimentally determine appropriate process parameters, such as laser power and coating thickness. Thus, numerical modeling offers an efficient approach to exploring embedment parameters and their effect on fiber survivability. This work employs transient thermal models of embedment processes to identify and simulate significant design parameters such as coating thickness, embedment geometry, and cooling time. A transient thermal simulation was developed and is presented which models fiber optic embedment processes via Laser Engineered Net Shaping (LENS®, a blown powder, direct energy deposition process) and trends in peak fiber core temperatures, as well as thermal shock are discussed.