Search Results for thermal modeling

This article provides information on the various stages of quenching, sources of distortion, and factors that affect the creation of thermal gradients. It reviews the various determinations of heat-transfer coefficients by the thermal conductivity and diffusivity method, analytical and empirical methods, application of cooling curves, computational fluid dynamics, and the inverse conduction calculation and measurement of parts. Suitable examples are also provided.

This article outlines a general approach to develop a coupled electrical-thermal-mechanical analysis for the resistance spot welding process. It provides information on the discretization of sheet-electrode geometry and distribution of contact resistivity along the sheet-sheet and electrode-sheet interfaces. The distribution can be estimated based on the discretized geometry used for the numerical modeling. The article also details the results obtained from this modeling.

Friction welding is based on the rapid introduction of heat, causing the temperature at the interface to rise sharply and leading to local softening. This article illustrates the basic principles of direct-drive rotational friction welding and inertia friction welding. Modeling the effective friction response of the materials is central to simulating the welding process. The article discusses a series of distinct frictional stages during continuous drive friction welding. Modeling of the evolution of the thermal field has been an important objective since the early days of rotational friction welding. The article describes analytical thermal models and numerical thermal models for rotational friction welding. It concludes with information on the modeling of residual stresses.

This article provides an overview of different modeling approaches used to capture the phenomena present in the additive manufacturing (AM) process. Inherent to the thermomechanical processing that occurs in AM for metals is the development of residual stresses and distortions. The article then provides an overview of thermal modeling. It presents a discussion on solid mechanics simulation and microstructure simulation.

During fusion welding, the thermal cycles produced by the moving heat source cause physical state changes, metallurgical phase transformation, and transient thermal stress and metal movement. This article presents an analysis of heat flow in the fusion welding process. The primary objective of welding heat flow modeling is to provide a mathematical tool for thermal data analysis, design iterations, or the systematic investigation of the thermal characteristics of any welding parameters. The article addresses analytical heat-flow solutions and their practical applications. It describes the effects of material property and welding condition on the temperature distribution of weldments. The thermal properties of selected engineering materials are provided in a table.

The finished product, after fusion welding, may contain physical discontinuities due to excessively rapid solidification, adverse microstructures due to inappropriate cooling, or residual stress and distortion due to the existence of incompatible plastic strains. To analyze these problems, this article presents an analysis of the welding heat flow, with focus on the fusion welding process. It discusses the analytical heat-flow solutions and their practical applications. The article concludes with a description of the effects of material property and welding condition on the temperature distribution of weldments.

This article provides a detailed overview of the thermomechanical modeling of additive manufacturing (AM) process. It begins with information on a basic understanding of the formation of residual stress during AM processing followed by a discussion on models commonly applied in AM modeling, such as heat-input models, material models, and material activation models. Information on experimental setup for validation and simulation of directed-energy deposition model is then included. The article also provides information on moving-source and part-scale analyses to simulate the laser powder-bed fusion AM process.

This article discusses the fundamentals of friction stir welding (FSW) and presents governing equations and an analytical solution for heat transfer. It provides the solutions for structural distortion in FSW. The article describes various techniques that have been adopted to solve the equations and simulate the FSW process. The techniques include modeling without convective heat transfer and modeling with convective heat transfer in a workpiece. The article concludes with information on active research topics in the simulation of FSW.

This article presents the analytics challenges in additive manufacturing. It discusses the types and applications of data analytics. Data analytics can be classified into four types: descriptive, diagnostic, predictive, and prescriptive. The diverse applications of data analytics and machine learning include design, process-structure-properties (PSP) relationships, and process monitoring and quality control. The article also presents tools used for data analytics.

This article provides an overview of the models of two induction heating devices, namely, induction crucible furnace (ICF) and induction furnace with slits, or segmented and water-cooled induction furnace with cold crucible (IFCC). These devices are used for melting with skull formation of low-conductivity materials such as glasses and oxides. The article presents the governing equations and boundary conditions for ICF and IFCC modeling. It includes a discussion on three electromagnetic field models in IFCC, namely, two-dimensional (2-D), quasi-three-dimensional, and three-dimensional (3-D) models. The article provides information on the simulation of skull formation in IFCC, and elucidates the transient axisymmetrical 2-D model and the transient 3-D model, including the primary results achieved for both glasses and skull formation.

Additive manufacturing produces a change in the shape of a substrate by adding material progressively. This article discusses the simulation of laser deposition and three principal thermomechanical phenomena during the laser deposition process: absorption of laser radiation; heat conduction, convection, and phase change; and elastic-plastic deformation. It provides a description of four sets of data used for modeling and simulation of additive manufacturing processes, namely, material constitutive data, solid model, initial and boundary conditions, and laser deposition process parameters. The article considers three aspects of simulation of additive manufacturing: simulation for initial selection of process parameter setup, simulation for in situ process control, and simulation for ex situ process optimization. It also presents some examples of computational mechanics solutions for automating various components of additive manufacturing simulation.

This article briefly reviews the physical phenomena that influence the input-energy distribution. It discusses the several simplified and detailed heat source models used in the modeling of arc welding, high-energy-density welding, and resistance welding processes.

This article provides an overview of integrated weld modeling and discusses the fundamentals of the underlying physics and methodologies involved in process modeling. It presents approaches for microstructure modeling that help to predict phase fractions as well as grain size in the heat-affected zone and weld metal region as a function of alloy composition and thermal cycles. The article discusses the uses of computational thermodynamic and kinetic tools. It describes the concept of performance modeling, whose goal relates to the prediction of weldability, geometrical distortion, and/or locked-in residual stress as a function of material, restraint, process, and process parameters as well as service temperature. Finally, the article presents a case study, evaluating the use of X-65 steels using the E-WeldPredictor tool.

This article provides information on the boundary conditions that must be applied to model the heat-transfer coefficient (HTC) in a component being cooled. It describes the historical perspective of various experiments to determine the HTCs. Computational fluid dynamics codes have also been used to predict the HTCs around a part. The article provides information on the various modeling studies used to predict cooling rates in a component. The prediction of residual stresses by validation and optimization of residual stress models is also discussed. Several techniques, such as models neglecting and incorporating material transformation effects, used to predict residual stresses are reviewed. The article also explains the various aspects of models used to prevent cracking during heating and quenching.

This article provides an overview of integrated weld modeling and presents strategic goals for the welding industry. It discusses the fundamentals of the underlying physics and the methodologies to solve the same. The article presents the pioneering work done to predict the heat-affected zone and weld metal microstructure in the early 1980s and 1990s. Applications of computational thermodynamics and kinetics tools to weld metal microstructure prediction for liquid-gas reactions and liquid-slag reactions that happen as a function of high-to-low temperature during fusion welding are discussed. The article also includes a brief discussion on weldability prediction, residual stress prediction, and distortion prediction. It concludes with information on the use of optimization methodologies.