Search Results for inverse heat-conduction problem

This article presents the modes of heat transfer and the stages of cooling during quenching. It provides an overview on the wetting process and then focuses on the evaluation of heat transfer during quenching. It also presents the challenges of thermal process evaluation based on an inverse heat conduction analysis. The article contains a compilation of best practice examples on heat transfer evaluation, which are intended to represent the practical aspects and applicability of the methods aiming the prediction of heat-transfer coefficients.

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 describes the mechanisms and characteristics of heat transfer in the quenching of steel. This article describes the characterization of boiling heat transfer, including pool boiling, forced convective boiling, and rewetting, which plays a key role in defining the heat-extraction characteristics of a liquid quenchant. It provides information on heat generated microstructural field evolution and information on the analysis and characterization of heat transfer boundary conditions.

This article provides a discussion on probes for laboratory tests and resultant curves of industrial quenching processes. It describes the scope of the tests, and the calculation of heat-transfer coefficient (HTC) based on the tests. The article highlights the differences between the laboratory tests and characterization of industrial quenching processes. It reviews the importance of initial heat-flux density and first critical heat-flux density. The theoretical principle behind and the purpose of the temperature gradient method are discussed. The article provides information on the design of the probe, heat-extraction dynamics, and influence of wetting kinematics. It also includes discussions on the simplified 1-D temperature-distribution model, calculation of the HTC, and the finite-volume method for the heat-conduction equation.

A key aspect of solidification process modeling is the treatment of the interface between the solidifying casting and the mold in which it is contained. This article begins with information on casting-mold interface heat-transfer phenomena. It describes practical considerations and methods for incorporating interface heat-transfer coefficient into models and for quantifying the heat transfer coefficient experimentally. The article concludes with information on the selection of the heat transfer coefficient for a given casting configuration.

This article provides a comprehensive review and critical assessment of numerical modeling of heat and mass transfer in fusion welding. The different fusion welding processes are gas tungsten arc welding, gas metal arc welding, laser welding, electron beam welding, and laser-arc hybrid welding. The article presents the mathematical equations of mass, momentum, energy, and species conservation. It reviews the applications of heat transfer and fluid flow models for different welding processes. Finally, the article discusses the approaches to improve reliability of, and reduce uncertainty in, numerical models.

Computational fluid dynamics (CFD) provides an efficient, alternate, virtual approach for simulating and analyzing quenching processes with an impact on component design, manufacturing process, and quality. This article provides domain insights for quenching researchers and CFD practitioners for the modeling of the industrial quenching process and for supporting the diverse multifunctional needs in an industry, ranging from primary metallurgical companies (steel, aluminum, and other alloys), original equipment manufacturers, engineering companies, captive and commercial heat treating facilities, quench system manufacturers, and quench fluid suppliers. It describes the governing differential equations for the fluid flow and heat-transfer phenomena during quenching. The article also discusses different modeling categories to determine a CFD methodology for quenching.

This article describes the fundamental concepts of heat treatment simulation, including the physical events and their interactions, the heat treatment simulation software, and the commonly used simulation strategies. It summarizes material data needed for heat treatment simulations and discusses reliable data sources as well as experimental and computational methods for material data acquisition. The article provides information on the process data needed for accurate heat treatment simulation and the methods for their determination. Methods for validating heat treatment simulations are also discussed with an emphasis on the underlying philosophy for the selection and design of validation tests. The article also discusses the applications, capabilities, and limitations of heat treatment simulations via selected industrial case studies for a better understanding of the effect of microstructure, distortion, residual stress, and cracking in gears, shafts, and bearing rings.

This article provides an overview of common quenching media, the factors involved in the mechanism of quenching, and process variables, namely, surface condition, mass and section size of the workpiece, and flow rate of the quenching liquid. It describes the methods of quenchant characterization using hardening-power and cooling-power tests. The article discusses the fundamentals involved in heat-transfer coefficient and heat flux of quenching processes. This discussion is followed by various actual examples of applications of these methods using simplified equations. Quenchant evaluation, classification, selection, and maintenance are reviewed in detail. The article addresses the various reasons for quench oil variability and complications due to aging and contamination.

Welding and joining processes are essential for the development of virtually every manufactured product. This article discusses the fundamentals of fusion welding processes, with an emphasis on the underlying scientific principles. It reviews the role of energy-source intensity and the width of the heat-affected zone in fusion welding processes. The article contains figures from which the properties of any heat source can be estimated readily.

The article discusses the fundamentals of fusion welding processes with an emphasis on the underlying scientific principles. It describes how surface temperature varies on steel with surface power densities that range from 400 to 8000 W/cm2. The article illustrates the spectrum of practical heat intensities used for fusion welding. It contains tables that present information on the thermal diffusivities of common elements and alloys from 20 to 100 °C.

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.

A unidirectional fiber composite (UDC) consists of aligned continuous fibers that are embedded in a matrix. This article describes a variety of analytical methods that are used to determine the various physical properties of the UDC. These properties include elasticity, thermal expansion coefficients, moisture swelling coefficients, static and dynamic viscoelastic properties, conductivity, and moisture diffusivity.

Thermomechanical are used to gain insight into the causes of problems that arise during a given thermomechanical process. This article provides examples to demonstrate how significant the parameters were selected for specific tests. It examines the types of problems that can occur during a thermomechanical process. The article provides information on the thermophysical properties, which include specific heat, coefficient of thermal expansion, thermal conductivity/diffusivity, and density. It concludes with examples that illustrate how the various considerations in testing are successfully used to solve practical thermomechanical processing problems.

Temperature is a typical parameter characterizing the heating level of any particle belonging to a heated body. The basic problem of heat transfer computation is associated with appropriate determination of heat transfer coefficients. This article provides a discussion on the basic equations, initial and boundary conditions, and multiple reflection phenomena of mathematical modeling. These boundary conditions include the Dirichlet, Neumann, and Henkel conditions.

This article is a comprehensive collection of formulas, tables, and analytical solutions, addressing hundreds of heat-transfer scenarios encountered in science and engineering. It also demonstrates how to set up and solve real-world problems, while accounting for material properties, environmental variables, boundary and state conditions, and the primary modes of heat transfer: conduction, convection, and radiation.

This article is a comprehensive collection of formulas, tables, and analytical solutions, addressing hundreds of heat-transfer scenarios encountered in science and engineering. With detailed explanations and dimensioned drawings, the article demonstrates how to set up and solve real-world problems, accounting for material properties, environmental variables, boundary and state conditions, and the primary modes of heat transfer: conduction, convection, and radiation. The article also includes reference data and provides closed-form solutions for common heat-transfer applications such as insulated pipes, cooling fins, radiation shields, and composite structures and configurations.

Process optimization is the discipline of adjusting a process to optimize a specified set of parameters without violating engineering constraints. This article reviews data-driven optimization methods based on genetic algorithms and stochastic models and demonstrates their use in powder-bed fusion and directed energy deposition processes. In the latter case, closed-loop feedback is used to control melt pool temperature and cooling rate in order to achieve desired microstructure.

Modeling will help reduce machining problems and thereby enable more rapid introduction of high-performance materials and components. This article discusses the technical needs of aircraft engine and airframe structural components and modeling of heat-treat-induced residual stress by finite-element residual-stress analysis. It describes the two-dimensional (2-D) and three-dimensional (3-D) procedures involved in finite-element residual-stress analysis. The article deals with the 2-D and 3-D machining distortion validation on engine-disk-type components. It describes methods for obtaining machining-induced residual stresses, including detailed finite-element analysis of the cutting process, the simple fast-acting mechanistic model, and the semi-empirical linear stress model. The article concludes with information on the modeling benefits and implementation of modeling in a production environment.