ANSYS13.0理论参考手册.doc

Theory ReferenceRelease 13.0 - 2010 SAS IP, Inc. All rights reserved.Table of Contents1. Analyzing Thermal Phenomena1.1. How ANSYS Treats Thermal Modeling1.1.1. Convection1.1.2. Radiation1.1.3. Special Effects1.1.4. Far-Field Elements1.2. Types of Thermal Analysis1.3. Coupled-Field Analyses1.4. About GUI Paths and Command Syntax2. Steady-State Thermal Analysis2.1. Available Elements for Thermal Analysis2.2. Commands Used in Thermal Analyses2.3. Tasks in a Thermal Analysis2.4. Building the Model2.4.1. Using the Surface Effect Elements2.4.2. Creating Model Geometry2.5. Applying Loads and Obtaining the Solution2.5.1. Defining the Analysis Type2.5.2. Applying Loads2.5.3. Using Table and Function Boundary Conditions2.5.4. Specifying Load Step Options2.5.5. General Options2.5.6. Nonlinear Options2.5.7. Output Controls2.5.8. Defining Analysis Options2.5.9. Saving the Model2.5.10. Solving the Model2.6. Reviewing Analysis Results2.6.1. Primary data2.6.2. Derived data2.6.3. Reading In Results2.6.4. Reviewing Results2.7. Example of a Steady-State Thermal Analysis (Command or Batch Method)2.7.1. The Example Described2.7.2. The Analysis Approach2.7.3. Commands for Building and Solving the Model2.8. Performing a Steady-State Thermal Analysis (GUI Method)2.9. Performing a Thermal Analysis Using Tabular Boundary Conditions2.9.1. Running the Sample Problem via Commands2.9.2. Running the Sample Problem Interactively2.10. Where to Find Other Examples of Thermal Analysis3. Transient Thermal Analysis3.1. Elements and Commands Used in Transient Thermal Analysis3.2. Tasks in a Transient Thermal Analysis3.3. Building the Model3.4. Applying Loads and Obtaining a Solution3.4.1. Defining the Analysis Type3.4.2. Establishing Initial Conditions for Your Analysis3.4.3. Specifying Load Step Options3.4.4. Nonlinear Options3.4.5. Output Controls3.5. Saving the Model3.5.1. Solving the Model3.6. Reviewing Analysis Results3.6.1. How to Review Results3.6.2. Reviewing Results with the General Postprocessor3.6.3. Reviewing Results with the Time History Postprocessor3.7. Reviewing Results as Graphics or Tables3.7.1. Reviewing Contour Displays3.7.2. Reviewing Vector Displays3.7.3. Reviewing Table Listings3.8. Phase Change3.9. Example of a Transient Thermal Analysis3.9.1. The Example Described3.9.2. Example Material Property Values3.9.3. Example of a Transient Thermal Analysis (GUI Method)3.9.4. Commands for Building and Solving the Model3.10. Where to Find Other Examples of Transient Thermal Analysis4. Radiation4.1. Analyzing Radiation Problems4.2. Definitions4.3. Using LINK31, the Radiation Link Element4.4. Modeling Radiation Between a Surface and a Point4.5. Using the AUX12 Radiation Matrix Method4.5.1. Procedure4.5.2. Recommendations for Using Space Nodes4.5.3. General Guidelines for the AUX12 Radiation Matrix Method4.6. Using the Radiosity Solver Method4.6.1. Procedure4.6.2. Further Options for Static Analysis4.7. Advanced Radiosity Options4.8. Example of a 2-D Radiation Analysis Using the Radiosity Method (Command Method)4.8.1. The Example Described4.8.2. Commands for Building and Solving the Model4.9. Example of a 2-D Radiation Analysis Using the Radiosity Method with Decimation and Symmetry (Command Method)4.9.1. The Example Described4.9.2. Commands for Building and Solving the ModelRelease 13.0 - 2010 SAS IP, Inc. All rights reserved.Chapter1:Analyzing Thermal PhenomenaA thermal analysis calculates the temperature distribution and related thermal quantities in a system or component. Typical thermal quantities of interest are: The temperature distributions The amount of heat lost or gained Thermal gradients Thermal fluxes.Thermal simulations play an important role in the design of many engineering applications, including internal combustion engines, turbines, heat exchangers, piping systems, and electronic components. In many cases, engineers follow a thermal analysis with a stress analysis to calculate thermal stresses (that is, stresses caused by thermal expansions or contractions).The following thermal analysis topics are available: How ANSYS Treats Thermal Modeling Types of Thermal Analysis Coupled-Field Analyses About GUI Paths and Command Syntax1.1.How ANSYS Treats Thermal ModelingOnly the ANSYS Multiphysics, ANSYS Mechanical, ANSYS Professional, and ANSYS FLOTRAN programs support thermal analyses.The basis for thermal analysis in ANSYS is a heat balance equation obtained from the principle of conservation of energy. (For details, consult the Theory Reference for the Mechanical APDL and Mechanical Applications.) The finite element solution you perform via ANSYS calculates nodal temperatures, then uses the nodal temperatures to obtain other thermal quantities.The ANSYS program handles all three primary modes of heat transfer: conduction, convection, and radiation.1.1.1.ConvectionYou specify convection as a surface load on conducting solid elements or shell elements. You specify the convection film coefficient and the bulk fluid temperature at a surface; ANSYS then calculates the appropriate heat transfer across that surface. If the film coefficient depends upon temperature, you specify a table of temperatures along with the corresponding values of film coefficient at each temperature.For use in finite element models with conducting bar elements (which do not allow a convection surface load), or in cases where the bulk fluid temperature is not known in advance, ANSYS offers a convection element named LINK34. In addition, you can use the FLOTRAN CFD elements to simulate details of the convection process, such as fluid velocities, local values of film coefficient and heat flux, and temperature distributions in both fluid and solid regions.1.1.2.RadiationANSYS can solve radiation problems, which are nonlinear, in four ways: By using the radiation link element, LINK31 By using surface effect elements with the radiation option (SURF151 in 2-D modeling or SURF152 in 3-D modeling) By generating a radiation matrix in AUX12 and using it as a superelement in a thermal analysis. By using the Radiosity Solver method.For detailed information on these methods, see Radiation.1.1.3.Special EffectsIn addition to the three modes of heat transfer, you can account for special effects such as change of phase (melting or freezing) and internal heat generation (due to Joule heating, for example). For instance, you can use the thermal mass element MASS71 to specify temperature-dependent heat generation rates.1.1.4.Far-Field ElementsFar-field elements allow you to model the effects of far-field decay without having to specify assumed boundary conditions at the exterior of the model. A single layer of elements is used to represent an exterior sub-domain of semi-infinite extent. For more information, see Far-Field Elements in the Low-Frequency Electromagnetic Analysis Guide.1.2.Types of Thermal AnalysisANSYS supports two types of thermal analysis: 1. A steady-state thermal analysis determines the temperature distribution and other thermal quantities under steady-state loading conditions. A steady-state loading condition is a situation where heat storage effects varying over a period of time can be ignored.2. A transient thermal analysis determines the temperature distribution and other thermal quantities under conditions that vary over a period of time.1.3.Coupled-Field AnalysesSome types of coupled-field analyses, such as thermal-structural and magnetic-thermal analyses, can represent thermal effects coupled with other phenomena. A coupled-field analysis can use matrix-coupled ANSYS elements, or sequential load-vector coupling between separate simulations of each phenomenon. For more information on coupled-field analysis, see the Coupled-Field Analysis Guide.1.4.About GUI Paths and Command SyntaxThroughout this document, you will see references to ANSYS commands and their equivalent GUI paths. Such references use only the command name, because you do not always need to specify all of a commands arguments, and specific combinations of command arguments perform different functions. For complete syntax descriptions of ANSYS commands, consult the Command Reference.The GUI paths shown are as complete as possible. In many cases, choosing the GUI path as shown will perform the function you want. In other cases, choosing the GUI path given in this document takes you to a menu or dialog box; from there, you must choose additional options that are appropriate for the specific task being performed.For all types of analyses described in this guide, specify the material you will be simulating using an intuitive material model interface. This interface uses a hierarchical tree structure of material categories, which is intended to assist you in choosing the appropriate model for your analysis. See Material Model Interface in the Basic Analysis Guide for details on the material model interface.Release 13.0 - 2010 SAS IP, Inc. All rights reserved.Chapter2:Steady-State Thermal AnalysisThe ANSYS Multiphysics, ANSYS Mechanical, ANSYS FLOTRAN, and ANSYS Professional products support steady-state thermal analysis. A steady-state thermal analysis calculates the effects of steady thermal loads on a system or component. Engineer/analysts often perform a steady-state analysis before performing a transient thermal analysis, to help establish initial conditions. A steady-state analysis also can be the last step of a transient thermal analysis, performed after all transient effects have diminished.You can use steady-state thermal analysis to determine temperatures, thermal gradients, heat flow rates, and heat fluxes in an object that are caused by thermal loads that do not vary over time. Such loads include the following: Convections Radiation Heat flow rates Heat fluxes (heat flow per unit area) Heat generation rates (heat flow per unit volume) Constant temperature boundariesA steady-state thermal analysis may be either linear, with constant material properties; or nonlinear, with material properties that depend on temperature. The thermal properties of most material do vary with temperature, so the analysis usually is nonlinear. Including radiation effects also makes the analysis nonlinear.The following steady-state thermal analysis topics are available: Available Elements for Thermal Analysis Commands Used in Thermal Analyses Tasks in a Thermal Analysis Building the Model Applying Loads and Obtaining the Solution Reviewing Analysis Results Example of a Steady-State Thermal Analysis (Command or Batch Method) Performing a Steady-State Thermal Analysis (GUI Method) Performing a Thermal Analysis Using Tabular Boundary Conditions Where to Find Other Examples of Thermal Analysis2.1.Available Elements for Thermal AnalysisThe ANSYS and ANSYS Professional programs include about 40 elements (described below) to help you perform steady-state thermal analyses.For detailed information about the elements, see the Element Reference, which manual organizes element descriptions in numeric order.Element names are shown in uppercase. All elements apply to both steady-state and transient thermal analyses. SOLID70 also can compensate for mass transport heat flow from a constant velocity field.Table2.12-D Solid ElementsElementDimens.Shape or CharacteristicDOFsPLANE352-DTriangle, 6-nodeTemperature (at each node)PLANE552-DQuadrilateral, 4-nodeTemperature (at each node)PLANE752-DHarmonic, 4-nodeTemperature (at each node)PLANE772-DQuadrilateral, 8-nodeTemperature (at each node)PLANE782-DHarmonic, 8-nodeTemperature (at each node)Table2.23-D Solid ElementsElementDimens.Shape or CharacteristicDOFsSOLID703-DBrick, 8-nodeTemperature (at each node)SOLID873-DTetrahedron, 10-nodeTemperature (at each node)SOLID903-DBrick, 20-nodeTemperature (at each node)SOLID2783-DBrick, 8-nodeTemperature (at each node)SOLID2793-DBrick, 20-nodeTemperature (at each node)Table2.3Radiation Link ElementsElementDimens.Shape or CharacteristicDOFsLINK312-D or 3-DLine, 2-nodeTemperature (at each node)Table2.4Conducting Bar ElementsElementDimens.Shape or CharacteristicDOFsLINK333-DLine, 2-nodeTemperature (at each node)Table2.5Convection Link ElementsElementDimens.Shape or CharacteristicDOFsLINK343-DLine, 2-nodeTemperature (at each node)Table2.6Shell ElementsElementDimens.Shape or CharacteristicDOFsSHELL1313-DQuadrilateral, 4-nodeMultiple temperatures (at each node)SHELL1323-DQuadrilateral, 8-nodeMultiple temperatures (at each node)Table2.7Coupled-Field ElementsElementDimens.Shape or CharacteristicDOFsPLANE132-DThermal-structural, 4-nodeTemperature, structural displacement, electric potential, magnetic vector potentialFLUID1163-DThermal-fluid, 2-node or 4-nodeTemperature, pressureSOLID53-DThermal-structural and thermal-electric, 8-nodeTemperature, structural displacement, electric potential, and magnetic scalar potentialSOLID983-DThermal-structural and thermal-electric, 10-nodeTemperature, structural displacement, electric potential, magnetic vector potentialLINK683-DThermal-electric, 2-nodeTemperature, electric potentialSHELL1573-DThermal-electric, 4-nodeTemperature, electric potentialTARGE1692-DTarget segment elementTemperature, structural displacement, electric potentialTARGE1703-DTarget segment elementTemperature, structural displacement, electric potentialCONTA1712-DSurface-to-surface contact element, 2-nodeTemperature, structural displacement, electric potentialCONTA1722-DSurface-to-surface contact element, 3-nodeTemperature, structural displacement, electric potentialCONTA1733-DSurface-to-surface contact element, 4-nodeTemperature, structural displacement, electric potentialCONTA1743-DSurface-to-surface contact element, 8-nodeTemperature, structural displacement, electric potentialCONTA1752-D/3-DNode-to-surface contact element, 1 nodeTemperature, structural displacement, electric potentialPLANE2232-DThermal-structural, thermal-electric, structural-thermoelectric, and thermal-piezoelectric, 8-nodeTemperature, structural displacement, electric potentialSOLID2263-DThermal-structural, thermal-electric, structural-thermoelectric, and thermal-piezoelectric, 20-nodeTemperature, structural displacement, electric potentialSOLID2273-DThermal-structural, thermal-electric, structural-thermoelectric, and thermal-piezoelectric, 10-nodeTemperature, structural displacement, electric potentialTable2.8Specialty ElementsElementDimens.Shape or CharacteristicDOFsMASS711-D, 2-D, or 3-DMass, one-nodeTemperatureCOMBIN371-DControl element, 4-nodeTemperature, structural displacement, rotation, pressureSURF1512-DSurface effect element, 2-node to 4-nodeTemperatureSURF1523-DSurface effect element, 4-node to 9-nodeTemperatureMATRIX501Matrix or radiation matrix element, no fixed geometry1INFIN9 2 2-DInfinite boundary, 2-nodeTemperature, magnetic vector potentialINFIN47 2 3-DInfinite boundary, 4-nodeTemperature, magnetic vector potentialINFIN110 2 2-DInfinite boundary, 4 or 8 nodesTemperature, magnetic vector potential, electric potentialINFIN111 2 3-DInfinite boundary, 8 or 20 nodesTemperature, magnetic scalar potential, magnetic vector potential, electric potentialCOMBIN141-D, 2-D, or 3-DCombination element, 2-nodeTemperature, structural displacement, rotation, pressureCOMBIN391-DCombination element, 2-nodeTemperature, structural displacement, rotation, pressureCOMBIN401-DCombination element, 2-nodeTemperature, structural displacement, rotation, pressure1. As determined from the element types included in this superelement.2. For information on modeling the effects of far-field decay, see Far-Field Elements in the Low-Frequency Electromagnetic Analysis Guide.2.2.Commands Used in Thermal AnalysesExample of a Steady-State Thermal Analysis (Command or Batch Method) and Performing a Steady-State Thermal Analysis (GUI Method) show you how to perform an example steady-state thermal analysis via command and via GUI, respectively. For detailed, alphabetized descriptions of the ANSYS commands, see the Command Reference.2.3.Tasks in a Thermal AnalysisThe procedure for performing a thermal analysis involves three main tasks: Build the model. Apply loads and obtain the solution. Review the results.The next few topics discuss what you must do to perform these steps. First, the text presents a general description of the tasks required to complete each step. An example follows, based on an actual steady-state thermal analysis of a pipe junction. The example walks you through doing the analysis by choosing items from ANSYS GUI menus, then shows you how to perform the same analysis using ANSYS commands.2.4.Building the ModelTo build the model, you specify the jobname and a title for your analysis. Then, you use the ANSYS preprocessor (PREP7) to define the element types, element real constants, material properties, and the model geometry. (These tasks are common to most analyses. The Modeling and Meshing Guide explains them in detail.)For a thermal analysis, you also need to keep these points in mind: To specify element types, you use either of the following: Command(s): ETGUI: MainMenu Preprocessor Element Type Add/Edit/Delete To define constant mater