【導(dǎo)讀】TheoryReference. 第1頁共79頁。TheoryReference. 第2頁共79頁。TableofContents. .Convection. .Radiation. .SpecialEffects. .Far-FieldElements. .Coupled-FieldAnalyses. .BuildingtheModel. .ApplyingLoads. .GeneralOptions. .NonlinearOptions. .OutputControls. .SavingtheModel. .SolvingtheModel. .Primarydata. .Deriveddata. .ReadingInResults. .ReviewingResults. .BuildingtheModel. TheoryReference. 第3頁共79頁。.NonlinearOptions. .OutputControls. .SavingtheModel. .SolvingtheModel. .PhaseChange. 4.Radiation. .Definitions. .Procedure. .Procedure. Symmetry(CommandMethod). TheoryReference. 第4頁共79頁

　　

【正文】 y, depending on the size and shape of the structure you wish to model. Therefore, the next few paragraphs provide only a generic overview of the tasks typically required to build model geometry. For more detailed information about modeling and meshing procedures and techniques, see the Modeling and Meshing Guide. The first step in creating geometry is to build a solid model of the item you are analyzing. You can use either predefined geometric shapes such as circles and rectangles (known within ANSYS as primitives), or you can manually define nodes and elements for your model. The 2D primitives are called areas, and 3D primitives are called volumes. Model dimensions are based on a global coordinate system. By default, the global coordinate system is Cartesian, with X, Y, and Z axes。 however, you can choose a different coordinate system if you wish. Modeling also uses a working plane a movable reference plane used to locate and orient modeling entities. You can turn on the working plane grid to serve as a drawing tablet for your model. You can tie together, or sculpt, the modeling entities you create via Boolean operations, For example, you can add two areas together to create a new, single area that includes all parts of the original areas. Similarly, you can overlay an area with a second area, then subtract the second area from the first。 doing so creates a new, single area with the overlapping portion of area 2 removed from area 1. Once you finish building your solid model, you use meshing to fill the model with nodes and elements. For more information about meshing, see the Modeling and Meshing Guide. . Applying Loads and Obtaining the Solution You must define the analysis type and options, apply loads to the model, specify load step options, and initiate the finite element solution. Theory Reference 第 13 頁 共 79 頁 . Defining the Analysis Type During this phase of the analysis, you must first define the analysis type: ? In the GUI, choose menu path Main Menu Solution Analysis Type New Analysis Steadystate (static). ? If this is a new analysis, issue the mand ANTYPE,STATIC,NEW. ? If you want to restart a previous analysis (for example, to specify additional loads), issue the mand ANTYPE,STATIC,REST. You can restart an analysis only if the files and from the previous run are available. If your prior run was solved with VT Accelerator (STAOPT,VT), you will also need the file. You can also do a multiframe restart. . Applying Loads You can apply loads either on the solid model (keypoints, lines, and areas) or on the finite element model (nodes and elements). You can specify loads using the conventional method of applying a single load individually to the appropriate entity, or you can apply plex boundary conditions as tabular boundary conditions (see Applying Loads Using TABLE Type Array Parameters in the Basic Analysis Guide) or as function boundary conditions (see Using the Function Tool). You can specify five types of thermal loads: . Constant Temperatures (TEMP) These are DOF constraints usually specified at model boundaries to impose a known, fixed temperature. For SHELL131 and SHELL132 elements with KEYOPT(3) = 0 or 1, use the labels TBOT, TE2, TE3, . . ., TTOP instead of TEMP when defining DOF constraints. . Heat Flow Rate (HEAT) These are concentrated nodal loads. Use them mainly in lineelement models (conducting bars, convection links, etc.) where you cannot specify convections and heat fluxes. A positive value of heat flow rate indicates heat flowing into the node (that is, the element gains heat). If both TEMP and HEAT are specified at a node, the temperature constraint prevails. For SHELL131 and SHELL132 elements with KEYOPT(3) = 0 or 1, use the labels HBOT, HE2, HE3, . . ., HTOP instead of HEAT when defining nodal loads. Note: If you use nodal heat flow rate for solid elements, you should refine the mesh around the point where you apply the heat flow rate as a load, especially if the elements containing the node where the load is applied have widely different thermal conductivities. Otherwise, you may get an nonphysical range of temperature. Whenever possible, use the alternative option of using the heat generation rate load or the heat flux rate load. These options are more accurate, even for a reasonably coarse mesh. . Convections (CONV) Convections are surface loads applied on exterior surfaces of the model to account for heat lost to (or gained from) a surrounding fluid medium. They are available only for solids and shells. In line element models, you can specify convections through the convection link element (LINK34). You can use the surface effect elements (SURF151, SURF152) to analyze heat transfer for convection/radiation effects. The surface effect elements allow you to generate film coefficient calculations and bulk temperatures from FLUID116 elements and to model radiation to a point. You can also transfer external loads (such as from CFX) to ANSYS using these elements. Theory Reference 第 14 頁 共 79 頁 . Heat Fluxes (HFLUX) Heat fluxes are also surface loads. Use them when the amount of heat transfer across a surface (heat flow rate per area) is known, or is calculated through a FLOTRAN CFD analysis. A positive value of heat flux indicates heat flowing into the element. Heat flux is used only with solids and shells. An element face may have either CONV or HFLUX (but not both) specified as a surface load. If you specify both on the same element face, ANSYS uses what was specified last. . Heat Generation Rates (HGEN) You apply heat generation rates as body loads to represent heat generated within an element, for example by a chemical reaction or an electric current. Heat generation rates have units of heat flow rate per unit volume. Table : Thermal Analysis Load Types below summarizes th