当前位置:首页 >> 工学 >>

Basic User Guide for ANSYS


ANSYS User Guide

Chapter 1. Getting Started with ANSYS 1.1. Performing a Typical ANSYS Analysis
The ANSYS program has many finite element analysis capabilities, ranging from a simple, linear, static analysis to a complex, nonlinear, transient dynamic analysis. The analysis guide manuals in the ANSYS documentation set describe specific procedures for performing analyses for different engineering disciplines. The next few sections of this chapter cover general steps that are common to most analyses. A typical ANSYS analysis has three distinct steps: 1. Build the model. 2. Apply loads and obtain the solution. 3. Review the results.

1.2. Building a Model
Building a finite element model requires more of your time than any other part of the analysis. First, you specify a jobname and analysis title. Then, you use the PREP7 preprocessor to define the element types, element real constants, material properties, and the model geometry.

1.2.1. Specifying a Jobname and Analysis Title
This task is not required for an analysis, but is recommended. 1.2.1.1. Defining the Jobname The jobname is a name that identifies the ANSYS job. When you define a jobname for an analysis, the jobname becomes the first part of the name of all files the analysis creates. (The extension or suffix for these files' names is a file identifier such as .DB.) By using a jobname for each analysis, you ensure that no files are overwritten.

If you do not specify a jobname, all files receive the name FILE or file, depending on the operating system. You can change the default jobname as follows:
? ?

By using the initial jobname entry option when you enter the ANSYS program, either via the launcher or on the ANSYS execution command. From within the ANSYS program, you can use either of the following: Command(s): /FILNAME GUI: Utility Menu> File> Change Jobname

The /FILNAME command is valid only at the Begin level. It lets you change the jobname even if you specified an initial jobname at ANSYS entry. The jobname applies only to files you open after using /FILNAME and not to files that were already open. If you want to start new files (such as the log file, Jobname.LOG, and error file Jobname.ERR) when you issue /FILNAME, set the Key argument on /FILNAME to 1. Otherwise, those files that were already open will still have the initial jobname. 1.2.1.2. Defining an Analysis Title The /TITLE command (Utility Menu> File> Change Title), defines a title for the analysis. ANSYS includes the title on all graphics displays and on the solution output. You can issue the /STITLE command to add subtitles; these will appear in the output, but not in graphics displays. 1.2.1.3. Defining Units The ANSYS program does not assume a system of units for your analysis. Except in magnetic field analyses, you can use any system of units so long as you make sure that you use that system for all the data you enter. (Units must be consistent for all input data.) For micro-electromechanical systems (MEMS), where dimensions are on the order of microns, see the conversion factors in System of Units in the ANSYS Coupled-Field Analysis Guide. Using the /UNITS command, you can set a marker in the ANSYS database indicating the system of units that you are using. This command does not convert data from one system of units to another; it simply serves as a record for subsequent reviews of the analysis.

1.2.2. Defining Element Types

The ANSYS element library contains more than 150 different element types. Each element type has a unique number and a prefix that identifies the element category: BEAM4, PLANE77, SOLID96, etc. The following element categories are available: BEAM CIRCUit COMBINation CONTACt FLUID HF (High Frequency) HYPERelastic INFINite INTERface LINK MASS MATRIX MESH Multi-Point Constraint PIPE PLANE PRETS (Pretension) SHELL SOLID SOURCe SURFace TARGEt TRANSducer USER VISCOelastic (or viscoplastic) The element type determines, among other things:
?

?

The degree-of-freedom set (which in turn implies the discipline structural, thermal, magnetic, electric, quadrilateral, brick, etc.) Whether the element lies in 2-D or 3-D space.

BEAM4, for example, has six structural degrees of freedom (UX, UY, UZ, ROTX, ROTY, ROTZ), is a line element, and can be modeled in 3-D space. PLANE77 has a thermal degree of freedom (TEMP), is an 8-node quadrilateral element, and can be modeled only in 2-D space. You must be in PREP7, the general preprocessor, to define element types. To do so, you use the ET family of commands (ET, ETCHG, etc.) or their GUI path equivalents; see the ANSYS Commands Reference for details. You define the element type by name and give the element a type reference number. For example, the commands shown below define two element types, BEAM4 and SHELL63, and assign them type reference numbers 1 and 2 respectively. ET,1,BEAM4 ET,2,SHELL63

This table of type reference number versus element name is called the element type table. While defining the actual elements, you point to the appropriate type reference number using the TYPE command (Main Menu> Preprocessor> Modeling> Create> Elements> Elem Attributes). Many element types have additional options, known as KEYOPTs, and are referred to as KEYOPT(1), KEYOPT(2), etc. For example, KEYOPT(9) for BEAM4 allows you to choose results to be calculated at intermediate locations on each element, and KEYOPT(3) for SHELL63 allows you to suppress extra displacement shapes. You can specify KEYOPTs using the ET command or the KEYOPT command (Main Menu> Preprocessor> Element Type> Add/Edit/Delete).

1.2.3. Defining Element Real Constants
Element real constants are properties that depend on the element type, such as cross-sectional properties of a beam element. For example, real constants for BEAM3, the 2-D beam element, are area (AREA), moment of inertia (IZZ), height (HEIGHT), shear deflection constant (SHEARZ), initial strain (ISTRN), and added mass per unit length (ADDMAS). Not all element types require real constants, and different elements of the same type may have different real constant values. You can specify real constants using the R family of commands (R, RMODIF, etc.) or their equivalent menu paths; see the ANSYS Commands Reference for further information. As with element types, each set of real constants has a reference number, and the table of reference number versus real constant set is called the real constant table. While defining the elements, you point to the appropriate real constant reference number using the REAL command (Main Menu> Preprocessor> Modeling> Create> Elements> Elem Attributes). While defining real constants, keep these rules and guidelines in mind:
?

?

?

When using one of the R commands, you must enter real constants in the order shown in Table 4.n.1 for each element type in the ANSYS Elements Reference. For models using multiple element types, use a separate real constant set (that is, a different REAL reference number) for each element type. The ANSYS program issues a warning message if multiple element types reference the same real constant set. However, a single element type may reference several real constant sets. To verify your real constant input, use the RLIST and ELIST commands, with RKEY = 1 (shown below). RLIST lists real constant values for all sets. The command ELIST,,,,,1 produces an easier-to-read list

that shows, for each element, the real constant labels and their values. Command(s): ELIST GUI: Utility Utility Utility Utility Menu> List> Elements> Attributes + RealConst Menu> List> Elements> Attributes Only Menu> List> Elements> Nodes + Attributes Menu> List> Elements> Nodes + Attr + RealConst

Command(s): RLIST GUI:
?

Utility Menu> List> Properties> All Real Constants Utility Menu> List> Properties> Specified Real Const

For line and area elements that require geometry data (cross-sectional area, thickness, diameter, etc.) to be specified as real constants, you can verify the input graphically by using the following commands in the order shown: Command(s): GUI: /ESHAPE and EPLOT Utility Menu> PlotCtrls> Style> Size and Shape Utility Menu> Plot> Elements

ANSYS displays the elements as solid elements, using a rectangular cross-section for link and shell elements and a circular cross-section for pipe elements. The cross-section proportions are determined from the real constant values. 1.2.3.1. Creating Cross Sections If you are building a model using BEAM44, BEAM188, or BEAM189, you can use the section commands (SECTYPE, SECDATA, etc.) or their GUI path equivalents to define and use cross sections in your models. See Chapter 15: "Beam Analysis and Cross Sections" in the ANSYS Structural Analysis Guide for information on how to use the BeamTool to create cross sections.

1.2.4. Defining Material Properties
Most element types require material properties. Depending on the application, material properties can be linear (see Linear Material Properties) or nonlinear (see Nonlinear Material Properties). As with element types and real constants, each set of material properties has a material reference number. The table of material reference numbers

versus material property sets is called the material table. Within one analysis, you may have multiple material property sets (to correspond with multiple materials used in the model). ANSYS identifies each set with a unique reference number. While defining the elements, you point to the appropriate material reference number using the MAT command. 1.2.4.1. Linear Material Properties Linear material properties can be constant or temperature-dependent, and isotropic or orthotropic. To define constant material properties (either isotropic or orthotropic), use one of the following: Command(s): MP GUI: Main Menu> Preprocessor> Material Props> Material Models

(See Material Model Interface for details on the GUI.) You also must specify the appropriate property label; for example EX, EY, EZ for Young's modulus, KXX, KYY, KZZ for thermal conductivity, and so forth. For isotropic material you need to define only the X-direction property; the other directions default to the X-direction value. For example: MP,EX,1,2E11 MP,DENS,1,7800 MP,KXX,1,43 ! Young's modulus for material ref. no. 1 is 2E11 ! Density for material ref. no. 1 is 7800 ! Thermal conductivity for material ref. no 1 is 43

Besides the defaults for Y- and Z-direction properties (which default to the X-direction properties), other material property defaults are built in to reduce the amount of input. For example, Poisson's ratio (NUXY) defaults to 0.3, shear modulus (GXY) defaults to EX/2(1+NUXY)), and emissivity (EMIS) defaults to 1.0. See the ANSYS Elements Reference for details. You can choose constant, isotropic, linear material properties from a material library available through the GUI. Young's modulus, density, coefficient of thermal expansion, Poisson's ratio, thermal conductivity and specific heat are available for 10 materials in four unit systems.

Caution

The property values in the material library are provided for your convenience. They are typical values for the materials you can use for preliminary analyses and noncritical applications. As always, you are responsible for all data input to the ANSYS program. To define temperature-dependent material properties, you can use the MP command in combination with the MPTEMP or MPTGEN command. You also can use the MPTEMP and MPDATA commands. The MP command allows you to define a property-versus-temperature function in the form of a polynomial. The polynomial may be linear, quadratic, cubic, or quartic: Property = C0 + C1T + C2T2 + C3T3 + C4T4

Cn are the coefficients and T is the temperature. You enter the coefficients using the C0, C1, C2, C3, and C4 arguments on the MP command. If you specify just C0, the material property is constant; if you specify C0 and C1, the material property varies linearly with temperature; and
so on. When you specify a temperature-dependent property in this manner, the program internally evaluates the polynomial at discrete temperature points with linear interpolation between points (that is, piecewise linear representation) and a constant-valued extrapolation beyond the extreme points. You must use the MPTEMP or MPTGEN command before the MP command for second and higher-order properties to define appropriate temperature steps. The second way to define temperature-dependent material properties is to use a combination of MPTEMP and MPDATA commands. MPTEMP (or MPTGEN) defines a series of temperatures, and MPDATA defines corresponding material property values. For example, the following commands define a temperature-dependent enthalpy for material 4: MPTEMP,1,1600,1800,2000,2325,2326,2335 ! 6 temperatures (temps 1-6) MPTEMP,7,2345,2355,2365,2374,2375,3000 ! 6 more temps (temps 7-12) MPDATA,ENTH,4,1,53.81,61.23,68.83,81.51,81.55,82.31 ! Corresponding MPDATA,ENTH,4,7,84.48,89.53,99.05,112.12,113.00,137.40 ! enthalpy values If an unequal number of property data points and temperature data points are defined, the ANSYS program uses only those locations having both points defined for the property function table. To define a different set of temperatures for the next material property, you should first erase the current temperature table by issuing MPTEMP (without any arguments)

and then define new temperatures (using additional MPTEMP or MPTGEN commands). The MPPLOT command displays a graph of material property versus temperature. Figure 1.1: "Sample MPPLOT Display" shows a plot of the enthalpy-temperature curve defined in the example above. The MPLIST command lists material properties. Figure 1.1 Sample MPPLOT Display

Following are some notes about temperature-dependent material properties:
?

?

?

To modify a property data point on an existing curve, simply redefine the desired data point by issuing MPDATA with the appropriate location number. For example, to change the ENTH value in location 6 of the above enthalpy-temperature curve from 82.31 to 83.09, the command would be MPDATA,ENTH,4,6,83.09 To modify a temperature data point on an existing curve, you need two commands: MPTEMP with the appropriate location number to specify the new temperature value, and MPDRES to associate the new temperature table with the material property. For example, to change the temperature in location 7 of the above enthalpy-temperature curve from 2345 to 2340, the commands would be: MPTEMP,7,2340 ! Modifies location 7, retains other locations MPDRES,ENTH,4 ! Associates ENTH for material 4 with new temps

You need to use the MPDRES command to modify stored properties. Whenever you define a temperature-dependent property, the temperature-property data pairs are immediately stored in the database. Modifying the temperature data points affects only material properties that are subsequently defined, not what is already stored. The MPDRES command forces modification of what is already stored in the database. Two additional fields on MPDRES allow you to modify a stored property and store it under a new label or a new material reference number. The MPTRES command allows you to replace the current temperature table with that of a previously defined material property in the database. You can then use the previous temperature data points for another property.

For temperature-dependent secant coefficients of thermal expansion (ALPX, ALPY, ALPZ), if the base temperature for which they are defined (the definition temperature) differs from the reference temperature (the temperature at which zero thermal strains exist, defined by MP,REFT or TREF), then use the MPAMOD command to convert the data to the reference temperature. This conversion is not necessary when you input the thermal strains (THSX, THSY, THSZ) or the instantaneous coefficients of thermal expansion (CTEX, CTEY, CTEZ). ANSYS accounts for temperature-dependent material properties during solution when element matrices are formulated. The materials are evaluated at once (at or near the centroid of the element) or at each of the integration points. For more information about how ANSYS evaluates temperature-dependent material properties, see Linear Material Properties. You can save linear material properties (whether they are temperature-dependent or constant) to a file or restore them from a text file. (See Using Material Library Files for a discussion of material library files.) You also can use CDWRITE,MAT to write both linear and nonlinear material properties to a file.

Note
If you are using the CDWRITE command in any of the ANSYS-derived products (ANSYS Emag, ANSYS Professional, etc.), you must edit the Jobname.CDB file that CDWRITE creates to remove commands which are not available in the derived product. You must do this before reading the Jobname.CDB file. 1.2.4.2. Nonlinear Material Properties Nonlinear material properties are usually tabular data, such as plasticity data (stress-strain curves for different hardening laws), magnetic field data (B-H curves), creep data, swelling data, hyperelastic material data, etc. The first step in defining a nonlinear material property is to activate a data table using the TB command (see Material Model Interface for the GUI equivalent). For example, TB,BH,2 activates the B-H table for material reference number 2. To enter the tabular data, use the TBPT command. For example, the following commands define a B-H curve: TBPT,DEFI,150,.21 TBPT,DEFI,300,.55

TBPT,DEFI,460,.80 TBPT,DEFI,640,.95 TBPT,DEFI,720,1.0 TBPT,DEFI,890,1.1 TBPT,DEFI,1020,1.15 TBPT,DEFI,1280,1.25 TBPT,DEFI,1900,1.4 You can verify the data table through displays and listings using the TBPLOT or TBLIST commands. Figure 1.2: "Sample TBPLOT Display" shows a sample TBPLOT (of the B-H curve defined above): Figure 1.2 Sample TBPLOT Display

1.2.4.3. Anisotropic Elastic Material Properties Some element types accept anisotropic elastic material properties, which are usually input in the form of a matrix. (These properties are different from anisotropic plasticity, which requires different stress-strain curves in different directions.) Among the element types that allow elastic anisotropy are SOLID64 (the 3-D anisotropic solid), PLANE13 (the 2-D coupled-field solid), SOLID5 and SOLID98 (the 3-D coupled-field solids). The procedure to specify anisotropic elastic material properties resembles that for nonlinear properties. You first activate a data table using the TB command (with Lab = ANEL) and then define the terms of the elastic coefficient matrix using the TBDATA command. Be sure to verify your input with the TBLIST command. See Data Tables - Implicit Analysis in the ANSYS Elements Reference manual and the appropriate element descriptions for more information. 1.2.4.4. Material Model Interface ANSYS includes an intuitive hierarchical tree structure interface for defining material models. A logical top-down arrangement of material categories guides you in defining the appropriate model for your analysis. You use this material model interface in all ANSYS analyses except for CFD analyses that require the use of any of the FLDATA family of commands.

1.2.4.4.1. Accessing the Interface

You access the material model interface from Main Menu> Preprocessor> Material Props> Material Models. The Define Material Model Behavior dialog box appears, which originally displays the top level of the tree structure, as shown in Figure 1.3: "Material Model Interface Initial Screen". Figure 1.3 Material Model Interface Initial Screen

1.2.4.4.2. Choosing Material Behavior

The Material Models Available window on the right displays a list of material categories (for example, Favorites, Structural, Thermal, CFD, Electromagnetics).

Note
If you choose an ANSYS LS-DYNA element type, only one category, LS-DYNA appears. If a category is preceded by a folder icon, there are subcategories available under the main category. When you double-click on the category, the subcategories appear indented, and below the category as shown in Figure 1.4: "Material Model Interface Tree Structure". Figure 1.4 Material Model Interface Tree Structure

For example, under Structural are categories Linear, Nonlinear, and others. The models are further categorized so that you will eventually see a vertical list of material property sets or material models that are included under that category (for example, under von Mises Plasticity are: Bilinear, Multilinear, and Nonlinear). Once you have decided which material property set or model you will use, you then choose it by double-clicking on the item. A dialog box appears that prompts you for the required input data for that particular model or property set. Details of a data input dialog box are presented in Entering Material Data.
Material Favorites Folder

A Material Favorite is a template of material properties. It is used as a short cut to frequently used properties, instead of navigating through the detailed tree structure each session. You can create a named template based on a currently defined material model through Favorite>New Favorite.You can also delete a named template through Favorite menu. For any consecutive sesisons of ANSYS, you will then be able to access this named template in the Favorites folder shown in the Material Models Available window.
1.2.4.4.3. Entering Material Data

Included in a data input dialog box is a table whose rows and columns you can alter depending on the requirements of the specific material property or model you have chosen. A typical data input dialog box is shown in Figure 1.5: "A Data Input Dialog Box". Figure 1.5 A Data Input Dialog Box

There are two interaction areas within a material data input dialog box: the data input table, and a series of action buttons that appear at the bottom. Depending on the material item you are defining, the labels in the table vary, as do the number of rows and columns that appear initially. The material item also dictates the number of rows and columns that you are allowed to add or delete. In most cases, the columns represent temperatures, and the rows represent data values (for example, density as a linear isotropic property, or constants for a particular nonlinear model). Temperature Dependent Data Initially, the table is set up for temperature independent data so the temperature field is grayed out. At this point, should you decide to enter data for various temperatures, you can quickly add columns of text fields for the data representing each temperature. You can add or delete the temperature dependent data at any time. You do not need to predetermine if the data should be temperature dependent. Adding and Deleting Columns To add a column, position the text cursor in any field in the existing column, then click on the Add Temperature button. A new column appears

to the right of the existing column, and both temperature fields become active, as shown in Figure 1.6: "Data Input Dialog Box - Added Column". Figure 1.6 Data Input Dialog Box - Added Column

You then enter the two temperatures and the associated data in the rows. You can add more temperature columns, as needed, by following the same procedure. You can insert columns between existing columns by clicking the text cursor in a field within a column that is to the left of where you want to insert the new column, then clicking on the Add Temperature button. A scroll bar appears across the bottom of the table when the number of columns exceeds the width of the dialog box. You can delete a temperature column by positioning the text cursor in any field within the column, and clicking on the Delete Temperature button. Adding and Deleting Rows You may have the need to add another row of constants or other data for a specific temperature. You add or delete rows in a similar way as is described above for adding or deleting columns. To add a row, click the text cursor in any field in an existing row, then click on the Add Row (or Add Point) button. A new row appears beneath the existing row, as shown in Figure 1.7: "Data Input Dialog Box - Added Row". Figure 1.7 Data Input Dialog Box - Added Row

You can add more rows, as needed, by following the same procedure. You can insert rows between existing rows by positioning the text cursor in a field in the top row, then clicking on the Add Row (or Add Point) button. A vertical scroll bar appears in the table when the number of rows exceeds the height of the dialog box. You can delete a row by positioning the text cursor in any field within the row, and clicking on the Delete Row (or Delete Point) button. Entering/Editing Data in Text Fields

When a data dialog box first appears, one of the text fields is selected (black highlight), meaning that the field is ready to accept and display data as you type. You can use the arrow keys to move the selection status to other text fields. Also, pressing the Tab key allows you to move the selection status to the text field positioned to the right of the field that is currently selected. When you start typing within a text field, the highlight is replaced by the characters that you type. You can use the left and right arrow keys to position the text cursor anywhere within the field should you need to replace or delete characters in that field. To edit data, you must first select the text field either by clicking on the field, or using the arrow keys to move the selection status to the particular field. To copy/paste data, select the text fields whose data you want to copy, use Ctrl-c to copy the data to the clipboard, select the empty destination text fields, then paste the data into these fields using Ctrl-v. You select multiple adjacent text fields either by dragging the mouse from the first field to the last field, or by clicking on the first field, holding down the Shift key, then clicking on the last field. For selecting multiple nonadjacent text fields, click on each field while you hold down the Ctrl key. Action Buttons
?

?

?

?

?

Add Temperature: Adds a new column of data entry fields to the right of the column where the text cursor is currently positioned. If the button does not appear, the material item has no temperature dependency. Delete Temperature: Deletes the column of data entry fields where the text cursor is currently positioned. If the button does not appear, the material item has no temperature dependency. Add Row (or Add Point): Adds a new row of data entry fields beneath the row where the text cursor is currently positioned. If the button does not appear, the material item has no provision for adding more data. Delete Row (or Delete Point): Deletes the row of data entry fields where the text cursor is currently positioned. If the button does not appear, the material item requires that all data entry fields must be completed. Graph: Displays a graph of the current data in the ANSYS Graphics window. If required, you can change the data in the table and click on the Graph button again before clicking on the OK button.

?

? ?

OK: Commits all data that you have entered to the ANSYS database and removes this dialog box[1]. Material Model Number # appears in the Material Models Defined tree structure window, where # = 1 for the first model, or the number that you specified in the Define Material ID dialog box. Cancel: Cancels all data entered, and removes the dialog box[1]. Help: Displays help information that is specific to the particular material property or material constant.

1. Click on OK or Cancel to remove the data input dialog box. Pressing the Enter key will not remove the dialog box. If a button appears, but is grayed out, then the function is defined for the particular material property, but you have not yet entered enough data for the function to become active. Some material data input dialog boxes may include other buttons or interaction components that are necessary for completely defining a material property or model. See A Dialog Box and Its Components in the ANSYS Operations Guide if you need help on the use of any of these interaction components. Considerations for a Structural Analysis When performing a structural analysis, several inelastic material models (listed by double-clicking on the following in the tree structure: Structural, Nonlinear, Inelastic) require you to input values for elastic material properties (elastic modulus and/or Poisson's ratio) in addition to the inelastic constants that are specific to the model (for example, Yield Stress and Tangent Modulus for the Bilinear Isotropic Hardening model). In these instances, you must enter the elastic material properties before you enter the inelastic constants. If you try to enter the inelastic constants first, a Note appears stating that you must first enter the elastic properties. After you click on OK in the Note, a data input dialog box appears that prompts you for the elastic material properties. After you enter these properties and click on OK, another data input dialog box appears that prompts you for the inelastic constants associated with the specific model you chose.
1.2.4.4.4. Logging/Editing Material Data

The Material Models Defined window (the left window in the Define Material Model Behavior dialog box) displays a log of each material model you have specified. After you have chosen OK in the data input dialog box, this window displays a folder icon, and Material Model Number # (the first #

is 1 by default), followed by the properties defined for this model. You can define additional models with unique numbers by choosing Material> New Model, then typing a new number in the Define Material ID dialog box. If you double-click on any material model or property (furthest to the right in the tree), the associated data input dialog box appears where you can edit the data, if you choose.
1.2.4.4.5. Example: Defining a Single Material Model

This example and the following two examples show typical uses of the material model interface for use in structural analyses. If your specialty or interest is in performing analyses other than structural analyses, it is recommended that you still read and perform these examples to become familiar with maneuvering within the material model interface. You are then encouraged to try one of your own problems in your particular discipline, or try one of the many sample problems presented throughout the various ANSYS analysis guides. Here is a sampling of these problems:
? ? ? ?

Doing a Steady-State Thermal Analysis (GUI Method) in the ANSYS Thermal Analysis Guide. Example of a 3-D Static Edge-Based Analysis (GUI Method) in the ANSYS Low-Frequency Electromagnetic Analysis Guide. Example problems in the ANSYS High-Frequency Electromagnetic Analysis Guide. Sample Thermal-Structural Analysis (GUI Method) in the ANSYS Coupled-Field Analysis Guide.

The first example below is intended to show you how to completely define a single material model. It steps you through a procedure that uses the material model interface to define a model for simulating nonlinear isotropic hardening, using the Voce law, in a large strain structural analysis at two temperatures. 1. From the ANSYS Main Menu, click on the following menu path: Preprocessor> Material Props> Material Models. The Define Material Model Behavior dialog box appears. 2. In the Material Models Available window, double-click on the following options: Structural, Linear, Elastic, Isotropic. A dialog box appears. 3. Enter values for material properties, as required (EX for elastic modulus, and PRXY for Poisson's ratio). Click on OK. Material Model Number 1 properties appear listed in the Material Models Defined window. 4. In the Material Models Available window, double-click on the following options: Nonlinear, Inelastic, Rate Independent,

5. 6. 7.

8. 9.

Isotropic Hardening Plasticity, von Mises Plasticity, Nonlinear. A dialog box appears that includes a table where you can add temperature columns or add rows for material data, as needed for your application. Note that the temperature field is grayed out. This is because ANSYS assumes a temperature independent application, by default, so you would not need to enter a temperature value. Because this example is temperature dependent (involving two temperatures), you must first add another temperature column, as described in the next step. Click on the Add Temperature button. A second column appears. Enter the first temperature in the Temperature row and the T1 column. Enter the Voce constants required for the first temperature in the rows under the T1 column (see Nonlinear Isotropic Hardening in the ANSYS Elements Reference). Enter the second temperature in the Temperature row, and the T2 column. Enter the Voce constants required for the second temperature in the rows under the T2 column. Note that if you needed to input constants for a third temperature, you would position the cursor in the Temperature row of the T2 column, then click on the Add Temperature button again. This would cause a third column to appear. This material model only requires four constants per temperature. If you were using another model that allowed more constants, the Add Row button would be active. For those models, the same functionality is included for adding or inserting rows by using the Add Row (or Add Point) button.

10.Click on OK. The dialog box closes. The properties defined for that material are listed under Material Model Number 1.
1.2.4.4.6. Example: Editing Data in a Material Model

This example shows you how to use some of the basic editing features within the material model interface. It assumes that you have completed the previous example (see Example: Defining a Single Material Model), and that the completed material model is listed in the Material Models Defined window. Editing data typically falls into two general categories: changing data within an existing material property, and copying an entire material property set to form another model with slightly different properties.

Consider a case where you need to change the constants that you assigned to the Nonlinear Isotropic model. To perform this task: 1. Double-click on Nonlinear Isotropic. The associated dialog box appears with the existing data displayed in the fields. 2. Edit the constants in the appropriate fields, and click on OK. Note that if you needed to change any of the other material properties, you would double-click on Linear Isotropic in the previous step. This would cause the dialog box associated with linear isotropic properties to appear. You could then edit those properties. Consider another case where you have the requirement for two material models, where the second model is the same as the first except that it needs to include constants for one more temperature. To perform this task: 1. In the Define Material Model Behavior dialog box, click on the following menu path: Edit> Copy, then choose 1 for from Material number, and enter 2 for to Material number. Click on OK. The Material Models Defined window now includes Material Model Number 2 in its list. If you double-click on Material Model Number 2, the identical material properties appear below Material Model Number 2 as those listed for Material Model Number 1. 2. Double-click on Nonlinear Isotropic under Material Model Number 2. The associated dialog box appears. 3. Move the text cursor to the Temperature row in the column furthest to the right, and click on the Add Temperature button. A T3 column appears. 4. In the new column, enter the new temperature and the four constants associated with this temperature. 5. Click on OK. The dialog box closes. If you double-click on Nonlinear Isotropic under Material Model Number 2, the associated dialog box appears and reflects the new temperature data that you added for Material Model Number 2.
1.2.4.4.7. Example: Defining a Material Model Combination

This example is intended to show you how to define a material based on a combination of two material models. It steps you through a procedure that uses the material model interface to define a material for simulating cyclic softening at one temperature. This is accomplished by using the Nonlinear Isotropic model combined with the Chaboche model.

If you performed either of the previous examples in this section, start a new ANSYS session before beginning the following example. 1. From the ANSYS Main Menu, click on the following menu path: Preprocessor> Material Props> Material Models. The Define Material Model Behavior dialog box appears. 2. In the Material Models Available window, double-click on the following options: Structural, Linear, Elastic, Isotropic. A dialog box appears. 3. Enter values for material properties, as required (EX for elastic modulus, and PRXY for Poisson's ratio). Click on OK. Material Model Number 1 and Linear Isotropic appear in the Material Models Defined window. 4. In the Material Models Available window, double-click on the following options: Nonlinear, Inelastic, Rate Independent, Combined Kinematic and Isotropic Hardening Plasticity, von Mises Plasticity. 5. Double-click on Chaboche and Nonlinear Isotropic. A dialog box appears for defining the constants for the Chaboche model. 6. Enter the first three constants associated with the Chaboche model (click on the Help button for information on these constants). 7. The Chaboche model allows you to specify more constants. If you choose to specify more constants, click on the Add Row button, and enter the next constant. 8. Repeat the previous step for all the remaining Chaboche constants that you want to define. 9. Click on OK. The dialog box closes and another dialog box appears for defining the constants for the Nonlinear Isotropic model. 10.Enter the constants associated with the Nonlinear Isotropic model (click on the Help button for information on these constants). 11.Click on OK. The dialog box closes. Under Material Model Number 1, the following are listed: Linear Isotropic, Chaboche, and Nonlinear Isotropic. You can then edit any of the data (see Example: Editing Data in a Material Model).
1.2.4.4.8. Material Model Interface - Miscellaneous Items

Other characteristics of the material model interface are the following:
?

?

Any batch files you use to enter material data will be converted to material models and will appear listed in the Material Models Defined window of the Define Material Model Behavior dialog box. The material model interface does not import data from the ANSYS material library discussed in Using Material Library Files.

?

The material model interface does not support input through either TB,MOONEY, or the *MOONEY command.

1.2.4.5. Using Material Library Files Although you can define material properties separately for each finite element analysis, ANSYS lets you store a material property set in an archival material library file, then retrieve the set and reuse it in multiple analyses. (Each material property set has its own library file.) The material library files also enable several ANSYS users to share commonly used material property data. The material library feature offers you other advantages:
?

?

?

?

Because the archived contents of material library files are reusable, you can use them to define other, similar material property sets quickly and with fewer errors. For example, suppose that you have defined material properties for one grade of steel and want to create a material property set for another grade of steel that is slightly different. You can write the existing steel material property set to a material library file, read it back into ANSYS under a different material number, and then, within ANSYS, make the minor changes needed to define properties for the second type of steel. Using the /MPLIB command (Main Menu> Preprocessor> Material Props> Material Library> Library Path), you can define a material library read and write path. Doing this allows you to protect your material data resources in a read-only archive, while giving ANSYS users the ability to write their material data locally without switching paths. You can give your material library files meaningful names that reflect the characteristics of the data they contain. For example, the name of a material library file describing properties of a steel casting might be STEELCST.SI_MPL. (See Creating (Writing) a Material Library File for an explanation of file naming conventions.) You can design your own directory hierarchy for material library files. This enables you to classify and catalog the files by material type (plastic, aluminum, etc.), by units, or by any category you choose.

The next few paragraphs describe how to create and read material library files. For additional information, see the descriptions of the /MPLIB, MPREAD, and MPWRITE commands in the ANSYS Elements Reference.

1.2.4.6. Format of Material Library Files Material library files are ANSYS command files. The file format supports both linear and nonlinear properties. You can reuse material library files because the commands in them are written so that, once you read a material property set into the ANSYS database, you can associate that set with any material number you wish. 1.2.4.7. Specifying a Default Read/Write Path for Material Library Files Before you create any material library files, define a default read path and write path for those files: Command(s): /MPLIB,R-W_opt,PATH GUI: Main Menu> Preprocessor> Material Props> Material Library> Library Path

Note
The ANSYS-supplied material library is located at /ansys90/matlib/. In place of R-W_opt, specify READ (to set the read path), WRITE (to set the write path), or STAT to see what read and write paths currently are in use. In place of PATH, specify the path to be used for material library files. 1.2.4.8. Creating (Writing) a Material Library File To create an archival material library file, perform these steps: 1. To tell the ANSYS program what system of units you are using, issue the /UNITS command. For example, to specify the international system of units, you would issue the command /UNITS,SI. You cannot access the /UNITS command directly from the GUI. 2. Define a material property using the MP command (Main Menu> Preprocessor> Material Props> Isotropic). To do so, you must specify a material number and at least one material property value (for example, magnetic permeability or MURX). 3. From the PREP7 preprocessor, issue the command shown below: MPWRITE,Filename,,,LIB,MAT

Filename is the name to assign to the material library file. Issue MPWRITE (Main Menu> Preprocessor> Material Props> Material Library> Export Library) and specify the filename for the material library file. Issuing MPWRITE writes the material data specified by material number MAT into the named file in the current working directory. (If you previously specified a material library write path by issuing the /MPLIB command (Main Menu> Preprocessor> Material Props> Material Library> Library Path), ANSYS writes the file to that location instead.) Naming conventions for a material library file are as follows:
? ?

The name of the file is the name you specify on the MPWRITE command. If you do not specify a filename, the default name is JOBNAME. The extension of a material library filename follows the pattern .xxx_MPL, where xxx identifies the system of units for this material property sets. For example, if the system of units is the CGS system, the file extension is .CGS_MPL. The default extension, used if you do not specify a units system before creating the material library file, is .USER_MPL. (This indicates a user-defined system of units.)

1.2.4.9. Reading a Material Library File To read a material library file into the ANSYS database, perform these steps: 1. Use the /UNITS command or its GUI equivalent to tell the ANSYS program what system of units you are using.

Note
The default system of units for ANSYS is SI. The GUI lists only material library files with the currently active units. 2. Specify a new material reference number or an existing number that you wish to overwrite: Command(s): MAT GUI: Main Menu> Preprocessor> Modeling> Create> Elements> Elem Attributes

3. Caution

4. Overwriting an existing material in the ANSYS database deletes all of the data associated with it. 5. To read the material library file into the database, use one of the following: Command(s): MPREAD,Filename,,,LIB GUI: Main Menu> Preprocessor> Material Props> Material Library> Import Library

The LIB argument supports a file search hierarchy. The program searches for the named material library file first in the current working directory, then in your home directory, then in the read path directory specified by the /MPLIB command, and finally in the ANSYS-supplied directory /ansys90/matlib. If you omit the LIB argument, the programs searches only in the current working directory.

1.2.5. Creating the Model Geometry
Once you have defined material properties, the next step in an analysis is generating a finite element model - nodes and elements - that adequately describes the model geometry. The graphic below shows some sample finite element models: Figure 1.8 Sample Finite Element Models

There are two methods to create the finite element model: solid modeling and direct generation. With solid modeling, you describe the geometric shape of your model, then instruct the ANSYS program to automatically mesh the geometry with nodes and elements. You can control the size and shape in the elements that the program creates. With direct generation, you "manually" define the location of each node and the connectivity of each element. Several convenience operations, such as copying patterns of existing nodes and elements, symmetry reflection, etc. are available. Details of the two methods and many other aspects related to model generation - coordinate systems, working planes, coupling, constraint equations, etc. - are described in the ANSYS Modeling and Meshing Guide.

1.2.6. Apply Loads and Obtain the Solution

In this step, you use the SOLUTION processor to define the analysis type and analysis options, apply loads, specify load step options, and initiate the finite element solution. You also can apply loads using the PREP7 preprocessor. 1.2.6.1. Defining the Analysis Type and Analysis Options You choose the analysis type based on the loading conditions and the response you wish to calculate. For example, if natural frequencies and mode shapes are to be calculated, you would choose a modal analysis. You can perform the following analysis types in the ANSYS program: static (or steady-state), transient, harmonic, modal, spectrum, buckling, and substructuring. Not all analysis types are valid for all disciplines. Modal analysis, for example, is not valid for a thermal model. The analysis guide manuals in the ANSYS documentation set describe the analysis types available for each discipline and the procedures to do those analyses. Analysis options allow you to customize the analysis type. Typical analysis options are the method of solution, stress stiffening on or off, and Newton-Raphson options. To define the analysis type and analysis options, use the ANTYPE command (Main Menu> Preprocessor> Loads> Analysis Type> New Analysis or Main Menu> Preprocessor> Loads> Analysis Type> Restart) and the appropriate analysis option commands (TRNOPT, HROPT, MODOPT, SSTIF, NROPT, etc.). For GUI equivalents for the other commands, see their descriptions in the ANSYS Elements Reference. If you are performing a static or full transient analysis, you can take advantage of the Solution Controls dialog box to define many options for the analysis. For details about the Solution Controls dialog box, see Chapter 3: "Solution". You can specify either a new analysis or a restart, but a new analysis is the choice in most cases. A singleframe restart that allows you to resume a job at its end point or abort point is available for static (steady-state), harmonic (2-D magnetic only), and transient analyses. A multiframe restart that allows you to restart an analysis at any point is available for static or full transient structural analyses. See Restarting an Analysis for complete information on performing restarts. The various analysis guides discuss additional details necessary for restarts. You cannot change the analysis type and analysis options after the first solution.

A sample input listing for a structural transient analysis is shown below. Remember that the discipline (structural, thermal, magnetic, etc.) is implied by the element types used in the model. ANTYPE,TRANS TRNOPT,FULL NLGEOM,ON Once you have defined the analysis type and analysis options, the next step is to apply loads. Some structural analysis types require other items to be defined first, such as master degrees of freedom and gap conditions. The ANSYS Structural Analysis Guide describes these items where necessary. 1.2.6.2. Applying Loads The word loads as used in ANSYS documentation includes boundary conditions (constraints, supports, or boundary field specifications) as well as other externally and internally applied loads. Loads in the ANSYS program are divided into six categories:
? ? ? ? ? ?

DOF Constraints Forces Surface Loads Body Loads Inertia Loads Coupled-field Loads

You can apply most of these loads either on the solid model (keypoints, lines, and areas) or the finite element model (nodes and elements). For details about the load categories and how they can be applied on your model, see Chapter 2: "Loading" in this manual. Two important load-related terms you need to know are load step and substep. A load step is simply a configuration of loads for which you obtain a solution. In a structural analysis, for example, you may apply wind loads in one load step and gravity in a second load step. Load steps are also useful in dividing a transient load history curve into several segments.

Substeps are incremental steps taken within a load step. You use them
mainly for accuracy and convergence purposes in transient and nonlinear analyses. Substeps are also known as time steps - steps taken over a period of time.

Note

The ANSYS program uses the concept of time in transient analyses as well as static (or steady-state) analyses. In a transient analysis, time represents actual time, in seconds, minutes, or hours. In a static or steady-state analysis, time simply acts as a counter to identify load steps and substeps. 1.2.6.3. Specifying Load Step Options Load step options are options that you can change from load step to load step, such as number of substeps, time at the end of a load step, and output controls. Depending on the type of analysis you are doing, load step options may or may not be required. The analysis procedures in the analysis guide manuals describe the appropriate load step options as necessary. See Chapter 2: "Loading" for a general description of load step options. 1.2.6.4. Initiating the Solution To initiate solution calculations, use either of the following: Command(s): SOLVE GUI: Main Menu> Solution> Solve> Current LS Main Menu> Solution> solution_method

When you issue this command, the ANSYS program takes model and loading information from the database and calculates the results. Results are written to the results file (Jobname.RST, Jobname.RTH, Jobname.RMG, or Jobname.RFL) and also to the database. The only difference is that only one set of results can reside in the database at one time, while you can write all sets of results (for all substeps) to the results file. You can solve multiple load steps in a convenient manner: Command(s): LSSOLVE GUI: Main Menu> Solution> Solve> From LS Files

Chapter 3: "Solution" discusses this and other solution-related topics.

1.2.7. Review the Results
Once the solution has been calculated, you can use the ANSYS postprocessors to review the results. Two postprocessors are available: POST1 and POST26.

You use POST1, the general postprocessor, to review results at one substep (time step) over the entire model or selected portion of the model. The command to enter POST1 is /POST1 (Main Menu> General Postproc), valid only at the Begin level. You can obtain contour displays, deformed shapes, and tabular listings to review and interpret the results of the analysis. POST1 offers many other capabilities, including error estimation, load case combinations, calculations among results data, and path operations. You use POST26, the time history postprocessor, to review results at specific points in the model over all time steps. The command to enter POST26 is /POST26 (Main Menu> TimeHist Postpro), valid only at the Begin level. You can obtain graph plots of results data versus time (or frequency) and tabular listings. Other POST26 capabilities include arithmetic calculations and complex algebra. Details of POST1 and POST26 capabilities and how to use them are described in chapters later in this document.


相关文章:
ANSYS基本分析过程指南(Basic Analysis Guide)_图文.pdf
ANSYS基本分析过程指南(Basic Analysis Guide)_物理_自然科学_专业资料。ansys帮助...(Pretension) SHELL SOLID SOURCe SURFace TARGEt TRANSducer USER VISCOelastic (...
Maxwell V15-2D-User-Manual.pdf
Software Version: 15 Maxwell 2D User’s Guide Contents This document discusses some basic concepts and terminology used throughout the ANSYS Maxwell ...
The Basic Analysis Guide of ANSYS Software(节选)汉译报告.pdf
The Basic Analysis Guide of ANSYS Software(节选)汉译报告_电子/电路_工程... ansys_external connect... 209人阅读 14页 免费 ansys_connection users.....
60_Basic7_ANSYS接触基础教程(经典)教程_图文.pdf
基本概念接触协调 增广 lagrange法 Training Manual Basic Structural Structural Nonlinearities Nonlinearities 11.0 11.0 Basic ? 多数 ANSYS 接触单元可以将罚...
ANSYS非线性基础培训手册_Basic5解析_图文.ppt
ANSYS非线性基础培训手册_Basic5解析_职高对口_职业教育_教育专区。ANSYS Training Manual 第五章几何非线性基础 5. 几何非线性基础什么是几何非线性行为? Training ...
ANSYS非线性基础培训手册_Basic3_图文.ppt
ANSYS非线性基础培训手册_Basic3_工程科技_专业资料。Training Manual 第三章求解 3. 求解非线性求解的特点: Training Manual Basic Structural Nonlinearities 11.0...
ANSYS非线性基础培训手册_Basic5a_图文.ppt
ANSYS非线性基础培训手册_Basic5a_工程科技_专业资料。Training Manual 第五章 - 附录几何非线性基础 几何非线性基础 G. 附录 Training Manual Basic Structural ...
ANSYS非线性基础培训手册_Basic7_图文.ppt
ANSYS非线性基础培训手册_Basic7_工程科技_专业资料。Training Manual 第七章接触介绍 7. 接触介绍什么是接触? ? 当两个分离的表面互相碰触并互切 时, 就称它们...
Ansys 二次开发手册.pdf
Guide to ANSYS User Programmable Features 1 Using User Programmable Features ...These manuals assume that you have at least a basic knowledge of ...
ANSYS FLUENT Tutorial Guide_图文.ppt
ANSYS FLUENT Tutorial Guide_其它_高等教育_教育专区。ANSYS FLUENT Tutorial ...Set some basic meshing parameters for the ANSYS Meshing application Note:...
带斜撑组合结构-附录:ANSYS命令流.doc
定义芯材的约束条件 CSYS,0 附录:ANSYS 命令流 NSEL,S,LOC,Z,0 D,ALL,UX...设置求解输出 OUTPR,BASIC,ALL, OUTRES,ALL,ALL, SOLVE FINISH !画出第一阶...
ansys Basic Analysis Procedures Guide.doc
ansys Basic Analysis Procedures Guide_计算机软件及应用_IT/计算机_专业资料。...(This indicates a user-defined system of units.) 1.2.25 Reading a ...
Maxwell_v16_3D_WS04_BasicDCConductionAnalysis_图文.pdf
Workshop 4 : Basic DC Conduction Analysis ANSYS Maxwell 3D V16 ? 2013 ...Scale tab User Limits: ? Checked 1. Min: 0 2. Max: 9e+7 2. ...
ansys培训作业指导-Mech-Intro_14.0_WS02.1_Basic中文_图文.pdf
ansys培训作业指导-Mech-Intro_14.0_WS02.1_Basic中文_机械/仪表_工程科技_专业资料。Workshop 2.1 ANSYS Mechanical 基础 14. 0 Release ANSYS Mechanical ...
Visual Basic 6.0对Ansys调用的技术研究_论文.pdf
Visual Basic 6.0对Ansys调用的技术研究_信息与通信_工程科技_专业资料。以桁架结构在ANSYS软件中建模和求解为例,利用Visual Basic 6.0高级开发语言对ANSYS软件分析...
基于Visual Basic的钢筋混凝土柱火灾下温度场的ANSYS参数化分析_....pdf
基于Visual Basic的钢筋混凝土柱火灾下温度场的ANSYS参数化分析_建筑/土木_工程科技_专业资料。基于Visual BasicANSYS提供的二次开发工具APDL,开发了界面友好的火灾...
弹性力学基础及有限元法-11_图文.pdf
? 1)To build a theoretical basis for students to learn FEM software; 2) To let students master the basic operations of ANSYS ? 2. Teaching method(...
UPFs.doc
This chapter provides a basic introduction to UPFs. For detailed information, see the ANSYS Guide to User Programmable Features. ANSYS 程序开放式结构允许...
ANSYS非线性基础培训手册_Basic6解析_图文.ppt
ANSYS非线性基础培训手册_Basic6解析_职高对口_职业教育_教育专区。ANSYS Training Manual 第六章 塑性基础 6. 塑性基础什么是塑性? Training Manual Basic ...
VisualBasic6_0对Ansys调用的技术研究.pdf
VisualBasic6_0对Ansys调用的技术研究_信息与通信_工程科技_专业资料。ansys ...User Inter face ZHANG Hai- Jun1, WANG Gao- Ping2, LIU Yao3 (1....