How to Use Ansys Software – Step by step Tutorial for Ansys
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.
A typical ANSYS analysis has three distinct steps:
- Build the model.
- Apply loads and obtain the solution.
- Review the results.
Building a Model
Building a finite element model requires more of an ANSYS user’s time than any other part of the analysis. First, you specify a job name and analysis title. Then, you use the PREP7 preprocessor to define the element types, element real constants, material properties, and the model geometry.
Specifying a Job name and Analysis Title –
This task is not required for an analysis, but is recommended.
Defining the Job name –
The job name is a name that identifies the ANSYS job. When you define a job name for an analysis, the job name 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 job name for each analysis, you insure that no files are overwritten. If you do not specify a job name, all files receive the name FILE or file, depending on the operating system.
GUI: Utility Menu>File>Change Job name
Defining Element Types
The ANSYS element library contains more than 100 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.
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 two-dimensional or three-dimensional space.
For example, BEAM4, 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 eight-node quadrilateral element, and can be modeled only in 2-D space.
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.
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>Create>Elements>Elem Attributes).
Defining Material Properties
Most element types require material properties. Depending on the application, material properties may be:
- Linear or nonlinear
- Isotropic, orthotropic, or anisotropic
- Constant temperature or temperature-dependent.
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.
Main Menu > Preprocessor> Material Props > Material Models.
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.
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, and then instruct the ANSYS program to automatically mesh the geometry with nodes and elements. You can control the size and shape of 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.
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.
The word loads as used in this manual 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
- 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).
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.
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