Create a User Material with Helius PFA

Use the Helius PFA plug-in interface to choose from a variety of material and analysis options.

The options include:

1. Selection of a composite material to use in the analysis (Helius PFA compatible material definitions must be created outside of CAE using Composite Material Manager)
2. The choice of four unit systems
3. Selection of the principle material direction
4. Creating additional output variables that provide fiber and matrix constituent stresses and strains
5. Inclusion of progressive failure in the analysis. When this option is used, Helius PFA will degrade (reduce) the material properties when failure in the matrix or fiber is detected. If this feature is inactive (the focus of this tutorial), the material retains its original (undamaged) properties when failure is detected.
6. Inclusion of pre-failure nonlinearity
7. Setting the matrix and fiber post-failure degradation ratios

Using these options, you can tailor the analysis to the requirements of the problem. For a detailed discussion of the options available, refer to the Helius PFA User's Guide.

In the following steps, a user-material is defined using the Helius PFA GUI.

1. Click the HELIUS button from the Ansys Toolbar and choose Create Composite Material.

   Note: The HELIUS button only works in the model creation preprocessor (/PREP7).

2. From the Material Library list, select the material IM7_8552.

   The unit dependent Engineering Constants specific to this material are listed in the plug-in for you to review. Note the Ansys Material ID (matID) corresponding to this material is also shown in the dialog box. This value may vary from computer to computer.

3. Since this model uses inches and pounds as base units, select lb/in/R from the Select Units list.

   There are 4 unit systems to choose from. The default unit system is N/m/K.

4. Select 1 as the fiber direction.

   2 can also be used as the fiber direction, but it would require a different composite layup orientation than the 1 direction. As a general rule, it is recommended that 1 be used as the fiber direction to maintain consistency from model to model. On occasion, however, it will not be possible to create an orientation in Ansys that allows for the 1 direction to be the fiber direction due to the combination of complex model geometry and orientation limitations. In such cases, it may be necessary to use the 2 direction as the fiber direction.

5. In the Analysis Criteria box, uncheck Progressive Failure Analysis. With progressive failure deactivated, the stiffness of the elements will remain unchanged throughout the analysis. In contrast, when progressive failure is activated, the stiffness of the elements are reduced after failure has been predicted by the failure criterion. The dialog box should appear as shown below.

6. Click OK.