Create the User Material Definition

Add the appropriate user material entries to the bulk data file.

Helius PFA uses the MATUSR and MATUDS entries instead of the conventional material definitions. In this step, the user material is added and formatted for use with Helius PFA.

1. View Tutorial 1 and create the user material with the instructions provided in the Characterize a User Material with Composite Material Manager section.
2. Open Tutorial_2_Nastran.bdf in a text editor.
3. Locate the material definition by searching for the MAT1 entry. The MAT1 entry defines an isotropic material, 9025. We will keep this entry and add the MATUSR and MATUDS entries. The MAT1 entry acts as a temporary material required for use with a layered solid composite in MSC Nastran.

   Certain bulk data file property entries, such as the PCOMPLS entry defined in this bulk data file, don't operate with user defined materials. Therefore, we need to create a temporary material with the same material ID as our user material to run the analysis.

4. Above the MAT1 entry, type the following:

   MATUSR, 9025, 1, 23

   This entry specifies the user-defined material model. 9025 is the material identification number for the Tutorial_1 material we created with Composite Material Manager in step 1. Note, this number may vary from computer to computer. Refer to the HPFAMatDB.xml file to determine the appropriate material identification number on your machine.
5. Now type the following:

   MATUDS, 9025, MATUSR, hpfa, UMAT
   , REAL, 3, 1, 1, 0, 0, 0, 0,
   ,     , 0, 0, 0, 0, 0.1, 1E-06

   This entry defines the enhanced material model for use with Helius PFA. The last two lines identify the user material constants used by Helius PFA to determine the precise form of multiscale constitutive relations to use for the composite material.

User Material Constants

The user material constants (UMCs) immediately follow the REAL field in the MATUDS entry. Of particular importance to this tutorial are UMCs 1-3, 8, and 12-13. For a detailed description of each UMC, refer to Appendix A of the User's Guide.

• UMC#1 - The first constant specifies the use of the lb/in/R units system. Since our part has dimensions of inches and our material was defined in terms of pounds and inches, we set UMC#1 = 3.
• UMC#2 - The second constant identifies 1 as the fiber direction.
• UMC#3 - The third constant turns on the progressive failure feature of Helius PFA.
• UMC#8 - The eighth constant specifies the failure criterion to use for the analysis. Set UMC#8 = 0 (default) to use the MCT criterion.
• UMC#12 - The 12th constant specifies the matrix post-failure stiffness. Set UMC#12 = 0.1.
• UMC#13 - The 13th constant specifies the fiber post-failure stiffness. Set UMC#13 = 1E-06.

The complete material definition should now appear as follows:

MATUSR, 9025, 1, 23
MATUDS, 9025, MATUSR, hpfa, UMAT
, REAL, 3, 1, 1, 0, 0, 0, 0,
,     , 0, 0, 0, 0, 0.1, 1E-06
MAT1, 9025, 1.806E+07