Appendix A - HELIUSPFA Command Arguments
A set of arguments are required as part of the HELIUSPFA command.
The Helius PFA user programmable feature uses these arguments to determine the precise form of multiscale constitutive relations that should be used for that particular composite material. For any given Helius PFA material, the number of arguments must be at least 5. The general form of the HELIUSPFA command is:
HELIUSPFA, arg1, arg2, arg3, . . . , arg16
The table below provides a short description of the constitutive modeling issue controlled by each of the 16 possible arguments along with the allowable range of values for each constant. A detailed description of the arguments is found in Appendices A.1 through A.13.
| Argument | Constitutive Issue Controlled by the Argument | Allowable Values | Notes |
|---|
| 1 | Material Reference Number | Integer > 0 | |
| 2 | Number of State Variables to be tracked (SVARs) | Unidirectional → 7 or 35 Woven → 7 or 90 | |
| 3 | System of Units | 1 - N/m/K 2 - N/mm/K 3 - lb/in/R 4 - lb/ft/R 5 - Custom | 1 is default |
| 4 | Principal Material Coordinate System | Unidirectional: 1 - (1 = fiber, 23 = plane of transverse isotropy) 2 - (2 = fiber, 13 = plane of transverse isotropy) Woven: 1 - (1 = fill tow, 2 = warp tow, 3 = out of plane) 2 - (2 = fill tow, 1 = warp tow, 3 = out of plane) 3 - (3 = fill tow, 2 = warp tow, 1 = out of plane) | 1 is default |
| 5 | Progressive Failure Analysis | 0 (off), 1 or 2 (on) | 2 is used in conjuction with Arguments 14 & 15 |
| 6 | Pre-Failure Nonlinearity | Uni → 0 (off), 1 (on) Woven → 0 (off), 1 (on) | 0 is default, must have Argument 5 activated |
| 7 | Unused | 0 or blank | |
| 8 | Hydrostatic Strengthening | 0 (off), 1 (on - uni only) | 0 is default, must have Argument 5 activated |
| 9 | Temperature | -1 (activate temperature dependence) value ≥ 0.0 (temperature corresponding to environment in mdata file) | 0 is default |
| 10 | Failure Criterion | Uni → -1, 0, 1, 2, 3, 4, 5, 6, 7, 8 Woven → -1, 0, 1, 2 | 0 is default |
| 11 | Auxiliary Criterion Parameter | -1.0 ≤ value ≤ 1.0 | |
| 12 | Auxiliary Criterion Parameter | Must be > 0 | |
| 13 | Unused | 0 or blank | |
| 14 | Matrix Post Failure Stiffness | 0 < value ≤ 1 | |
| 15 | Fiber Post Failure Stiffness | 0 < value ≤ 1 | |
| 16 | Moisture | 0 (Ambient), 1 (Dry), 2 (Wet) | 0 is default |