| Influencing factors | Label | Levels | ||
| 1 | 2 | 3 | ||
| Hardening modulus (MPa) | K | 550 | 700 | 850 |
| Initial strain (%) | ε0 | 0.575 | 1.05 | 1.525 |
| Hardening coefficient | n | 0.2 | 0.25 | 0.3 |