Table 1.
Summary of brain element/node numbers (excluding those for other components such as skull and face, as they are irrelevant when simplified into rigid bodies in simulation), average element size, hourglass (HG) control type, brain material models and their corresponding material property parameters for the three WHIMs. HGO: Holzapfel-Gasser-Ogden model; μi, αi, G0, G∞, K, ki, k, gi, are material property parameters defined in Supplementary A (constitutive equations) and elsewhere25,57.
| Isotropic WHIM V1.0 | Anisotropic WHIM V1.0 | (Anisotropic) WHIM V1.5 | ||
|---|---|---|---|---|
| # of brain elements | 55.1k | 202.8 k | ||
| # of brain nodes | 56.6 k | 227.4 k | ||
| Avg. elm. Size (mm) | 3.3±0.79 | 1.810.4 | ||
| HG control type | Enhanced | Relax stiffness | ||
| Brain mat. model | 2nd-order Ogden and viscoelastic | HGO and viscoelastic | ||
| Brain mat. prop. | μ1 (Pa) | 271.7 | G0 (Pa) | 2673.23 |
| α1 | 10.1 | G∞ (Pa) | 895.53 | |
| μ2 (Pa) | 776.6 | K (MPa) | 219 | |
| α2 | −12.9 | k1 (Pa)** | 25459 | |
| i = 1 | 7.69E-1 | k2 | 0 | |
| i = 2 | 1.86E-1 | κ | Depending on FA* values | |
| i = 3 | 1.48E-2 | g1 | 0.6521 | |
| i = 4 | 1.90E-2 | g1 | 0.0129 | |
| i = 5 | 2.56E-3 | τ1 | 0.0067 | |
| i = 6 | 7.04E-3 | τ2 | 0.0747 | |
*
FA: Fractional anisotropy.
**
Property parameters for the gray matter are identical, except that k1 was set to 0 as no fiber reinforcement existed in this region. k1 was based on G0/k1 from experiment37.