### MAT, $i$, NEOHOOK, $\mu$, $\kappa$, $\rho$

Defines the Neo-Hookean slightly compressible hyperelastic material by the formula:

The last parameter $\rho$ denotes the material density. Parameter $i$ denotes the block’s number.

### MAT, $i$, GENT, $\mu$, ${J}_{m}$, $\kappa$, $\rho$

Defines the Gent slightly compressible hyperelastic material by the formula:

$\psi =-\frac{\mu {J}_{m}}{2}\mathrm{ln}\left(1-\frac{{J}^{-\frac{2}{3}}{I}_{1}-3}{{J}_{m}}\right)+\frac{\kappa }{2}\left(\frac{{J}^{2}-1}{2}-\mathrm{ln}J\right)$

The last parameter $\rho$ denotes the material density. Parameter $i$ denotes the block’s number.

### MAT, $i$, ANISOGENT, $\mu$, ${\mu }^{\mathrm{aniso}}$, ${J}_{m}^{\mathrm{aniso}}$$m$, $\kappa$, $\beta$, $\rho$

Defines the anisotropic Gent slightly compressible hyperelastic material by the formula:

${J}_{4}=\frac{{I}_{4}+{I}_{6}}{2}$
${I}_{4}={a}_{0}^{T}·C{a}_{0}$
${I}_{6}={g}_{0}^{T}·C{g}_{0}$

where ${a}_{0}$, ${g}_{0}$ are two fiber directions. Unit fiber directions ${a}_{0}$, ${g}_{0}$ are defined by angle $\beta$ and the local coordinate system of an element. Angle $\beta$ has to be entered in degrees. The last parameter $\rho$ denotes the material density. Parameter $i$ denotes the block’s number .