The Saint Venant-Kirchhoff hyperviscoelastic solid constitutive model.
**Parameters**
- The bulk modulus $`\kappa`$.
- The shear modulus $`\mu`$.
- The bulk viscosity $`\zeta`$.
- The shear viscosity $`\eta`$.
**External variables**
- The deformation gradient $`\mathbf{F}`$.
- The deformation gradient rate $`\dot{\mathbf{F}}`$.
**Internal variables**
- None.
**Notes**
- The Green-Saint Venant strain measure is given by $`\mathbf{E}=\tfrac{1}{2}(\mathbf{C}-\mathbf{1})`$.