Fully non-linear wave models in fiber-reinforced anisotropic incompressible hyperelastic solids

• Nonlinear models are derived for hyperelastic solids containing a single fiber family.
• Several ansatze compatible with incompressibility are considered.
• It is shown that when displacements are independent of fiber direction, fiber effects vanish.
• Point and contact symmetries are classified for the chosen ansatze.
• Linearization by contact transformation and exact solutions are computed and discussed.

Many composite materials, including biological tissues, are modeled as non-linear elastic materials reinforced with elastic fibers. In the current paper, the full set of dynamic equations for finite deformations of incompressible hyperelastic solids containing a single fiber family are considered. Finite-amplitude wave propagation ansätze compatible with the incompressibility condition are employed for a generic fiber family orientation. Corresponding non-linear and linear wave equations are derived. It is shown that for a certain class of constitutive relations, the fiber contribution vanishes when the displacement is independent of the fiber direction.Point symmetries of the derived wave models are classified with respect to the material parameters and the angle between the fibers and the wave propagation direction. For planar shear waves in materials with a strong fiber contribution, a special wave propagation direction is found for which the non-linear wave equations admit an additional symmetry group. Examples of exact time-dependent solutions are provided in several physical situations, including the evolution of pre-strained configurations and traveling waves.