Contact mechanics and friction for transversely isotropic viscoelastic materials

Transversely isotropic materials are an unique group of materials whose properties are the same along two of the principal axes of a Cartesian coordinate system. Various natural and artificial materials behave effectively as transversely isotropic elastic solids. Several materials can be classified as transversely isotropic materials including crystals, rocks, piezoelectrics, some biological tissues such as muscles, skin, cartilage tissue or brainstem and fibrous composites. In this study, the theory of contact mechanics developed by Persson is extended in such a way that it can model the contact and friction of a transversely isotropic viscoelastic solid in contact with a rigid rough surface. Numerical results show that anisotropy should be taken into account when dealing with transversely isotropic materials. The hysteresis friction between a transversely isotropic viscoelastic rubber, reinforced unidirectionally by fibers and two rough counter surfaces are measured by a pin-on-disk setup. The experimental results validate the theory