  The frame-indifferent viscoelasticity in Kelvin-Voigt rheology at large
strains is formulated in the reference configuration (i.e. using the Lagrangian
approach) considering also the possible self-contact in the actual deformed
configuration. Using the concept of 2nd-grade nonsimple materials, existence of
certain weak solutions which are a.e. injective is shown by converging an
approximate solution obtained by the implicit time discretisation.
