Fronti d'onda principali nei mezzi ipoelastici di grado uno

We study the propagation of weak discontinuities in a hypoelastic isotropic bodies of first order. We obtain that a wave front travelling down a «principal» axis of stress is always either longitudinal or transverse. In general we have two «different» kinds of transverse waves, which travel at the same normal propagation speed if and only if the corresponding eigenstresses are egual. Finally, the growth of the amplitude of infinitesimal discontinuities, so as to form shock fronts, is studied for the longitudinal waves