DETERMINATION OF ALL ELASTIC-CONSTANTS OF TRANSVERSELY ISOTROPIC MEDIA WITH A CUSP AROUND THE SYMMETRICAL AXIS BY USE OF ELASTIC PULSES PROPAGATING IN 2 PRINCIPAL DIRECTIONS

This paper describes a method of determining all five elastic constant s of a hexagonal or transversely isotropic medium of type II which has the cuspidal region of group velocity around the highest-symmetry axi s [001] perpendicular to the transversely isotropic basal plane. The e lastic constants are obtained from wave-speed data of broad-band ultra sonic signals propagating in two principal directions, namely the [001 ] and the other parallel to the basal plane. The method uses specific cuspidal features of the slow transverse (ST) mode propagating in the [001] direction with two distinct group velocities. An analytic formul a that relates the slower group velocity of the ST mode with the elast ic constant C-13 is derived. An example is provided with a single crys tal of zinc exhibiting hexagonal symmetry. The advantages of this meth od lie in both its simplicity for implementation and its improved accu racy for determination of the elastic constant C-13.