Experimental investigations of nonlinear acoustic phenomena in polycrystalline zinc

The results of experimental and theoretical investigations of nonlinear aco ustic phenomena (nonlinear losses, shift of resonance frequency, generation of the third harmonic, and nonlinear sound-by-sound damping) in polycrysta lline zinc nonannealed and annealed resonating rods are presented. The meas urements were carried out in the 10(-7)-10(-5) strain range at a frequency of about 3 kHz; the frequency of the weak ultrasonic pulse was about 270 kH z. The experimentally observed phenomena are described in frames of phenome nological equations of state containing elastic hysteresis and dissipative nonlinearity. The nonlinear acoustic parameters of these equations are dete rmined by comparison between theoretical dependencies and experimental resu lts. The influence of structural changes in zinc due to annealing on the no nlinear acoustic phenomena is shown. (C) 2000 Acoustical Society of America . [S0001-4966(00)03803-0].