Adiabatic third-order elastic constants of fused silica

Results of ultrasonic harmonic generation are combined with those of ultrasonic beam mixing [R. W. Dunham and H. B. Huntington], to obtain a complete set of truly adiabatic third-order elastic constants of a strain-free sample of G.E. type 151 fused silica: C111+64.8±0.5×1011 dyn/cm2; C144=+5.4±0.3×1011 dyn/cm2; and C456=−1.32±0.08×1011 dyn/cm2. Differences among values of the third-order elastic constants for different samples are great enough that care in sample selection is necessary for consistent results.