PRESSURE DERIVATIVES OF ELASTIC MODULI OF VYCOR GLASS TO 8 KBAR

Longitudinal- and shear-wave velocities in Vycor glass were measured to 8 kbar at 25°C, using the ultrasonic interferometry method. Corresponding bulk and shear moduli were also computed. The pressure derivatives of the shear-wave velocity and shear modulus at zero pressure were anomalously negative. dvs dP=-2.44×10-2km/sec/k and. dG dP = -2.67kbar/kbar. and constant throughout the 8 kbar range. On the other hand, the pressure derivatives of the longitudinal-wave velocity and bulk modulus, though also anomalously negative, ( dvp dP = -4.74×10-2 km/sec/kbar and dBp dP = -4.72 kbar/kbar), tended to become normal (i.e. less negative) at pressures of about 4 kbar and higher. For the Vycor glass, dσp dP at zero pressure, where σ is the Poisson's ratio, is negative (-1.67 × 10-3/kbar). © 1969.