POROSITY-DEPENDENCE OF ELASTIC PROPERTIES AND ULTRASONIC VELOCITY IN POLYCRYSTALLINE ALUMINA - A MODEL-BASED ON CYLINDRICAL PORES

Effective elastic moduli and ultrasonic velocity of materials having a ligned cylindrical pores have been derived using a series expansion in terms of the difference between the upper and lower bounds of elastic moduli obtained by the variational method. The theoretical results fo r polycrystalline alumina agree well with the experimental data, confi rming the suggestion of previous researchers that a matrix containing parallel cylindrical pores orientated perpendicular to the applied str ess, provide a better model than a spherical one in describing the por osity-dependence of elastic moduli in sintered specimens.