First Pressure Derivative of the Bulk Modulus for Porous Materials

Summary A new method for calculating the first pressure derivative of the effective bulk modulus of a material containing a dilute, random distribution of spherical cavities, is given. The result obtained is identical to that obtained by considering the model of a hollow sphere of the same porosity (Walsh 1971). The possible extensions of the two methods to find the other second order moduli, and to the case of non-spherical cavities, are discussed.