Theoretical Approach to Enhanced Pressure Apparatus Design

The possibility of obtaining an enhanced stress level within a solid is investigated for a spherical configuration consisting of a solid homogeneous isotropic core encapsulated by a nonhomogeneous isotropic shell. Utilizing a linear elastic analysis, the enhancement is maximized (1) for the case when the nonhomogeneous shell is composed of a number of concentric homogeneous shells; and (2) for the case where the elastic shell modulus varies as a power of the radius. The dependence of the enhancement on the various parameters is depicted graphically and the results are discussed in terms of presently available materials. It is felt that the attainable enhancement may be significant only in the region up to 10 kbar and very limited above 30 kbar.