Date of Award


Degree Type


Degree Name

Master of Engineering (ME)




R. Sowerby


The effects of pressurization on the properties of metals has long been of interest to scientists. Bridgman found that in general, the ductility (ability of the metal to deform without fracture) increased with superimposed hydrostatic pressure. Pugh et al. confirmed similar findings.

The effects of hydrostatistic pressure on the mechanical properties of thin anisotropic zinc, heat treated and non heat treated zinc alloy sheets subjected to biaxial tension (via the circular bulge test) is investigated in this project.

A brief look is taken into the generalized conditions for the onset of tensile plastic instability in a thin circular diaphragm bulged under superimposed hydrostatic pressure. The material is assumed to obey Hill's theory of yielding for anisotropic materials. These predictions are verified by conducting bulge tests using back pressures up to 10,000 psi. It is concluded that within the pressure range of investigation there is no detectable changes in the properties of the materials tested.

In the appendix section a brief look is taken into the microstructure of the materials tested.