Experimental results of three commercially fabricated 2: l ellipsoidal heads are reported. The models were subjected to increments of internal pressure until collapse occurred. At each load level, the pressure, strains, and deflections were recorded on an Automatic Data Acquisition System. The data reduction was primarily based upon a computer program developed by FWDC. From the raw data, strain versus pressure and deflection versus pressure plots were generated. Isopressure plots of strain and deflection versus meridional position were also generated for several circumferential locations. Plots of von Mises equivalent stress values versus pressure were obtained for each rosette location. In almost all cases a regression analysis was performed and then the limit of linear behavior was determined. In addition, isostress plots of the von Mises equivalent stress, circumferential stress and meridional stress components (total, membrane and bending) versus meridional location were generated for a given pressure at a given circumferential location, on both the inside and outside surfaces of the vessel. The initial yield pressure, i.e., the pressure level at which a change from linear to nonlinear behavior began, was determined at each of the strain and LVDT gage locations.

This Bulletin provides extensive data to determine the validity of the theoretical predictions of limit pressure via elastic plastic computer programs and the effects of geometrical and yield strength variations in actual fabricated heads.