Experimental and numerical collapse properties of externally pressurized egg-shaped shells under local geometrical imperfections

The present investigation is devoted to the nonlinear elastic collapse properties of externally pressurized egg shaped shells under local geometrical imperfections. The shells have nominal major axis, nominal minor axis, and nominal wall thickness of 256 mm, 180 mm, and 2 nun, respectively. Nine resin egg-shaped shells are manufactured, measured accurately, tested hydrostatically, and analysed numerically. Of these, three each have nominally identical perfect geometries, nominally identical geometries with local flat imperfections, and local dimple imperfections. Furthermore, the effect of local and eigenmode imperfection depths on the collapse pressures of egg-shaped shells are studied numerically using nonlinear elastic buckling analysis. Both experimental and numerical data are presented and compared through graphs and tables.