Buckling Pressures on Shallow Spherical Sandwich Shells Made of Fiberglass Fabric (2)
Alternatively, the inner chamber would be filled with fluid with the outer chamber remaining filled with gas. By initially pressurizing both chambers equally, a load on the shell could be developed by the differential pressure due to controlled bleeding of the fluid inside the inner chamber fiberglass fabric, while the gas in the outer chamber was maintained at the initial pressure. This is an accurate volume control experiment and this testing procedure was termed hard. In the latter case, it was possible to monitor the displacements of the shell for each load increment with a nest of clip gages of an unique design. It was found that there is no substantial difference in the buckling loads between the hard and soft systems. All shells buckled in the plastic range. A reasonably good correlation is obtained with a linear theory using the double modulus for the sandwich segments.