Shell structures are used in many applications including rail cars, aircraft fuselages and truck tanks. The present study is aimed at providing methods of analysis and solutions for a shell structure with curved corners and flat sides as shown in Fig (1). The corss-section cna be varied by varying the radii of the corners and the lengths of the flat portions. The cross-section is symmetric about the vertical axis. The present analysis is carried out for generalized plant-strain case by considering a slice at a location in the shell not within the bending boundary layer at the ends of the shell. One half of the structure is analyzed due to symmetry about the vertical axis. The shell theory assumptions are retained by the structure is modeled as a combination of rings and beams. Fig (2) show the five sections and the coordinate system used for each section. Two load conditions are considered, one being constant internal pressure due to gas storage and the next being a liquid pressure due to liqudi storage. Solutions are verified by comparison with the membrane solutions for a circular cylindrical shell with constant internal presusre. This is acheived by letting the lengths of the flat sides of Fig (1) be zero and having all the radii equal. Results are then presneted for liquid filled sandwich structure made of Aluminum Honeycomb core and Titanium Alloy (Ti6A14V) faces. in this example problem, the structure has radii equal to 40 with a face thickness of 0.4 inches each. The radial displacement at the middle point of the top beam is set equal to zero for uniquences. The other boundary conditions at the top and bottom of the section considered are derived from the symmetry of the structure. There are four sets of matching ocnditions between the three beams and two ring sections at their joints.
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