Elastic buckling of externally pressurized Cassini oval shells with various shape indices

This study examines the effect of shape index on the elastic buckling of Cassini oval shells under uniform external pressure. Shells are evaluated under a uniform wall thickness (2 mm) and capacity (3.63×106 mm3), with the shape index, kc=c/a, ranging from 0 to 0.99. Several numerical computations, involving linear elastic bifurcation analysis and geometrically nonlinear elastic analysis including eigenmode imperfections, are conducted for these shells. Some of them are investigated experimentally. The results show that a Cassini oval shell with a stable character seems to be an unfavorable shape due to its low load-carrying capacity, which is at variance with previous findings regarding this problem. Notably, the kc=0.1 Cassini oval geometry, exhibiting a high load-carrying capacity, appears to be a favorable shape in various fields such as underwater tanks, pressure hulls, and artificial capsules.