Implosion behavior of sandwich ellipsoidal shells with strengthened core of variable thickness

The implosion behavior of sandwich ellipsoidal shells under external hydrostatic pressure was investigated in this study. An atypical sandwich shell structure with a strengthened core of variable thickness was designed on the basis of the constant stress principle. The inner and outer layers of this structure were fabricated from photosensitive resin by using high-precision rapid prototyping, and the core was filled with a strengthened resin that is stiffer and stronger than the photosensitive resin. To assess the structural benefits of the sandwich configuration, its ultimate bearing capacity was compared with that of a homogeneous ellipsoidal shell, which was fabricated using photosensitive resin. Three nominally identical sandwich shells and one homogeneous shell were fabricated, and their geometric dimensions and wall thicknesses were measured prior to implosion testing. Additionally, computational simulations were performed and the energy evolution was analyzed to determine the pressure and failure pattern of implosion. The results indicated that the sandwich shells had approximately 22% higher implosion pressure and 16% greater peak internal energy relative to the homogeneous shell. The use of the constant stress principle in the design of the shell structure contributes to a uniform distribution of stress across the shell, ensuring efficient material utilization. Moreover, the strengthened core of variable thickness improves the ultimate bearing capacity and energy absorption capacity of the shell.