Investigation on the free vibration behavior of sandwich conical shells with reinforced cores

The free vibration behavior of sandwich conical shells with reinforced cores is investigated in the present study using experimental, analytical, and numerical methods. A new effective smeared method is employed to superimpose the stiffness contribution of skins with those of the stiffener in order to achieve equivalent stiffness of the whole structure. The stiffeners are also considered as a beam to support shear forces and bending moments in addition to the axial forces. Using Donnell's shell theory and Galerkin method, the natural frequencies of the sandwich shell are subsequently derived. To validate analytical results, experimental modal analysis (EMA) is further conducted on the conical sandwich shell. For this purpose, a method is designed for manufacturing specimens through the filament winding process. For more validation, a finite element model (FEM) is built. The results revealed that all the validations were in good agreement with each other. Based on these analyses, the influence of the cross-sectional area of the stiffeners, the semi-vertex angle of the cone, stiffener orientation angle, and the number of stiffeners are investigated as well. The results achieved are novel and can be thus employed as a benchmark for further studies.

Automated summary

In this study, the free vibration behavior of sandwich conical shells with reinforced cores was investigated using experimental, analytical, and numerical methods. A new effective smeared method was employed to determine equivalent stiffness of the whole structure. The results were validated through experimental modal analysis, finite element modeling, and considering factors such as stiffener cross-sectional area and orientation angle. The findings can serve as a benchmark for future studies.