Stability of advanced grid stiffened carbon fiber/epoxy composite conical shells with novel distribution of circumferential ribs

The influence of rib non-uniform distribution on the stability of advanced grid stiffened (AGS) carbon fiber/epoxy composite conical shells was studied. Firstly, considering the non-uniform distribution of ribs on common AGS conical shells, which ultimately resulted in over safety at the small side, a novel distribution of circumferential ribs was proposed to reduce the spacing between circumferential ribs at the big side, yet to increase the spacing at the small side. Then, the tensile, bending and coupling stiffness matrices of AGS conical shells along the longitudes were deduced based on equivalent stiffness model. With the use of Donnell form of relations for shells and the minimum potential principle, the critical buckling load of typical AGS conical shells was predicted. The relative error of the present analytical model is about only 1% for typical AGS conical shells compared with FEM results, which indicates the accuracy and validity of the analytical model. Finally, a series of parameter studies were conducted. The results indicate that the optimized distribution of circumferential ribs can significantly enhance the stability of carbon fiber/epoxy AGS conical shells. The present study provides useful guideline for configuration of carbon fiber/epoxy AGS conical shells, as well as an analytical model for calculating the equivalent stiffness and buckling resistance.