Reliability analysis of composite anisogrid lattice interstage structure

Abstract

Application of composite lattice structures in aerospace application can bring about considerable weight savings, thus allowing for increased payload weight. This study is devoted to reliability analysis of composite anisogrid lattice interstage structure (CALIS) used in typical launch vehicle (LV). CALIS is usually formed in to thin-walled cylindrical or conical shell via helical and circumferential ribs that can act as a lightweight load bearing support structure interfacing any two stages of the LV. Thus, the current study is of practical importance as the interstage structure is acted upon by rather high axial and bending forces emanating from LV external aerodynamics, thrust and inertial forces. As there are always uncertainties associated with the material properties, structural geometry, loading conditions as well as the manufacturing processes, CALIS is faced with stochastic load and strength characteristics. In this sense, CALIS structural reliability is of importance and is thus investigated with respect to material strength, local and global buckling via different reliability techniques. The analytical reliability results are verified against a Monte Carlo simulation and analysis. In addition, a comprehensive sensitivity analysis is performed for some of key CALIS design variables that dominantly affect its structural reliability.