Numerical Analysis And Experiment Research For Sandwich Cylindrical Shell Under Combined Axial Compression-Torsion Load

As the composite is widely used in the aerospace and aeronautic structures, the stability of sandwich composite cylindrical shells subjected to combined axial compression and torsion is concerned by lots of engineers. The buckling and post-buckling properties of sandwich composite cylindrical shells under combined axial compression and torsion are studied numerically and experimentally in this thesis.Firstly, based on the finite element package ABAQUS, the postbuckling of composite cylindrical shells containing geometric imperfection subjected to compression, torsion and combined compression-torsion loads was simulated. The equilibrium paths were obtained. The influence of geometric imperfection on the compression, torsion and combined compression-torsion buckling response was analyzed in detail. The linear and non-linear finite element methods were respectively used to calculate the buckling loads under the combined compression-torsion. The results show that nonlinear buckling load is less than linear buckling load when axial compression plays a dominant role and nonlinear buckling load is larger than linear buckling load when torsion does.Secondly, the molding craft of glassfibre composite cylindrical shells was studied and experimental clamp was designed, and then the buckling experiment subjected to combined compression-torsion loads was carried out. The load vs displacement curves obtained from experiment are consistent to the postbuckling path from finite element modeling.Finally, on the basis of finite element package PATRAN/NASTRAN, the influences of elastic constant, length-radius ratio, radius-thickness ratio and the sequence of ply on the buckling loads were discussed in detail. The results would be useful for the structure designing and analysis.