Torsional Buckling and Post-buckling of a CFC Geodetic Cylinder

Abstract

A linear buckling and large displacement non-linear finite element analysis have been used to model composite cylindrical geodetic shells. The non-linear analysis is based on the Co-Rotational formulation in which the rigid body motion is removed from the overall motion of the element. The element deformations are then measured in a local convected axes system. The finite element analysis has been compared with experimental results for the cylindrical geodetic shell under torsion. Initial linear buckling results produced errors of 30% when compared with the experimental buckling torque. The non-linear analysis did not greatly reduce this error, but it did predict the correct overall behaviour of the shell and is essential to predict the final failure load. Recent work has shown that the local joint flexibility is the dominant factor in the shell behaviour. When this is incorporated in the finite element models the error in the buckling torque is reduced to about 7%.