Nonlinear characteristics of torsional stiffness of a coilable mast with triangular section

With numerous applications coilable masts in high-precision astronomical observations, such as X-ray source observations, it is important to investigate mast stiffness. To date, there have been many studies on the bending stiffness of coilable masts, but few studies on their torsional stiffness, especially regarding the nonlinear characteristics of torsional stiffness of coilable masts under large torsional deformation. In this paper, a nonlinear analysis method is presented to examine the torsional stiffness of coilable masts with triangular sections. Based on the second-order bending buckling hypothesis of battens under large torsion deformation, the nonlinear relationship between torsional torque and torsional angle is obtained by analyzing torsional deformation and force of coilable masts. This method is used to analyze the torsional stiffness nonlinearity of a certain type of coilable mast which will be used in a practical application in the future and the results are verified by simulation and testing. The comparison results show that the error is within the acceptable range, which proves the effectiveness of the proposed method.