Study On Triangular Prism Modular Deployable Mast And Its Folding Screw Drive Mechanism

With the deepening of space exploration,the size of the spacecraft has also increased.The spatial one-dimensional deployable mast has been widely applied in the field of space detection because of its large ratio of extensibility and high deployment stiffness.Based on the one-dimensional deployable mast in the existing space,and in view of the characteristics that the deployable mast has greater force at the root and less force at the top,several variable cross-section improvement plans for the deployable mast were proposed,and the fundamental frequency through these solutions was proposed.Gave the best choice based on the fundamental frequency.Comparing the scheme with the traditional modal vibration mode of the constant section deployable mast,the complexity of the comprehensive structure and other factors,and thus gave the basis for the scheme selection in practical application.On the basis of the traditional screw drive deployable mast deployment scheme,two modified configurations of the driving deployment scheme and expansion-screw driving deployment scheme were proposed to reduce the height of the deployable mast in the folded state and further increase the extension-deflection ratio of the deployable mast.The continuous beam equivalent of the screw driving system was analyzed.The influence of the rigidity of the screw folding hinge on the rigidity of the entire screw driving system was analyzed,and the rigidity of the screw against the stiffness of the screw was quantified.The modal analysis of the variable-section deployable mast and the equal-section deployable mast under load and no-load conditions was performed,and the difference between the natural frequency and the vibration mode of these four cases was compared.The influence of the structural parameters of the variable cross-section arm on the natural frequency was analyzed,and the sensitivity of the influence of different parameters on the natural frequency was compared.The results showed that the sensitivity of the rope diameter to the natural frequency was the highest.Taking a deployment unit of the deployable mast as a research object,the stiffness of the deployable mast support bar hinge was analyzed to figure out its influence on the stiffness of the deployment unit.Assuming that the rope was always under tension,the formulae between the axial,shearing,bending and torsional stiffness of the deployment unit and the axial and shearing stiffness of the support bar hinge are derived.Verified its correctness through finite element simulation.The prototype of the deployment unit was developed,and a preload was applied to the eccentric hinge with tooling.The stiffness of the hinge could be changed by changing the preload force.The axial,shearing,bending,and torsional stiffness of the deployment unit under different hinge stiffness were measured,and the theoretical calculation formula between the stiffness of the hinge and the stiffness of the unfolding element of the extension arm was verified.