Design And Thermal-induced Vibration Analysis Of A Circular Expandable Antenna Truss Based On Bennett Mechanism

With the rapid development of technology,there is an increasing demand for higherspeed and more accurate data transmission,leading to the trend of larger satellite antennas.However,due to the limited size of the payload compartment in launch vehicles,deployable mechanisms with large scale,high aspect ratio,high stiffness,and lightweight characteristics have become the optimal choice for satellite antenna trusses.Additionally,spacecraft frequently transition between Earth shadow and sunlight during operation,which can result in thermal-induced vibrations in large aperture antenna trusses due to the alternating effects of solar thermal radiation and non-radiative heating.These vibrations can significantly impact the precision and lifespan of satellite antennas,making the study of thermal-induced vibrations in spacecraft crucial.In this paper,a novel design method for circular expandable trusses is proposed,using the Bennett alternative configuration as the basic unit.The thermal-structural response of the circular truss is analyzed.An indirectly coupled computational approach,combining structural beam elements and thermal analysis shell elements,is employed for finite element simulation of the circular truss.This approach provides new perspectives and methods for the construction of large-scale circular expandable trusses.The main research objectives of this paper are as follows:Firstly,the over-constrained Bennett mechanism with a single degree of freedom is introduced.By changing the relationship between the rotational pair and the connecting rod in the Bennett mechanism,a stable alternative configuration of the Bennett mechanism is obtained.Using this alternative configuration as the basic unit,transitional mechanisms are constructed to connect the basic units and transfer moments,thus building a circular expandable truss.Secondly,a comparison is made between the circular truss with the Bennett alternative configuration and three other circular expandable trusses: diagonal stretching,scissor-type,and V-shaped parallel-bar type.The evaluation criteria used are stiffness ratio and modal ratio,and the influence of antenna parameters on the fundamental frequency is analyzed.Experimental results show that the Bennett alternative configuration circular truss has better stability with higher stiffness ratio and modal frequency than the other three types of circular expandable antenna trusses.Next,the thermal-structural dynamics of the circular truss are simulated using the finite element method,and the thermo-vibration response is analyzed.A finite element model of the circular truss is established,and the transient temperature field of the truss is calculated using the Fluent module.The thermal-structural indirect coupling is conducted using ANSYS software to obtain the thermo-vibration response of the truss in a vacuum environment,and a comparison is made with the diagonal stretching circular truss.Finally,the influence of the outer diameter of the expandable truss members,the aperture of the truss deployment,and the wall thickness of the truss members on the thermal-induced vibration response of the annular truss was studied separately.The simulation results show that the Bennett substitute configuration of the annular expandable truss exhibits smaller amplitude and greater structural stability under thermal loading.By increasing the diameter and wall thickness of the truss members while reducing the antenna aperture,the thermal-induced vibration amplitude can be effectively reduced,ensuring antenna accuracy.The Taguchi experiment was conducted to optimize the design parameters of the annular truss.