基于Bennett机构的环形可展开桁架设计与分析

Design and Analysis of Ring-Shaped Expandable Truss Based on Bennett Mechanism

针对环形天线桁架在面对大口径卫星天线时存在柔性较大、容易引起卫星天线形变的问题,提出一种基于Bennett机构的环形可展桁架。首先,介绍空间过约束Bennett机构,通过改变Bennett机构的转动副与连杆关系,得到稳定的Bennett机构替代构型;其次,以替代构型为基本单元,构建基本单元之间的过渡机构,实现单元之间的衔接和力矩的传递,从而构建出环形可展桁架;最后,通过结构优化和仿真实验,验证了该桁架的可靠性,并与现有的三种环形桁架进行对比。结果表明,该桁架的比刚度与比模态频率均大于其它三种环形可展天线桁架,具备良好的稳定性。

To address the issue of large flexibility and potential deformation of satellite antennas when faced with large-diameter antennas,a ring-expandable truss based on a Bennett mechanism is proposed.Firstly,the overconstrained Bennett mechanism in space is introduced.By changing the relationship between the rotary pair and the linkage of the Bennett mechanism,a stable Bennett mechanism substitution configuration is obtained.Then,using the substitution configuration as the basic unit,transitional mechanisms between the basic units are constructed to achieve the connection and torque transmission between the units,thus constructing the ring-expandable truss.Finally,through structural optimization and simulation experiments,the reliability of the truss is verified and compared with three existing ring-expandable antenna trusses.The results show that the stiffness ratio and modal frequency ratio of the proposed truss are both greater than those of the other three ring-expandable antenna trusses,indicating good stability.