重力对大型环形可展天线展开动力学的影响研究

GRAVITY EFFECT ON DEPLOYMENT DYNAMICS OF ASTROMESH

受限于火箭尺寸,大型星载环形天线在发射时收拢,入轨后在零重力环境下展至工作态。然而在地面实验重力环境下,克服重力的悬吊卸载系统并不能完全抵消重力场的全部影响,导致地面实验难以准确预测在轨展开动力学行为。因此,有必要借助仿真深入对比分析地面上重力加卸载展开与太空中无重力展开的动力学异同。该文基于柔性多体动力学的仿真方法,建立了天线在零重力和重力加卸载系统两种工况下的全尺寸展开动力学模型。仿真结果不但复现了地面实验的非同步展开现象,而且系统地给出了天线在整个展开历程中所有杆件载荷和驱动力的变化规律。并进一步基于能量分析,半解析地研究了重力对驱动力的影响。该文的研究不但有助于理解大型网状天线的展开动力学,为天线的机构设计、优化和地面实验设计提供技术支撑,而且提出的建模方法和得到的认识也可用于研究和理解其他大型网状天线。

Due to the limitation of rocket fairings,deployable mesh antennas have to be folded compactly for launch and then deploy on orbit under zero-gravity conditions.On ground tests,however,the suspension system used to compensate the gravity cannot eliminate all of the effects of the gravity.This makes the ground tests fail to precisely predict the deployment behaviors in space.Therefore,it is in great demand to reveal and to understand the crucial differences of deployment dynamics between zero-gravity in space and gravity with a suspension system on ground through simulations.Based on the flexible multibody method,this paper presents full-scale multibody models of a state-of-art mesh antenna,Astromesh,for the cases of both zero-gravity and gravity.Using these models,the asynchronous deployment phenomenon was repeated,in which the bays of the antenna near the motor unfold faster than the bays far from it,as observed in the ground experiment.Besides,the driving force and the internal forces of all of the struts during the entire deployment process were systematically studied.Furthermore,the energetics was proposed to semi-analytically investigate the effect of gravity on the driving force.This study can support the structural and experimental design and optimization of the Astromesh.Moreover,the presented modeling method and the obtained results are helpful for understanding the deployment dynamics of other kinds of large mesh antennas.