杆状空间柔性展开机构展收动力学的时变建模与分析

Flexible Deployable Mast, which has been widely used in space applications to support antennas and solar arrays, is the key component of high-resolution earth observation satellite and space station. The dynamics of deployable mast during deployment and retraction has greatly attracted the attention of researchers, since it may fail the mission of spacecraft immediately. Dramatic process has been achieved in recent two decades on modeling flexible bodies undergoing arbitrary large three dimensional deformations. However, the calculation time of deployment or retraction for flexible deployable mast is not acceptable at all because a huge number of degrees of freedom are involved to model the flexible parts with current approach. And little study has been done on the stability and reliability of deployment and retraction. Due to this reason, this project is planning to conduct the following three studies: (1) Develop a new model method and numerical integration method to speed up the calculation time based on handling the time-varying features of deployable mast. Study the relationship between reliability of deployment or retraction and the physical and geometrical parameters of deployable mast. (2) Propose a new kind of time-varying length beam element to investigate the lateral and torsional stability. (3) Study the dynamical behavior of several typical deployable masts during deployment and retraction to reveal the key points of design. These studies will help us to understand the behavior of flexible deployable mast more thoroughly and systematically. The results may be used to help design the deployable mast which is being developed or will be developed in China. The achieved modeling approach will also provide another way to study the rigid-flexible coupled system in other research fields.

杆状柔性空间展开机构作为卫星天线和太阳翼的主要承力部件，是建造高分辨率对地观测卫星和空间站的关键部件。其在太空轨道，能否正常展开和收拢直接关系到飞行器任务的成败，故对其展收动力学的研究受到广泛关注。近年来，人们对柔性体的建模工作已取得很大成功，但用现有非时变方法研究柔性展开机构引入自由度多、求解时间长，以致对展收过程的稳定性和可靠性等问题仍缺乏深入研究。鉴于此，本课题拟开展如下三项工作：(1)发展柔性多体系统的时变建模和数值求解方法，提高计算效率并研究展收组件几何和物理参量对展收可靠性的影响；(2)发展时变梁单元，研究展收过程的侧向和扭转稳定性；(3)针对几类杆状柔性展开机构研究其展收动力学特性，揭示机构设计关键。本项目研究结果有望应用于我国正在和即将研制的杆状柔性展开机构的设计中，所发展的时变建模方法亦可用于其他柔性系统仿真中，为科学研究和工程应用提供有力的建模方法和计算工具。

大型空间可展机构是卫星天线和太阳翼的主要承力部件，是建造高分辨率对地观测卫星和空间站的关键部件。其在太空轨道，能否正常展开直接关系到巨额投资的飞行器任务的成败，故对其展开动力学的研究受到广泛关注。近年来，人们对柔性体的建模工作虽已取得很大成功，但用现有方法来建模大型复杂柔性展开机构时，引入的广义坐标数目多、求解时间长，以致对展开动力学内在特性的认识仍然十分匮乏。鉴于此，本课题重点开展了如下几项研究：（1）对绳索滑轮系统，提出了考虑摩擦的时变索建模方法，在相同的计算精度下大幅减少了计算广义坐标数，提高了计算效率。（2）开发了基于子结构建模的柔性多体系统动力学求解器及相应前后处理程序，大大简化了建模复杂系统的难度。（3）系统深入的分析了盘饶式杆状伸展臂的展开动力学特性，为我国空间站太阳翼的展开方案选型提供了重要的技术支持。（4）系统深入的分析了大型环形可展天线的展开动力学特性，获得了制约展开驱动力和部件载荷的核心因素，为我国首个大天线的设计提供了重要的理论支撑。（5）对环形天线的能效学分析指出，天线展开需要的驱动力是非线性的，初期小后期大，而传统驱动器提供的驱动力是线性的，初期大后期小。为此提出借助凸轮或非圆齿轮调制传统弹簧力输出曲线，使其更适合天线展开所需大的非线性力位移曲线。本课题发展的时变建模方法以及开发的动力学求解程序，亦可用于其他柔性系统仿真中，为科学研究和工程应用提供有力的建模方法和计算工具。提出了非线性驱动器也可用于其他工程系统中。