【作者】 邓强；

【导师】 李兵；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2010， 硕士

【摘要】 在太空探索和空间站的建设中,由于受到发射器空间的限制,航天设备不可能都是以展开的状态发射到太空中,所以随着航天科技的进步,可展机构得到前所未有的发展机遇,并且在许多地方得到了实际的应用。可展机构是一类能够从折叠状态变化到展开状态,并能够形成稳定结构而承受一定载荷的机构。相对其它可展机构,空间可展桁架虽然结构比较简单,但在大型空间结构中具有更广泛的应用价值,如用于展开柔性太阳能帆板、支撑太空望远镜及合成孔径雷达等。空间可展桁架要求具有高刚性、高可靠性、大的折叠比和尽量小的质量。目前对于可展桁架的研究都是集中于等截面桁架,本课题提出一种新颖的锥形可展桁架,同等质量情况下具有更好机械性能,对于推动可展桁架的发展具有一定的意义。由于可展桁架可以转换为连续梁等效模型,本文首先分析比较了锥形梁和等截面梁的强度、刚度性能,提出设计锥形可展桁架的可行性。对锥形可展桁架进行了构型设计和驱动设计,分析了锥形可展桁架的展开折叠机理。考虑到机构的复杂性,应用螺旋理论分析了单自由度锥形可展桁架的运动度,证明了单自由度可展桁架设计的正确性。利用机构综合理论,提出三自由度可展桁架的机构方案。分析了锥形可展桁架所必须满足的几何条件和折叠率等,并提出多种锥形可展桁架的设计方案。锥形可展桁架的各个杆件的截面面积、桁架锥度等参数对桁架性能影响很大,且不易直接观察,对其优化分析可以使桁架获得最优性能。首先建立优化数学模型,然后应用有限元分析软件ANSYS参数化设计语言APDL对桁架参数化建模并进行优化分析,得出优化结果。分别比较等刚度和等质量情况下锥形可展桁架可等截面桁架的相关性能,证明了锥形可展桁架可以获得较高的质量刚度比。分析了锥形可展桁架的模态性能,得出桁架的固有频率和对应的振型,航天器的控制频率应当避开桁架的固有频率,以免发生共振。建立单自由度可展桁架实体模型,应用ADAMS对其进行运动学分析,说明了桁架的展开过程,并得到桁架展开时的位移、速度、加速度曲线。对三自由度锥形可展桁架进行运动学分析,并用MATLAB获得仿真结果。更多还原

【Abstract】 In the activity of space exploration and space station construction, equipments can not be all launched into aerospace in deployed status as the limit of rocket’s carrying capacity. Deployable structures obtain unprecedented development opportunities and have been widely applied in many areas with the advancement of related space technology. Deployable structure is the broad category of prefabricated structures that can be transformed from a closed compact or folded configuration to a predetermined expanded form of a complete stable structure capable of supporting loads. Space deployable truss is one kind of deployable structures that has simpler mechanical structure relative to other deployable structures and it is always used in large space structures. It is usually used as support structures of solar panels, space telescope and synthetic aperture radar, etc. The main technique requirements of deployable truss are high rigidity, high reliability, large stowage ratio and light weight. Current researches on space trusses are focusing on the kind of identical cross section. In this paper, a kind of truss that has tapering cross section is proposed. Tapered truss performs more excellent mechanical characters compared to normal truss. This issue will promote the development of deployable truss in a certain degree.As deployable truss can be converted to the equivalent beam model, this paper first analyzes and compares the strength and stiffness performance of tapered beam and normal beam. Then the feasibility of tapered deployable truss is discussed. Configuration and driving mechanism of developable module is devised. The extending or retracting principle of tapered mast is briefly depicted. Taking the complexity of 1-DOF (degree of freedom) tapered deployable truss into account, screw theory is adopted to analyze the degree of freedom, and the mobility is also pointed out. The result proves this design is correct. Using mechanism synthesis theory, a 3-DOF tapered deployable truss is brought out. Geometry conditions this mechanism must satisfy and stowage radio is derived.The performance of tapered deployable truss is significantly affected by cross sectional area of bars, taper of truss, etc. And it is not intuitive. Optimization analysis can make truss obtain optimum performance. After establishing optimal mathematical model, Parametric Design Language APDL of finite element analysis software ANSYS is used to model and optimize the truss. Comparison of tapered truss and consistent-cross-sectional truss on equal mass or stiffness is then implemented. The result shows that tapered truss can have higher quality truss stiffness ratio. Through modal analysis, natural frequencies and corresponding vibration mode of truss is acquired. The control frequency of spacecraft should avoid the natural frequencies of truss in order to avoid resonance. Solid model of 1-DOF tapered deployment truss is founded and kinematics analysis is analyzed with multi-system dynamic analysis software ADAMS. The simulation result gives the deployment process and displacement, velocity, acceleration curves of truss when extending. Kinematics analysis of 3-DOF tapered deployment truss is executed and the simulation results are acquired with MATLAB.更多还原