Dynamics Modelling of Ultra-light and Cable-Harnessed Space Structures: Theory and Experimental Validation

发射卫星系统的高成本一直是轻得多的空间结构设计的主要动机。在这方面，充气薄纱技术为轻型、可存放的卫星提供了有趣的设计，这些卫星在发射时可以压缩成几英寸厚的折叠堆栈，然后部署在数百英尺的太空中。这种超轻型技术可以为在太空中放置大型计量系统提供有前景的解决方案，覆盖范围更广，同时满足发射量和质量目标。 虽然充气结构因其轻便的设计而备受赞誉，但由于额外的部件，如太空飞行电缆，其动态性能可能会受到显著影响。在传统空间结构中，缆索与有效载荷的质量比可以高达20%；对于充气结构，由于重量小得多，这个数字将显著增加。此外，飞行程序测试表明，当结构元件被信号和电力电缆控制时，空间结构动态行为的复杂性被放大。美国空军研究实验室/VSSV也发现了这个问题，以便在卫星系统的振动建模和验证及其地面发射前测试中产生重大问题。另一方面，充气空间任务所需的高灵活性、小质量和高带宽的控制器要求建立准确的模型来预测这些结构的高阶动力学。这对于更大的结构尤其重要，因为它们在发射前不能进行全面测试。因此，本研究的一个主要目的是研究空间缆索对充气刚性结构及其主要部件如充气刚性复合材料吊杆的动力效应。这项研究建立在申请人之前的研究基础上，基于均化技术和组合动力系统方法开发新的分析模型，以更好地了解主体结构和线束之间的动态相互作用。这项研究还旨在开发具有显著更少的计算时间和更强的结合低阶振动控制算法的能力的降阶模型。通过建立分布参数模型来表征阻尼、增加空间飞行缆索引起的结构动力响应的非线性、对这些结构可能的频率相关动力学的研究以及实验模型的验证，提出了所提出的研究计划的一些新的方面和短期/长期目标。此外，拟议研究的一部分将集中于申请人对充气膜结构的形状控制的继续研究，以提高其在天线应用中的表面精度。

The high costs to launch satellite systems have been a major motivation for much lighter space structures’ designs. In this regard, inflatable gossamer technology offers interesting designs for lightweight, stow-able satellites that can be compressed into folded stacks of a few inches of thickness during launch before deployed over hundreds of feet in space. This ultra-light technology can offer promising solution for placing large metrology systems in space with improved coverage while meeting the launch volume and mass goals. While prized for their light designs, the dynamic behaviour of inflatable structures can be significantly impacted due to additional components such as space flight cables. The cables to payload mass ratio can be up to 20% in a traditional space structure; this number will increase significantly for inflatable structures due to much smaller weights. Additionally, flight program tests have shown that the complexities in dynamic behaviour of space structures are magnified when structural elements are harnessed with signal and power cables. This problem has also been identified by the US Air Force Research Lab/VSSV to impose major issues in vibrations modeling and verification of the satellite systems and their ground-based pre-launch tests. On the other hand, high flexibility, small mass, and high bandwidth controllers required for inflatable space missions mandate the need for accurate models to predict higher-order dynamics of these structures. This is particularly important for larger structures, as they cannot be fully tested prior to launch. Therefore, a major objective of the proposed research pertains to studying the dynamic effects of space flight cables on inflatable rigidizable structures and their major components such as inflatable rigidizable composite booms. This research builds on the previous research by the applicant to develop novel analytical models based on homogenization techniques and combined dynamical systems approaches to better understand the dynamic interactions between the host structures and the harnessing cables. The research is also aimed at the development of reduced-order models with significantly smaller computational time and increased ability to incorporate low-order vibrations control algorithms. Characterization of damping through the development of distributed parameter models, nonlinearities in a structure’s dynamic response due to the addition of the space flight cables, investigation of possible frequency dependent dynamics of these structure and experimental model validations present some of the novel aspects and short/long-term goals of the proposed research program. Additionally, part of the proposed research will focus on a continuation of the research by the applicant on shape control of inflatable membrane structures to improve their surface accuracy for antenna applications.