Nonlinear dynamic modelling and testing of slack tether handling system

松弛系绳处理系统的非线性动态建模和测试

• 批准号: 341917-2008
• 负责人: Zhu, ZhengHong(George)
• 金额: $ 1.31万
• 依托单位: York University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=399692
• 关键词: Nonlinear; dynamic; modelling; testing; slack

The objective of the proposed research is to develop a new simulation based tether handling technology to enhance the stability and controllability of low-tension tether systems used in the space, aeronautics, marine engineering, among others. The tether is the single load path between the control point and the rest of system. It responds to external loads by adapting its equilibrium geometry to carry the loads by tension. As a result, a tether becomes unstable and consequently the tether system becomes uncontrollable when tether tension approaches zero. The new handling system will control the tether system based on the computer prediction of tether dynamics in addition to the conventional tether tension feedback control that does not work well in the low-tension range. Most existing tether models suffer from certain limitations such as singularity arising from zero tension, high frequency oscillations due to stiffness mismatch between membrane and bending modes after the bending stiffness is included to alleviate the singularity, numerical inaccuracies resulting from large 3D rotations in the conventional finite element (FE) methods, and numerical singularity from Euler's angles. The applicant will develop a generic tether model to address these shortcomings by devising a new adaptive tether finite element using (i) variable order shape functions based on tension magnitude and (ii) a new global position vector finite element formulation. The resulting equations of motion of tethers will be treated using the modified generalized-alpha method to achieve high numerical accuracy and stability. Based on the new tether model and handling technology, the applicant will develop a nano-satellite end-of-mission deorbitor using an electrodynamic tether. Both numerical studies, using the new element and tether handling technology, and experimental investigations, using instrumented tethers, photogrammetry and digital imaging techniques, will be conducted. The work will train HQPs, add a new FE method to our knowledge, and develop a new tether handling technology leading to the development of tether systems in the space propellantless propulsion, deorbit and repositioning devices, and in the aerial-tether pickup and delivery system in aerospace.

拟议研究的目标是开发一种新的基于仿真的系绳处理技术，以提高在空间，航空，海洋工程等领域使用的低压系绳系统的稳定性和可控性。系绳是控制点和系统其余部分之间的单一载荷路径。它通过调整其平衡几何形状以通过张力承载载荷来响应外部载荷。结果，系绳变得不稳定，并且因此当系绳张力接近零时，系绳系统变得不可控。除了在低张力范围内不能很好工作的传统系绳张力反馈控制之外，新的操纵系统将基于系绳动力学的计算机预测来控制系绳系统。大多数现有的系绳模型遭受一定的限制，如奇异性所产生的零张力，高频振荡，由于刚度之间的不匹配膜和弯曲模式后，弯曲刚度，以减轻奇异性，数值不准确性所造成的大的三维旋转在传统的有限元（FE）方法，和数值奇异欧拉角。申请人将开发一种通用系绳模型，通过设计一种新的自适应系绳有限元来解决这些缺点，该自适应系绳有限元使用（i）基于张力大小的可变阶形状函数和（ii）新的全局位置矢量有限元公式。由此产生的运动方程的系绳将被视为使用修改的广义α方法，以实现高的数值精度和稳定性。根据新的系绳模型和处理技术，申请人将开发一种使用电动系绳的纳米卫星使命末端减速器。将使用新元素和系绳处理技术进行数值研究，并使用仪器系绳、摄影测量和数字成像技术进行实验研究。这项工作将培训HQP，为我们的知识增加一种新的FE方法，并开发一种新的系绳处理技术，从而开发空间无推进剂推进，脱轨和重新定位装置中的系绳系统，以及航空航天中的航空系绳拾取和递送系统。