采用绝对节点坐标法的剪式单元可展机构动力学分析

Dynamic Analysis on Deployable Mechanisms with ScissorLike Elements Using Absolute Nodal Coordinate Formulation

针对可展机构在工程实践中由于质量轻、柔度大、尺寸大等特点而暴露出展开精度低、控制复杂和运动失稳等问题,采用绝对节点坐标法(ANCF)从多柔体角度分析了构件柔性对剪式单元可展机构动态特性的影响。首先,基于绝对节点坐标法,提出了一种新型无闭锁平面梁单元;然后,考虑服役于太阳能帆板、伸展臂等空间机构的剪式单元可展机构的构型特点与运动条件,基于第一类拉格朗日方程建立了三单元可展机构动力学模型;最后,采用动力学模型分析了杆件柔性对可展机构动力学行为的影响。研究结果表明:所提出的新型单元在解决单元闭锁问题的同时,将计算效率提升了18.2%;构件柔性会导致不同构件间产生共振和谐振现象,影响可展机构的展开精度。该研究可为大型、超大型伸展臂的在轨展开提供理论参考。

For problems of low deployment accuracy,complex control,and motion instability of deployable mechanisms exposed in engineering due to the characteristics of light weight,large flexibility,and large size of components,the absolute nodal coordinate formulation(ANCF)is used to analyze the impact of component flexibility on the dynamic characteristics of deployable mechanisms with scissorlike elements from the perspective of multiple flexible bodies.Firstly,based on ANCF,a new nonlocking planar beam element is proposed.Secondly,considering the configuration characteristics and motion conditions of deployable mechanisms with scissorlike elements serving in spatial mechanisms such as solar panels and extension arms,a dynamic model for deployable mechanisms with three scissorlike elements is established using the first type Lagrange equation.Finally,the influence of rod flexibility on dynamic behaviors of deployable mechanisms is analyzed by this model.The research results show that the proposed new element improves the computational efficiency by 18.2%via solving the element locking problem,and the flexibility of components can lead to resonance of different components,affecting the deployment accuracy of deployable mechanisms.The research can provide theoretical reference for the deployment of large/ultra large extension arms in orbit.