薄壁弹药机械臂的柔性动力学建模与辨识研究

Flexible dynamics modeling and identification of thin-walled ammunition manipulator

薄壁结构是机械设计中常用的结构形式,其柔性动力学问题一直是工程研究的前沿。针对具有薄壁结构特性的弹药机械臂,发展了一种基于板壳理论的弹药机械臂柔性多体动力学建模方法.我们在浮动参考坐标框架下,得到了Reissner-Mindlin壳结构的运动学方程,其中结构膜变形和弯曲变形与刚性运动的耦合,这是区别于实体结构的特点。为了克服壳体单元模拟中的膜锁定和剪切锁定问题,引入一种基于边中心的应变平滑DSG(ECSS-DSG)单元对结构离散.该方法可以获得更好的膜变形和弯曲变形行为,并且有效克服剪切自锁问题,在结构模态分析中表现出更好的效果.在此基础上,结合实验对弹药机械臂模型参数进行了辨识,并且对辨识模型在各种工况下的动态响应进行了验证,证明了本文方法具有良好的鲁棒性.本文的工作不仅可以为弹药机械臂的进一步研究提供理论支撑,而且可以为薄壁结构多体系统的动力学研究提供参考.

Thin-walled structures are commonly used in the design of mechanical systems,and their flexible dynamic problems are the frontiers in engineering research.In this paper,a flexible multibody system modeling method based on the shell theory is firstly developed for the dynamics of ammunition manipulator with thin-walled structure.We obtained the kinematic equation of the Reissner-Mindlin shell structure based on the floating frame of reference formulation.The coupling of membrane deformation and bending deformation with rigid motion is integrated in the proposed model,which is the characteristic of Reissner-Mindlin shell different from solid structure.In order to overcome membrane-locking and shear-locking problems in shell element simulation,an edge-center based strain smoothing-discrete shear gap(ECSS-DSG)element is introduced.The ECSS-DSG method achieves better membrane and bending behavior,as well as effectively overcoming shear-locking.Accordingly,the ECSS-DSG shows better performance in the structural analysis.Based on these works,the parameters of the ammunition manipulator model are identified by combining with experimental results.Subsequently,the prediction of model dynamic response under various working conditions is verified,which shows its excellent robustness.Our research can not only provide theoretical support for the further study of the ammunition manipulator,but also provide reference for the study of the dynamics of multibody system with thin wall structure.