基于模态自适应的大变形多体系统动力学分析

Dynamics Analysis of Large⁃Deformation Flexible Multibody Systems Based on the Adaptive Modal Selection Method

柔性大变形系统在进行模态降阶时,若模态选取不当,会影响求解精度甚至导致求解结果发散.对此,提出了基于绝对节点坐标法(ANCF)的柔性大变形系统模态自适应选择方法.通过ANCF梁单元建立系统的动力学模型;利用全模态稀疏表示内部区域的坐标;根据Latin超立方抽样构建采样矩阵,作用于动力学方程,以减少方程的数量;以采样后的动力学方程作为约束,构造模态坐标范数优化问题;求解优化问题可以得到具有重大贡献的模态.通过两个实例表明:数值计算结果与常用方法的结果高度吻合并且求解效率显著提升.

During the modal truncation to reduce the model order of flexible multibody systems,the inappro-priate modal selection would impair the precision of dynamic responses,or even cause divergent solutions.Thus,an efficient method of adaptive modal selection based on the absolute nodal coordinate formulation(AN-CF)was proposed for large-deformation flexible multibody systems.The dynamic model for the system was es-tablished with the ANCF beam elements.The full modal sparse representation was used for the coordinates of the interior region.The sampling matrix was built through the Latin hypercube sampling to reduce the number of dynamic equations.The sparse modal coordinates’norm optimization problem was constructed with the sampling dynamic equations as constraints,to which the solution could give modes of significant contribution.Two examples show that,the numerical results are very close to the results of common methods and the com-putation efficiency markedly improves.