...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Multibody system dynamics >Definition of the Elastic Forces in the Finite-Element Absolute Nodal Coordinate Formulation and the Floating Frame of Reference Formulation
【24h】

Definition of the Elastic Forces in the Finite-Element Absolute Nodal Coordinate Formulation and the Floating Frame of Reference Formulation

机译：有限元绝对节点坐标公式和参考公式的浮动框架中的弹力定义

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The equivalence of the finite-element formulations used in flexible multibody dynamics is the focus of this investigation. This equivalence will be used to address several fundamental issues related to the deformations, flexible body coordinate systems, and the geometric centrifugal stiffening effect. Two conceptually different finite-element formulations that lead to exact modeling of the rigid body dynamics will be used. The first one is the absolute nodal coordinate formulation in which beams and plates can be treated as isoparametric elements. This formulation leads to a constant and symmetric mass matrix and highly nonlinear elastic forces. In this study, it is demonstrated that different element coordinate systems which are used for the convenience of describing the element deformations lead to similar results as the element size is reduced. In particular, two element frames are used; the pinned and the tangent frames. The pinned frame has one of its axes passing through two nodes of the element, while the tangent frame is rigidly attached to one of the ends of the element. Numerical results obtained using these two different frames are found to be in good agreement as the element size decreases. The relationship between the coordinates used in the absolute nodal coordinate formulation and the floating frame of reference formulation is presented. This relationship can be used to obtain the highly nonlinear expression of the strain energy used in the absolute nodal coordinate formulation from the simple energy expression used in the floating frame of reference formulation. It is also shown that the source of the nonlinearity is due to the finite rotation of the element. The result of the analysis presented clearly demonstrates that the instability observed in high-speed rotor analytical models due to the neglect of the geometric centrifugal stiffening is not a problem inherent to a particular finite-element formulation. Such a problem can only be avoided by considering the known linear effect of the geometric centrifugal stiffening or by using a nonlinear elastic model as recently demonstrated. Fourier analysis of the solutions obtained in this investigation also sheds new light on the fundamental problem of the choice of the deformable body coordinate system in the floating frame of reference formulation. Another method for formulating the elastic forces in the absolute nodal coordinate formulation based on a continuum mechanics approach is also presented.
机译：柔性多体动力学中使用的有限元公式的等效性是该研究的重点。这种等效性将用于解决与变形，弹性体坐标系和几何离心刚度效应有关的几个基本问​​题。将使用两种概念上不同的有限元公式，这些公式可以对刚体动力学进行精确建模。第一个是绝对节点坐标公式，其中梁和板可以视为等参元素。这种表述导致一个恒定且对称的质量矩阵和高度非线性的弹力。在这项研究中，证明了随着元素尺寸的减小，为方便描述元素变形而使用的不同元素坐标系会产生相似的结果。特别是，使用了两个元素框架。固定和切线框架。固定框架的轴之一穿过元素的两个节点，而切线框架牢固地连接到元素的一端。发现使用这两个不同框架获得的数值结果在元素尺寸减小时具有很好的一致性。给出了绝对节点坐标公式中使用的坐标与参考公式的浮动框架之间的关系。该关系可用于从参考公式的浮动框架中使用的简单能量表达式中获得绝对节点坐标公式中使用的应变能量的高度非线性表达式。还显示了非线性的来源是由于元素的有限旋转。给出的分析结果清楚地表明，由于忽略了几何离心刚度，在高速转子分析模型中观察到的不稳定性不是特定有限元公式固有的问题。仅通过考虑几何离心刚度的已知线性效应或使用最近证明的非线性弹性模型，才能避免这种问题。在这项研究中获得的解决方案的傅立叶分析也为参考配方浮动框架中可变形体坐标系的选择这一基本问题提供了新的思路。还提出了另一种基于连续力学方法的绝对节点坐标公式中的弹力公式。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号