基于虚拟单元的模态综合法

针对实验模态综合法中存在的界面对接信息不足问题,提出了具有高刚度低质量特性的虚拟单元概念,给出了其数学意义上的存在性条件,并通过参数优化方法得到了力学意义上的虚拟单元.引入虚拟单元以后,基于定频剩余动柔度的概念给出了实验模型和有限元模型的混合建模方法.数值计算表明,经过参数优化以后的虚拟单元可用于实验模态综合,综合的精度较传统的模态综合法有所下降,然而虚拟单元的意义在于给子结构之间提供更多的对接信息,有助于增加实验模态综合的可靠性.

Component mode synthesis method based on virtual elements

To solve the problem of insufficient interface information in experimental component mode synthesis (CMS) method, the concept of virtual element with high stiffness and low mass characteristics is developed. The existence conditions of the virtual element in a sense of pure mathematics are proposed. By solving a parametric optimization problem for the substructure with virtual elements the mechanical virtual elements are obtained. By using the virtual elements, a hybrid modeling technique is developed to synthesis the experimental model of substructure A and the finite element model of substructure B. The numerical example shows that the mechanical virtual elements can be used in the experimental CMS method although the accuracy of the final results will decrease with respect to the traditional CMS method. It should be pointed out that the significance of the virtual elements is that more interface informations are provided using virtual elements and these informations are helpful to construct a reliable experimental model for a substructure.