Modal substructuring is an established subdomain of dynamic substructuring in which the handling of multi-point connections between subcomponents proves to be a problematic task. This is particularly the case with experimental models, where even small inconsistencies in the interface dynamics can greatly affect the accuracy of the substructuring process. An established solution to this problem is based on the projection of physical interface motion on the modal basis of one of the substructures. Although both the dimension and the origin of the projection basis prove to have a great impact on the accuracy of the substructuring prediction, the established procedures do not provide a general criterion for their appropriate selection. The aim of this paper is to propose an alternative weakening approach based on singular value decomposition (SVD) that enables the construction of a vector space and the establishment of a criterion for the selection of its dominant components. Considering two substructures involved in a certain step of a substructuring procedure, SVD is performed on the interface-related components of the substructures’ concatenated modal bases. The dominant left singular vectors, therefore, embody the interface dynamics of both substructures and provide a consistent orthonormal basis for the constraint-weakening process. The proposed empiric criterion for estimating the required vector-space dimension is based on the magnitude of singular values. The efficiency of the proposed methodology is presented in comparison to the established modal-constraint approach with three numerical examples and an experimental–analytical transmission simulator coupling procedure. It is shown that the proposed singular vector constraint approach in conjunction with the criterion to estimate the weakening basis size, provides a consistent and reliable substructuring procedure.

模态子结构是动态子结构的一个既定子域，其中子组件之间的多点连接的处理被证明是一个有问题的任务。实验模型尤其如此，即使界面动力学中很小的不一致也会极大地影响子结构化过程的准确性。该问题的既定解决方案基于物理界面运动在子结构之一的模态基础上的投影。Although both the dimension and the origin of the projection basis prove to have a great impact on the accuracy of the substructuring prediction, the established procedures do not provide a general criterion for their appropriate selection. 本文的目的是提出一种基于奇异值分解 (SVD) 的替代弱化方法，该方法能够构建向量空间并为其主要成分的选择建立标准。考虑到在子结构化过程的某个步骤中涉及两个子结构，对子结构的级联模态基的界面相关组件执行 SVD。因此，主要的左奇异向量体现了两个子结构的界面动力学，并为约束弱化过程提供了一致的正交基础。用于估计所需向量空间维度的建议经验标准基于奇异值的大小。所提出的方法的效率与已建立的模态约束方法相比，具有三个数值示例和实验-分析传输模拟器耦合程序。结果表明，所提出的奇异向量约束方法与估计弱化基大小的准则相结合，提供了一致且可靠的子结构化程序。