Accurate estimation of rotational frequency response functions (FRFs) is an essential element of successful structural coupling. It is well known that the experimental estimation of structural excitations is very difficult with current technology. This paper proposes a scheme to improve the performance of the frequency-based substructuring (FBS) method by estimating unmeasured FRFs, including those corresponding to rotational degrees of freedom, from a set of experimentally determined translational FRFs. More specifically, the modal parameters extracted by modal analysis (EMA) from the experimentally determined FRFs are used for model updating, modal expansion and FRF synthesis. For this purpose, an approximate modelling approach is proposed, where a simplified and approximate finite element model (ASFE) is developed and updated to accurately reproduce the experimental responses. A modal expansion basis is then constructed from the ASFE to expand the mode shapes using the system equivalent reduction and expansion process (SEREP). FRF synthesis is then used to derive unmeasured translational and rotational FRFs. The synthesised FRFs within the frequency range of interest agree well with the experimental FRFs. The synthesised full FRF matrix is then used with the FBS method to derive the response model for the coupled structure in a bottom-up modelling approach.

准确估计旋转频率响应函数 (FRF) 是成功结构耦合的基本要素。众所周知，利用现有技术对结构激励进行实验估计是非常困难的。本文提出了一种方案，通过从一组实验确定的平移频响函数中估计未测量的频响函数（包括与旋转自由度相对应的频响函数）来提高基于频率的子结构（FBS）方法的性能。更具体地说，通过模态分析（EMA）从实验确定的频响函数中提取的模态参数用于模型更新、模态扩展和频频合成。为此，提出了一种近似建模方法，其中开发并更新了简化的近似有限元模型（ASFE），以准确地再现实验响应。然后从 ASFE 构建模态展开基础，以使用系统等效缩减和展开过程 (SEREP) 来展开模态振型。然后使用频响函数合成来导出未测量的平移和旋转频响函数。感兴趣频率范围内的合成频响函数与实验频响函数非常吻合。然后将合成的完整 FRF 矩阵与 FBS 方法结合使用，以自下而上的建模方法导出耦合结构的响应模型。然后使用频响函数合成来导出未测量的平移和旋转频响函数。感兴趣频率范围内的合成频响函数与实验频响函数非常吻合。然后将合成的完整 FRF 矩阵与 FBS 方法结合使用，以自下而上的建模方法导出耦合结构的响应模型。然后使用频响函数合成来导出未测量的平移和旋转频响函数。感兴趣频率范围内的合成频响函数与实验频响函数非常吻合。然后将合成的完整 FRF 矩阵与 FBS 方法结合使用，以自下而上的建模方法导出耦合结构的响应模型。