Hyper-reduction modeling and energy transfer analysis of fluid-transporting series-parallel pipes

This work proposes a parameterized hyper-reduction modeling method for the fluid-transporting series-parallel pipe systems using the improved transfer matrix method of the multi-body system (MSTMM) and FEM (FEM-IMSTMM), which can predict the dynamic stress response of pipe systems efficiently and accurately. Furthermore, a camera-based vibration test is conducted to obtain the global vibration responses of the pipe systems, followed by energy transfer analysis between pipes through structural intensity analysis. Specifically, the improvements of the improved MSTMM are twofold: firstly, pre-processing of the substructure boundaries is achieved by constructing virtual nodes and rigid binding, thus avoiding the ill-conditioned transfer matrix encountered when the MSTMM is directly applied to three-dimensional solid element models; Secondly, a state transfer matrix at parallel connections is constructed, thus extending MSTMM to parallel structures. Moreover, the FEM-IMSTMM sequentially achieves the reduction of boundary, internal, modal, and intermediate interface degrees of freedom (DOFs), and the number of DOFs of the final reduced-order model is only six times the number of pipes. Finally, the influence of series and parallel connection positions on the vibration transfer behaviors is analyzed, revealing rich vibration transfer phenomena, such as energy convection, convergence, and circulation transfer.