Dynamic modeling and stress reduction optimization of parallel pipelines based on pipe-solid element coupling

In aero-engine, spatially parallel pipelines are prone to damage under the harmonic excitation produced by rotors, thus there is an urgent need for vibration reduction research. This paper presents a finite element modeling method for parallel pipelines based on pipe-solid element coupling and performs clamp layout optimization with the objective of reducing the stress response. The modeling idea can be described as follows: the regions of the pipeline with higher stress, such as single and dual clamps and bend sections, are modeled using solid elements, while other regions are modeled using pipe elements, and the different parts are coupled together to complete the overall modeling. An optimization model is created with clamp positions as design variables and the objective function is set as reducing stress response under the resonance condition of the fundamental frequency excitation. The procedure for solving the optimization model is provided based on genetic algorithms. A case study is conducted on a parallel pipeline system with one dual clamp and four single clamps. The rationality of the created spatial parallel pipeline model based on pipe-solid element coupling is demonstrated through a constructed pipeline test system. The model is shown to provide sufficient accuracy while having higher computational efficiency compared with a full 3D solid element model. Furthermore, the stress reduction optimization is performed, and a clamp layout that minimizes the maximum resonant stress of the parallel pipeline system is obtained.