Research on fluid-structure interaction vibration and bandgap properties of periodic composite hydraulic pipes

This research incorporates the Bragg scattering mechanism in phononic crystal theory into fluid-structure interaction vibration suppression of hydraulic pipes. Based on steel pipes and hydraulic composite hoses, a periodic composite hydraulic pipe structure is developed, and its vibration and bandgap properties are investigated. Firstly, based on the anisotropic laminated shell theory, fluid dynamic equations and fluid-structure interaction boundary conditions, the one-dimensional fluid-structure interaction axial and transverse vibration models of the hydraulic composite hoses are derived. This model is compatible with the classical fluid-structure interaction model; specifically, when the pipe material is steel, it degenerates into the classical fluid-structure interaction 8-equation model. Secondly, the transfer matrix is constructed using the Laplace-characteristics method to solve the fluid-structure interaction model of the steel and hose-based periodic composite hydraulic pipes. By incorporating the Bloch wave vector theorem, the bandgaps and frequency response functions of the composite pipes are determined. The accuracy of the proposed method is validated by comparing the results with those from finite element simulations. On this basis, the influence of the fluid-structure interaction effect on bandgaps and vibration properties is investigated. Numerical results indicate that in the axial direction, Poisson coupling modulates the pulsation pressure and vibration wave vectors to form new bandgaps, while friction coupling has minimal impact on bandgaps but dissipates high-frequency vibration energy. In the transverse direction, the mass and inertia effects of the fluid shift the vibration bandgaps towards lower frequencies. Finally, the effects of fluid and pipe parameters on axial and transverse vibration bandgaps are examined. This research provides a novel and effective approach for vibration suppression in hydraulic pipes and offers valuable theoretical guidance for the engineering design of periodic composite hydraulic pipes.