The theoretical derivation and frequency-domain solution for axial fluid-structure interaction vibration of thick-walled pressurized fluid-filled pipes in marine engineering were carried out. The proposed calculation method was validated by comparison with literature examples. The applicability of thick-walled and thin-walled theories was investigated using finite element method(FEM) calculation and axial fluid pressure wave speed analysis. The effects of flow velocity and internal static pressure on vibration and noise transmission of straight pipes and assembled pipes were discussed. Results show that the thick-walled theory is more accurate for calculating the vibration response of pipes with a thickness-to-radius ratio greater than 0.5; the axial fluid pressure wave speed is mainly affected by pipe material, sectional thickness-to-radius ratio, and length-to-diameter ratio; internal pressure mainly influences transverse vibration, especially lower-order frequencies, and enhances vibration transmission.

In this paper, based on the exact solution of vibration governing equations and the relationship between the displacements and forces on the boundaries, the dynamic stiffness method is proposed to analyze the vibration characteristics of aconical-cylindrical coupled structure with arbitrary boundary conditions. By changing the semi-vertex angle, the conical shell can degenerate into an annular plate, which can be used to simulate ribbed structures. The conical-cylindrical combined shell structure can alsodegenerate into an annular plate-cylindrical shell coupled structure or a cylindrical-cylindrical coupled structure. During the assembly process, it is necessary to transform the dynamic stiffness matrices of each substructure shells into a global coordinate system, utilizing the displacement continuity and internal force balance conditions on the connecting edges of the substructure shells. The correctness of the method proposed in this article has been verified through finite element models and experimental results. This article studies the influence of semi-vertex angle and arbitrary elastic boundary parameters on the natural frequencies of combined shells under different circumferential modal numbers. The research results can provide guides for the acoustic design of combined shell structures.

The double-layered cylindrical shell represents a key structural configuration for underwater vehicles, where its vibration behavior remains a primary concern in engineering design and analysis. This study develops a spectral element method (SEM) for dynamic modeling of multi-component shell systems by extending the vibrational governing equations of conical shells. The methodology is validated through finite element method (FEM) case studies on both conical shells and double-layered cylindrical configurations. Parametric investigations examine ribbed substructures and solid rib plates within the cylindrical shell assembly, while artificial spring techniques model arbitrary boundary conditions—with validation against classical benchmarks confirming their effectiveness for elastic constraints. Numerical demonstrations reveal the following: rib and plate thickness variations exhibit a negligible impact on low-frequency vibrational responses; the natural frequency sensitivity peaks when the elastic boundary stiffness approaches the inherent dynamic stiffness of the shell’s base configuration, while extreme stiffness values approximate clamped or free boundary conditions with engineering significance. The proposed SEM framework demonstrates a superior computational efficiency and accuracy compared to conventional FEM approaches. These findings deliver practical guidance for marine structural engineering, particularly in the boundary condition specifications and performance optimization of composite shell systems.

Reducing vibration and noise in fluid-filled pipeline systems is critical for enhancing the acoustic stealth of underwater vehicles. However, uncertainties inherent in the complex vibro-acoustic response and transmission of these systems render traditional deterministic methods inadequate. To address this, this paper proposes a hybrid methodology, named ISM-PCE, combining the impedance synthesis method (ISM) and polynomial chaos expansion (PCE), to efficiently estimate the low-order statistical moments of the frequency response function (FRF) of pipelines, validated by experiments and numerical simulations on homogeneous straight pipes. Results show that the normal ISM-PCE accurately estimates the mean FRF under single dimensional parameter (pipe inner diameter) uncertainty, but its variance estimation accuracy is insufficient in the resonance frequency band. Therefore, a stochastic frequency transformation method was introduced, significantly improving variance estimation accuracy and enabling successful multiple dimensional parameters uncertainty analysis. The results demonstrate that the normal ISM-PCE and its improved variant provide an efficient and accurate methodology for uncertainty quantification of vibration responses in fluid-filled pipeline systems. Although only fluid-filled straight pipes have been analyzed in this paper, the proposed methodology is generalizable and applicable to more complex fluid-filled pipeline systems.

Due to the fluid-structure interaction, external perturbation, and internal fluid, etc., the terrible vibration and noise emission in pipes conveying fluid may make the engineering structures facilitate to be instability, serious failure, and catastrophic destruction. In this work, inspired by the band gaps formation of photonic crystal (PC) and the wave attenuation in acoustic black hole (ABH), four novel types of periodic pipes conveying fluid including the unidirectional and axisymmetric ABH cells are proposed and used as basic models to analyze the mechanism of band gap formation. Considering a novel spinning two-dimensional (2D) PC model, the governing and dispersion equations of the proposed pipes conveying fluid are established based on the Timoshenko beam theory. By adopting the spectral element method (SEM) compared with the transfer matrix method (TMM), as well as introducing the Bloch theorem, the wave propagation mechanism in these spinning periodic ABH pipes conveying fluid is disclosed through investigating the frequency response, flexible wave shapes, energy transfer mode and BGs distribution. We find that, in the case of periodic pipes conveying fluid, the concentration of kinetic energy at the junction of the sub-cell can enhance Bragg scattering, which leads to the formation of band gaps (BGs), while the pass bands are generated due to the drastic variation of wave mode induced by the resonance in the strain energy. Based on the BGs mechanism, the parameter analysis is carried out to indicate the vibration suppression of the spinning periodic pipes decrease periodically with the spinning speed. More importantly, by adjusting the ABH geometric parameters, it is found that all four types of periodic pipes conveying fluid can generate lower-frequency and broader BGs, which further leads to weaken the disadvantage effect of the spinning speed on vibration self-suppression of the pipe system. Based on the above analysis of the mechanism and parameters of BG's formation, a novel vibration control method with the cooperation of the periodic structure and the ABH effect is developed. The study provides a novel design idea of the PC development in the axially moving continuum, which may be beneficial for controlling the vibration of engineering fluidconveying devices.

Fluid-filled piping system are widely used in power cooling, fuel transportation and underwater vessel, which not only produce vibration along the system, but also transmit to the connecting structure to generate noise in ambient environment. Most investigations have concentrated on either the vibration characteristics of piping systems or of combined shells separately. In this work, an analytical impedance synthesis method (ISM) is proposed to analyze the vibration characteristics of a pipe-hull coupled system, in which the hull can be simplified to a combined conical-stiffened cylindrical-hemisphere shell. The piping system is modeled by fluid-filled beams in three-dimensional configuration. Wave function and power series solution are used to describe the displacements of cylindrical and conical shell respectively. Based on exact analytical solutions, the impedance matrix of each segment is established separately and assembled in the global coordinate by displacement continuity and force balance boundary conditions. Forced responses are compared with the experimental results to verify the correctness of the method.

Fluid-filled pipelines are widely used in engineering and industry. An analysis of the frequency dynamic responses of three-dimensional pipes is presented in this paper. A general formulation is developed based on an impedance matrix transmission approach in which a T-shaped pipe system can be assembled from three straight pipes. For validation purposes, numerical results are compared with data given by finite element method (FEM) software, previous literature, and an experiment. In the experiment, the three-dimensional pipe system is suspended horizontally on spring wires and is excited in the X and Y directions. It is found that the results calculated using the proposed method match the experimental results well. A dimensionless analysis of Poisson's coupling is then carried out, and the junction coupling of the branch pipe is analyzed as a function of its angle. Through this work, it is shown that the proposed method is efficient and can be used to predict the vibration of three-dimensional pipes.

Phononic crystals with periodic structures have attracted extensive attentions, since the vibration wave propagation characteristics can be utilized for vibration control. The vibration of periodic composite cylindrical shells containing or surrounded by fluid is studied in this article. Thin shell theory and non-viscous incompressible fluid equations are applied during the modeling, and the dynamic stiffness method (DSM) is developed for solving the vibration characteristics of periodic structures. The discretization of elements is reduced to a minimum by the use of DSM, which gives rise to improvements on computation efficiency. Results show that the inclusion of fluid would narrow the frequency ranges of propagation wave bands, especially in high frequency. The unit length and material property may also affect the propagation wave bands. This periodic model may provide references for the further vibration control of cylindrical structures.

Here, to study fluid-structure coupled characteristics of braided composite liquid-filled pipeline, a 1D fluid-structure coupled dynamic model of composite pipeline was established using the transfer matrix method based on anisotropic material constitution equation, physical equation and boundary conditions. The model was degenerated into isotropic pipeline to verify calculation method, and the fluid-structure interaction verification of composite pipeline FEM software was further performed. The calculation results showed that the calculation results using the proposed method are consistent to those of the classical “4 equation” model and the finite element 3D model. After proving the correctness of the proposed model and calculation method, effects of laying angle and fiber volume fraction in composite pipeline on natural frequencies and wave number of liquid-filled pipeline were further studied. The results showed that natural frequencies of pipeline increase and its propagation wave number decreases with increase in volume fraction of reinforcement material; as laying angle increases, natural frequencies decrease, and propagation wave number in pipe wall increases; the study results can provide a reference for design and control of liquid-filled pipeline.

Abstract Two kinds of periodic composite pipes with support or dynamic vibration absorber are designed based on the theory of phononic crystals. Axial vibration and band gaps of composite fluid-filled pipe are calculated by using transfer matrix method and Bloch wave theory. The present fluid–structure interaction model and frequency domain calculation method are validated by comparing the velocity of fluid from a FEM model. The results show that the stop bands frequency of velocity responses are in good agreement with band gap. Longer length of a single cell decreases the beginning frequency and width of both two kinds’ band gaps.

In this paper, an analytical method is proposed for analyzing the dynamic behavior of cross-ply laminated combined conical–cylindrical shells. First, the exact impedance solution for each substructure is derived from the governing equations for laminated thin shells, then the total impedance matrix in the global coordinates of the combined structure with arbitrary boundary conditions is assembled by displacement continuity and force balance at the joined interface. The results for free and forced vibrations are compared and validated against published and finite-element results, and remarkable advantages in computational accuracy and efficiency of this impedance synthesis method are presented through vibration characteristics compared with the finite-element method. Finally, how the boundary conditions, semi-vertex angle, and ply angle affect the natural frequencies and dynamic responses of this joined shell is investigated.

Free and forced vibro-acoustic characteristics of fluid-filled laminated cylindrical shell under initial hydrostatic pressure are analyzed. The vibration equation of shell is based on Love's theory, and filled fluid is adopted acoustic wave equation. Initial hydrostatic pressure is introduced into shell governing equation as axial and radial direction forces. The present fluid-structure interaction model is verified by comparing the natural frequencies with those in literatures and dynamic responses with FEM results. The two results show good agreement, and on basis of this, some parameters analysis is carried out. Numerical results show that boundary condition and ply-angle have influence on natural frequencies. Hydrostatic pressure increases the stiffness of composite cylindrical shell and natural frequencies. The results of this paper could provide some suggestions for the structural design of fluid contained cross-ply laminated composite cylindrical shell.

The nonlinear, in-plane mechanics of a thin-walled honeycomb with zero Poisson's ratio under large deformation is investigated in this paper. A theoretical method for calculating in-plane tensile modulus, modified factors of linear constitutive relations of the honeycomb structures with zero Poisson's ratio is proposed based on the theory of Euler-Bernoulli beam and the bending theory of beam in large deflection, and a finite element simulation is given to validate. In addition, parametric analysis for revealing the impacts of geometrical configurations and material parameters on in-plane mechanical properties of the honeycombs have been studied systematically. These findings suggest that geometric and/or material parameters provide different contributions to the effective mechanical properties and lead to a separate design for the in-plane mechanical properties. After that, the effects of geometric and/or material nonlinearities on mechanical properties of the honeycomb structures with zero Poisson's ratio are revealed by considering the dimensionless tangent stiffness of the honeycombs.

In this paper, torsional vibration band gap properties of a fluid filled pipe were studied by using the transfer matrix method (TMM). By comparing the results obtained from the fem software, the established torsional dynamic model and the proposed method were verified. The effects of pipe wall's material and parameters of support on the torsional vibration band gap properties were analyzed. Furthermore, the relationship between torsional displacement and vibration band gaps was investigated. These attenuation regions of responses show good agreement with the frequency of Bragg band gaps. Explained the locally resonant (LR) phononic crystals (PCs) band gaps form mechanism from the point of mechanical impedance mismatch theory, the results show that the peak frequency of impedance mismatch defines the beginning of both LRs and Bragg band gaps. In essence, the locally resonant is the same as periodic support from the impedance theory. The results of this paper could give some valuable suggestions on the vibration control of the pipeline system.

Pipe systems connected to large cylindrical shells are common structures in submarines and airplanes. The vibration behavior of such structures has attracted not much attention. Based on the kinematic compatibility and force equilibrium conditions at the connection points, the main aspect of this work is to establish a dynamic model of a thin cylindrical shell coupled with a pipe system by using the impedance synthesis method. The structure is divided into a piping substructure and a cylindrical-shell substructure. Impedance formulations of the pipes and the large cylinder are based on Timoshenko beam theory and Flügge shell theory, respectively. Natural frequencies and dynamic responses are obtained by the proposed method and validated against analytical results and finite-element (FEM) simulations. The vibration spectrum of one coupled test structure was analyzed. The so-called cross impedance has a significant effect on the vibration of the coupled structure when the stiffness of the connection points is large compared to that of pipes and shell. It is shown that the impedance synthesis method is an efficient and fast (compared to FEM) tool.

This paper studies the vibration band gap characteristics of a liquid-filled composite pipeline. The transfer matrix method is used to create a one-dimensional fluid–structure interaction model of the composite pipeline from the constitutive equation, physical equations, and boundary conditions of the anisotropic material. A phononic crystal pipeline is designed with a periodic arrangement on the axial pipe wall. The method used to analyze the fluid–structure interaction of liquid-filled composite and phononic crystal pipelines is verified by comparing responses with finite-element method results. The results’ agreement demonstrates the method’s and calculation code’s correctness. Furthermore, the band gaps for an empty composite phononic crystal pipe, water hammer, and a liquid-filled pipe are calculated by Bloch vector theory, and the effects of fluid–structure interaction and the composite parameters on the three band gap characteristics are analyzed. The numerical results show that Poisson’s coupling affects the band gap at some frequency points, while the laying angle and fiber volume fraction in the composite pipe influence the band gap length and amplitude change. The research results of this paper provide a reference for the design and vibration control of liquid-filled composite pipelines.

Pipelines are designed to carry seawater with hydrostatic pressure below sea level in the ship industry. Previously conducted studies have established the FSI (Fluid–Structure Interaction) equations for thin-walled, fluid-filled pipelines based on the Timoshenko beam model; these equations now need to be modified for analyzing the vibration characteristics of thick-walled pipelines with hydrostatic pressure. The vibration of thick-walled pressurized pipes is studied in this paper. Effective and accurate numerical methods for solving vibration responses to either harmonic excitation or a random load have been developed using the spectral element method and pseudo-excitation method. It is found that the thick-walled theory and the thin-walled theory differ in axial wave transmissions. The internal pressure mainly affects the transverse vibration, which results in an increase in the natural frequencies in the lower frequency domain, an increase in the vibration transmission in the assembled pipeline, and an increase in the displacements when subjected to random loads. Using relatively thicker pipelines and introducing flexible pipes may reduce the vibration transmission when subjected to internal pressure.

There exists strong fluid-structure interaction phenomenon in fluid filled branched pipe system. In this paper, the fluid-structure interaction transfer matrix of the pipe is transformed into the impedance matrix. By using four continuous conditions of displacement, force, fluid and sound pressure at the branch node, a fluid-structure interaction calculation model of the branched pipe is established with coordinate transformation.The acoustic induced vibration and vibration power flow are compared with the results in FEM. The results show that the impedance synthesis method in this paper is simple and accurate. At the junction of branch pipe,the power flow of the elastic wave will be converted into other wave forms.

为抑制充液管路中轴向振动波传播,利用吸振器安装点处位移与轴向力连续条件,采用传递矩阵法建立充液管路带多个吸振器动力学耦合模型,与有限元计算结果对比,验证了该计算方法的正确性.计算分析了轴向波在吸振器前后的透射与反射系数,并进一步计算了吸振器周期排列时管路轴向振动带隙.研究结果表明:轴向波在吸振器共振频率全部反射,反射系数带宽随吸振器刚度与阻尼增大而变化;吸振器周期分布时,管路系统轴向振动同时存在局域共振型带隙与Bragg带隙,轴向波在局域共振型带隙内得到了有效的抑制.研究结果可为管路轴向减振、吸振器设计提供参考.

In this paper, an analytical impedance synthesis method (ISM) is proposed to analyze the vibration characteristics of a pipe-hull coupled system, in which the hull of a submarine can be simplified to a combined conical-stiffened cylindrical-hemisphere shell. Wave solution and power series solution are used to describe the displacement of cylindrical and conical shell respectively. Rib stiffened and bulkhead are modeled as annular plate and circular plate. Based on exact general solutions, the impedance matrix of each segment is established separately and assembled in the global coordinate by displacement continuity and force balance boundary conditions. Natural frequency and forced responses are compared with open literature and FEM results to verify the correctness of the method. In the numerical examples, the effects of direction of external force and stiffness of support on the forced vibration characteristics are discussed, which can provide some guides for acoustic design of pipe in submarine.