Revealing the combined influence of interfacial damage and nonlinear factors on the forced vibration is significant for the stability design of fluid-conveying pipes, which are usually assembled in aircraft. The nonli...Revealing the combined influence of interfacial damage and nonlinear factors on the forced vibration is significant for the stability design of fluid-conveying pipes, which are usually assembled in aircraft. The nonlinear forced resonance of fluid-conveying layered pipes with a weak interface and a movable boundary under the external excitation is studied. The pipe is simply supported at both ends, with one end subject to a viscoelastic boundary constraint described by KelvinVoigt model. The weak interface in the pipe is considered in the refined displacement field of the layered pipe employing the interfacial cohesive law. The governing equations are derived by Hamilton's variational principle. Geometric nonlinearities including nonlinear curvature, longitudinal inertia nonlinearity and nonlinear constraint force are comprehensively considered during the theoretical derivation. Amplitude-frequency bifurcation diagrams are obtained utilizing a perturbation-Incremental Harmonic Balance Method(IHBM). Results show that interfacial damage and viscoelastic constraints from boundary and foundation have an important influence on the linear and nonlinear dynamic behavior of the system.展开更多
A new model of periodic structure is proposed and analyzed.This structure is composed of an inner fluid-conveying pipe with periodic material arrangement carrying periodic arrays of outer cantilever pipes.The generali...A new model of periodic structure is proposed and analyzed.This structure is composed of an inner fluid-conveying pipe with periodic material arrangement carrying periodic arrays of outer cantilever pipes.The generalized differential quadrature rule(GDQR)method combined with the Bloch theorem is used to calculate the vibration band gaps of the structure.Results are verified by the forced vibration responses obtained using the GDQR method.Results indicate that the first two band gaps of the fluid-conveying pipe with periodic material arrangement can get close to each other and move to low frequency regions by changing the length of cantilever pipes.For high fluid velocity values in which the first band gap starts from zero frequency,since the second band is very close to the first band,this periodic structure can be used for vibration reduction over a wide band gap starting from zero frequency.Based on these results,it can be concluded that instead of increasing the total size of the periodic structure,these periodic arrays of cantilever pipes can be implemented to create a wide ultra-low-frequency band gap.Finally,verification of the GDQR method shows that it can be used as a precise numerical method for vibration analysis of the structures such as fluid-conveying pipes and moving belts.展开更多
This study investigates the dynamical behavior of two parallel fluid-conveying pipes by developing a non-planar dynamical model of the two pipes coupled with an intermediate spring. A systematic analysis is conducted ...This study investigates the dynamical behavior of two parallel fluid-conveying pipes by developing a non-planar dynamical model of the two pipes coupled with an intermediate spring. A systematic analysis is conducted to evaluate the effects of spring parameters on the non-planar vibration characteristics and buckling behaviors of the coupled system. The nonlinear governing equations are derived with Hamilton's principle,subsequently discretized through Galerkin's method, and finally numerically solved by the Runge-Kutta algorithm. Based on the linearized equations, an eigenvalue analysis is performed to obtain the coupled frequencies, modal shapes, and critical flow velocities for buckling instability. Quantitative assessments further elucidate the effects of the spring position and stiffness coefficient on the coupled frequencies and critical flow velocities.Nonlinear dynamic analyses reveal the evolution of buckling patterns and bifurcation behaviors between the lateral displacements of the two pipes and the flow velocity. Numerical results indicate that the intermediate spring increases the susceptibility to buckling instability in the out-of-plane direction compared with the in-plane direction. Furthermore, synchronized lateral displacements emerge in both pipes when the flow velocity of one pipe exceeds the critical threshold. This work is expected to provide a theoretical foundation for the stability assessment and vibration analysis in coupled fluid-conveying pipe systems.展开更多
In recent years,scholars around the world have shown increasing interest in elastic support structures,leading to significant progress in dynamic modeling techniques for pipeline systems.Although multiple analytical a...In recent years,scholars around the world have shown increasing interest in elastic support structures,leading to significant progress in dynamic modeling techniques for pipeline systems.Although multiple analytical approaches exist,engineers increasingly prioritize computationally efficient,precise low-order models for practical implementation.In order to address this need,this study develops an innovative nonlinear dynamic formulation for pipelines accounting for both foundation and boundary nonlinearities.The proposed solution methodology initiates with global mode extraction using the global mode technique,followed by a detailed implementation procedure.Model validation is conducted through a cantilever pipeline case study featuring nonlinear support conditions,where strong agreement between the proposed model's predictions and finiteelement benchmark solutions demonstrates its reliability.Subsequently,a comprehensive parametric study investigates the combined effects of foundation stiffness,boundary constraints,excitation intensity,and nonlinear interaction terms on the vibrational response of the cantilever pipe.This systematic approach yields critical insights for practical engineering designs and applications.展开更多
This study investigates the nonlinear dynamics of geometrically imperfect graphene platelet-reinforced metal foam(GPLRMF)fluid-conveying pipes under the 1:1 internal resonance condition.With simply supported boundary ...This study investigates the nonlinear dynamics of geometrically imperfect graphene platelet-reinforced metal foam(GPLRMF)fluid-conveying pipes under the 1:1 internal resonance condition.With simply supported boundary conditions,the system is subject to the combined external lateral loads and internal pulsating fluid excitations.The nonlinear dynamic model is established with the Euler-Lagrange equations and then systematically discretized via the Galerkin method.The multi-scale analysis reveals how material properties and geometric imperfections influence the internal resonance.Particular emphasis is placed on elucidating,through the modal energy analysis,the energy exchange mechanisms between the first two vibration modes.展开更多
To solve the problem of low broadband multi-directional vibration control of fluid-conveying pipes,a novel metamaterial periodic structure with multi-directional wide bandgaps is proposed.First,an integrated design me...To solve the problem of low broadband multi-directional vibration control of fluid-conveying pipes,a novel metamaterial periodic structure with multi-directional wide bandgaps is proposed.First,an integrated design method is proposed for the longitudinal and transverse wave control of fluid-conveying pipes,and a novel periodic structure unit model is constructed for vibration reduction.Based on the bandgap vibration reduction mechanism of the acoustic metamaterial periodic structure,the material parameters,structural parameters,and the arrangement interval of the periodic structure unit are optimized.The finite element method(FEM)is used to predict the vibration transmission characteristics of the fluid-conveying pipe installed with the vibration reduction periodic structure.Then,the wave/spectrum element method(WSEM)and experimental test are used to verify the calculated results above.Lastly,the vibration attenuation characteristics of the structure under different conditions,such as rubber material parameters,mass ring material,and fluid-structure coupling effect,are analyzed.The results show that the structure can produce a complete bandgap of 46 Hz-75 Hz in the low-frequency band below 100 Hz,which can effectively suppress the low broadband vibration of the fluidconveying pipe.In addition,a high damping rubber material is used in the design of the periodic structure unit,which realizes the effective suppression of each formant peak of the pipe,and improves the vibration reduction effect of the fluid-conveying pipe.Meanwhile,the structure has the effect of suppressing both bending vibration and longitudinal vibration,and effectively inhibits the transmission of transverse waves and longitudinal waves in the pipe.The research results provide a reference for the application of acoustic metamaterials in the multi-directional vibration control of fluid-conveying pipes.展开更多
The dynamics and stability of fluid-conveying corrugated pipes are investigated. The flow velocity is assumed to harmonically vary along the pipe rather than with time. The dimensionless equation is discretized with t...The dynamics and stability of fluid-conveying corrugated pipes are investigated. The flow velocity is assumed to harmonically vary along the pipe rather than with time. The dimensionless equation is discretized with the differential quadrature method (DQM). Subsequently, the effects of the mean flow velocity and two key parameters of the corrugated pipe, i.e., the amplitude of the corrugations and the total number of the corrugations, are studied. The results show that the corrugated pipe will lose stability by flutter even if it has been supported at both ends. When the total number of the corrugations is sufficient, this flutter instability occurs at a micro flow velocity. These phenomena are verified via the Runge-Kutta method. The critical flow velocity of divergence is analyzed in detail. Compared with uniform pipes, the critical velocity will be reduced due to the corrugations, thus accelerating the divergence instability. Specifically, the critical flow velocity decreases if the amplitude of the corrugations increases. However, the critical flow velocity cannot be monotonously reduced with the increase in the total number of the corrugations. An extreme point appears, which can be used to realize the parameter optimization of corrugated pipes in practical applications.展开更多
The axial fluid-induced vibration of pipes is very widespread in engineering applications.The nonlinear forced vibration of a viscoelastic fluid-conveying pipe with nonlinear supports at both ends is investigated.The ...The axial fluid-induced vibration of pipes is very widespread in engineering applications.The nonlinear forced vibration of a viscoelastic fluid-conveying pipe with nonlinear supports at both ends is investigated.The multi-scale method combined with the modal revision method is formulated for the fluid-conveying pipe system with nonlinear boundary conditions.The governing equations and the nonlinear boundary conditions are rescaled simultaneously as linear inhomogeneous equations and linear inhomogeneous boundary conditions on different time-scales.The modal revision method is used to transform the linear inhomogeneous boundary problem into a linear homogeneous boundary problem.The differential quadrature element method(DQEM)is used to verify the approximate analytical results.The results show good agreement between these two methods.A detailed analysis of the boundary nonlinearity is also presented.The obtained results demonstrate that the boundary nonlinearities have a significant effect on the dynamic characteristics of the fluid-conveying pipe,and can lead to significant differences in the dynamic responses of the pipe system.展开更多
This paper studies the vibration absorber for a fluid-conveying pipe,where the lever-type nonlinear energy sink(LNES)and spring supports are coupled to the asymmetric ends of the system.The pseudo-arc-length method in...This paper studies the vibration absorber for a fluid-conveying pipe,where the lever-type nonlinear energy sink(LNES)and spring supports are coupled to the asymmetric ends of the system.The pseudo-arc-length method integrated with the harmonic balance method is used to investigate the steady-state responses analytically.Meanwhile,the numerical solution of the fluid-conveying pipe is calculated with the Runge-Kutta method.Moreover,a special response,called the collapsible closed detached response(CCDR),is first observed when the vibration response of mechanical structures is studied.Then,the relationship between the CCDR and the main structure primary response(PR)is obtained.In addition,the closed detached response(CDR)is also observed to research the resonance response of the fluid-conveying pipe.The appearance of either the CCDR or the CDR does affect the resonance attenuation.Furthermore,the mentioned two phenomena underline that the trend of vibration responses under external excitation goes continuous and gradual.Besides,the main advantage of the LNES is presented by contrasting the LNES with the nonlinear energy sink(NES)coupled to the same pipe system.It is found that the LNES can reduce the resonance response amplitude by 91.33%.展开更多
The fluid-conveying pipes made of polymer-like materials are widely applied in engineering fields. However, the fractional dynamics of fluid-solid interaction remain unknown. In this work, the fractional dynamics of t...The fluid-conveying pipes made of polymer-like materials are widely applied in engineering fields. However, the fractional dynamics of fluid-solid interaction remain unknown. In this work, the fractional dynamics of the pipes subjected to the excitation of supporting foun- dation are studied. A new nonlinear, fractional-order dynamic model is presented. The method of multiple scales is adopted directly to solve the model for the case of primary resonances. Numerical results are presented to show the effects of fractional order, foundation vibration, and other physical parameters on the steady-state response and stability.展开更多
In this study,a coupling model of fluid-conveying pipes made of functionally graded materials(FGMs)with NiTiNOL-steel(NiTi-ST)for vibration absorption is investigated.The vibration responses of the FGM fluid-conveying...In this study,a coupling model of fluid-conveying pipes made of functionally graded materials(FGMs)with NiTiNOL-steel(NiTi-ST)for vibration absorption is investigated.The vibration responses of the FGM fluid-conveying pipe with NiTi-ST are studied by the Galerkin truncation method(GTM)and harmonic balance method(HBM).The harmonic balance solutions and the numerical results are consistent.Also,the linearized stability of the structure is determined.The effects of the structure parameters on the absorption performance are also studied.The results show that the NiTi-ST is an effective means of vibration absorption.Furthermore,in studying the effect of the NiTi-ST,a closed detached response(CDR)is first observed.It is noteworthy that the CDR may dramatically change the vibration amplitude and that the parameters of the NiTi-ST may determine the emergence or disappearance of the CDR.This vibration absorption device can be extended to offer more general vibration control in engineering applications.展开更多
An analytical model is developed to study the surface effects on the vibration behavior including the natural frequency and the critical flow velocity of fluid-conveying nanotubes embedded in an elastic medium.The eff...An analytical model is developed to study the surface effects on the vibration behavior including the natural frequency and the critical flow velocity of fluid-conveying nanotubes embedded in an elastic medium.The effects of surface elasticity and residual surface stress are accounted through the surface elasticity model and the Young-Laplace equation.A Winkler-type foundation is employed to model the interaction of nanotubes and the surrounding medium.The results show that the surface effects have more prominent influences on the nature frequency with smaller nanotube thickness,larger aspect ratio and larger elastic medium constants.Both surface layers and the elastic medium enhance the stability of nanotubes.This study might be helpful for designing the fluid-conveying nanotube devices in NEMS and MEMS systems.展开更多
The double-beam system is a crucial foundational structure in industry,with extensive application contexts and significant research value.The double-beam system with damping and gyroscopic effects is termed as the dam...The double-beam system is a crucial foundational structure in industry,with extensive application contexts and significant research value.The double-beam system with damping and gyroscopic effects is termed as the damped gyroscopic double-beam system.In such systems,the orthogonality conditions of the undamped double-beam system are no longer applicable,rendering it impossible to decouple them in modal space using the modal superposition method(MSM) to obtain analytical solutions.Based on the complex modal method and state space method,this paper takes the damped pipe-in-pipe(PIP) system as an example to solve this problem.The concepts of the original system and adjoint system are introduced,and the orthogonality conditions of the damped PIP system are given in the state-space.Based on the derived orthogonality conditions,the transient and steady-state response solutions are obtained.In the numerical discussion section,the convergence and accuracy of the solutions are verified.In addition,the dynamic responses of the system under different excitations and initial conditions are studied,and the forward and reverse synchronous vibrations in the PIP system are discussed.Overall,the method presented in this paper provides a convenient way to analyze the dynamics of the damped gyroscopic double-beam system.展开更多
Fluid-conveying pipes generally face combined excitations caused by periodic loads and random noises.Gaussian white noise is a common random noise excitation.This study investigates the random vibration response of a ...Fluid-conveying pipes generally face combined excitations caused by periodic loads and random noises.Gaussian white noise is a common random noise excitation.This study investigates the random vibration response of a simply-supported pipe conveying fluid under combined harmonic and Gaussian white noise excitations.According to the generalized Hamilton’s principle,the dynamic model of the pipe conveying fluid under combined harmonic and Gaussian white noise excitations is established.Subsequently,the averaged stochastic differential equations and Fokker–Planck–Kolmogorov(FPK)equations of the pipe conveying fluid subjected to combined excitations are acquired by the modified stochastic averaging method.The effectiveness of the analysis results is verified through the Monte Carlo method.The effects of fluid speed,noise intensity,amplitude of harmonic excitation,and damping factor on the probability density functions of amplitude,displacement,as well as velocity are discussed in detail.The results show that with an increase in fluid speed or noise intensity,the possible greatest amplitude for the fluid-conveying pipe increases,and the possible greatest displacement and velocity also increase.With an increase in the amplitude of harmonic excitation or damping factor,the possible greatest amplitude for the pipe decreases,and the possible greatest displacement and velocity also decrease.展开更多
This paper proposes a novel three-directional functionally graded(3D FG)vibration energy harvesting model based on a bimorph pipe structure.A rectangular pipe has material properties that vary continuously along the a...This paper proposes a novel three-directional functionally graded(3D FG)vibration energy harvesting model based on a bimorph pipe structure.A rectangular pipe has material properties that vary continuously along the axial,width,and height directions,and a steady fluid flows inside the pipe.Two piezoelectric layers are attached to the upper and lower surfaces of the pipe,and are connected in series with a load resistance.The output electricity is predicted theoretically and validated by finite element(FE) simulation.The complex mechanisms regulating the energy harvesting performance are investigated,focusing particularly on the effects of 3D FG material(FGM) parameters,load resistance,fluid-structure interaction(FSI),and geometry.Numerical results indicate that among several material gradient parameters,the axial gradient index has the most significant impact.Increasing the axial and height gradient indices can markedly enhance the energy harvesting performance.The optimal resistances differ between the first two modes.Overall,the maximum power is generated at lower resistances.The FSI effect can also improve the energy harvesting performance;however,higher flow velocities may destabilize the system,causing failure of harvesting energy.This research is capable of providing new insights into the design of a pipe energy harvester in engineering applications.展开更多
Presented in this paper is a precise investigation of the effect of surface stress on the vibration characteristics and instability of fluid-conveying nanoscale pipes.To this end,the nanoscale pipe is modeled as a Tim...Presented in this paper is a precise investigation of the effect of surface stress on the vibration characteristics and instability of fluid-conveying nanoscale pipes.To this end,the nanoscale pipe is modeled as a Timoshenko nanobeam.The equations of motion of the nanoscale pipe are obtained based on Hamilton＇s principle and the Gurtin-Murdoch continuum elasticity incorporating the surface stress effect.Afterwards,the generalized differential quadrature method is employed to discretize the governing equations and associated boundary conditions.To what extent important parameters such as the thickness,material and surface stress modulus,residual surface stress,surface density,and boundary conditions influence the natural frequency of nanoscale pipes and the critical velocity of fluid is discussed.展开更多
In this study,the nonplanar post-buckling behavior of a simply supported fluid-conveying pipe with an axially sliding downstream end is investigated within the framework of a three-dimensional(3 D)theoretical model.Th...In this study,the nonplanar post-buckling behavior of a simply supported fluid-conveying pipe with an axially sliding downstream end is investigated within the framework of a three-dimensional(3 D)theoretical model.The complete nonlinear governing equations are discretized via Galerkin’s method and then numerically solved by the use of a fourth-order Runge-Kutta integration algorithm.Different initial conditions are chosen for calculations to show the nonplanar buckling characteristics of the pipe in two perpendicular lateral directions.A detailed parametric analysis is performed in order to study the influence of several key system parameters such as the mass ratio,the flow velocity,and the gravity parameter on the post-buckling behavior of the pipe.Typical results are presented in the form of bifurcation diagrams when the flow velocity is selected as the variable parameter.It is found that the pipe will stay at its original straight equilibrium position until the critical flow velocity is reached.Just beyond the critical flow velocity,the pipe would lose stability by static divergence via a pitchfork bifurcation,and two possible nonzero equilibrium positions are generated.It is shown that the buckling and post-buckling behaviors of the pipe cannot be influenced by the mass ratio parameter.Unlike a pipe with two immovable ends,however,the pinned-pinned pipe with an axially sliding downstream end shows some different features regarding post-buckling behaviors.The most important feature is that the buckling amplitude of the pipe with an axially sliding downstream end would increase first and then decrease with the increase in the flow velocity.In addition,the buckled shapes of the pipe varying with the flow velocity are displayed in order to further show the new post-buckling features of the pipe with an axially sliding downstream end.展开更多
In this paper,an electrically active,ultra-thin,easy-to-implement,and tunable phononic crystal(PC)-based device is proposed to suppress excessive vibration in pipes conveying fluids.We demonstrate that this device can...In this paper,an electrically active,ultra-thin,easy-to-implement,and tunable phononic crystal(PC)-based device is proposed to suppress excessive vibration in pipes conveying fluids.We demonstrate that this device can be realized by periodic implementation of piezoelectric patches with shunt circuits on the pipe acting as PCs for vibration suppression.The mathematical model of the pipe structure is simplified to the form of the Euler Bernoulli beam,and the transfer matrix method and the finite element method are used to predict the effective bandgap.Conversion between mechanical vibration energy and electrical energy via the piezoelectric effect is observed.As a result,the pipe vibration is suppressed by combined Bragg and electroelastic bandgaps.The comparison with previous literature shows that this ultra-compact device provides a new solution for vibration and noise control in long-distance fluid-conveying pipe systems.展开更多
On the basis of finite element analysis,an eigenvalue problem is performed to examine the vibrational characteristics of a hetero-nanotube made of carbon(C)and boron nitride(BN)nanotubes in magnetic and thermal enviro...On the basis of finite element analysis,an eigenvalue problem is performed to examine the vibrational characteristics of a hetero-nanotube made of carbon(C)and boron nitride(BN)nanotubes in magnetic and thermal environment.By incorporating the assumption of nonlocal elasticity theory,the size-dependent behavior of the considered structure is also taken into account.The obtained results demonstrate that the onset of the divergence and flutter instabilities may be postponed by exploiting a hetero-nanotube rather than a uniform one composed of carbon nanotube.Moreover,it is exhibited that,in the presence of fluid flow,the mode shape configuration of nanotubes may be different from those of classical modes and therefore the later one should not be utilized in the dynamic analysis of fluid-conveying tubes.Finally,it is shown that,as the temperature decreases,the natural frequencies of the system decrease in high temperature conditions and increase for the case of room temperature.展开更多
Oscillation of fluid flow may cause the dynamic instability of nanotubes,which should be valued in the design of hanoelectromechanical systems.Nonlinear dynamic instability of the fluid-conveying nanotube transporting...Oscillation of fluid flow may cause the dynamic instability of nanotubes,which should be valued in the design of hanoelectromechanical systems.Nonlinear dynamic instability of the fluid-conveying nanotube transporting the pulsating harmonic flow is studied.The nanotube is composed of two surface layers made of functionally graded materials and a viscoelastic interlayer.The nonlocal strain gradient model coupled with surface effect is established based on Gurtin-Murdoch's surface elasticity theory and nonlocal strain gradient theory.Also,the size-dependence of the nanofluid is established.by the slip flow model.The stability boundary is obtained by the two-step perturbation-Galerkin truncation-Incremental harmonic balance(IHB)method·and compared with the linear solutions by using Bolotin's method.Further,the Runge-Kutta method is utilized to plot the amplitudefrequency bifurcation curves inside/outside the region.Results reveal the influence of nonlocal stress,strain gradient,surface elasticity and slip flow on the response.Results also suggest that the stability boundary obtained by the IHB method represents two bifurcation points when sweeping from high frequency to low frequency.Differently,when sweeping to high.frequency,there exists a hysteresis boundary where amplitude jump will occur.展开更多
文摘Revealing the combined influence of interfacial damage and nonlinear factors on the forced vibration is significant for the stability design of fluid-conveying pipes, which are usually assembled in aircraft. The nonlinear forced resonance of fluid-conveying layered pipes with a weak interface and a movable boundary under the external excitation is studied. The pipe is simply supported at both ends, with one end subject to a viscoelastic boundary constraint described by KelvinVoigt model. The weak interface in the pipe is considered in the refined displacement field of the layered pipe employing the interfacial cohesive law. The governing equations are derived by Hamilton's variational principle. Geometric nonlinearities including nonlinear curvature, longitudinal inertia nonlinearity and nonlinear constraint force are comprehensively considered during the theoretical derivation. Amplitude-frequency bifurcation diagrams are obtained utilizing a perturbation-Incremental Harmonic Balance Method(IHBM). Results show that interfacial damage and viscoelastic constraints from boundary and foundation have an important influence on the linear and nonlinear dynamic behavior of the system.
文摘A new model of periodic structure is proposed and analyzed.This structure is composed of an inner fluid-conveying pipe with periodic material arrangement carrying periodic arrays of outer cantilever pipes.The generalized differential quadrature rule(GDQR)method combined with the Bloch theorem is used to calculate the vibration band gaps of the structure.Results are verified by the forced vibration responses obtained using the GDQR method.Results indicate that the first two band gaps of the fluid-conveying pipe with periodic material arrangement can get close to each other and move to low frequency regions by changing the length of cantilever pipes.For high fluid velocity values in which the first band gap starts from zero frequency,since the second band is very close to the first band,this periodic structure can be used for vibration reduction over a wide band gap starting from zero frequency.Based on these results,it can be concluded that instead of increasing the total size of the periodic structure,these periodic arrays of cantilever pipes can be implemented to create a wide ultra-low-frequency band gap.Finally,verification of the GDQR method shows that it can be used as a precise numerical method for vibration analysis of the structures such as fluid-conveying pipes and moving belts.
基金supported by the National Natural Science Foundation of China(Nos.12325201,12272140,and 12322201)。
文摘This study investigates the dynamical behavior of two parallel fluid-conveying pipes by developing a non-planar dynamical model of the two pipes coupled with an intermediate spring. A systematic analysis is conducted to evaluate the effects of spring parameters on the non-planar vibration characteristics and buckling behaviors of the coupled system. The nonlinear governing equations are derived with Hamilton's principle,subsequently discretized through Galerkin's method, and finally numerically solved by the Runge-Kutta algorithm. Based on the linearized equations, an eigenvalue analysis is performed to obtain the coupled frequencies, modal shapes, and critical flow velocities for buckling instability. Quantitative assessments further elucidate the effects of the spring position and stiffness coefficient on the coupled frequencies and critical flow velocities.Nonlinear dynamic analyses reveal the evolution of buckling patterns and bifurcation behaviors between the lateral displacements of the two pipes and the flow velocity. Numerical results indicate that the intermediate spring increases the susceptibility to buckling instability in the out-of-plane direction compared with the in-plane direction. Furthermore, synchronized lateral displacements emerge in both pipes when the flow velocity of one pipe exceeds the critical threshold. This work is expected to provide a theoretical foundation for the stability assessment and vibration analysis in coupled fluid-conveying pipe systems.
基金supported by the National Natural Science Foundation of China(Nos.52401342 and 12572025)the Fundamental Research Funds for the Central Universities of China(Nos.D5000240076 and G2025KY05171)+1 种基金the Natural Science Basic Research Program of Shaanxi Province(No.2025JCYBMS-026)the Basic Research Programs of Taicang(No.TC2024JC36)。
文摘In recent years,scholars around the world have shown increasing interest in elastic support structures,leading to significant progress in dynamic modeling techniques for pipeline systems.Although multiple analytical approaches exist,engineers increasingly prioritize computationally efficient,precise low-order models for practical implementation.In order to address this need,this study develops an innovative nonlinear dynamic formulation for pipelines accounting for both foundation and boundary nonlinearities.The proposed solution methodology initiates with global mode extraction using the global mode technique,followed by a detailed implementation procedure.Model validation is conducted through a cantilever pipeline case study featuring nonlinear support conditions,where strong agreement between the proposed model's predictions and finiteelement benchmark solutions demonstrates its reliability.Subsequently,a comprehensive parametric study investigates the combined effects of foundation stiffness,boundary constraints,excitation intensity,and nonlinear interaction terms on the vibrational response of the cantilever pipe.This systematic approach yields critical insights for practical engineering designs and applications.
基金supported by the Shanghai Shuguang Program(No.18SG36)。
文摘This study investigates the nonlinear dynamics of geometrically imperfect graphene platelet-reinforced metal foam(GPLRMF)fluid-conveying pipes under the 1:1 internal resonance condition.With simply supported boundary conditions,the system is subject to the combined external lateral loads and internal pulsating fluid excitations.The nonlinear dynamic model is established with the Euler-Lagrange equations and then systematically discretized via the Galerkin method.The multi-scale analysis reveals how material properties and geometric imperfections influence the internal resonance.Particular emphasis is placed on elucidating,through the modal energy analysis,the energy exchange mechanisms between the first two vibration modes.
基金supported by the National Natural Science Foundation of China(Nos.11991032 and 52241103)。
文摘To solve the problem of low broadband multi-directional vibration control of fluid-conveying pipes,a novel metamaterial periodic structure with multi-directional wide bandgaps is proposed.First,an integrated design method is proposed for the longitudinal and transverse wave control of fluid-conveying pipes,and a novel periodic structure unit model is constructed for vibration reduction.Based on the bandgap vibration reduction mechanism of the acoustic metamaterial periodic structure,the material parameters,structural parameters,and the arrangement interval of the periodic structure unit are optimized.The finite element method(FEM)is used to predict the vibration transmission characteristics of the fluid-conveying pipe installed with the vibration reduction periodic structure.Then,the wave/spectrum element method(WSEM)and experimental test are used to verify the calculated results above.Lastly,the vibration attenuation characteristics of the structure under different conditions,such as rubber material parameters,mass ring material,and fluid-structure coupling effect,are analyzed.The results show that the structure can produce a complete bandgap of 46 Hz-75 Hz in the low-frequency band below 100 Hz,which can effectively suppress the low broadband vibration of the fluidconveying pipe.In addition,a high damping rubber material is used in the design of the periodic structure unit,which realizes the effective suppression of each formant peak of the pipe,and improves the vibration reduction effect of the fluid-conveying pipe.Meanwhile,the structure has the effect of suppressing both bending vibration and longitudinal vibration,and effectively inhibits the transmission of transverse waves and longitudinal waves in the pipe.The research results provide a reference for the application of acoustic metamaterials in the multi-directional vibration control of fluid-conveying pipes.
基金Project supported by the National Natural Science Foundation of China(Nos.11872044,11702192,and 11672187)the National Key Research and Development Program of China(No.2018YFB0106200)
文摘The dynamics and stability of fluid-conveying corrugated pipes are investigated. The flow velocity is assumed to harmonically vary along the pipe rather than with time. The dimensionless equation is discretized with the differential quadrature method (DQM). Subsequently, the effects of the mean flow velocity and two key parameters of the corrugated pipe, i.e., the amplitude of the corrugations and the total number of the corrugations, are studied. The results show that the corrugated pipe will lose stability by flutter even if it has been supported at both ends. When the total number of the corrugations is sufficient, this flutter instability occurs at a micro flow velocity. These phenomena are verified via the Runge-Kutta method. The critical flow velocity of divergence is analyzed in detail. Compared with uniform pipes, the critical velocity will be reduced due to the corrugations, thus accelerating the divergence instability. Specifically, the critical flow velocity decreases if the amplitude of the corrugations increases. However, the critical flow velocity cannot be monotonously reduced with the increase in the total number of the corrugations. An extreme point appears, which can be used to realize the parameter optimization of corrugated pipes in practical applications.
基金supported by the National Natural Science Foundation of China(Nos.12072181 and 12121002)the State Key Laboratory of Mechanical System and Vibration of China(No.MSV202105)。
文摘The axial fluid-induced vibration of pipes is very widespread in engineering applications.The nonlinear forced vibration of a viscoelastic fluid-conveying pipe with nonlinear supports at both ends is investigated.The multi-scale method combined with the modal revision method is formulated for the fluid-conveying pipe system with nonlinear boundary conditions.The governing equations and the nonlinear boundary conditions are rescaled simultaneously as linear inhomogeneous equations and linear inhomogeneous boundary conditions on different time-scales.The modal revision method is used to transform the linear inhomogeneous boundary problem into a linear homogeneous boundary problem.The differential quadrature element method(DQEM)is used to verify the approximate analytical results.The results show good agreement between these two methods.A detailed analysis of the boundary nonlinearity is also presented.The obtained results demonstrate that the boundary nonlinearities have a significant effect on the dynamic characteristics of the fluid-conveying pipe,and can lead to significant differences in the dynamic responses of the pipe system.
基金Project supported by the National Natural Science Foundation of China (Nos.11902203 and 12022213)the General Scientific Research Foundation of Liaoning Educational Committee (No.JYT2020035)。
文摘This paper studies the vibration absorber for a fluid-conveying pipe,where the lever-type nonlinear energy sink(LNES)and spring supports are coupled to the asymmetric ends of the system.The pseudo-arc-length method integrated with the harmonic balance method is used to investigate the steady-state responses analytically.Meanwhile,the numerical solution of the fluid-conveying pipe is calculated with the Runge-Kutta method.Moreover,a special response,called the collapsible closed detached response(CCDR),is first observed when the vibration response of mechanical structures is studied.Then,the relationship between the CCDR and the main structure primary response(PR)is obtained.In addition,the closed detached response(CDR)is also observed to research the resonance response of the fluid-conveying pipe.The appearance of either the CCDR or the CDR does affect the resonance attenuation.Furthermore,the mentioned two phenomena underline that the trend of vibration responses under external excitation goes continuous and gradual.Besides,the main advantage of the LNES is presented by contrasting the LNES with the nonlinear energy sink(NES)coupled to the same pipe system.It is found that the LNES can reduce the resonance response amplitude by 91.33%.
基金supported by the National Natural Science Foundation of China (No.11672187)the Natural Science Research Project of the Institutions of Higher Education in Anhui Province (Nos.KJ2017A114,KJ2017A106,TSKJ2016B18)+1 种基金Natural Science Foundation of Liaoning Province (201602573)the Opening fund of Key Laboratory of Mechanics,Anhui Polytechnic University (No.201607)
文摘The fluid-conveying pipes made of polymer-like materials are widely applied in engineering fields. However, the fractional dynamics of fluid-solid interaction remain unknown. In this work, the fractional dynamics of the pipes subjected to the excitation of supporting foun- dation are studied. A new nonlinear, fractional-order dynamic model is presented. The method of multiple scales is adopted directly to solve the model for the case of primary resonances. Numerical results are presented to show the effects of fractional order, foundation vibration, and other physical parameters on the steady-state response and stability.
基金Project supported by the National Natural Science Foundation of China(Nos.12272240 and12022213)。
文摘In this study,a coupling model of fluid-conveying pipes made of functionally graded materials(FGMs)with NiTiNOL-steel(NiTi-ST)for vibration absorption is investigated.The vibration responses of the FGM fluid-conveying pipe with NiTi-ST are studied by the Galerkin truncation method(GTM)and harmonic balance method(HBM).The harmonic balance solutions and the numerical results are consistent.Also,the linearized stability of the structure is determined.The effects of the structure parameters on the absorption performance are also studied.The results show that the NiTi-ST is an effective means of vibration absorption.Furthermore,in studying the effect of the NiTi-ST,a closed detached response(CDR)is first observed.It is noteworthy that the CDR may dramatically change the vibration amplitude and that the parameters of the NiTi-ST may determine the emergence or disappearance of the CDR.This vibration absorption device can be extended to offer more general vibration control in engineering applications.
基金supported by YL acknowledges China Scholarship Council(CSC)the Provost Award(University of Miami)+1 种基金the Ralph E.Powe Junior Faculty Enhancement Award(ORAU)NSF(OISE1043161)
文摘An analytical model is developed to study the surface effects on the vibration behavior including the natural frequency and the critical flow velocity of fluid-conveying nanotubes embedded in an elastic medium.The effects of surface elasticity and residual surface stress are accounted through the surface elasticity model and the Young-Laplace equation.A Winkler-type foundation is employed to model the interaction of nanotubes and the surrounding medium.The results show that the surface effects have more prominent influences on the nature frequency with smaller nanotube thickness,larger aspect ratio and larger elastic medium constants.Both surface layers and the elastic medium enhance the stability of nanotubes.This study might be helpful for designing the fluid-conveying nanotube devices in NEMS and MEMS systems.
基金Project supported by the National Natural Science Foundation of China (No. 12272323)。
文摘The double-beam system is a crucial foundational structure in industry,with extensive application contexts and significant research value.The double-beam system with damping and gyroscopic effects is termed as the damped gyroscopic double-beam system.In such systems,the orthogonality conditions of the undamped double-beam system are no longer applicable,rendering it impossible to decouple them in modal space using the modal superposition method(MSM) to obtain analytical solutions.Based on the complex modal method and state space method,this paper takes the damped pipe-in-pipe(PIP) system as an example to solve this problem.The concepts of the original system and adjoint system are introduced,and the orthogonality conditions of the damped PIP system are given in the state-space.Based on the derived orthogonality conditions,the transient and steady-state response solutions are obtained.In the numerical discussion section,the convergence and accuracy of the solutions are verified.In addition,the dynamic responses of the system under different excitations and initial conditions are studied,and the forward and reverse synchronous vibrations in the PIP system are discussed.Overall,the method presented in this paper provides a convenient way to analyze the dynamics of the damped gyroscopic double-beam system.
基金supported by the National Natural Science Foundation of China(Nos.12272211 and 12072181).
文摘Fluid-conveying pipes generally face combined excitations caused by periodic loads and random noises.Gaussian white noise is a common random noise excitation.This study investigates the random vibration response of a simply-supported pipe conveying fluid under combined harmonic and Gaussian white noise excitations.According to the generalized Hamilton’s principle,the dynamic model of the pipe conveying fluid under combined harmonic and Gaussian white noise excitations is established.Subsequently,the averaged stochastic differential equations and Fokker–Planck–Kolmogorov(FPK)equations of the pipe conveying fluid subjected to combined excitations are acquired by the modified stochastic averaging method.The effectiveness of the analysis results is verified through the Monte Carlo method.The effects of fluid speed,noise intensity,amplitude of harmonic excitation,and damping factor on the probability density functions of amplitude,displacement,as well as velocity are discussed in detail.The results show that with an increase in fluid speed or noise intensity,the possible greatest amplitude for the fluid-conveying pipe increases,and the possible greatest displacement and velocity also increase.With an increase in the amplitude of harmonic excitation or damping factor,the possible greatest amplitude for the pipe decreases,and the possible greatest displacement and velocity also decrease.
基金Project supported by the National Natural Science Foundation of China (Nos. 12372025 and 12072311)。
文摘This paper proposes a novel three-directional functionally graded(3D FG)vibration energy harvesting model based on a bimorph pipe structure.A rectangular pipe has material properties that vary continuously along the axial,width,and height directions,and a steady fluid flows inside the pipe.Two piezoelectric layers are attached to the upper and lower surfaces of the pipe,and are connected in series with a load resistance.The output electricity is predicted theoretically and validated by finite element(FE) simulation.The complex mechanisms regulating the energy harvesting performance are investigated,focusing particularly on the effects of 3D FG material(FGM) parameters,load resistance,fluid-structure interaction(FSI),and geometry.Numerical results indicate that among several material gradient parameters,the axial gradient index has the most significant impact.Increasing the axial and height gradient indices can markedly enhance the energy harvesting performance.The optimal resistances differ between the first two modes.Overall,the maximum power is generated at lower resistances.The FSI effect can also improve the energy harvesting performance;however,higher flow velocities may destabilize the system,causing failure of harvesting energy.This research is capable of providing new insights into the design of a pipe energy harvester in engineering applications.
文摘Presented in this paper is a precise investigation of the effect of surface stress on the vibration characteristics and instability of fluid-conveying nanoscale pipes.To this end,the nanoscale pipe is modeled as a Timoshenko nanobeam.The equations of motion of the nanoscale pipe are obtained based on Hamilton＇s principle and the Gurtin-Murdoch continuum elasticity incorporating the surface stress effect.Afterwards,the generalized differential quadrature method is employed to discretize the governing equations and associated boundary conditions.To what extent important parameters such as the thickness,material and surface stress modulus,residual surface stress,surface density,and boundary conditions influence the natural frequency of nanoscale pipes and the critical velocity of fluid is discussed.
基金Project supported by the National Natural Science Foundation of China(Nos.11622216,11602090,and 11672115)the Natural Science Foundation of Hubei Province(No.2017CFB429)the fundamental Research Funds for the Central Universities of China(No.2017KFYXJJ135)
文摘In this study,the nonplanar post-buckling behavior of a simply supported fluid-conveying pipe with an axially sliding downstream end is investigated within the framework of a three-dimensional(3 D)theoretical model.The complete nonlinear governing equations are discretized via Galerkin’s method and then numerically solved by the use of a fourth-order Runge-Kutta integration algorithm.Different initial conditions are chosen for calculations to show the nonplanar buckling characteristics of the pipe in two perpendicular lateral directions.A detailed parametric analysis is performed in order to study the influence of several key system parameters such as the mass ratio,the flow velocity,and the gravity parameter on the post-buckling behavior of the pipe.Typical results are presented in the form of bifurcation diagrams when the flow velocity is selected as the variable parameter.It is found that the pipe will stay at its original straight equilibrium position until the critical flow velocity is reached.Just beyond the critical flow velocity,the pipe would lose stability by static divergence via a pitchfork bifurcation,and two possible nonzero equilibrium positions are generated.It is shown that the buckling and post-buckling behaviors of the pipe cannot be influenced by the mass ratio parameter.Unlike a pipe with two immovable ends,however,the pinned-pinned pipe with an axially sliding downstream end shows some different features regarding post-buckling behaviors.The most important feature is that the buckling amplitude of the pipe with an axially sliding downstream end would increase first and then decrease with the increase in the flow velocity.In addition,the buckled shapes of the pipe varying with the flow velocity are displayed in order to further show the new post-buckling features of the pipe with an axially sliding downstream end.
基金the Natural Science Foundation of China[Grant Numbers 11972245,11672187,11902001]the China Postdoctoral Science Foundation funded project[Grant Number 2018M641643].
文摘In this paper,an electrically active,ultra-thin,easy-to-implement,and tunable phononic crystal(PC)-based device is proposed to suppress excessive vibration in pipes conveying fluids.We demonstrate that this device can be realized by periodic implementation of piezoelectric patches with shunt circuits on the pipe acting as PCs for vibration suppression.The mathematical model of the pipe structure is simplified to the form of the Euler Bernoulli beam,and the transfer matrix method and the finite element method are used to predict the effective bandgap.Conversion between mechanical vibration energy and electrical energy via the piezoelectric effect is observed.As a result,the pipe vibration is suppressed by combined Bragg and electroelastic bandgaps.The comparison with previous literature shows that this ultra-compact device provides a new solution for vibration and noise control in long-distance fluid-conveying pipe systems.
文摘On the basis of finite element analysis,an eigenvalue problem is performed to examine the vibrational characteristics of a hetero-nanotube made of carbon(C)and boron nitride(BN)nanotubes in magnetic and thermal environment.By incorporating the assumption of nonlocal elasticity theory,the size-dependent behavior of the considered structure is also taken into account.The obtained results demonstrate that the onset of the divergence and flutter instabilities may be postponed by exploiting a hetero-nanotube rather than a uniform one composed of carbon nanotube.Moreover,it is exhibited that,in the presence of fluid flow,the mode shape configuration of nanotubes may be different from those of classical modes and therefore the later one should not be utilized in the dynamic analysis of fluid-conveying tubes.Finally,it is shown that,as the temperature decreases,the natural frequencies of the system decrease in high temperature conditions and increase for the case of room temperature.
基金supported by the National Natural Science Foundation of China(Grant No.52172356)Hunan Provincial Innovation Foundation for Postgraduate(Grant No.CX20210384).
文摘Oscillation of fluid flow may cause the dynamic instability of nanotubes,which should be valued in the design of hanoelectromechanical systems.Nonlinear dynamic instability of the fluid-conveying nanotube transporting the pulsating harmonic flow is studied.The nanotube is composed of two surface layers made of functionally graded materials and a viscoelastic interlayer.The nonlocal strain gradient model coupled with surface effect is established based on Gurtin-Murdoch's surface elasticity theory and nonlocal strain gradient theory.Also,the size-dependence of the nanofluid is established.by the slip flow model.The stability boundary is obtained by the two-step perturbation-Galerkin truncation-Incremental harmonic balance(IHB)method·and compared with the linear solutions by using Bolotin's method.Further,the Runge-Kutta method is utilized to plot the amplitudefrequency bifurcation curves inside/outside the region.Results reveal the influence of nonlocal stress,strain gradient,surface elasticity and slip flow on the response.Results also suggest that the stability boundary obtained by the IHB method represents two bifurcation points when sweeping from high frequency to low frequency.Differently,when sweeping to high.frequency,there exists a hysteresis boundary where amplitude jump will occur.
