Coupled Vibration Analysis Research Articles

Coupling vibration analysis of high-speed maglev train-viaduct systems with control loop failure

Coupling vibration analysis of high-speed maglev train-viaduct systems with control loop failure

CFD-FEM Analysis of Flow-Induced Vibrations in Waterjet Propulsion Unit

This paper investigates the problem of vibration in an axial flow waterjet propeller with high power density and low specific speed. Based on fluid–structure coupling vibration analysis, combined with modal analysis and ship tests, the unsteady fluid–structure coupling of a waterjet propeller is examined, and the vibration characteristics of the propeller under different speed conditions are studied. The results show that the vibrations of the waterjet propeller mainly come from the frequency response of the rotor and the structural resonance response. The frequency distribution characteristics and amplitude intensity are observed to increase with increasing rotation speed. The variations in the propeller vibration characteristics, with respect to parameter changes, are analyzed at different gap spacings between the rotor and stator, allowing the variation law of vibration intensity with rotor stator spacing to be obtained.

Dynamic Analysis of Wind–Vehicle–Bridge Systems: An Advanced Hybrid Method

To investigate the dynamics of the wind–vehicle–bridge (WVB) system in the multi-body dynamics framework, which avoids the large computation cost of programming the motion equation of complex vehicle models and improves the calculation efficiency, an advanced hybrid method is proposed to optimize the WVB system coupling vibration analysis model. The dummy body coupling (DBC) method is integrated to build the connection between the MBS and the FE model, which cannot change the mechanical characteristics of the MBS vehicle model and the bridge FE model. The proposed method makes full use of the high efficiency of the established structure modeling, the powerful wheel–rail analysis function, and vehicle modeling in the multi-body dynamics framework. The complex bridge is modeled by a number of elements to reflect the actual dynamic characteristics of structure, which cannot satisfy the requirement of calculation in the multi-body dynamics framework. Thus, to avoid forming the wheel–rail relationship function, the bridge modeling as a finite element model would be transferred into multi-body dynamics coupling model of the WVB system as a flexible body. The verification of the relationship among the sub-systems of the multi-body model of the WVB system is investigated by analysis of the wind–vehicle, wind–bridge, and vehicle–bridge sub-systems. Finally, a dynamic analysis of the WVB system based on the proposed method is carried out for a double-track railway continuous bridge, in which the effects of different vehicle speeds and the incoming wind directions are studied. The simulation of the WVB system by the hybrid method has a high computational efficiency and strong practicability.

Dynamic modelling of gearbox with multiple localized defects and its coupled vibration analysis

Gearboxes are one of critical components of railroad vehicles, aero-engines and other rotating machinery, and their health condition is crucial for the safe operation of these rotating machines. Fault signature extraction is a vital step for gearbox health condition monitoring. To this end, knowing the characteristics of fault signature is a prerequisite. Dynamic model is an effective tool for analysing the fault features of gearbox. However, in reality, the vibrations measured from the gearbox housing are usually coupled with the vibrations of the rolling bearings, the gear mesh and the gearbox housing, which are influenced by the friction, lubrication, surface roughness, etc., of each contact pair. Consequently, any dynamic model of individual components cannot accurately reflect the actual vibration behavior of the gearbox and also the resulted vibration response cannot match the vibrations measured from the gearbox housing. To resolve this problem, this paper develops a comprehensive dynamic model to analyze the vibration response of a gearbox with multiple localized defects by coupling the effects of spur gear mesh, deep groove ball bearings, time-varying displacement excitation of the bearing caused by localized defects, time-varying mesh stiffness (TVMS) of the gear, and mixed elastohydrodynamic (EHD) lubrication. The coupled vibrations of the gearbox housing can then be obtained to analyze the vibration behavior of a gearbox with multiple localized defects. In addition, the influences of the relative motion of the bearing rollers and flexible cage on the gearbox vibration are analyzed. At last, the proposed dynamic model is validated by experiments.

Veering of frequency loci and nonlinear coupling vibration analysis between traveling waves of rotational hard-coated cylindrical shells

The studies on the veering of frequency loci and coupling forced vibration between traveling waves of rotational hard-coated cylindrical shells have been rarely found in previous papers, especially in the presence of the strain-dependent property of coatings. This paper establishes the semi-analytical model of rotational hard-coated cylindrical shells by utilizing Sanders’ shell theory and the Lagrange equation. The non-uniform arc constraint is presented to characterize the boundary of bolted shells through reforming the traditional uniform and continuous constraint. A unified method based on the region division approach is developed to introduce the strain-dependent property of coatings in the rotational state. Moreover, a general and effective algorithm for solving the nonlinear equation with strain-dependent property is developed. The convergence of the region division approach is evaluated. Combined with the FEA, published papers, modal test, and nonlinear response test, the accuracy of the present model in calculating the natural characteristics and nonlinear response with the strain-dependent property is validated. Further, the mechanism of nonlinear traveling-wave vibration is analyzed. The essence of veering for frequency loci and vital rules of nonlinear traveling-wave coupling vibration are revealed.

Coupled vibration analysis of partially liquid-filled cylindrical shell considering free surface sloshing

In this paper, a semi-analytical method is proposed to analyze the dynamic behavior of horizontal cylindrical shells partially filled with liquid, considering the sloshing effect of the free surface. Two coordinate systems are set at the midpoint of the free liquid surface and the geometric center of the cylindrical shell’s cross-section, respectively. The internal fluid is an inviscid, irrotational, and incompressible fluid. The liquid potential functions which satisfy the Laplace function are described in the anti-symmetrical/symmetrical forms based on the liquid surface coordinate system. Meanwhile, the coupled motion functions of the shell are established on the structural coordinate system using the Flugge shell theory. Through the continuous condition on the internal wet surface, the coupled system’s governing equations are achieved and solved by the coordinate transformation and the Galerkin method. The fluid sloshing frequencies and the coupled vibration frequencies of the shell are simultaneously obtained in this coupled model. The accuracy of this method is verified by the published data and the finite element method. Furthermore, the influences of the coupled system’s parameters on the shell’s natural frequencies and sloshing frequencies are discussed, and the coupling effect is revealed between the shell’s vibration and the sloshing of the free surface.

Simulation Analysis of Coupled Structural Vibration of Highway Railway Combined Bridge Induced by Overlapping Action of Vehicle and Train

In order to study the dynamic response of bridge coupling caused by the overlapping of vehicle and railway dynamic loads, by using the time-domain samples of pavement irregularity compiled by MATLAB software and the secondary development function of ANSYS software, the vehicle, bridge, and train models are established in ANSYS software at the same time, and the train supported beam bridge coupling program is compiled with MATLAB software. The model considers the influence of initial conditions and vehicle speed on the system before entering the bridge, the interaction between the coupled large-scale highway and railway bridge system, and the influence of different adverse factors on the system. The influence of a vehicle or train on the bridge structure when the vehicle or train passes through the continuous steel truss bridge under different factors is calculated, respectively, and the displacement and acceleration limits of the bridge are evaluated in combination with the corresponding specifications.

Vibration analysis of the continuous beam bridge considering the action of jump impacting

In the existing vehicle-bridge coupling vibration analysis, the vehicle model was mostly coupled with the bridge node by interpolation methodology, therefore, it was difficult to accurately consider the bridge vibration response under the condition of vehicle-bridge separation. In order to further study the effect of vehicle jumping impact on the vehicle-bridge coupling vibration system, a model which can describe the vehicle jumping impact process is established based on a designed integrated simulation platform with the interface contact algorithm. The effects of jumping impact on wheel contact force and bridge vibration displacement response were studied under two parameters including jumping height and vehicle speed. The simulation results show that the vehicle-bridge coupling vibration considering the action of the vehicle jump impacting can be effectively analyzed and the wheel contact forces/displacements are significantly affected by the jumping height.

Thermoelastic coupling vibration analysis of precision coated TPU film

TPU (thermoplastic polyurethane) films are subjected to heating in production. As the temperature rises, thermal stress will be generated inside the TPU film. It causes defects, such as wrinkles and cracks, in the moving TPU film; therefore, it is of great significance to study the thermoelastic coupling effect of the moving TPU film in the printing process. To study the thermoelastic coupling vibration characteristics of the moving TPU film under the opposite edge tension, it includes combining the thermal conduction equation with temperature coupling term and the vibration differential equation with variable temperature effect to get the coupling equation. The differential quadrature method is used to discretize the vibration differential equation. The influence of the thermoelastic coupling coefficient, aspect ratio, and tension ratio on the vibration characteristics of the TPU film is studied.

Coupling Vibration Analysis of Turbine Shared Support Rotor-Bearing System with Squeeze Film Dampers

The turbine shared support structure is used widely in aeroengines, but theoretical and experimental research on a rotor-bearing system containing a shared turbine support structure is lacking. This paper reports research into the coupling vibration response of a squeeze-film-damper rotor-bearing system that has two spools with different rotation speeds and is supported by a turbine shared support structure. The problem is addressed by means of experimental tests and the finite-element method. Based on the features of a turboshaft engine with a turbine shared support structure, a rotor-bearing test system with a shared support structure and squeeze film damper is designed, and a finite-element model of the test system is built based on Timoshenko beam elements. The experimental and simulation results indicate that the unbalanced response of the rotor-bearing system with a shared support structure may involve either the sum or difference of the fundamental frequencies of the rotors of the gas generator and power turbine. The simulations show that the unbalance of the power turbine rotor, the radial and bending stiffnesses of the shared support structure, and the radial clearances of squeeze film dampers at the shared support structure of the rotor-bearing system all affect the coupling response. The amplitude of the coupling response can be suppressed effectively by (i) selecting reasonable parameter values for the turbine shared support structure and (ii) exerting strict control over the spool unbalance.

An Original 2-D Analytical Model for Investigating Coupled Vibrations of Finite Piezoelectric Resonators.

This article deals with 2-D modeling of coupled vibrations of finite piezoelectric resonators. A general solution for all the physical quantities in the Cartesian and cylindrical coordinate systems is deduced from the governing equations by expansion in series summation of trigonometric functions of thickness coordinate and trigonometric or Bessel functions of the lateral one. The essential difference between this model and the earlier ones is that instead of expressing mainly in the thickness coordinate and integration through the thickness, the solutions are expressed in the form of double Fourier series augmented by single Fourier or Fourier-Bessel series, which contributes to better satisfy the mechanical and electrical boundary conditions. The dynamic stiffness matrix of the system is developed. Electrical impedances of a typical piezoelectric parallelepiped under stress-free and symmetrical loading conditions and its frequency spectrum for different width-to-thickness ratios are calculated using our model as well as by the finite element method. A comparison shows an excellent agreement. Finally, theoretical and measured electrical impedances of a piezoelectric parallelepiped and a piezoelectric disk are compared and discussed. The 2-D theoretical model proposed here is shown to be accurate and efficient for coupled vibration analysis of piezoelectric resonators and is applicable for any set of finite dimensions and crystal symmetry.

Fluid–Vehicle–Tunnel Coupled Vibration Analysis of a Submerged Floating Tunnel Based on a Wake Oscillator Model

Abstract The submerged floating tunnel (SFT) is a newly developed traffic structure for crossing the long waterway. On the basis of the vehicle–tunnel coupled vibration, the vortex-induced effect o...

Reinforcement Effect Evaluation on Dynamic Characteristics of an Arch Bridge Based on Vehicle-Bridge Coupled Vibration Analysis

To numerically evaluate the reinforcement effect on dynamic characteristics of a concrete-filled steel tube arch bridge with vibration problems, a 12-degree-of-freedom sprung-mass dynamic vehicle model and a 3D finite element bridge model were established. Then, the coupled equations of vehicle-bridge interaction were derived and a computer program was developed using the FORTRAN language. This program can accurately simulate vehicle-bridge coupled vibration considering the bumping effect and road surface irregularity during motion of the vehicle. The simulated results were compared with those of relevant literatures to verify the correctness of the self-developed program. Then, three reinforcement schemes for the bridge (Addition of longitudinal beams, Reinforcement of bridge decks, and Replacement of suspenders) were proposed and numerically simulated, and the vibration reduction effects of the three schemes were evaluated based on the numerical results to find effective ones. It is confirmed that the reinforcement scheme of Addition of longitudinal beams shows the most significant vibration reduction effect. It is recommended in the engineering practice that the combination of the reinforcement schemes of Addition of longitudinal beams and Replacement of bridge deck can be used to solve the excessive vibration problem.

Coupled vibration analysis of fluid-filled baffled tank equipped with Kirchhoff plate

In the present paper, free coupled vibration of partially fluid-filled baffled tank equipped with elastic thin plate is studied by a variational fluid-domain-decomposition scheme, focusing on obtaining the analytically approximate coupled plate bulging and fluid sloshing modes. Different types of fluid-coupled elastic thin plates are considered: partially submerged elastic baffle, elastic baffle partially covering the free fluid surface, immersed elastic baffle, and elastic thin plates forming the tank wall. The elastic thin plate is modeled by the Kirchhoff plate, and the lateral plate deflection is approximated using the summation of its dry (in vacuum) modes multiplied by unknown weight coefficients. The baffled tank is partially filled with a fluid having multi free surface and assumed to be inviscid, incompressible, and irrotational. The present scheme is based on a variational principle related to free linear vibration of the thin elastic plates coupled with bounded multi-layer immiscible fluid. The eigenfrequency equation of the coupled plate–fluid system obtained by the present scheme has a much more unified and compact form when compared with the previous domain-decomposition scheme employing the Rayleigh–Ritz method or the Galerkin method. This is realized by constructing the variational formulation of the coupled plate–fluid problem expressed in differential form. The convergence and accuracy of the present scheme are studied for both convex and non-convex liquid domains. The results from the present scheme agree well with published numerical or experimental results.

Vehicle-Bridge Coupling Vibration Analysis for Simply Supported Girders of High-Speed Railway Bridges Based on the Cross-Sectional Decentralized Centre of Mass and Shear

Taking the simply supported box girder bridge of high-speed railway as an example, the effect of cross-sectional decentralized centre of mass and shear on the spatial beam element stiffness matrix was theoretically derived. Based on the vehicle-bridge coupling vibration analysis method of the railway bridge, an analysis program of vehicle-bridge coupling vibration for the high-speed railway was compiled, and its reliability was verified through an example analysis. On this basis, considering the cross-sectional decentralized centre of mass and shear, the influence factors of vehicle-bridge coupling vibration response were studied, which included the offset distance of the beam section’s mass and shear centre, offset distance of track centreline, vehicle weight, and vehicle speed. The results show that the additional items of the spatial beam element stiffness matrix are generated by the torsion effect when the cross-sectional decentralized centre of mass and shear is considered, and it will affect the lateral and vertical stiffness of the element. The cross-sectional decentralized centre of mass and shear has a significant effect on the lateral dynamic response of the bridge’s mid-span, but the influence on the vertical response of the bridge and the dynamic response of the car body is small. The main influence factors of the lateral dynamic response of the bridge are the vertical offset distance of the beam section’s centre of mass and shear, the lateral offset distance of the track centreline, and the vehicle weight.

Theoretical and Numerical Analysis of Coupled Axial-Torsional Nonlinear Vibration of Drill Strings

Based on a lumped parameter model with two degrees of freedom, the periodic response of the coupled axial-torsional nonlinear vibration of drill strings is studied by HB-AFT (harmonic balance and alternating frequency/time domain) method and numerical simulations. The amplitude-frequency characteristic curves of axial relative displacement and torsional relative angular velocity are given to reveal the mechanism of bit bounce and stick-slip motion. The stability of periodic response is analyzed by Floquet theory, and the boundary conditions of bifurcation of periodic response are given when parameters such as nominal drilling pressure, angular velocity of turntable, and formation stiffness are varied. The results show that the amplitude of the periodic response of the system precipitates a spontaneous jump and Hopf bifurcation may occur when the angular velocity of the turntable is varied. The variation of parameters may lead to the complex dynamic behavior of the system, such as period-doubling motion, quasiperiodic motion, and chaos. Bit bounce and stick-slip phenomenon can be effectively suppressed by varying the angular velocity of turntable and nominal drilling pressure.

Study on the Coupled Vibration Characteristics of a Two-Stage Bladed Disk Rotor System

This paper conducts a coupled vibration analysis of a two-stage bladed disk rotor system. According to the finite element method, the bladed disk rotor system is established. The substructure modal synthesis super-element method (SMSM) with a fixed interface and free interface is presented to obtain the vibration behaviors of the rotor system. Then, the free vibration results are compared with the ones calculated by the cyclic symmetry analysis method to validate the analysis in this paper. The results show that the modes of the two-stage bladed disk not only include the modes of the first- and second-stage bladed disk, but also the coupled modes of the two-stage bladed disk.

Accurate coupled vibration analysis of a piezoelectric array element by the superposition method

In this paper, the superposition method is extended to obtain analytical solutions for the coupled vibration of a piezoelectric slender bar in a configuration corresponding to a typical ultrasonic linear array transducer element. The problem can be described mathematically by three partial differential equations with electrical and mechanical boundary conditions. To solve this, the vibrations in lateral and thickness directions are referred to as two building blocks. In each building block, the expressions of displacements and electric potential are assumed first based on their symmetry properties and then the induced dynamic responses, such as in-plane stress and electric displacements, are calculated. Finally, the vibration responses of the two building blocks are superimposed to satisfy the boundary conditions using Fourier series expansions. Electrical impedance and mode shapes, represented by the spatial distribution of displacements and electric potential, are calculated analytically and compared with the results of the finite element method. An excellent agreement is observed. The method can be applied to design and optimize piezoelectric array transducers for various applications.

Analysis of Coupled Vibration and Swing Characteristics of Bridge Crane

The vibration of the crane bridge structure and the swing of the load will cause fatigue damage to the bridge structure and affect the precise positioning of the load. The moving mass constituted by the load, the crane trolley and the flexible main girder is passed through the multi-body rigid-flexible coupling dynamics system of the bridge, and the virtual prototype of the physical model is established. The influence of the swing Angle of the load on the vibration of the main girder, the influence of the running speed of the crane trolley on the vibration of the main girder and the vertical displacement of the running trolley is simulated and analyzed. The simulation results show that the running speed of the crane car affects the vibration frequency of the bridge structure, and has little effect on the vertical displacement of the crane car. The load swing affects the vibration amplitude of the bridge structure and the vertical displacement of the crane trolley. The vibration of the main beam structure has little effect on load swing.

Steady-state coupling vibration analysis of shaft–disk–blade system with blade crack

Steady-state coupling vibration analysis of shaft–disk–blade system with blade crack