Analysis Of Vibration Characteristics Research Articles

A hybrid methodology for predicting train-induced vibration on sensitive equipment in far-field buildings

The prediction of train-induced vibration on far-field buildings is a challenging issue in the transportation environment communities. In this work, a hybrid prediction method is put forward utilizing the idea of substructure analysis, which can high-effectively calculate the train-induced vibration under different operation conditions. Based on vehicle-track coupled dynamics theory, wavenumber finite element theory (2.5D FEM) and Green’s function method, this method could comprehensively analyze vibration characteristics of the source, propagation path and sensitive target/vibration receiver by appropriately considering the boundary conditions between each part. The proposed model possesses the advantages of 2.5D FEM in calculation efficiency and could consider the dynamic interaction between vehicle and track system more elaborately. In addition, the vibration response under different operation conditions can be high-efficiently obtained by updating the track supporting forces without repeatedly solving the Green’s functions of the system. On this basis, this work predicts the vibration impact of subway train operation on the sensitive equipment in a far-field large-scale building, and uses the generic vibration criteria for sensitive equipment to evaluate the vibration responses. Further, to mitigate the impact of train-induced vibration, floating slab track is adopted to achieve the vibration attenuation in the concerned frequency. Results show that the train-induced vibration on the monolithic bed track exceeds the limit specified in the standard in some frequency bands. The use of floating slab track can effectively reduce the vibration response of the building and ensure the routine use of sensitive equipment.

Vibration characteristics analysis and structure optimization of air-pressure subsoiler

Aiming at the problems of strong vibration, inconsistent subsoiling depth and high failure rate of air-pressure subsoiler, air-pressure subsoiler vibration characteristics was studied. In order to decrease the vibration, For the first time, the vibration characteristics of air-pressure subsoiler were obtained by modal analysis and vibration test. The vibration characteristics of the whole air-blown subsoiler are analyzed Through time domain analysis, it is found that the vibration acceleration of four deep loosening shovel is inconsistent. When the diesel engine is started, it is easy to cause inconsistent subsoiler depth. Then, by analyzing the vibration characteristics of the whole air-pressure subsoiler, it can be known that the external excitation source of the air-blown subsoiler is close to its own natural frequency. In order to avoid resonance caused by the vibration frequency of the external excitation source being close to the natural frequency of the air-pressure subsoiler, and to reduce the inconsistency of the subsoil depth, we optimize the design of air-pressure subsoiler. Instead of diesel engines, the steering gear box is connected with tractor power output shaft to provide power. The modal simulation of the optimized air-pressure subsoiler shows that the first-order natural frequency is obviously improved and the external excitation frequency is successfully avoided. It not only avoids resonance, reduces the damage of resonance components, but improves the service life of the subsoiler, greatly improves the structural reliability of the air-pressure subsoiler, at the same time, removes the main external excitation source, which greatly reduces the vibration in actual production and the inconsistency of subsoiling, which is of great significance in actual production. It provides a reference for the research of vibration characteristics, resonance avoidance and structure optimization of agricultural equipment.

Vibration characteristics analysis and structural improvement of natural gas venting ignition pipeline

In order to study the flow-induced vibration characteristics of the natural gas vent pipeline under the internal flow field, taking the gas transmission station pipeline as an example, the ANSYS Workbench software was used to establish models under two working conditions, uncoupling and fluid-solid coupling, for modal analysis, and analyze and compare the calculation results and propose a structural improvement plan. The results show that the maximum amplitude of the first three modes under the two working conditions is concentrated on the riser mouth, and the amplitude under the fluid-solid coupling condition is slightly larger than that of no coupling; the inner diameter of the pipe elbow is large and the pressure is small, and the outside diameter is small and the pressure is small. Large, this instability will increase the air pulsation of the flow field. In the improved scheme, adding a restriction on the top to increase the rigidity of the pipeline can significantly reduce the maximum amplitude of the gas pipeline; adding an orifice to eliminate air flow pulsation has a certain effect on reducing the maximum amplitude and natural frequency, and the combination of the two can make the pipeline more stable. The research results of this paper can provide improved ideas for vibration reduction at the natural gas venting operation site.

Dynamic Modeling and Vibration Characteristics Analysis of Deep-Groove Ball Bearing, Considering Sliding Effect

To study the vibration characteristics of deep-groove ball bearing, considering the influence of sliding, the dynamic model of the DGB 6205 system is established in this paper. The DGB 6205 system model includes the movement of the bearing inner ring in the X and Y directions, the rotation of the cage, the rotation movement of each ball, the revolution movement of each ball and the movement along the radial direction of each ball. Based on the system model, the differential equations of motion of the system are established, and the correctness of the model is verified by experiment. The slip characteristics of the DGB 6205 system are studied by numerical simulation. At the same time, the influence of time-varying load on the vibration characteristics of the system is studied. Then, the sensitivity of system parameters is analyzed. The results show that the sliding speed between the ball and the inner raceway is greater than that between the ball and the outer raceway. The radial vibration response of DGB 6205 system under time-varying load is less than that under constant load. The increase of radial clearance will increase the vibration response of DGB 6205 system.

Vibration characteristics analysis of composite floating rafts for marine structure based on modal superposition theory

Abstract Composite materials have become a research hotspot in the field of vibration and noise reduction for their high strength, high damping, and other outstanding mechanical properties in recent years. In this paper, the effect of laminated materials on the dynamic performance of floating rafts is investigated based on modal superposition theory using the finite element method. The detailed derivation of the modal superposition theory was made, and taking T700 fiber-reinforced composite material as an example the damping effect of the floating raft structure in three cases was discussed: whether the composite material is laid or not, different layup angles, and different layup positions. The research shows that laying composite materials can improve damping effect of the floating raft and the changes in both the laying angle and the laying position will affect its dynamic performance. Moreover, the damping performance of the structure is inversely correlated with its stiffness within a certain range.

Modeling, calculation, and analysis of torsional vibration characteristics of the hydrodynamic transmission system in engineering vehicle

According to the typical working conditions of a loader and considering the complexity of the working conditions, the hydrodynamic transmission powertrain system was modeled in this study. Because the hydrodynamic torque converter is a flexible fluid transmission component in the transmission system, this study proposes and establishes equivalent variable damping and equivalent variable stiffness models of the hydrodynamic torque converter. Based on this, a torsional vibration simulation model of the loader with variable damping and stiffness is proposed, and the frequencies and amplitudes of the torsional resonance modes of the transmission system varying with engine speed and hydrodynamic torque converter speed ratio are obtained. It is determined that the variable stiffness of the hydrodynamic torque converter has little effect on the natural frequency of the vehicle, and taking variable damping and stiffness as input, the natural frequency and resonance points of the transmission system can be calculated more accurately. The simulation modeling and calculation approach are experimentally verified, and the simulation results are valid and closer to the real resonance.

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.

Free and Forced Vibration Characteristics Analysis of a Multispan Timoshenko Beam Based on the Ritz Method

The uniform formulation of dynamic vibration analysis of multispan beams is presented by using an efficient domain decomposition method in this paper. Firstly, the structure is divided into several equal sections based on domain decomposition method. Next, the artificial spring is used to simulate complex boundaries and continuity condition of multispan beam. Finally, the admissible displacement functions are expanded through Jacobi orthogonal polynomials, and the free and forced vibration characteristics of multispan beam structures can be obtained by using Rayleigh–Ritz method. Results for various boundary conditions, ratios of thickness to length (h/L), numbers, and stiffness of supporting springs are presented. It is clearly shown that accurate solutions can be obtained by using the proposed method, and this study extends the application range of the Jacobi polynomials-Ritz method. In addition, the research results of this paper can provide data support for engineers such as bridge designers to design multispan bridges.

Vibration characteristic analysis for emulsion droplet excited by chaotic frequency pulsed electric field

In this paper, taking single emulsion droplet as the research object, the vibration characteristics of emulsion droplet in chaotic electric field is explored. The fixed amplitude and equal pulse width chaotic frequency pulsed electric field is constructed by using the Chaotic-Pulse-Position Modulation method, the vibration dynamics model of emulsified oil droplet in chaotic electric field is established, and the chaotic electric field parameters and vibration response of droplet are solved. Results show that the optimal pulse width is 0.009s, the optimal chaotic boundary of pulse electric field frequency is 170 rad/s to 690 rad/s, the droplet is excited into chaotic vibration, and there is resonance. Besides, the droplet vibration in chaotic pulsed electric field is unsteady, but the droplet will enters the steady state vibration from the second same pulse.

An efficient method for vibration equations with time varying coefficients and nonlinearities

An efficient method for solving vibration equations is the basis of the vibration analysis of a cracked multistage blade–disk–shaft system. However, dynamic equations are usually time varying and nonlinear, and the time required for solving is greatly increased accompanied by an increase in the model order caused by the multistage system and the nonlinearity caused by cracks. In this article, an efficient method for solving the time varying and nonlinear vibration equation is investigated. In the proposed method, the time varying terms are transformed into constant terms, while the local nonlinear matrix of the cracked blade is separated from the assembly stiffness matrix under the constraint of proper orthogonal decomposition (POD) transformation rules. Furthermore, the POD transformations of the constant terms and the linear assembled stiffness matrix can be implemented in the pretreatment steps to achieve a more efficient POD reduction operation. This research provides a method for efficiently performing the comprehensive and rapid analysis of nonlinear vibration characteristics of rotor systems.

Comparative Analysis of Longitudinal and Transverse Vibration Characteristics of Ocean Mining Pipe

In this paper, the 5000 m mining pipe is taken as the research object, and the transverse and longitudinal vibration laws of the pipe under different working conditions are analyzed. Based on the finite element method (FEM), the pipe is discretized and calculated by the Wilson-θ Wilson - θ integral method; finally, the corresponding vibration laws of the mining pipe are obtained. The research shows that the mining pipe vibration responses are irregular motion, with the obvious oscillation phenomenon, and the overall vibration trend decreases first and then increases from the top to the bottom; the maximum vibration response occurs at the pipe top. Under the same working conditions, increasing the towing velocity will decrease the overall longitudinal vibration amplitude and increase the overall transverse vibration amplitude. While the ore bin weight will increase the longitudinal vibration amplitude and decrease the transverse vibration amplitude, increasing the mining pipe large diameter stepped section length and damping will decrease the longitudinal and transverse vibration simultaneously. When the towing velocity is between 0–2.8 m/s, the longitudinal vibration intensity is large, which is the main vibration mode. When the towing velocity is 2.8 m/s, the critical point is reached, and the longitudinal and transverse vibrations have the same intensity. When the towing velocity is greater than 2.8 m/s, the transverse vibration intensity is gradually greater than the longitudinal vibration intensity; at this time, the control of the transverse vibration should be appropriately increased.

Analysis of vibration and sound characteristics of fluid conveying pipeline considering the effect of acoustic-solid coupling

Objectives In order to accurately grasp the vibration and sound characteristics of pipelines, a numerical simulation is carried out. Methods Based on the theory of acoustic-solid coupling, a numerical model of a pipeline is established. The dispersion curve of the vibration and acoustic modes of the pipeline is solved by parametric scanning. The dispersion characteristics of the elastic wall pipeline with air, water and crude oil, as well as the absolute pressure stress distribution in the pipeline, are analyzed, and the effects of wall thickness, elastic wall and hard sound field wall on the dispersion characteristics of the pipeline are studied. Results The results show that wall thickness has little effect on the propagation mode of elastic waves in the pipeline, and the dispersion curve is shifted to high frequency with the increase in wall thickness, mainly influencing the cut-off frequency. Due to the effects of acoustic-solid coupling, the number of modes of the elastic pipeline increases, and the increased mode number is mainly the deformation mode of the pipeline wall. The absolute sound pressure distribution in the elastic wall is basically the same as that in the hard sound field wall. The dispersion characteristics of liquid or gas inside are different, while the dispersion characteristics of water or oil inside are similar, but the direct modes of the two are different. Conclusions The results of this study can provide a theoretical basis for the pipeline acoustic detection of ships.

Analysis of Electromagnetic and Vibration Characteristics of a Spoke Type PMBLDC Motor

Analysis of Electromagnetic and Vibration Characteristics of a Spoke Type PMBLDC Motor

Vibration characteristics analysis of an elastically restrained cylindrical shell with arbitrary thickness variation

A novel and unified solution is established to investigate the vibration characteristics of circular cylindrical shells with arbitrary variable thickness and general boundary conditions. Energy equation based on Donnell–Mushtari shell theory is formulated, with a modified Fourier series utilized for the construction of radial, circumferential and longitudinal displacements of shell structure, in which the auxiliary terms are introduced to tackle with differential discontinuity associated with elastic boundary restraints. Arbitrary thickness function is invariantly expanded into Fourier series to compress thickness variation information into Fourier coefficients accordingly. The proposed model is validated through the comparisons with those in the literature or finite element method. Excellent convergence can be observed with several truncated terms of modified Fourier series. Natural frequencies of a circular cylindrical shell with linearly varying thickness and constant mass decrease for constrained boundary conditions, and the distribution of modal displacement moves to the thinner side as the slope ratio increases. Axial thickness variation has more significant influence on natural frequencies of a step-wise cylindrical shell compared with that in circumferential direction.

Analysis of vibration characteristics of FGM sandwich joined conical–conical shells surrounded by elastic foundations

The main objective of this paper is focused on the vibration behavior analysis of functionally graded material (FGM) sandwich joined conical–conical shell surround by elastic foundations. In the analysis, four kinds of sandwich distributions, including FGM core and isotropic skins, and isotropic core and FGM skins are considered and the power law distribution is employed to estimate the volume of the constituents. The governing equation of conical shell surround by elastic foundations is established by the first-order shear deformation shell theory and Hamilton’s principle. Then generalized differential quadrature (GDQ) method is used to discretize the obtained equations. By using the continuity conditions of displacement, rotation, force and moment between two adjacent shells and the boundary conditions at the end of the connected shell, a set of homogeneous equations are obtained, which control the free vibration of the two joined shell. By comparing the numerical results with the existing solutions in open literature, the validity of the proposed theoretical model is verified. Finally, the influences of sandwich distribution types, gradient indexes, skin–core–skin ratio and boundary conditions on the vibration behavior of FGM sandwich joined conical–conical shell have been investigated. It has found that for different sandwich distribution types, the influences of gradient index on the natural frequency are obvious when the gradient index is minor, but when high values of the gradient index are taken, the gradient index has no significant effect on the natural frequency.

Optimization Analysis of Vibration Characteristics for Precision Positioning Stage

As the core of semiconductor equipment, the vibration of precision positioning stage has great influence on its comprehensive performance. The research object of this paper is a high-precision positioning stage for chip detection. The precision positioning stage is driven by linear motors and supported by rolling linear guides. During the movement, vibration will be generated due to the influence of cable disturbance force and motor thrust harmonics. Based on Newton mechanics, the dynamic formula group of the motion table is established, and the reasons for the vibration of each degree are analyzed. Based on the geometric nonlinear theory, the cable model is established with the help of finite element software, and the influence of installation dimensions on the dynamic change of the cable assembly is analyzed. The motor thrust formula is established based on the equivalent magnetizing current method, the characteristics and influencing factors of the thrust harmonics are analyzed, and the method to suppress the thrust harmonics from the source is sought. In this paper, the vibration source characteristics of the stage are obtained through theory and simulation, which lays a foundation for the subsequent use of control strategy compensation.

Analysis of vibration characteristics of elastic metamaterial sandwich beam

Elastic metamaterials (EMs) are a new kind of artificial composite medium composed of complex micro-structural elements, which have unique dynamic properties and elastic wave regulation ability that their constituent materials do not possess. The existing researches on EMs mainly focus on wave characteristics in two-dimensional and three-dimensional infinite domains. However, actual EM structures are always in the form of finite structures such as rods, beams and plates, so it is more important for engineering applications to understand and master their natural and forced vibration characteristics. Therefore, it is necessary to establish an effective simplified solution method and framework with certain accuracy for the vibration analysis of such structures. In the early stage, we have studied the natural and forced vibration characteristics of EM beams from this point of view, and presented a simplified solution process. In this paper, a kind of sandwich beam structure with EMs as the core is further constructed, the simplified solution process is extended to such more practical model analysis, and the free and steady forced vibration analysis processes of the finite-size sandwich beam are given. The vibration characteristics different from the traditional sandwich beam are investigated, and some interesting and useful phenomena are revealed, including the absence of natural frequencies within bandgap (BG), the gathering of natural frequencies in the vicinity of band edges, and the particular modal correspondence before and after BG. Then, the corresponding formation mechanisms are explained from the perspective of wave propagation.

Free vibration of conical shells under arbitrary elastic boundary and simulation verification

This paper presents an analysis of free vibration characteristics of truncated conical shells under complex boundary conditions. Firstly, the geometric equation of conical shells are obtained by using Reissner shell theory. Then, by using Rayleigh- Ritz method with improved Fourier series, the motion equations of modal parameters (modal stiffness, modal mass, natural frequency and model shapes) with elastic boundary are obtained. The mode shapes and natural frequencies of conical shells can be obtained by solving the motion equations. Moreover, by comparing the results for simulation numerical method and finite element method(FEM) respectively, the validity of present methodology has been verified.

Analysis of projectile-barrel coupling vibration characteristics considering the radial effect of propellant gas pressure

In view of the influence of projectile-barrel coupling on tank firing accuracy, a finite element model of projectile-barrel coupling based on vibration theory was established. By defining user subroutines to simulate the change of the physical field of interior ballistics, the load condition under which the propellant gas radial pressure acts on the inner wall of the barrel and varies with the motion of the projectile is realized. On this basis, the dynamic characteristics of projectile-barrel coupling considering the radial effect of propellant gas pressure were studied. The reference targets such as cradle, projectile and muzzle were selected for analysis, and compared with the situation without considering the radial effect of propellant gas pressure. The results show that the motion trend of the projectile in the bore and the response law of muzzle vibration change greatly when considering the radial effect of propellant gas pressure and these changes may seriously affect the law of projectile dispersion. The radial effect of propellant gas pressure can cause stronger dynamic response, which cannot be ignored in the simulation of artillery firing process. This work provides a practical reference for further study of tank firing accuracy.

Analysis of Vehicle Platform Vibration Based on Empirical Mode Decomposition

Vehicle platform vibration (VPV) directly affects the measurement accuracy of precise measuring instrument (PMI) fixed on it. In order to reduce the influences of VPV on measurement accuracy, it is necessary to perform vibration isolation between vehicle platform and PMI. Analysis of vibration characteristics is a prerequisite for vibration isolation. However, empirical mode decomposition (EMD) and ensemble empirical mode decomposition (EEMD) reveal that there is obvious mode mixing phenomenon in the collected VPV signals. In this paper, a noise stretch ensemble empirical mode decomposition (NSEEMD) method is proposed to suppress mode mixing, and the specific operation process of NSEEMD is expounded. By NSEEMD, mode mixing of the collected platform vibration data is well suppressed, and the principal component of platform vibration can be obtained.