Analysis Of Vibration Characteristics Research Articles

Transversal vibration of a multi-span axially moving beam with multiple elastic supports

Using the transfer matrix method for multibody systems (MSTMM), this paper presents a dynamical model of a multi-span axially moving system with multiple elastic supports under different boundary conditions. The complex transfer matrices of an axially moving beam and a spring-damping supporting element are derived. According to the system topology, the overall transfer equation is acquired for vibration characteristic analysis. However, when dealing with multi-span systems that involve a large number of components, numerical instability may arise due to the instability of the corresponding boundary value problems. To address this issue, the reduced complex transfer matrix method (RCTMM) is developed. The state vector is artificially partitioned corresponding to the boundary condition of the system input. Numerical simulation results show that the developed method has the same computational accuracy as the MSTMM. More importantly, the RCTMM exhibits superior numerical stability, as indicated by the condition numbers of the system transfer matrix. It will provide an efficient tool for the design of mechanical multi-span axially moving systems.

Comprehensive analysis of flow-induced vibration and rotation characteristics of near-wall hydrofoil

Comprehensive analysis of flow-induced vibration and rotation characteristics of near-wall hydrofoil

A Review on High-speed Electric Spindle Dynamics Modeling and Vibration Response Research

Background: One of the main directions of modern technology in the field of precision machining is high-speed operation. The spindle system is commonly utilized in this kind of operation, and the electric spindle is the main preference among high-speed machine tool spindles. Objective: High-speed electric spindle vibration characteristics affect the machining accuracy of the machine tool and the quality of the workpiece, so the research on high-speed electric spindle vibration characteristics has important engineering practical significance. Methods: The research status of high-speed electrospindle at home and abroad has been summarized in this paper. Combined with the patents related to the dynamics modelling of electrospindle, the research on the dynamics modelling of high-speed electrospindle is analyzed. On this basis, the computational and analytical methods for the vibration modelling of the electrospindle, including the transfer matrix method and the finite element method, are investigated, the theoretical foundations of these methods are discussed in depth, and the advantages and disadvantages of the methods are evaluated. The applicability and limitations of the two methods are also compared. Results: The analysis has shown that the current research on the vibration characteristics of highspeed electrospindle is mainly based on mechanical modal analysis and electromagnetic analysis. At present, the dynamic modeling of the electrospindle mainly includes bearing modeling, shaft bearing modeling, spindle-case modeling, electrospindle electromechanical coupling modeling, electrospindle thermal coupling modeling, etc. The correctness of the modelling theory is verified through experimental and simulation results. Although these models tend to be perfected, they are still insufficient in the case of multiple influencing factors coupling and need further development. Conclusion: Finally, through the analysis of the patent and dynamic characteristics related to the high-speed electric spindle, thermal deformation, magnetic tension, material, and other factors should be considered comprehensively, and these factors should be coupled to establish an overall dynamics model for the vibration characteristics analysis. The dynamic modelling, vibration modelling method, and vibration characteristics of the high-speed electric spindle have been summarized in this study, and the outlook is presented.

Vibration characteristics analysis of piezoelectric vibration motor based on magnetic interaction

Vibration characteristics analysis of piezoelectric vibration motor based on magnetic interaction

Study on semi-active damping control strategies to improve dynamic behavior of high-speed trains subject to strong crosswinds

The aerodynamic loads on high-speed trains (HSTs) increase as the running speed increases. Particularly, strong crosswinds can significantly increase these loads and generate a safety risk to trains. This paper focuses on the application of semi-active control strategies based on secondary lateral suspension for HST operating in crosswinds, aiming to enhance the running safety of HST. First, a vehicle nonlinear dynamics model with 50 degrees of freedom (DOFs) is established. The aerodynamic loads caused by crosswinds are simulated using Simiu wind spectra, and the track irregularities are acquired through field tests of the high-speed railway line. Second, a semi-active control model is set up using Matlab/Simulink to replace the secondary lateral damper, and the co-simulation for vehicle dynamics and semi-active control is undertaken. Then, the vibration characteristic analysis of the vehicle system caused by aerodynamic loads under crosswind conditions is conducted in both time and frequency domains, while a conventional semi-active control strategy is employed to attenuate the vibrations. Moreover, a single coefficient mixed skyhook and groundhook control strategy (SMSG) regulated by a single mixing coefficient β, and mixed skyhook and acceleration driven damper control strategy (MSA) is proposed. The simulation results demonstrate that the proposed mixed skyhook and groundhook control strategy not only enhances the running safety of the trains in crosswind environments by adjusting the mixing coefficients but also improves ride performance compared to passive suspensions. While the suggested mixed skyhook and ADD control strategy can apparently reduce the vibration of the carbody.

Modeling and vibration characteristics analysis of the NES-plate coupling system under arbitrary elastic boundary conditions

Modeling and vibration characteristics analysis of the NES-plate coupling system under arbitrary elastic boundary conditions

Calculation of Natural Frequencies and Analysis of Vibration Characteristics of Stators of Electrical Machines Considering Radial Symmetric and Antisymmetric Modes

Calculation of Natural Frequencies and Analysis of Vibration Characteristics of Stators of Electrical Machines Considering Radial Symmetric and Antisymmetric Modes

Vibration characteristics analysis of liquid hydrogen lubricating herringbone spiral-grooved thrust bearing considering cavitation

The liquid-lubricated spiral-grooved thrust bearing is widely applied in rotational devices with high speed. In the bearing, hydrodynamic effect induced cavitation and axial clearance undulation interact with each other. The load capacity, friction torque, stiffness, and other bearing parameters oscillate with the periodic undulation of clearance. The oscillation of bearing performance induces instability of high rotational speed devices, which can lead to serious mechanical failure. In this investigation, the coupling effect of cavitation and sinusoidal oscillating clearance on high-speed spiral-grooved thrust bearing performance is numerically researched. The influence of vibration period, clearance amplitude, and equilibrium clearance height on bearing performance is acquired by comparison. The load capacity, friction torque, and other parameters are dealt with by fast Fourier transform, wavelet transform, and Hilbert-Huang transform. The transient, frequency, and time-frequency characteristics of bearing performances are analyzed and compared. According to the analytical results of the load capacity, the influence extent of these three vibration factors on the bearing performance is evaluated. The structure of herringbone spiral grooved thrust bearing should be optimized to acquire better load and cavitation performances under vibration conditions.

Vibration characteristics analysis of multi-layer composite cylindrical shell casing with different layer thickness ratios under external pressure using energy method

PurposeAero-engine casings commonly use composite cylindrical shell structures with excellent properties such as corrosion resistance and fatigue resistance. Still, their vibration behavior is relatively complex and may cause fatigue vibration damage, so it is essential to analyze the vibration characteristics of composite cylindrical shells. The purpose of this paper is to analyze the vibration characteristics of multilayer composite cylindrical shells subjected to external pressures and having different interlayer thickness ratios and provide some theoretical basis for the fatigue damage prediction of cylindrical shell casing to ensure the safety and stability of the engine during flight.Design/methodology/approachFirstly, the vibration differential equation with external pressure is established based on Soedel theory considering nonlinear effects, while four symmetric boundary conditions are chosen to constrain the cylindrical shell. Then the Rayleigh–Ritz method, which is more efficient and accurate in calculating large structural systems, is applied to solve the problem, and the theoretical model of three-layer cylindrical shell under external pressure is established. The accuracy of the model is verified by comparing the data with the specialized literature. Subsequently, the effects of different external pressures and different thickness-to-diameter ratios, different length-to-diameter ratios and different interlayer thickness percentages on the natural frequency of multilayer composite cylindrical shells were investigated by control variable analysis.FindingsThe conclusions obtained show that the external pressure increases the natural frequency of the cylindrical shell and that the frequency characteristics of the cylindrical shell vary for different boundary conditions. The effect of length-to-diameter ratio, thickness-to-diameter ratio and the percentage of the thickness of the intermediate layer on the natural frequency of the cylindrical shell are significantly increased under external pressure. Because the presence of external pressure increases the frequency of the cylindrical shell by about 70%, it has almost no effect on the frequency at the minimum number of circumferential waves, and the effect on the frequency at the maximum number of circumferential waves is reduced to about 50%. The frequencies in the SL-SL boundary condition are all in perfect agreement with the S-S boundary condition under the influence of different influencing factors.Originality/valueIn this paper, the effect of external pressure and the natural properties of the cylindrical shell under external pressure on the cylindrical shell’s frequency is considered, emphasizing the effect of different layer thickness ratios on the frequency. This paper aims to summarize the changing law between the natural frequency of the cylindrical shell itself and different design parameters during the flight pressure process. Reliable theoretical predictions are provided for analyzing the vibrational behavior of shells subjected to external pressures in aerospace, as well as a database for the practical production of cylindrical shells.

Analysis of nonlinear vibration characteristics in all-composite honeycomb-core sandwich panel with material and geometric nonlinearity

Analysis of nonlinear vibration characteristics in all-composite honeycomb-core sandwich panel with material and geometric nonlinearity

Enhancing vibration control in multi-cable hybrid network systems: A parametric study and optimization evaluation

For large-span cable-stayed bridges, cross-ties and dampers can work together for vibration mitigation of cables. Common analyses pay attention to the effectiveness of cross-ties and external dampers on two adjacent cables, fewer studies are available on the combined effect in multiple-cable networks. Investigating the optimization of multi-cable system parameters is a crucial problem for effective vibration mitigation. This paper proposes a model of the multi-cable hybrid network (MCHN) system. The corresponding characteristic equation is derived, and the analytical solutions for modal frequency and damping ratio are calculated. Furthermore, the results are verified through comparison with finite element and experimental results of a three-cable hybrid system. An analysis of the in-plane natural vibration characteristics of MCHN systems is presented, utilizing a numerical example of a three-cable MCHN system. Key parameters such as cable length differences, mass-tension ratio, cross-tie stiffness, damper number, damper location, and damping coefficient are considered to investigate their influence on the damping. A multi-modal optimization criterion (MANDR) based on maximizing the average of damping ratio is proposed by normalization of the system modes. When dampers are selected according to the optimization criterion of MANDR and installed in appropriate locations, the damping capacity can be better utilized.

Vibration characteristic, quality factor and sensitivity analysis of a resonant micro-gyroscope based on the blue-sideband parameter modulation

In this paper, we design a nonlinear resonant micro-gyroscope based on the blue-sideband parameter modulation (BSPM), and Coriolis force acts in the axial direction of the resonant beam in the form of a twice-frequency parameter excitation. Considering the geometrical nonlinearity of the micro-beam, the dynamic equations of the resonant beam are derived and discretized according to Hamilton principle and Galerkin method. The discretized equations are subjected to perturbation analysis by using the multi-scale method, and the quality factors of the resonant beams are calculated by the half-power bandwidth method. Moreover, the sensitivity of micro-gyroscope is characterized by the amplitude ratio changes before and after the bifurcation of the nonlinear resonant beam. We conducted a detailed study on the effects of Coriolis force dynamic input, and BSPM on the amplitude-frequency response of resonant beam and the sensitivity of micro-gyroscope. The results indicate that when Coriolis force acts on the resonant beam in the form of a twice-frequency parameter excitation, it not only causes the resonant frequency of the micro-beam to shift but also significantly increases the amplitude of the resonant beam. The addition of BSPM significantly improves the quality factor of the resonant beam and enhances the signal-to-noise ratio. Under nonlinear conditions, when the modulation voltage is sufficiently large, the amplitude-frequency response of resonant beam exhibits two unstable regions near the resonant frequency. Although BSPM reduces the amplitude ratio sensitivity, there is still a 60 times improvement over conventional frequency shift sensitivity. Furthermore, BSPM reduces the nonlinearity degree of the amplitude ratio sensitivity by 64%, which is important for the design and fabrication of high-sensitivity resonant micro-gyroscope.

Analysis of Vibration Characteristics of Homopolar Inductor Machine with DC-Biased Air-Gap Magnetic Field

Analysis of Vibration Characteristics of Homopolar Inductor Machine with DC-Biased Air-Gap Magnetic Field

Vibration Characteristic Analysis of Sandwich Composite Plate Reinforced by Functionally Graded Carbon Nanotube-Reinforced Composite on Winkler/Pasternak Foundation

This paper presents numerical investigations into the free vibration properties of a sandwich composite plate with two fiber-reinforced plastic (FRP) face sheets and a functionally graded carbon nanotube-reinforced composite (FG-CNTRC) core made of functionally graded carbon nanotube-reinforced composite resting on Winkler/Pasternak elastic foundation. The material properties of the FG-CNTRC core are gradient change along the thickness direction with four distinct carbon nanotubes reinforcement distribution patterns. The Hamilton energy concept is used to develop the equations of motion, which are based on the high-order shear deformation theory (HSDT). The Navier method is then used to obtain the free vibration solutions. By contrasting the acquired results with those using finite elements and with the previous literature, the accuracy of the present approach is confirmed. Moreover, the effects of the modulus of elasticity, the carbon nanotube (CNT) volume fractions, the CNT distribution patterns, the gradient index p, the geometric parameters and the dimensionless natural frequencies’ elastic basis characteristics are examined. The results show that the FG-CNTRC sandwich composite plate has higher dimensionless frequencies than the functionally graded material (FGM) plate or sandwich plate. And the volume fraction of carbon nanotubes and other geometric factors significantly affect the dimensionless frequency of the sandwich composite plate.

Modeling and analysis of internal excitation and vibration characteristics of gears with early-stage crack and 3D tooth surface error

Affected by the tooth surface errors, the vibration characteristics of early crack failures are usually various under different tooth surface precision level. Therefore, to reveal the influence of three-dimensional (3D) tooth surface error (TSE) on the internal excitation and vibration characteristics of gears with early-stage crack (ESC), a coupling internal excitation model of gears with ESC and 3D errors is proposed based on a double-layer iterative method. In this model, the influence of meshing phase between tooth pair and along tooth width direction (TWD) on the time-varying mesh stiffness (TVMS) are simultaneously considered, which overcomes the limitations of traditional models that are only suitable for characterizing the coupled excitation of the two-dimensional tooth profile errors and TVMS. Based on verifying the proposed model, the effects of TSE type, parameters, and load on the TVMS, loaded static transmission error (LSTE), load distributions, and torsional deformation of the cracked gear teeth are investigated, and the vibration characteristics of ESC failures under the effects of 3D TSE are also explored. The research results show that the distribution parameters of 3D TSE have a significant effect on the internal excitation and vibration characteristics of gears with ESC, and thus measuring and evaluating the distribution parameters of TSE can help improve the accuracy of gear fault identification and diagnosis methods.

Application of the Integral Energy Criterion and Neural Network Model for Helicopter Turboshaft Engines’ Vibration Characteristics Analysis

This article presents a vibration signal analysis method to diagnose helicopter turboshaft engine defects such as bearing imbalance and wear. The scientific novelty of the article lies in the development of a comprehensive approach to diagnosing helicopter turboshaft engine defects based on the vibration signals amplitude and frequency characteristics integral analysis combined with a neural network for probabilistic defect detection. Unlike existing methods, the proposed approach uses the energy criterion for the vibration characteristics. It averages the assessment of unique signal processing algorithms, which ensures reliable defect classification under flight vibration conditions. The method is based on representing vibration signals as a sum of harmonic oscillations supplemented by noise components, which helps to identify deviations from typical values. The developed method includes a state function in which the amplitudes and frequency characteristics from nominal parameters estimate deviations. When the critical threshold is exceeded, the function signals possible malfunctions. A multilayer neural network is used to classify defect types, providing high classification accuracy (from 0.985 to 0.994). Computer experiments on the developed seminaturalistic modeling stand confirm that the method can detect increased vibration levels, which is the potential failure indicator. Comparative analysis shows the proposed method’s accuracy and noise resistance superiority, emphasizing the importance of introducing modern technologies to improve aircraft operation reliability and safety.

Free vibration characteristics of honeycomb sandwich cylindrical shells reinforced with graphene nanoplatelets/polymer coatings

This study conducts a comprehensive analysis of the free vibration characteristics of honeycomb sandwich cylindrical shells reinforced with graphene nanoplatelets (GNPs). The shells are modeled with a hexagonal honeycomb core, which not only provides a lightweight structure but also enhances the stiffness and dynamic stability. This core design is ideal for high-performance applications such as aerospace and light transport equipment. In addition, the incorporation of graphene nanoplatelet/polymer coatings further improves the structural stiffness, making these shells suitable for demanding environments where both strength and lightweight properties are critical. In the theoretical model, the refined trigonometric shear deformation theory (RTSDT) is applied to accurately represent both bending and shear deformations, capturing the complex behavior of honeycomb sandwich cylindrical shells without requiring shear correction factors. Various parameters, including axial and circumferential wave numbers, as well as geometry and material properties, are examined to assess their impact on natural frequencies. Comparisons with existing literature validate the theoretical models, demonstrating strong agreement with previous results. The analysis reveals that the fundamental natural frequency and other natural frequencies are significantly affected by the inclusion of GNPs and variations in sandwich cylindrical shell geometry. The findings underscore the effectiveness of the RTSDT in modeling these complex sandwich structures.

Analysis of the vibration behaviour of a gas turbine during operation

The vibratory behaviour of the gas turbine during operation is analysed in this article. The modern method consists of studying the state of a machine during its operation, to intervene only when the parameters allow it. However, experience has shown that vibration analysis is the most widely used technique to make a reliable diagnosis and to detect the appearance and evolution of most mechanical and hydraulic defects. In our study, we applied the method of vibration analysis of the gas turbine line using monitoring methods to diagnose mechanical defects in shaft bearings. In this sense, the experimental was carried out by measuring and monitoring the level of vibration produced by the turbine, an indicator on its condition was obtained. Should the rise in vibration levels of the machine facilitate the identification of a fault, the subsequent analysis of the machine's vibration characteristics will enable the source of the fault to be determined. It is then possible to determine with accuracy the time before the situation becomes critical.

Analysis of Vibration Characteristics for Rotating Braided Fiber-Reinforced Composite Annular Plates with Perforations.

In the current study, a comprehensive numerical model for analyzing the vibrational characteristics of braided fiber-reinforced composite (BFRC) rotating annular plate with perforations under diverse boundary constraints was introduced. This model employs the differential quadrature finite element method (DQFEM), which was developed based on the first-order shear deformation theory (FSDT) and coordinate transformation approach. The BFRC material, specifically a two-dimensional biaxial orthogonal fabric, was utilized to fabricate the annular plate with two distinct types of holes: circular and sector-shaped. The model's convergence, accuracy, numerical stability, and reliability were confirmed through comparative assessments utilizing data from the literature, from ABAQUS software, and from experimental findings. The analysis focuses on studying the influences of structural properties, material parameters, and boundary restraints on the frequencies of vibration for BFRC rotating annular plates with holes. This theoretical model helps provide scientific basis and technical guidance for the stability and lightweight design of rotating annular plates, such as rotor structures in aircraft engines.

Analysis of Natural Vibration Characteristics of Permanent Magnet Linear Synchronous Motor Considering Elastic Contact

Analysis of Natural Vibration Characteristics of Permanent Magnet Linear Synchronous Motor Considering Elastic Contact