Main Source Of Vibration Research Articles

Analytical Model to Calculate Radial Forces in Permanent-Magnet Synchronous Machines

There are three principal sources of noise and vibration in electrical machines: electromagnetic sources, mechanical sources, and aerodynamic sources. Nowadays, one of the major advantages of permanent-magnet synchronous machines is their torque density. This density is achieved through a high magnetic flux density in the air gap, which is achieved through hard magnets. Unfortunately, in these machines, electromagnetic forces have been identified as the main source of vibration and noise, and high magnetic flux densities make these vibrations and noises more significant. With the aim of better understanding the relationship between electromagnetic forces and design variables, this article, which is the continuation of previous work, firstly describes a study of the sources of magnetic forces in permanent-magnet synchronous machines. Subsequently, an analytical model for the computation of the radial forces originating from electromagnetic sources in permanent-magnet synchronous machines is stated. This model analyzes the forces on both the rotor surface and the base of the stator tooth. The analytical results were corroborated through simulations using the finite element method (FEM) and also by experimental tests performed over two prototypes. The results achieved by the analytical model show good agreement with both FEM results and experimental measurements.

Experimental comparison of localised magnetostriction difference under sinusoidal and PWM excitations

The majority of power transformers are usually energized by sinusoidal excitation. However, there is a growing demand for using PWM excitation on power electronics devices for energy savings. As awareness of the environment also increases, the importance of noise and vibration issues becomes more significant. Increasing non-linear loads over time affect the ageing and lifetime of transformers. Such cases also cause to change the nominal values ​​of transformers. It is important that mechanical parameters such as vibration and noise can be accurately measured and examined so that all necessary functions can be entirely performed as other electromagnetic performances. For this reason, it is necessary to analyse the vibration movements of transformers and determine their characteristics, especially locally under changing operating conditions. Magnetostrictive is known as the main source of vibration and noiseof the transformer core. This paper presents localized magnetostriction of transformer core measured by strain gauges under sine and PWM voltage excitations. For validation of the study in this paper, a no-load strain measurement was performed experimentally on a real 20kVA three-phase three-limb T-joint transformer assembled in a laboratory.Localized magnetostriction in the rolling and transverse directions of the lamination under sinusoidal and PWM voltage excitations was carried out. The results of the experiment were compared with each other in terms of the location of the sensors.The Finite Element Analysis (FEA) was used to simulate the magnetic behavior of the transformer based on time-dependent analysis of magnetic field density, force, e.t. distributions under no-load conditions, respectively.In conclusion, evaluating the localized magnetostriction characteristic, especially under PWM voltage excitation, is essential for interlamination electromagnetic and electromechanical behaviors.

FxLMS Algorithm for Active Vibration Control of Structure By Using Inertial Damper with Displacement Constraint

Engine is the main source of vibration that generates unwanted noise and vibration of vehicle chassis. Especially, in submarine applications, radiation of noise signatures can be detected at some distance away from the submarine using a sonar array. Thus quiet operation is crucial for submarine’s survivability. This study addresses reduction of the force transmissibility originating from engines and transmitted to hull through engine mounts. An inertial damper, as an actuator of hybrid mount system, is addressed to reduce even further the level of vibration. Narrow band FxLMS algorithms are broadly used to cancel the vibration of engine mount because of its excellent performance of canceling narrow band noise. However, in real active dampers, the maximum displacement of damper mass is kinematically restricted. When the control input signal from the FxLMS algorithm exceeds this limitation, the damper mass will collide with the mechanical stops and results in many problems. Originated from these, a modified narrow band FxLMS algorithm based on the equalizer technique with the maximum allowable displacement of active damper mass is proposed in this study. Some simulation results showed that the propose algorithm is effective to suppress vibration of engine mount while ensuring given displacement constraint.

Effects of Ship Propulsion Shafting Alignment on Whirling Vibration and Bearing Temperature Response

Ship’s propulsion shafting is one of the main sources of ship vibration and noise. The shafting, whirling vibrations, and alignment are important factors that affect the comfort, stability, and reliability during a ship’s navigation. However, the mechanism of the interacting of the both factors is not fully revealed. In this paper, the effect of shafting alignment on whirling vibration and the bearing temperature response is studied by experiment. The test scheme is designed reasonably according to the theoretical analysis. The results show that the horizontal component of the shafting whirling vibration can be effectively reduced by adjusting the shafting alignment state while the vertical component is not. The shafting axis balancing position (SABP) slightly moves upward in high speed, which should be considered in the dynamic alignment design of the shafting, especially for the high-speed shafting. Little ABSB (the angle between the shafting centre line and the No. 1 bearing centre line) is beneficial to the stable operation of shafting, while appropriately increasing the ABSB and bearing load is beneficial to reducing the shafting whirling vibration. By balancing the relationship between bearing load and ABSB, the performance of whirling vibration and bearing temperature response can be optimized.

Theoretical and Experimental Analysis of Dynamic Characteristics for a Valve Train System.

The valve train is one of the main sources of engine vibration, and its dynamic performance is crucial for output power and fuel consumption. The flexibilities of slender bars and beams should be emphasised in the design of valve trains to develop high-power and high-speed engines with industrial applications. A flexible dynamic model of a valve train system is proposed. In the proposed model, the components, except the cam and gear bodies, are modelled as flexible bodies with multidirectional deformations. The gyroscopic effects of the camshaft, cams and gear discs are also considered to predict dynamic responses at high speeds accurately. Gear meshing, the friction of the cam–tappet pair, the centrifugal force of the cams and valve clearance are also considered. Experiments on housing vibration and pushrod stress are conducted to validate the proposed model. Results show that the proposed model can predict the dynamic stress of the flexible components well and predict the trend shown by the housing vibration. The proposed model shows that excessive cam rotation speed and valve clearance will cause intense bounce and jump phenomena. The proposed model can be an important reference for designing engine work speed, adjusting valve clearance and improving component durability.

Error Compensation of Strapdown Inertial Navigation System for the Boom-Type Roadheader under Complex Vibration

The strapdown inertial navigation system can provide the navigation information for the boom-type roadheader in the unmanned roadway tunneling working face of the coal mine. However, the complex vibration caused by the cutting process of the boom-type roadheader may result in significant errors of its attitude and position measured by the strapdown inertial navigation system. Thus, an error compensation method based on the vibration characteristics of the roadheader is proposed in this paper. In order to further analyze the angular and linear vibration of the fuselage, as the main vibration sources of the roadheader, the dynamic model of the roadheader is formulated based on the cutting load. Following that, multiple sub-samples compensation algorithms for the coning and sculling errors are constructed. Simulation experiments were carried out under different subsample compensation algorithms, different coal and rock characteristics, and different types of roadheader. The experimental results show that the proposed error compensation algorithm can eliminate the effect of the angular and linear vibration on the measurement accuracy. The coning and sculling error of the strapdown inertial navigation system can reduce at least 52.21% and 42.89%, respectively. Finally, a strapdown inertial navigation error compensation accuracy experiment system is built, and the validity and superiority of the method proposed in this paper are verified through calculation and analysis of the data collected on the actual tunneling work face.

Dynamic and Vibration Analysis for Geometrical Structures of Planetary Gears

In industry applications, planetary gear systems are widely used in power transmission systems. In planetary gears, dynamic loads, noise and reduction the structural life are produced by system vibrations. For gear transmission systems, the parametric excitation which introduced by the periodically time–varying mesh stiffness of each gear oscillation is the main source of vibration. Generally, there are two methods to evaluate the gear mesh stiffnesses, the finite element method and the analytical method. In this wok, the periodically time–varying mesh stiffness of planetary gears is investigated. The influence of pressure angles on mesh stiffness of meshing gears is shown and the dynamic model of planetary gear sets is studied. When planets of the single–stage spur planetary gear system are meshed by new planets, the system is converted to special type of system with meshed planets. Vibration for geometrical structures (symmetric and anti–symmetric) of planetary system with meshed planets is investigated. Mesh stiffness of meshing gears by estimation function is obtained and numerical results of natural frequencies and vibration modes are derived.

Vibration damping of aircraft propeller blades using shunted piezoelectric transducers

Gas turbine engine blades experience vibrations due to the flow disturbances, these vibrations are critical to the engine durability and performance. Piezoelectric transducers (sensors and actuators) have been used for engine blade vibrations damping either through a passive or active vibration control. The propeller blades are part of turboprop engine and considered as one of the main source of turboprop engine vibrations. Piezoelectric blade damping ideas have been studied by other researchers for fan blades and compressor blades. In this research a vibration damping procedure using piezoelectric transducers applied to an unmanned aerial vehicle (UAV) composite propeller. Experimental investigation introduces an approach for the propeller vibration damping using piezoelectric transducers in conjunction with appropriate shunt circuit. Three thin piezoelectric transducers macro fiber composite (MFC) type PZT-5A are surface-mounted on the propeller, one at each blade. These transducers are placed at locations of high modal strain areas for the propeller first mode at each blade, where these locations are identified by finite element numerical simulation. Electronic resonance shunt circuit, resistor-inductor-capacitor type, for the piezoelectric transducers is designed and experimentally developed such that effective vibration suppression of the propeller is achieved. The experimental and numerical investigations in this research illustrate that piezoelectric transducers with appropriate shunt circuit reduces the aircraft propeller vibrations.

Finite Element Simulation Analysis of Fluid Pipeline Leakage

Due to the harsh working environment and the inconvenient maintenance, leakages of warship pipeline often occur. When the pipeline leaks, the fluid flow and pressure in the pipeline will change. The pressure fluctuation of the fluid is one of the main sources of abnormal vibration and noise in the pipeline system. In order to locate the leaking part of the pipeline effectively, it is necessary to use sensors to collect and capture these changing parameters to facilitate real-time monitoring of the pipeline system. In this paper, ANSYS finite element analysis software is used to establish the geometric model of “I” type combined pipeline, and the pressure variation characteristics under different leakage conditions are obtained through simulation.

Vibration reduction performance of an innovative vehicle seat with a vibration absorber and variable damping cushion

Road driving conditions are complicated, and road unevenness and speed bumps are main sources of vibration that cause the discomfort of passengers in vehicles. The vehicle seat can effectively reduce the system damage and human discomfort caused by this vibration. In this paper, an innovative damping seat that combines a vibration absorber and variable damping cushion is proposed for better vibration reduction performance under different external road excitations. A practical vertical human-seat-vehicle model is established, and uneven road excitation considering trapezoidal speed bumps and rectangular speed bumps is applied to the vertical model. The vibration reduction mechanisms of four different seats (without the absorber and variable damping cushion, with the absorber, with the variable damping cushion and with the new damping seat) are studied by comprehensive time-frequency analysis of the vibration responses. A comparison verifies the improved vibration damping performance of the newly proposed scheme, providing good theoretical guidance for the development of damping seats.

Improved analytical model for calculating mesh stiffness and transmission error of helical gears considering trochoidal root profile

Time-varying mesh stiffness (TVMS) and loaded static transmission error (LSTE) are considered the main sources of vibration in a gear system. TVMS and LSTE of a helical gear pair have been calculated by using an instantaneous pressure angle. However, this method could not consider the root profile accurately. In this study, an analytical model is proposed to calculate TVMS and LSTE of a helical gear pair. To consider the trochoidal root profile, the profile model is also developed by a virtual rack reflecting the cutter information. The finite element (FE) model of a helical gear is used to validate the proposed analytical model. The LSTE results are highly similar to FE analysis results and relative errors in peak-to-peak values of LSTE are also small. The proposed model is found to be more effective than traditional models in calculating the TVMS and LSTE of both helical gear pairs and spur gears. The changes in the radii of the base circle and root circle according to the helix angle are also investigated.

Nonlinear Adaptive Harmonics Vibration Control for Active Magnetic Bearing System With Rotor Unbalance and Sensor Runout

Rotor unbalance (RUB) and Sensor Runout (SR) are two main vibration sources for active magnetic bearing (AMB) system, and they not only produce considerable harmonic vibration but also endanger the stability of AMB system. Therefore, a nonlinear adaptive algorithm, whose asymptotic stability is guaranteed by Lyapunov's theory, is proposed in this paper to suppress the harmonic vibration. Nevertheless, RUB and the synchronous component of SR have the same frequency with the rotational frequency, and it is highly necessary to distinguish them from each other for the compensation of displacement stiffness force. Hence, the scheme of changing rotor speed is adopted for the permanent magnet biased magnetic bearing system. As a consequence, the harmonic current caused by RUB and SR is effectively attenuated and the displacement stiffness force is correctly compensated. The results of the numerical simulations and experiments demonstrate that the harmonic vibration is dramatically suppressed through the proposed method.

Wavelet transform analysis of composite signal under multi-source excitation

In practical engineering application, the response of mechanical structure may be the superposition effect of vibration source interaction, while the traditional detection method only considers the main vibration source, ignoring other vibration sources will cause analysis error. Therefore, it is of practical engineering significance to study the detection method of compound excitation in mechanical testing. This paper aims to present an extraction method of composite modulation signal under multi-source excitation by wavelet transform. The modulated signal is analyzed by short-time Fourier transform and wavelet transform. The time-frequency analysis results show that the resolution of wavelet can be automatically adjusted at high frequency, and the effect of wavelet is better at high frequency. The key contribution is to establish a method for extracting multi-source excitation signals and to provide certain technical support for the modulated signal under multi-source excitation.

Vibration Response of the Crawler Combine Chassis Frame Excited by the Engine

There are many problems of vibration and noise in combine working. As the main power source and excitation source of a combine, the working state of an engine directly affects the reliability and stability of the whole harvester. In order to analyze the vibration response characteristics of a chassis frame under engine excitation, the vibration mechanism and theoretical excitation characteristics of an engine vibration source on a crawler combine harvester are analyzed in this paper, and the vibration response of chassis under engine excitation is tested and analyzed. After theoretical derivation, a two-degree-of-freedom dynamic model of an engine and chassis is established. The experimental results show that the up and down vibration generated by the engine is the main vibration source in the Z direction, and the main excitation frequency is the second-order firing frequency. This paper provides a theoretical reference and experimental basis for vibration reduction and noise reduction of combine and vibration characteristics of the chassis frame.

Research the Influence of Hydraulic Model on Vibration of Pump

In this paper, the cooling water pump of centrifugal equipment is taken as the research object in ship system. The pump set is normally open. And, it is also one of the main vibration sources of ship. On the premise of meeting the requirement of hydraulic performance parameters, several different hydraulic model prototypes of this pump set are manufactured. On the same test bench, the vibration tests of this pump show that the measured values are quite different. Fluid software is used to analyse these hydraulic models under the same boundary conditions. It is found that there are obvious differences in hydraulic fluctuations and fluid vortices among impeller passage, vortex chamber, inlet and outlet passages. In order to verify the inference, vibration test and analysis are carried out on the whole pump set and the foots of installation. The corresponding relationship was found out between the fluid fluctuation of hydraulic components and the vibration characteristics. Based on the corresponding relationship, the current hydraulic model of pump is optimized and improved. The parameters of hydraulic model which can affect the vibration sensitivity of pump are optimized. Finally, the experimental results prove that this method can reduce the vibration effectively.

Vibration Response of Combine Harvester Chassis Undergoing Multisource Excitation Force Distribution

When a combine harvester is harvesting in field under complicated conditions, vibration characteristics of the chassis frame under the excitation of multiple sources are complex and changeable. In order to analyze the vibration characteristics of the chassis frame of the combine harvester under complex working conditions and multisource excitation, this paper carried out three-dimensional modeling and static calculation of the chassis frame of the combine harvester. On this basis, the experimental modal analysis was carried out on the designed chassis frame, and finally, the vibration response under multiple excitations and complex working conditions was tested and analyzed in the field. Results showed that when the combine harvester was fully loaded, the maximum bending moment was at the load-bearing beam under the grain box. The maximum bending moment was 2298.08 N/m, and it was located at the cross section of the left end of the bearing beam at 1.61 m. When the components of the whole machine were working, the vibration of the chassis frame at the rear right was the most intense. The horizontal vibration of the threshing drum, the reciprocating motion generated by the vibrating screen, and the vertical vibration generated by the engine were the main vibration sources of the combine harvester in the three directions of X, Y, and Z. With the i\ncrease of engine speed, the excitation capacity of each working component connected to the engine on the whole machine increased. The results of this paper provide experimental basis for the research on the vibration characteristics of the chassis frame of the rice combine harvester under multisource excitation and also provide a reference for the further improvement of the chassis frame of the combine harvester.

Oscillation of gear mechanisms of construction machines

The article is devoted to the study of the influence of gearing errors on the vibration activity of the open gear transmission of construction machines. A brief review of the literature on the relevance of the topic of gear dynamics in different industries and the results achieved so far is given. The features of open gears of turning mechanisms of construction machines are highlighted: a large gear ratio, a large gearing module, the absence of a common frame for the gear and wheel, poor transmission lubrication conditions, a small degree of precision in the manufacture of gears and the actual overlap coefficient is close to one. With these features, the main internal source of vibration is the difference between the main steps of the gear and the wheel and the error of the involute profile of the teeth. The results of the study of the influence of these features of vibration damping and open gear transmission on the dynamics of the turning mechanism of the construction machine are presented. The studies were carried out on a generalized two-mass nonlinear dynamic model with internal perturbation from the gear pair and with structural damping. The studies were conducted mainly for the transitional modes of resonance. Based on the analysis of the results obtained and presented in the article, recommendations are given to reduce the fluctuations of the turning mechanisms of construction machines.

APPROACHES TO CLASSIFICATION OF REDUCTION METHODS OF LOW FREQUENCY NOISE AND VIBRATION OF POWER PLANTS

The importance of the problem of low-frequency noise and vibration reduction now may be considered as urgent. Increased influence of low-frequency noise and vibration may cause both human health problems and equipment damage. Power plants (internal combustion engines, compressors, heat-exchanges etc.) are one of the main low-frequency noise and vibration sources. The principles of classification of methods of power plants low-frequency noise and vibration reduction are suggested. Author is proposing energetic approach, according of which all the methods and arrangements of reduction may be classified as passive (adaptive and non-adaptive), active and hybrid passive-active. The classification is illustrated by the different examples, including constructions of mufflers and dampers, some of which are developed by author.

Study for Influence of Harmonic Magnetic Fields on Vibration Properties of Core of Anode Saturable Reactor in HVDC Converter Valve System

The cores of anode saturated reactor (ASR) are the main vibration source of the HVDC converter valve system. The ASR is excited with an impulse voltage, which contains many harmonic components, and the magnetostriction of cores is usually the main reason of the ASR vibration. Therefore it is significant to study the influence of the harmonic on the vibration of core of ASR. In this paper, the magneto-mechanical coupling model is established based on the magnetostriction theory and the expression of vibration acceleration in the presence of third harmonic is derived. The vibration test platform is built to test the core's vibration acceleration. The magnetic and magnetostrictive properties of silicon steel sheet under different working conditions are measured. The three-dimensional simulation model of the core is established, and the vibration acceleration under different magnetic flux density is calculated. The comparison of the experiment and simulation results shows the rationality of the magneto-mechanical coupling model. The influence of third harmonic magnetic flux density on vibration is studied by changing the phase of the third harmonic magnetic flux density and the ratio of the third harmonic magnetic flux density to the fundamental magnetic flux density. Both the calculated and measured results show that the third harmonic magnetic flux density affects the vibration acceleration according to the double-frequency components of the third harmonic, as well the sum-frequency and difference-frequency components of the third harmonic and fundamental frequency.

Research on Control Strategy of Two Dimensional Output Force Vibration Damping Electric Actuator

The main spiral blades of helicopter and other non fixed wing aircraft are in the asymmetric and unsteady aerodynamic environment for a long time, which will make the body produce large-scale multi-directional low-frequency vibration, which will become the main vibration source of the body. The linear actuator can only produce single direction driving force, which is difficult to meet the high-precision vibration reduction requirements. Based on this, a direct drive vibration control system based on the space-time coupling method of rotating coordinate system is proposed. Firstly, the mathematical model of the output force of the single side of the electric actuator is deduced, and the space-time coupling method of the rotating coordinate system is proposed to derive the mathematical expression of the two-dimensional vibration suppression output force. Secondly, the two-dimensional output force control strategy based on the cross coupling control of multiple motors is proposed. The controller parameters are designed by state space method and the method of characteristic value of the feedback matrix to ensure the stability of the control system. The controller parameters are optimized according to the sensitivity H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> control theory to improve the anti-interference of the closed-loop system. Finally, a 14kg prototype is designed by the proposed control strategy, which completes the synchronous verification experiment of position and speed, steady state and dynamic verification experiment of output force. The experimental results show that the coordinated control strategy of multi motors proposed in this paper makes the actuator output force meet the performance requirements of the system vibration reduction and has a good stability.