Journal of Vibroengineering
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A review on wind turbines gearbox fault diagnosis methods
Full text linkAs an renewable and clean energy of the world, wind energy has gained more and more attention and its fault diagnosis becomes more and more important. The gearbox, as the kernel component of the wind turbine system, it’s robust conditions have a great influence on the whole wind turbines system. Wind turbine gearbox has complex structure, which is usually composed of solar planetary gearbox and cylindrical gearbox. In the process of operation, various kinds of faults easily occur, resulting in serious losses. Once the wind turbine gearbox is not functioning as smoothly as it could be, it may result in large economic losses for the company and owner. At the same time, the failure rate of wind turbine gearbox has always been high because of complicated mechanic structure and special motion. Therefore, the tasks of reducing the downtime and increasing the productivity of wind turbine gearbox are urgent. This paper reviewed some research results of faults diagnosis on wind turbines gearbox, such as time-frequency analysis method, vibration based methods, nondestructive testing methods, etc. Meanwhile, this paper finds out some key problems and the channel of the resolution of the issue in order to supply some information for the further research of wind turbines gearbox
Investigation for synchronization characteristics of double cam vibrating screen
Full text linkAiming at the shortcomings of traditional vibrating screens with large vibration mass, a double eccentric cam self-synchronous vibrating screen is proposed. The motion differential equation of the vibrating screen system is derived by using Lagrange equation and the steady state solution is obtained. According to Hamilton principle, the synchronization condition of the vibration system is deduced, and the stability condition of the self-synchronization motion is obtained. The influencing factors of synchronization and stability are investigated by using numerical calculation and simulation analysis methods. The results show that stable self-synchronous motion of the vibration system is implemented when the synchronization and stability conditions are satisfied; the value of the stable phase difference of two cams varies in the range of (–1.5 rad, 0), and compared with the residual torque difference, the eccentricity of eccentric cams has a greater impact on the stable phase difference; additionally, a linear motion track of the vibrating screen is achieved
Controlled experimental research and model design of double-layer high-frequency vibrating screen machine
Full text linkThe double-layer high-frequency vibrating screen machine is widely used in the tobacco industry, and its controllability of vibration has a great influence on the screening quality of cut tobacco. In this paper, we obtain the factors affecting the motion characteristics of the vibrating screen by theoretical derivation and experimental measurement of the motion parameters of the double-layer high-frequency vibrating screen machine, and determine the relationship between various factors and the amplitude of the vibrating screen. We also studied the properties of material motion. Through the overall research, we found that in the controllable process of realizing the high-frequency double-layer vibrating machine, we need to pay attention to the quality of the rotor of the motor, the angular velocity, and the radius of gyration, and also need to consider the number of spring piece and the rigidity of the spring piece. Also, the quality of the material will affect the movement of the screen
Applying deep learning and wavelet transform for predicting the vibration behavior in variable thickness skew composite plates with intermediate elastic support
Full text linkIn this paper, the vibration behavior features are extracted from the combination between Wavelet Transform (WT), and Finite Strip Transition Matrix (FSTM) of skew composite plates (SCPs), with variable thickness, and intermediate elastic support. Although, the results of this technique and based on the previous work done by the authors, that show the method can reflect the vibration behavior of the composite plates. Due to the method's difficulty in terms of, a lot of calculations with a large number of iterations these results may not be good choices for quick and accurate vibration behavior extracting. Thus, the new deep neural network (NN) is designed to learn and test these results carrying out by extracting vibration behavior features that reflect the important and essential information about the mode shapes in SCP. The results give high indications about the proposed technique of deep learning is a promising method, particularly when the type structures are complicated and the ambient environment is variable
Trajectory planning for mobile manipulators with vibration reduction
Full text linkA new method of online trajectory planning for mobile manipulators using the extended Jacobian approach, taking into account state and control constraints, allowing the mobile manipulator to reduce the arm vibrations is presented. The proposed approach is based on the concept of virtual control which scales the trajectory preventing robot controls from changing rapidly and ensuring that the control constraints are fulfilled. The simulation results presenting the features of the developed algorithm have been shown. The effectiveness of the method in vibration reduction is confirmed by an experiment involving a KUKA youBot mobile robot
Study on flow dynamic characteristic of bladder pressure pulsation attenuator based on dynamic mesh technology
Full text linkTo solve the problem that the flow dynamic characteristic of the bladder pressure pulsation attenuator cannot be quantitatively analyzed, a bladder pressure pulsation attenuator was taken as the research object, and the dynamic mesh technology was combined with the User-Defined-Function (UDF) to numerically simulate the working process of the attenuator. Overcoming the divergence problem in finite-element fluid calculation and the negative volume problem in mesh updating process, the bladder pressure pulsation attenuator was dynamically simulated under different fluctuating frequencies and different inflatable pressure, the change of internal flow field was monitored in time. The results show that the resistance loss through the attenuator increases with the increase of the frequency and the increase of the charging pressure. The local resistance loss is much higher than the frictional resistance loss. The simulation results match the experimental results, that verifies the model's validity and correctness, and also provides a new method and idea to improve bladder attenuator's resistance loss and analyze the variable boundary problem
Dynamic processes in the pulsation chamber vibration machine for disinfection of water
Full text linkThere is a design of vibrating machine proposed in this paper. In this vibrating machine low-frequency vibrations are used to form cavitation cavities in a liquid substance in order to disinfect it. To study the dynamics of a vibrating machine, an analytical model has been created, which makes it possible to determine the change in the maximum pressure in the working body of a vibrating machine and analyze the influence of drive operating modes and design parameters on the efficiency of the water disinfection process. From the accomplished experimental studies, graphical dependences of the influence of design parameters and drive operating modes on the change in maximum pressure in the working body of a vibrating machine are obtained. Using video, we visualized the processes taking place in the working body of the vibrating machine, and analyzed the occurrence of cavitation phenomena in the working body of the vibrating machine. According to the results of the studies, it is recommended for practical use in vibration machines the frequency boundaries of the drive’s vibrations, the oscillation amplitude, the size of the piston and the holes in it, and their ratio
Optical fiber deformation and vibration monitoring at distinct data rates with distinct photo-detectors devices
Full text linkThe transmission of the high data rate and information over the optical fiber is restricted by various dispersion phenomenon which further results into intersymbol interference (ISI). This article proposes two different methodologies for optical fiber deformation aiding vibration monitoring one using the pin diode as a photo-detector device and another manifesting the avalanche photo-detector. The novelty of this article lies in optical signal conversion using photo-detector processing followed by low pass Gaussian filter in order to reduce the extra contortion. This work is approaching electronic dispersion compensation technique (EDC) for compensation of chromatic dispersion at two distinct bit rates of 25 and 30 Gbps over 120 km of single mode fiber. Both the diodes have tested for theory performance using factors like Q-factor, bit error rate and eye height. It is found that pin diode is exhibiting a quality factor of 67.150 and 40.5944 at 25 and 30 Gbps, respectively. When avalanche pin diode is used at the same data rates, quality factor of 73.0240 and 43.3523 are obtained, respectively. Hence, use of avalanche photodiode at high bit rates is utilized and the simulations showed the optimum photo-diode for efficacious dispersion compensation at such a long transmission distance
Analyzing the compacting energy and force distribution during the tamper-asphalt mixture interaction
Full text linkTo enhance the compacting performance and the asphalt density during the tamper-asphalt mixture interaction (TAMI), a dynamics model of the TAMI is established to analyze the compacting energy of TAMI under the different excitation frequencies of the compacting mechanism. The MATLAB/Simulink software is then applied to solve the vibration equations of TAMI based on the lumped parameters of the compacting mechanism and hot mix asphalt. The experimental research is also performed to verify simulation results and force distribution characteristics of the compacting mechanism on the asphalt pavement. The research results indicate that the vibration excitation of the compacting mechanism should be used in a range from 18 to 22 Hz and the number of vibrations of the compacting mechanism at the same position should be used by N= 4 or 5 to improve the compacting performance and the asphalt density. Additionally, the experimental results also show that the compacting force distribution of compacting mechanisms is asymmetric, thus, the design parameters of the vibration screed system should be optimized to enhance the compacting performance of the asphalt paver
Mathematical simulation of adaptive vector finite element method for the analysis of electromagnetic vibration spectrum field response
Full text linkMathematical simulation plays a vital role in the analysis of electromagnetic vibration spectrum field response. This article realizes a three-dimensional adaptive vector finite meta-acting algorithm of controlled source electromagnetic vibration spectrum (CSEM) field to address 3D meshing for the simulation of terrain fluctuations and complex electrical anomalies. The adaptive methods utilized in this article is employed for one-time field and secondary field separation in order to calculate electromagnetic vibration spectrum field response. This response can effectively solve the source singularity in finite meta-simulation and improves the numerical accuracy of electromagnetic vibration spectrum field near the field source. The two approaches analysed in this article are CSEM one-dimensional positive algorithm and finite meta-method. The adaptive mesh refinement algorithm based on post-test error estimation is used in this paper to guide the mesh refinement to reduce man-made errors caused by designing a grid. The validity of the proposed algorithm is verified through numerical simulation of one-dimensional and three-dimensional models. The outcomes obtained reveals that the finite solution of one-dimensional model coincides well with the analytical solution. The relative error of electromagnetic vibration spectrum field amplitude is about 1 %, and the overall phase difference of less than 1 degree is observed. It is analysed that the three-dimensional model finite solution also fits well with the finite volume solution and the controlled source electromagnetic vibration spectrum response with three-dimensional tilt plate abnormality is simulated. This experimental analysis shows the ability and effectiveness of the algorithm to simulate the electromagnetic vibration spectrum field of complex geoelectrical structure