Journal of Vibroengineering
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A slope stability analysis for southern Wuchangping tin mine
Get PDFThis paper aims to provide a slope stability analysis for the southern part of Wuchangping mine. The methods of limit equilibrium analysis, finite element simulation and neural network were used to study the stability of the southern slope. The preventive measures, such as bolt reinforcement, drainage system and so on were carried out. The results are as follows. The slope angle for the lower slope of moderately weathered granite and slightly weathered granite is recommended as 60°-65°. The slope angle for the layer where locates near the ground of full weathered granite is recommended as 30°-32°. When the thickness of fully weathered granite layer is less than 10 meters, the slope is still stable enough. The angle is recommended as 38°-40°. The results of evaluation and calculation obtained by the neural network are not different from those of the limit equilibrium method and finite element simulation. The neural network can accurately predict slope stability. The conclusions can provide useful reference for similar mines
3D continuum-discrete coupling modeling of soil-hammer interaction under dynamic compaction
Get PDFTo investigate the compaction effect and environmental impact effect of dynamic compaction (DC), a 3D continuous-discrete coupling method was used to simulate the hammer-soil interaction process for the first time. Through the dynamic response analysis of the hammer, it is found that the force of the hammer changes through three stages: the contact force increases rapidly, the contact force decreases rapidly, and the contact force decreases slowly; in addition, the soil particles are compacted under the dynamic load, resulting in oscillating changes in the soil porosity. The granular soil is punched by the hammer to form a truncated punching surface in the bulk below the bottom of the hammer. Ellipsoidal compaction bands are formed inside the punching surface, and shear bands are formed outside the punching surface. The compression and shear zones affect the soil outside the continuous-discrete interface and form a stress concentration zone and a plastic strain zone near the interface, resulting in a sharp attenuation of the acceleration amplitude as the radial distance increases. Through an amplitude and Fourier spectrum analysis, it is found that the radial vibration caused by the DC is the strongest, while the tangential and vertical vibrations are almost the same. With the increase in the radial distance, the radial vibration attenuation rate is greater than that of the tangential and vertical vibrations, and their PGAs tend to be the same away from the impact point. These research results are helpful for evaluating the influence of the DC and the installation process on the reinforcement effect of the soft ground and for improving the accurate design and control level of soft ground strengthened by DC
Self-synchronization features of inertial vibration exciters in two-mass system
Get PDFThe paper presents the results of experimental analysis features of rotation of two unbalance vibration exciters that excite oscillations of a chain-type two-mass oscillatory system in order to identify stability of synchronous modes of the debalances rotation near the system resonances (in application to analysis of resonant vibrating machines dynamics). Experimentally obtained amplitude-frequency characteristics of the model, velocities and mutual phase shift of rotation of the debalances are analyzed. Areas of stable synchronous rotation of the debalances and types of their self-synchronization are revealed as dependence of both the frequency of voltage supplying to the electric motors and the imbalances value. It is shown that when approaching the resonant frequencies, both the debalances rotational speeds and their mutual phasing appear to be unstable
Adaptive control of a nonlinear suspension with time-delay compensation
Get PDFThis paper addresses the challenge of predictive control of a quarter-car nonlinear suspension and low controller-precision. This is done by designing and implementing an adaptive controller with time-delay compensation. First, a real-time control model is created. Then, time-delay compensation is realized and both frequency-domain and time-domain simulation of the controller performance are conducted. According to the simulation results, the sprung-mass acceleration of the suspension controlled by an adaptive controller with time-delay compensation is superior to that without time-delay compensation. Both the period to settle down and the peak of vibration acceleration are smaller. This means the proposed controller is capable of dealing with problems including variable time delay, nonlinear vibration and predictive control
The fatigue properties and damage of the corroded steel bars under the constant-amplitude fatigue load
Get PDFWe obtained the corroded steel bars by conducting electrically-accelerated corrosion tests. Then, to investigate the effects of the corrosion ratio and the stress amplitude on the fatigue life, and to further study the damage evolution law under corrosion and fatigue loads, we performed axial fatigue tests on 13 steel bars with various corrosion ratios. The laboratory results show that the fatigue life is logarithmical linear to the stress amplitude, and the increase in corrosion ratio leads to the accelerated decrease in the fatigue life. In addition, the increase in stress amplitude can accelerate the fatigue damage, and further decreases the fatigue life. With the laboratory data, we further established a model to predict the fatigue life of the steel bars with various corrosion ratios. The evolution of the residual strains includes the relatively rapid increase, stable increase and rapid increase stages. Moreover, we developed an evolution equation for the residual strain, and this equation can properly describe the laboratory results. Furthermore, considering the fatigue damage, we proposed a constitutive model to describe the stress-strain curve of the corroded steel bar under static tension. The comparison shows that the calculated stress curves agree well with the laboratory curves
An adaptive stochastic resonance method based on multi-agent cuckoo search algorithm for bearing fault detection
Get PDFBearing is widely used in the rotating machinery and prone to failure due to the harsh working environment. The bearing fault-induced impulses are weak because of poor background noise, long vibration transmission path, and slight fault degree. Therefore, the bearing fault detection is difficult. A novel adaptive stochastic resonance method based on multi-agent cuckoo search algorithm for bearing fault detection is proposed. Stochastic resonance (SR) is like a nonlinear filter, which can enhance the weak fault-induced impulses while suppressing the noise. However, the parameters of the nonlinear system exert an influence on the SR effect, and the optimal parameters are difficult to be found. Multi-agent cuckoo search (MACS) algorithm is an excellent heuristic optimization algorithm and can be used to search the parameters of nonlinear system adaptively. Two bearing fault signals are used to validate the effectiveness of our proposed method. Three other adaptive SR methods based on cuckoo search algorithm, particle swarm optimization or genetic algorithm are also used for comparison. The results show that MACS can find the optimal parameters more quickly and more accurately, and our proposed method can enhance the fault-induced impulses efficiently
Design and modeling of improved controller using DC source fed permanent magnet synchronous motor drive with enhanced DC-DC converter by reducing vibrations for industrial applications
Get PDFThe proposed research involves Design and Modeling of Improved Controller (PID), Using DC Source Fed Permanent Magnet Synchronous Motor Drive with Enhanced DC-DC Converter by reducing vibration for Industrial Applications. It consists of a DC-DC converter, voltage-link module, fractional second order system PID controller. In this proposed improved controller, enhanced converter, DC-link switching is achieved by a bridged ripple voltage which results in the improved quality of output power, and it also reduces vibration, and noise in the drive without affecting mechanical properties. Reduction of switches makes the system more cost effective. A simulation of fractional second-order function, Buck-Boost converter is designed, and its concert is analyzed for various functioning factor conditions. The Three-Port Converter and B4-Inverter fed Permanent Magnet Synchronous Motor Drive focused on the industrial applications. An Ampere-hour unit powered converter is used at inductor terminal, which has been realized by minimizing the distortion and decreasing the Ampere-hour unit rating a new topology is proposed. As Comparing with previous system, the proposed system results in the reduced voltage fluctuation at the switches. Hence the proposed system proves power switches are compact, with reduced inrush current and improved output transfer function. Based on this a fulfilling closed loop validation has been performed for both simulation and experimental arrangement
Anti-overturning stability coefficient of curved girder bridges considering seismic action
Get PDFTo overcome the limitation of terrain and ground objects, curved girder bridges normally adopt a single column pier, on which a single bearing or double bearings with small spacing are seated, making it weak in anti-overturning ability under eccentric load. Presently, the vehicle centrifugal force and seismic action are rarely considered when calculating the anti-overturning stability and tend to aggravate the deflection of curved girder bridges. In this paper, a calculation method is proposed to determine the anti-overturning stability coefficient under earthquake; the calculating equation of anti-overturning stability coefficient under static action is modified. The results show that the influence of centrifugal force cannot be neglected. Otherwise, the calculation of overturning stability is unsafe. The anti-overturning stability of curved girder bridges under earthquake is lower than that under static action. Further, the effect of different structural parameters on the anti-overturning stability coefficient under static and seismic action is similar: the anti-overturning stability coefficient decreases with the growth of bridge deck width, while first decreases sharply and then increases slowly with the growth of curvature radius
Erratum: Buffeting performance of long-span suspension bridge based on measured wind data in a mountainous region
Get PDFAnalytical solution of a vibrational problem for visco-elastic plate with Kelvin type boundary conditions
Get PDFWithin this time of science and technology, tapered plates with different geometry conditions are used as a for the construction of wings and blades of aeronautical as well as engineering structures. The main aim of current work is to analyze the vibration of rectangular structure tapered plate with thermal effect variation along x and y axis. Rayleigh-Ritz method is use for judgment the solution of frequency equation. Now for several values of thermal gradient, aspect ratio and taper constant are considered to calculate structural parameters such as logarithmic decrement, time period and deflection