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Nonlinear dynamic analysis on maglev train system with flexible guideway and double time-delay feedback control
Get PDFIn this paper, the dynamic behavior of time-delayed feedback control for maglev train system with double discrete time delays is considered with flexible guideway. Considering the maglev guideway as Beroulli-Euler beam, the mathematical model of maglev system with flexible guideway is constructed. The time delay of the two state feedback signals in the maglev system occurs simultaneously, and the values are different. The present treatment method only considers one single feedback delay, which are insufficiency. Thus, the Hopf bifurcation with double time-delay feedback of maglev train running on the flexible guideway is analyzed considering time-delayed position feedback signal τ1 and velocity feedback signal τ2. A novel method is presented to develop the double-parametric Hopf bifurcation diagram in relation to τ1 and τ2. Sufficient numerical simulations are provided to illustrate the complex dynamical behavior of the discrete delays τ1 and τ2 for maglev system and we verify the obtained theoretical analysis. Finally, the field experiments are carried out to validate the effectiveness of the Hopf bifurcation analytical method preliminarily
Design and implementation of DC source fed improved dual-output buck-boost converter for agricultural and industrial applications
Get PDFThe proposed research involves, a design and implementation of DC source fed improved Dual output Buck-Boost converter for agricultural and industrial applications. It consists of step up and step-down converter, DC-link module. Compared with conventional two converters, the designed system results in reduction of voltage tension across the switches, compact power switches, DC source reckoning and reduced inrush current. DC-link switching is achieved by reduced ripple voltage which results in improved quality of obtained output power. Reduction in switch count makes the system more cost effective. In addition, the motor speed is regulated by PI controller. Brushless DC Motor produce torque ripple and cause mechanical vibration, acoustic noise due to structural imperfectness and control system, to overcome this suppression control method of vibration for brushless DC motor utilizing feedforward compensation with Fourier transform utilizing a vibration signal acquired by an acceleration sensor attached to the motor frame is proposed. A simulation and prototype model of Dual output Buck-Boost converter is developed, and its performance is analysed for various operating conditions
Benchmark solutions of the free vibration of simply supported laminated composite plates
Get PDFDue to the high specific strength and stiffness, laminated composite plates, especially mid-plane symmetric laminated composite plates, are frequently used as structural component in aeronautical and aerospace engineering. Since obtaining analytic solutions are difficult even for simply supported mid-plane symmetric laminated composite plates, numerical methods have to be used to obtain approximate solutions. To evaluate various numerical methods, benchmark solutions are needed. In this article, highly accurate frequencies of simply supported angle-ply mid-plane symmetric laminated composite plates with two sets of equivalent material properties are obtained by the modified differential quadrature method and presented to serve as the benchmark solutions
Influence of semi-trailer truck operating conditions on road surface friendliness
Get PDFIn order to analyze the influence of semi-trailer truck operating conditions on road surface, a three-dimensional vehicle-pavement coupled model with 14 degrees of freedom is established for simulation and calculation. The influence of the different vehicle operating conditions on the dynamic tire loads, dynamic load coefficient (DLC) and road-friendliness which include road surfaces, vehicle speeds, vehicle loads are analyzed in this study. The results shown that the influence of the road surface roughness and vehicle loads on the tire dynamic load coefficient as well as road-friendliness is very obvious. Especially, the DLC values of the 3rd axle increase from 23.97 %, and 34.88 % when vehicle moves on three different road conditions with a velocity of 20 m/s and fully loaded. Finally, this study result gives the road-friendly limit of driving speed for 5-axle semi-trailer truck when vehicle operates under the different conditions
Analysis of corn ears movement within the threshing crescent using high-speed recording method
Get PDFThe main objective of the research was to establish movement of corn ears within the threshing crescent between the cylinder and the concave using high-speed recording method. Tangential threshing unit was used in the experimental trials. Cylinder rotation and linear velocity of rasp bars (11.00 m s-1, 14.14 m s-1 and 17.28 m s-1) were determined by using threshing cylinder covered with filler plates having 4 different shapes. During the trials, speed of corn ears within threshing crescent, number of impacts received by the corn ear, rising height of the corn ear after impact of rasp bar and time between two impacts of rasp bar to the corn ear, depending on the shape of filler plates of threshing cylinder were found. Video analysis of corn ear movement showed that the speed of corn ears movement in the threshing crescent highly depends on linear velocity of rasp bars. The average speed of corn ear within threshing crescent and number of impacts received by the corn ear were increased with increase of linear velocity of rasp bars irrespective of cylinder filler plates are used. Moreover, both above-mentioned parameters were larger in the second part of concave length than in the first one. A tendency of increase of the corn ear moving over the surface of the concave and decrease of number of impacts received by the corn ear was observable by reduction in the threshing crescent. Following reduction of linear velocity of rasp bars to 14.14 m s-1, it would be reasonable to cover the threshing cylinder with filler plates that can reduce the cross-section area between rasp bars and concave (to 94.26 cm2 in view of one gap between adjacent rasp bar). In this case, filler plates showed a substantial effect on behaviour of corn ears: they restrict a rising height of the corn ear, may be subject to additional rotational motion, deflect the corn ear to the clearance between the rasp bar and the concave bar as well as deflect threshed kernels towards concave grates
Theoretical and experimental investigation of the tube-shaped waveguide wire
Get PDFCardiovascular diseases are the leading cause of death among people up to 65 years old. One of the most common cardiovascular disease is thrombosis. To remove the blood clot inside the artery, usage of advanced invasive mechanical devices is needed. There is a need for the new alternative less risky and hazardous way of arterial thrombosis treatment. This paper presents a new design of a less risky ultrasonic blood vessels cleaning system
A multigrid method for EHL line contact problem with Grease as lubricant
Get PDFThe paper presents an isothermal Elastohydrodynamic lubrication (EHL) of line contact problem with grease as a lubricant, described by Herschel-Bulkley model. The simulation of the governing problem is analyzed using Multigrid method with full approximation scheme (FAS) for varying load, speed and rheological index n Herschel-Bulkley model. The EHL problem considered comprises of Reynolds equation and film thickness understudy for different parameters of interest. The minimum film thickness and pressure spike decrease with a decrease in rheological index n. The present paper traces out the comparison of minimum film thickness with the standard results of Dowson and Higginson. The results obtained are comparable and are presented in terms of graphs and tables
Numerical simulation for machining S-tube by abrasive flow with various particle volume fractions
Get PDFAbrasive flow machining has become an economical and efficient ultra-precision process for machining complex-shaped pipe parts, and processing effect is exceedingly subject to particle volume fraction. In this paper, aiming at uncovering the influence of various particle volume fractions on the machining result of abrasive flow finishing, based on fluid mechanics theory, mixed phase model and discrete phase model were conducted, FLUENT software was resorted to simulate the numerical characteristics of the solid-liquid two-phase flow field in the inner channel of S-tube with different-particle-volume-fraction abrasive flows, the mechanism of erosion and wear of particles was uncovered, which provides a theoretical basis for abrasive flow machining S-tube structured components
A torsional vibration damper based on a serial viscoelastic coupling of its seismic mass
Get PDFThe design of dynamic torsional vibration dampers of piston internal combustion engines is generally based on the principle of a dynamic damper with one degree of freedom in which the coupling of the seismic mass of the damper to the basic dynamic system is realized by a two-parameter parallel rheological model. With known realizations of this principle, it is usually difficult to achieve the optimum value of the respective damper parameters determined from the computational models, which is particularly true for optimal damping values. A dynamic torsional damper, based on the series arrangement principle of the elastic and damping element, offers better design options to achieve the optimum parameters of both the elastic and damping elements
Impact of road surface roughness and magnetic force on the in-wheel motor magnet gap
Get PDFFor an in-wheel-motor drive electric vehicle, the driving motors are directly mounted in the wheels. Using this chassis structure, the road excitation can cause a magnet gap deformation in the motor. The magnet gap deformation will lead to magnetic force which not only has a negative impact on vehicle dynamics but also affects the magnet gap deformation in turn. To further analyze the impact of the road and the magnetic force on the motor magnet gap, a test platform was built, and used to simulate cases of road and composite excitation. The results show that 1) road excitation can cause motor magnet gap deformation, and when the excitation frequency is increased for a constant amplitude, the deformation degree also increases. 2) For the same road excitation frequency, the deformation degree increases with the motor speed. This not only proves the existence of the magnetic force but also indicates that the size of the magnetic force is related to the motor rotating frequency. 3) A comparison between the simulated and experimental results not only confirms the validity of the theoretical derivation and analysis but also lays the foundation for subsequent vibration control of in-wheel-motor drive electric vehicles