Robotic Systems and Applications
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Optimum suspension design for non-linear half vehicle model using particle swarm optimization (PSO) algorithm
Get PDFThis paper is considered with a non-linear suspension design for half vehicle model by using particle swarm optimization technique. To analyze the ride comfort, a five-degree of freedom system is built, and it is integrated with the Particle Swarm Optimization (PSO) for optimizing the vehicle vibrations. A multi-objective function is proposed as the sum of the minimum seat and vehicle body acceleration, the minimum suspension deflection and the constraints and the design variables of the optimization problem are selected as the spring and damping coefficients of the front and rear suspension and the non-linear spring and the linear damping coefficients of the seat. The simulations are carried out and the results are compared with the non-optimized values. It is demonstrated that the vehicle vibration is decreased significantly with the help of the optimum values of the suspension parameters
Design study of a magnetoelectric-electromagnetic vibration energy converter for energy harvesting
Get PDFThe aim of this paper is to design a combination of a magnetoelectric-electromagnetic (ME-EM) vibration converter in order to reach an improved energy outcome. In this paper, the influence of magnets polarization and magnetoelectric transducer and coil direction are investigated. For this purpose, a finite element model is developed using one coil, one ME transducer in a magnetic circuit. Simulation results show that a better magnetic field distribution and variation is reached, if the magnetic circuit magnets are placed in attraction. Radial polarization shows decisive advantages in comparison with axial polarization. The placement of coil parallel to the magnetic circuit direction and the magnetization of the ME transducer along its width is the optimal direction relative to the magnetic circuit
Temperature stress of waste bunker in municipal solid waste incineration power generation plant
Get PDFWith large number of municipal solid waste incineration power generation plants appearing, serious environmental pollution will be caused if temperature cracks appear in waste bunkers. To reveal the interaction between the surrounding soil and bunker walls under the action of temperature, a finite element model is established. Considering the surrounding soil layer, the characteristics and influence laws of the interaction between the municipal solid waste bunker and the soil under different temperature conditions are studied. The simulation results show that the existence of the surrounding soil layer will affect the stress distribution, mainly at the bottom of the bunker and the surface of the bunker wall. Due to the thermal expansion and contraction, the municipal solid waste bunker is pressed during the heating process. In the process of cooling, there will be excessive tensile stress at the bottom of the bunker. To address this problem, expansion belt is arranged at the stress concentration portion to reduce the stress concentration. This measure proves to be effective according to analysis results, which provides a reference for the design of municipal solid waste bunkers
Research on the dynamic characteristics of the squeeze film damper of a certain aero-engine
Get PDFNumerical methods were conducted to simulate the characteristics of SFD under different clearance, eccentricity and precession angular velocity and verified by bidirectional excitation experiments, which is comparatively leading initiative in characteristic measurement of SFD. In addition, finite difference method was introduced to derive Reynolds equation and SOR method to obtain the distribution of oil film, the convergence was also mathematical proof. The results indicate the rotor system keep large vibration state for a long time due to the increasing of actual critical speed of system, which result from the oil film stiffness increases nonlinear excessively with the increase of eccentricity; clearance make a great influence on SFD, especially SFD with large radial size should be kept within 2 ‰
Dynamic characterization and modeling of steel foam sandwich structure
Get PDFThe purpose of the recent project is giving empirical research of the dynamic properties along with measuring the damping ratio for different metal foam sandwich specimens, and mathematical modeling of these particular structures. Besides, the various specimens were modeled by employing ANSYS for the FEM analysis. Concerning to have a reliable result for two-phase sample the random noise outcomes have been applied and associated with the FE model. The final results depict an appropriate evaluation of the vibrational damping for two-phase specimens
Controlled cascading waterfall technology of crushing raw materials on the value of its current strongholds
Get PDFThe results of laboratory studies of innovative technology for grinding raw materials are presented. Grinding technology is one of the most energy-intensive industries in the industry. The obtained data confirm the possibility of obtaining breakthrough technical and economic indicators in the implementation of the proposed innovative technology of grinding raw materials in ball mills. The latter is achieved by maintaining in them the optimal trajectories of intra mill loading on the basis of the use of a controlled cascade-waterfall grinding mode, depending on the constantly changing physical and mechanical properties (grind ability, strength) of the ground product. At the same time, the mill effectively implements the most efficient grinding regimes (blow, abrasion, crushing), depending on the current strength of the crushed raw materials. Tests have shown the possibility of reducing the specific energy consumption depending on the strength of the crushed material by 31-44 % with a simultaneous increase in the performance of the mill for raw materials of various strength classes by 22-57 %. For the industrial tests of the proposed technology, two systems of automatic control of the strength of the comminuted material in the mill have been developed
Modelling of pressure-temperature conditions for cavitation initiation in different liquids
Get PDFThe paper presents modelling of acoustic cavitation inception. The model is based on the structural-temporal approach, which has shown a predictive effectiveness in considering various transient processes. The presented calculations were performed for four different liquids at a high-frequency vibration and across a wide temperature range. The predictions of the presented theoretical model were validated by comparison with the experimental data, and good agreement was demonstrated
The effect of system improvement on regulation of pressure inside pneumatic spring element and on transmission of acceleration
Get PDFFollowing a patented solution, a seat which is possible to change its stiffness was created. The seat contains an actively controlled pneumatic spring element (the PSE). For the requirement of working faster and more precisely, an improvement was applied. This article focuses on a comparison of the effect of the improved system and the original system on regulation of pressure inside a PSE. For comparison, two system characteristics were used, the response time and the transmission of acceleration. The original and improved system were thoroughly studied and compared experimentally. The behavior of both systems is analyzed and evaluated. The function of pressure regulation is investigated under static conditions (without excitation) and the transmission of acceleration is performed under dynamic conditions (with excitation). The results describe the behavior of the system in two modes of controller setup: constant pressure and constant stiffness both under static and dynamic conditions
Fault diagnosis using an improved fusion feature based on manifold learning for wind turbine transmission system
Get PDFIn this paper, a novel fault diagnosis method based on vibration signal analysis is proposed for fault diagnosis of bearings and gears. Firstly, the ensemble empirical mode decomposition (EEMD) is used to decompose the vibration signal into several subsequences, and a multi-entropy (ME) is proposed to make up the fusion features of the vibration signal. Secondly, an improved manifold learning algorithm, local and global preserving embedding (LGPE), is applied to compress the high-dimensional fusion feature set into a two-dimension feature set. Finally, according to the clustering accuracy of different feature set, the fault classification and diagnosis can be performed in the reduced two-dimension space. The performance of the proposed technique is tested on the fault of wind turbine transmission system. The application results indicate that the proposed method can achieve high accuracy of fault diagnosis
Shadow effect compensation method for ultrasonic transducer array model
Get PDFAlthough ultrasonic wind meter is widely used in wind speed measurement, the disadvantages of the ultrasonic wind meter structure by its measurement way still exist. The ultrasonic probe will stop on the way of the wind, which in turn produces a shadow area at the back of the probe, probe produce turbulence ahead. Therefore, it will result in error during the process of our normal wind speed measurement. At present, the ultrasonic wind speed Angle compensation formula is deduced by using the wind speed compensation formula on the path. The measurement data and the compensation formula are used for fitting comparison. It is observed that the Angle compensation function of wind and ultrasonic path fits well with the measured data, and the wind speed error after compensation is reduced from 14.65 % to 1.74 %. The modified measurement of accuracy of wind speed and direction can be used in two-dimensional ultrasonic orthogonal wind array model