Maintenance, Reliability and Condition Monitoring
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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
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
On the combination of topology optimization and multiple mass dampers
Get PDFThis paper presents a vibration reducing mechanism combining the bi-directional evolutionary structural optimization (BESO) method and the multiple mass damper (MMD) method. The BESO method changes the mass and stiffness distribution of a structure, in order to push the most significant natural frequency away from the driving frequency. The removal of less stressed material by the BESO method creates hollow spaces in the structure. The MMD will be installed in the hollow spaces, and reduces the resonance vibration amplitude of the most significant mode
Coupling vibration model for hot rolling mills and its application
Get PDFIn this paper, we propose an effective mechanical-electrical-hydraulic-interfacial coupling vibration model for hot rolling mills and obtain a practical measure to relieve mill vibration. First, an experiment related to mill modulus control gain in automatic gauge control (AGC) is carried out during manufacturing. Rolling mill vibration is observed to gradually be enhanced with increasing mill modulus control gain. Then, to explain this phenomenon, the mechanical-electrical-hydraulic-interface coupling dynamic model is modeled based on Sims’ rolling force method. Finally, we analyze the influence of mill modulus control gain on the vibration numerically on the basis of the coupling dynamic model. Moreover, the agreement between the experiment result and the simulation result is confirmed and the measure reducing the mill modulus control gain is obtained to relieve mill vibration
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
Improving ride comfort for vibratory roller utilizing semi-active hydraulic cab mounts with control optimization
Get PDFHydraulic mounts can provide a better vibration attenuation performance than elastomeric mounts especially in the low frequency range. However, it is incapable of providing a response-dependent damper for the mount system to improve the ride comfort. In this study, a semi-active hydraulic cab mount (SHM) with control optimization was designed to improve ride comfort for the heavy vibratory roller. And a 7-DOF non-linear dynamic model of the vehicle was established for evaluation of the performance of hydraulic cab mounts based on different control optimization algorithms. To simulate roughness height the ISO level D road surface and deformed soil model were employed under the compaction work condition. The optimization study for two performance objectives as measured by responses of the vertical driver’s seat and cab pitch angle was carried out. It was shown that the SHM optimized by the fuzzy logic and proportional, integral, derivative controller methods (FLC-PID) giving best optimum values of the objective vector as compare to by multi-objective genetic algorithm (MOGA) and PID controller based on genetic algorithm (GA-PID)
Study on dynamic characteristic of closed-cell aluminum foam
Get PDFClosed-cell aluminum foam has been widely used in aerospace, rail transit and mechanical for its outstanding performance. But for a long time, the research on its vibration damping performance is only limited to the material damping test, there are relatively few studies on its dynamic characteristics. In this paper, we studied the relationship between dynamic characteristic and feature parameters. Modal assurance criterion and Finite element method were used to verify the accuracy of experimental model. It turned out that the average pore diameter of closed-cell aluminum foam conforms to Gaussian distribution. The modal analysis method can be used in the research of dynamic characteristic of closed-cell aluminum foam. Its damping ratio showed increasing trend with the increase of porosity, natural frequency and the decrease of mean pore size. Each order natural frequency increases along with the increase of porosity
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
Magneto-thermal coupling analysis of the permanent magnet eddy current brake under intensive impact load
Get PDFTo more realistically describe the operation of an eddy current brake under intensive impact load, a magnetic-thermal bidirectional coupling model of the eddy current brake is established considering the existence of temperature. The variation of material and convective heat transfer coefficient with temperature are considered in the model. The iterative method is used to decouple the model. Through the analysis of the numerical simulation results, the temperature distribution and transmission of the brake during operation are obtained. By comparison, it is found that the calculated braking force of the magneto-thermal coupling model is lower than the calculated value without considering the temperature field due to the influence of temperature. And the higher the temperature, the greater the decrease
Design of vibration standard device based on random comparison method
Get PDFIn order to meet the needs for aircraft vibration transducer and measurement equipment to be calibrated at the job site, it is necessary to design a compact, dynamic and functional vibration standard device. This paper introduces a vibration standard device based on random comparison method. The structure and working principle of software and hardware are described in detail. Unlike the calibration requirements under laboratory conditions, on-site calibration requires that the calibration process be more consistent with the actual operating conditions. A random vibration comparison calibration method using random signals as excitation sources is designed. The vibration standard device can be maneuvered from the laboratory environment to the aircraft maintenance site. It has been proved measurement uncertainty of the system is 1.0 % (k= 2) by the method of control accuracy