Applied Mechanics and Materials Vols. 105-107

Abstract: In the conditions of Rain-wind excitation, droplets suspended to the conductor within the strong electric field, which amplifies corona discharge and generate ionic wind. The ionic wind coupling with wind force induced vibration of the cable, which seriously affected the cable's normal operation of transmission and stability. Study on mechanism of corona discharge excitation, a finite element model of Rain-wind vibration is established based on the finite element theory and the Newmark algorithm. Take LGJ-240 as an instance, using experimental and numerical analysis to analyze the impact on amplitude of cable by the air humidity and density, conductor surface conditions, cable structure factors and tensions. Methods and conclusions in this paper can be used as references for designing UHV transmission liens, upgrading the existing lines and controlling vibration.

Abstract: Two turbine generator units with unstable vibration faults caused by unreasonable bearing elevation distribution are presented. Using the communicating vessel principle, elevation change among bearings with condenser vacuum and power are measured and analyzed. We found that elevation of bearings on low pressure cylinder in high vacuum state is the lowest among bearings. Shaft alignment in the cold state is not unreasonable. We pre-compensated and adjusted bearing elevation in the cold state on the base of the measured bearing elevation data. Vibration faults of two units were solved successfully. Vibration phenomenon, bearing elevation change monitoring data and fault troubleshooting method are presented. It is verified that bearing elevation pre-compensation method for solving such kind of faults is valuable.

Abstract: Due to its compact construction and high power density, the axial-flux permanent-magnet (AFPM) machine with coreless stator has obtained more and more attention and interest from researchers. For an AFPM machine with coreless stator, the axial magnetic attraction force may cause the rotors’ deflection and affect the machine’s reliability. In this paper, the magnetic field and the rotor mechanical strength of a coreless stator AFPM machine are studied. Finite-element method and analytic method are both used to calculate the axial attraction magnetic force between the two rotor discs. Structure finite-element analysis is used to simulate the maximum stress and deflection due to the axial magnetic force. The research is very significant to the power density elevation of the AFPM machine.

Abstract: The conventional planar near-field acoustic holography is not suitable for cyclostationary sound field radiated by the rotating machines. When the cyclic spectral density (CSD), instead of the complex sound pressure, is adopted as reconstructed physical quantity, the modulating wave and carrier wave components of the cyclostationary sound field can be extracted exactly and so the cyclostationary planar near-field acoustic holography (CPNAH) technique was proposed. Simulation and experimental results show that the modulation characteristics of the cyclostationary sound field can be extracted effectively and the sound source can be localized accurately.

Abstract: This paper shows the static strength analysis of the tractor front axle housing by using of the finite element analysis software ANSYS, visually shows equivalent stress and strain distribution and vertical displacement distribution of the front axle housing. At the same time it also shows the analysis results of the model processing, the results of accuracy and reliability, and the weak links of the structure. By analyzing the weakest link and the difference in strength between each node for the overall structure in the condition, it can provide a direction and theoretical basis for the design and optimization of geometric entities. And the results of the analysis may be as the basis for structural improvement. In this way, it can be verified that using computer virtual software for product development is positive.

Abstract: Due to the complicated structure and the high speed turbulence, it is difficult to measure and analyze the flow field characteristics of the main nozzle by experimental methods, naturally, some software such as FLUENT become a powerful tool to perform the numerical simulation for flow field of the main nozzle of an air-jet loom. The distribution of the airflow velocity and static pressure along axial and radial direction in main nozzle were investigated. The results indicated that the airflow in the main nozzle was extremely complex, its velocity in throat could be sonic and a certain backflow was produced. The research results will play an important role on the structural parameters optimization and energy conservation.

Abstract: In cantilever beam system, through the experimental method to study vibration reduction mechanism of particle collision damper. The filling rate of particle damping agent in damper is 40%, added the damper with different diameter impacters and different kinds of particle damping agent in combinations ways, the cantilever beam system obtained the varying vibration reduction, according to the quality of vibration reduction, analyzed the joined impacters and particle damping agent influence of vibration attenuation rule. Experimental results show that damper added impacters and particle damping agent can dramatically reduce the maximum amplitude of cantilever beam system in resonant frequency, and can effectively restrain vibration of cantilever beam system.

Abstract: The vibration of fire smoke exhausting robot affects a lot on running quality. The rotational speed of engine is fixed and the vibration of the robot’s engine has a certain dominant frequency, so a dynamic vibration absorber is possible to reduce the vibration. In this paper a typical structure has been designed, and the linear relationship between dominant frequency and engine speed has been surveyed. The elongation of the spring has been deduced to the only key parameter due to the linear relationship and determined speed. An evaluation standard of damping effect was set up, the maximum acceleration value and root mean square value of acceleration and relative value of acceleration were taken as the evaluation indexes. Comparison tests were made, the damping effect was taken into account. The experimental results demonstrate the practicability and effectiveness of the new simplified absorber.

Abstract: A 17-27-5 type BP neural network model was built, whose sampled data was got by hydrocyclone separation experiments; another 6-30-5 type BP neural network was also built, whose sampled data came from the simulation results of the LZVV of a hydrocyclone with CFD code FLUENT. The two neural network models also have good predictive validity aimed at hydrocyclone separation performance. It demonstrates LZVV structural parameters can embody hydrocyclone separation performance and reduce input parameter numbers of neural network model. It also indicates that the predictive model of hydrocyclone separation performance can be built by neural network.

Abstract: A modification of traditional FEM/BEM called element grouping method (EGM) is proposed to calculate the elastic vibration and acoustic field radiated from an underwater structure. Instead of rebuilding the structure using coarse FEs to save the computational time and data storage, the structural FEs on the coupled surface are grouped into clusters of BEs to reduce the number of fluid DOF. With the grouped elements (GEs) used as BEs, the problem of non-matching between fluid DOFs and structural DOFs is solved. The approach is illustrated and validated using known analytic solutions for submerged spherical shells subjected to uniformly applied incident pressure. Acoustic radiated from a ribbed cylindrical shell driven by a force is predicted by using different element grouping styles. Comparison between numerical and experimental results shows that fine grouped elements give a high computation efficiency and more efficient data storage saving.