Applied Mechanics and Materials Vols. 246-247

Abstract: This paper addressed a new approach of online diagnosis of induction motor with broken bar fault based on advanced digital filtering, ZOOM-FFT and acquiring slip by Rotor Slot Harmonics (RSH) techniques, the slip rate is accurately estimated from the precise measurements of the harmonic components of rotor and the power supply frequency, which enables us find the characteristic spectrum of a rotor with broken bar from the stator current spectrum. Thus, the motor broken bar fault can be detected by checking the existence of the characteristic spectrum. The proposed method overcomes the drawback of traditional current spectral analysis approaches. In particular, this paper addresses the problem that the side lobe spectral components are covered by the fundamental frequency and the noises. And the reliability of the fault detection method is improved. The experiment results have shown that the improved method is able to detect small broken rotor bar fault with good application value.

Abstract: Based on the the principle of generating line of spiral bevel gears, a new modeling method about spiral bevel gears is proposed. Mathematical pattern of spiral bevel gears with spherical involute is developed about two parameters. A kind of simulation modeling software of spiral bevel gears with spherical involute is developed in matlab-guide environment. The data of tooth-surface are collected and calculated in the simulation system according to the machining parameters of a pair of gears which are established. It is convenient to establish accurate solid models of spiral bevel gear by obtained data points. Thus it can provide a feasible and effective way for CAD/CAE modeling and is modeled perfectly in computer so as to simulate the platform of virtual manufacture and meshing analysis.

Abstract: The principles of fuselage design for crashworthiness are analyzed based on investigating the theory of energy and momentum to the impact of an aircraft’s crash on occupants in order to increase the chance of survival for occupants. It indicates that minimizing the amount of bumped soil leads to the reduction of resistance from soil to the aircraft while crashing along the y-axis direction (horizontal) and increasing the energy absorption improves the crashworthiness of the aircraft along the z-axis direction (vertical). The deformation of the aircraft cabin and the acceleration of the occupants during a crash are the two most important factors to consider for crashworthiness. The improved fuselage design for crashworthiness is proposed for both y-axis and z-axis directions. Suggestions for the crashworthy fuselage design are given in order to obtain high performance of crashworthiness design, which is meaningful to the future design for fuselage’s crashworthiness.

Abstract: Focusing on the actual demands from the packaging laboratory on the incline impact testing machine and the characteristics of the incline impact, a new incline testing machine with flexible impact panel has been designed. It firstly introduces the overall project design for the instrument, then gives detailed introduction to the major parts such as the winch, impact incline, impact panel, car, support and so on from the following three aspects, namely the design idea, design approach and design result, finally illustrates the assembly and usage for all the parts of the instrument. As for t this instrument in this paper, first place the impact panel horizontally, then under the drag of the winch, the car will be lifted slowly at a constant speed and the impact panel will be lifted to be perpendicular to the incline by the hydraulic cylinder. The design for this instrument has a great significance in the experimental teaching for packaging engineering and related scientific researches.

Abstract: When gear is working, the size of contact stress with tooth surface directly affects its service life and security. In this paper, creates a three-dimensional model of parametric gear by the UG parametric modeling tool, then transforms the modeling data and imports into ANSYS to analysis the loading-velocity of gear and the compressive stress produces through gear meshing. Finally, gets the distribution and the change rule of equivalent contact stress with tooth surface when produced radial displacement and in the case of several teeth contacted in gear running. Introduction

Abstract: On the base of Reynolds equation, the dynamic load of an engine crankshaft main journal bearing system is studied. The oil film pressure is solved from the non-Newtonian Reynolds equation with non-linear model of a finite length journal bearing. The flexible crankshaft is coupling with hydrodynamic lubrication of bearing film. The elastohydrodynamic bearing is treated as non-linear bearing with the finite difference method when considered the unstability load that was acted on the main journal. This paper aims to identify the non-linear effect of engine main bearing in the case of unstability load.

Abstract: To solve the problem of computational complexity in H bridge cascaded multilevel inverter (HBCMI) control, this paper proposes a simple space vector pulse width modulation control algorithm. Base on the topology configuration of HBCMI, the output voltage is deduced, which is the difference value between two-level inverter group output voltage formed by left bridge arms and by right bridge arms. The control complexity is independent of inverter voltage level and it is suitable to every voltage level. To verify the algorithms, different level cascaded H-bridge inverter drive systems were constructed and simulation results are present.

Abstract: Switched reluctance machine (SRM) has many outstanding advantages, and can be widely used in many electromechanical applications. However, it’s relatively difficult to analyze the control performance of SRM due to strong nonlinearity of the electromagnetic field. In this paper, the performance of SRM is analyzed by finite element method (FEM). Firstly, the simulation model of a 4-phase 8/6 pole SRM is built, and then the steady-state and dynamic simulation are carried out. In steady-state simulation, the magnetization and torque characteristics are obtained by parametric method. In dynamic simulation, the performance, include current and torque curve, under both motoring and generating mode are given. The simulation and analysis results are useful for performance optimization of SRM.

Abstract: To synchronize nodes’ time in mobile underwater sensor networks, a collision based time synchronization scheme called “Coll-Sync” is proposed, which is a novel time synchronization approach for underwater acoustic environment. Collision has been identified as a major challenge to communication, and current systems implement sophisticated solutions to detect and avoid it. Coll-Sync shows that collision contains highly useful information that can be leveraged to improve time synchronization greatly. It is the first time synchronization algorithm that does not suffer but benefit from collision in underwater acoustic channel. Simulation results show that Coll-Sync has high precision and low energy cost. It significantly outperforms existing time synchronization schemes.

Abstract: This paper will discuss the design methods of the programmable sample-encoder in the telemetry system, and compare the advantages of the design methods due to the development of the nowadays micro-electronics technology. To fulfill the requirements of combination, seriation, universalization and miniaturization for the equipments on the craft, the design of the programmable sample-encoder in the telemetry system adopts the CPLD control mode. This paper introduces in detail the main function of the CPLD realized in the programmable sample-encoder and the design method of CPLD. The performances of the sample-encoder such as bit-rate, format and so on can be programmable by using CPLD, meantime, the design input, verification and function-simulation can be realized by using the advanced EDA.