查看更多>>摘要：One of the biggest problems to predict the bending fatigue life of gear is lack of S-N data from the standard gear specimen. It is expensive and long time to spend to do the specimen tests. The bending fatigue property data from database is not enough to fulfill the engineering needs. To solve the problem, multiaxial methods are used to predict the bending fatigue life of gears and FEA method is used to analyze the stress of gear teeth root. Result shows that McDiarmid model, Findley model and Maximum shear stress model fulfill the engineering needs and McDiarmid method is the most accurate.
查看更多>>摘要：The definition and creation of assembly cells is one of the most important fundamentals of production general process planning. Currently, only a few researches made on this issue are still based on 2D engineering drawings at home and abroad. Moreover, during practical production general process planning, process designers partition assembly cells especially for complex structure on 2D engineering drawings by manual way. These methods cannot evidently meet the demands of 3D digital technology development and applications for modern products. In this paper, the techniques of assembly cell partition for complex structure are investigated based on its 3D modeling. The 3D Process Split Space is defined and constructed respectively, and the methods of the component recognition and assembly cell modeling are established. The proposed techniques are initially developed and verified on the CATIA V5 system.
查看更多>>摘要：A special seal is required at stern shaft, since it must serve the purposes of preventing both leakage of lubricating oil and seawater entering the stern shaft system. Improper design might cause leakage of fuel and pollution to the environment. Besides, the safety of machinery operation will also be affected. Ferrofluid seal is superior in terms of features such as long life, zero leakage, structure simplicity, fitting purposes of high-speed rotation, making it a new technology of sealing the stern shaft. In the following text, magnetic particles of Fe_3O_4 and solution of glyceride are made through proper chemical reactions, after which they are mixed as ferrofluid sealing liquid, and the performance of the liquid is studied experimentally. The experimental result indicates that magnetization intensity of the ferrofluid is increased as the intensity of outside magnetic field increases. Experimental instruments are designed for the purpose of research on ester magnetic fluid seal for stern. Through the experiment, performance of pressure resistance of esterified Fe_3O_4 ferrofliud is studied; also, main factors influencing pressure resistance of the studied ferrofliud are analyzed. The results indicate: pressure resistance decreases with increasing seal clearance or shaft rotation speed; whereby it is increased with the enhancement of saturated magnetic intensity of the ferrofliud.
查看更多>>摘要：Excitation force produced during gear mating of power transmission system induces vibration to the gearbox. Resonance occurs when excitation force frequency coincides to one of the natural frequencies of the gearbox which will bring not only sudden and unexpected vibration but also potential destruction to the gearbox. Natural frequency is determined by mass and stiffness of gearbox. These two determiners rely on sizes of the parts of the gearbox. That means natural frequency can be shifted by varying the sizes to prevent resonance. To demonstrate this, in this paper, the two stage parallel shaft gearbox modeled by shell-solid elements has been considered. The modal analysis and the real eigenvalue sensitivity analysis have been performed, in MSC. NASTRAN. The sensitivity coefficient and frequency spectrum at particular thickness of gearbox part show the effect on shifting the mode frequency.
查看更多>>摘要：The FE modeling of complex trunk structure often needs shell and solid elements. Different commercial software adopts different shell-solid coupling techniques. A simple, robust method has been demonstrated for shell-solid coupling by fictitious perpendicular shell. Systemic study on the method is performed through the FE analysis of T-trunk model to ensure the displacement compatibility and stress equilibrium. Modal analysis of gearbox is executed to observe the reliability and efficiency of the coupling method. Parametrical conclusions and practical suggestions are presented finally.
查看更多>>摘要：The design and manufacture for GGI are different and only several countries have the ability to produce it. Devising the feasible scheme for gravity gradiometer is the primary question.In this paper, a new type of GGI is designed using twelve accelerometers. First, the mathematical relationship between the accelerometer and GGI is derived and the method to separate the angular velocity and gravity gradient is disscussed. Second, the model of twelve-accelerometer gravity gradiometer is provided. Third, the estimation of angular velocity is analyzed when the GGI is installed in the form of strapdown or stabilized state. Finally, it is concluded that a new type of inertial navigation system using gravity gradiometers will be configured when it becomes possible to precisely measure gravity gradient.
查看更多>>摘要：Based on the characteristics of magneto-rheological fluid, a new type of transmission device has been developed in this paper, in which output torque can be controlled accurately by adjusting electric current. It can be applied to replace magnetic particle clutch widely used at present to achieve tension control in some small-sized winders. A structure design of prototype has been proposed. By using the Bingham plastic constitutive model, the output torque of the device has been derived. Electromagnetic finite element analysis has been employed to simulate the magnetic circuit of this magneto-rheological fluid tension control device. It is shown that this magneto-rheological fluid tension control transmission has its significant advantages comparing with traditional magnetic particle clutch. The new one can produce higher controllable torques, and may be applied widely in the future.
查看更多>>摘要：Plug-in hybrid electric vehicles (PHEVs) have been seen as promising vehicles which have merits of hybrid electric vehicles and electric vehicles. Because of difficulties of plug-in hybrid electric vehicles' development, it is necessary to study revamped method on the base of original car. Electric power steering (EPS) is an advanced steering system that uses an electric motor to provide steering assist. Because PHEVs are often on electric-electric operating mode, steering system power should be supplied with electric motor. Also, reconfigration of the power system including batteries results in added weight and the load change on front axle and rear axle. The steering characteristic of the revamped car are different from that of the original car. Based on the analysis and actual size, mass-force, etc. of the overall car and the parts of EPS, the multi-body dynamic model of the car equipped with EPS is established with multi-rigid-body dynamics analysing software (ADAMS). Based on the virtual prototype, simulation of steady state steering characteristic and transient state response characteristic of revamped car compared with original car under angulus step input of steering wheel have been finished. According to the simulation results, steering characteristic of the revamped car meets the design requirements. The research method is feasible.
查看更多>>摘要：Diesel engine power plant, gas turbine power plant and steam turbine power plant are in common use in ship main propulsion power. These power plants have each advantage and disadvantage at mass, size, most high-power, economic ability, and maneuverability. But any single power is difficult to meet the requirement of improving the ships' tactical performance, speed and maneuverability. In developing history of ship propulsion system, in order to solve the contradiction between full speed high-power and cruise economic ability, combined power plant form can change the performance of simple plant, which collected the advantage of all kinds of power plants[1]. Here combined power plant form is two or more same or not the same type engine combine used or trade off. The combined power plant can not only supply total power for ships when cruising, but also be more economical. So this plant is used widely. This paper, designs a multi-module experiment-rig and introduces its composition, working principle and disposition scheme, and carried out the dynamic characteristic experiment of the CODAG power plant.
查看更多>>摘要：With structure small and weight light, Variable Vector Propeller (VVP) can provide moving to any direction. In this paper, the mechanical and kinematical character is analyzed with taking disc-rod adjustment mechanism of VVP developed by Harbin Engineering University as an example. Combining the work environment of VVP, the kinematical model is established according to spatial mechanism knowledge. Several typical movement forms' results are obtained. The study lays the foundation for the further research on kinematical simulation, system control algorithm and trajectory planning.
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