Papers by Author: Ning Zhao

Abstract: A method—characteristic parameters analysis (CPA) is put forward, which is used for quantitative analysis of contact pattern of spiral bevel gears with installation errors. For forming the tooth surface of spiral bevel gears, local synthesis is used. To imitate rolling test machine, the pinion drive torque is calculated under the indentation depth 0.00635mm. Driven by this torque, the size, shape, location and variation of contact pattern are obtained by loaded tooth contact analysis (LTCA). A pair of aviation spiral bevel gears was taken to quantitatively analyze the various contact patterns under different installation errors. The results indicate that the contact pattern is more sensitive to pinion axis installation error.

Abstract: This design is an open-loop aviation electronic equipment rack based on ARINC600 for a aircraft under only air exhaust condition. Conduct tress and stiffness analysis via ANSYS calculating the maximum stress and the maximum distortion. Calculate the maximum power of electronic equipment suitable for this equipment suitable for this equipment rack through heat transfer theory and provide theory basis for electronic equipment layout on the overall aircraft.

Abstract: : The LT-MFS approach is proposed to solve two-dimensional transient heat conduction problem in functionally graded materials (FGMs). First, a Laplace transform approach is used to move the time variable. Then, a fundamental solution in Laplace space for FGMs is constructed. Next, the solution in Laplace space is approximated by the linear combination of fundamental solutions. Further, Stefest’s algorithm is employed to convert the results in Laplace space back into the time–space domain. Finally, the method is tested on several benchmark examples. The results demonstrate well the efficiency and accuracy of the proposed method.

Abstract: The coordinate systems for cutting face gears and for meshing of face gear drive with involute cylindrical pinion. The tooth surface equation of face gear with machining errors is deviated, such as change of shaft angle, change of shortest distance between face gear and cutter tool axes, helix angle of cutter tool. Tooth contact analysis applied in the paper considered with the alignment error of the driving system. The tooth contact path and the transmission error of the face gear drive were simulated through the tooth contact analysis for different alignment errors and machining errors. The simulation results indicate that all of the alignment errors and machining error don’t cause transmission error except helix angle error of the cutting tool. The errors will bring the shift of the contact path on gear teeth. The shift of bearing contact can be reduced by combination of different errors of alignment or machining.

Abstract: A kinematic analysis is apply to gear trains of the main reducer of helicopter , and established the mathematical model of the system structure and layout of the gear trains use the graph theory representation to caculate the mechanical efficiency of it base on the kinematics, moment balance theory, power conservation principle and so on. The paper also introduced the constrained optimization function to carried on the gear train to increase the efficiency of the gear trains and improve the layout of the system structure, which to provide the basis of system structural analysis and design of the reducer.

Abstract: According to the characteristic of the thin-walled components, through the analysis which carries on to the complex stents structure and the material, This article found the reason of the components’ distortion, and then designed the self-made jig, the self-made cutting tool, and choiced the optimized processing parameter and so on, summarized the processing technique of the stents cavity, improved the components processing quality and the processing efficiency.

Abstract: This paper proposes a modification method for tooth surface of face gear drive with a grinding worm on a numerical grinding machine. The surface equation of grinding worm is derived, and the coordinate System of generating the worm is established. Tooth contact analysis (TCA) is performed to investigate the performance of face gear drive before and after modification, and the alignment error is considered. This method can obtain a more stable bearing contact in contrast to the method by increasing tooth number of shaper. The longitudinal bearing contact on the face-gear tooth surface has been obtained which will increase the contact ratio. By modification the edge contact at surface edges of the gears can be avoided and the modification magnitude can be controlled freely.

Abstract: Magnesium alloys have been increasingly used in automotive and aerospace components and in portable microelectronic devices due to their “ultralightness” and high specific strength. Machining is an important method used to process magnesium alloys. The advantages of machining over other processing methods such as die casting include reduction in power consumption and excellent surface finish. However, the ignition of chips presents a dangerous problem during machining. This problem has attracted considerable research interests. Though coolants can be used effectively to prevent ignition, the pollution of environment and reclamation of chips can not be resolved easily. Therefore, one better approach is to control the machining parameters for minimizing ignition hazard of magnesium alloy chips during dry machining. A systematic study was conducted for a few different magnesium alloys (including AM50A and AZ91D) to understand effect of cutting parameters (cutting speed, feedrate and depth of cut) on ignition of chips during face milling. It is interesting to find that for any fixed cut depth ignition in the forms of sparks, flares or ring of fire occurs only in the moderate cutting speeds and feedrates and can thus be easily prevented by adopting either higher or lower cutting speeds or feedrates. Chips produced in different machining conditions were collected and their morphology was analyzed to understand mechanisms of ignition.

Abstract: This paper introduces the generation of face-gear by a worm and the coordinates system. A scheme for cutting face gears using a CNC hobbing machine is described in detail. The determination method for the machine parameters is given. An experiment is done for validating the method.

Abstract: According to the forming theory of face gear’s teeth surface, abrasive machining of face gear was studied through establishing abrasive machining coordinating system. The movement of every device of the grinding machine for face gear’s abrasive machining was also analyzed. In addition, a geometric model of the grinding machine was initially built on this base, which could be referred to during the designing and reforming of face gear’s grinding machine