Advanced Materials Research Vols. 655-657

Abstract: Magic formula tire model under different conditions can be obtained by means of tire experimental data identification. The effects of speed and load on the tire cornering stiffness and peak friction coefficient under different conditions were analyzed. The results indicate that the variation of tire cornering stiffness and peak friction coefficient with the normal load at different speeds for both dry and wet conditions is a quadratic function. And the tire cornering stiffness decreases basically with the vehicle speed increasing on the wet roads due to hydroplaning effects. The peak friction coefficient decreases as the speed increases on wet roads, and it may not be less than one.

Abstract: Based on Donnell’s thin shell theory and basic equations, the wave propagation method is discussed here in detail, which is used to investigate the vibration and sound radiation characteristics of non-uniform ring stiffened cylindrical shells under various boundary conditions. The structure damp effects of cylindrical shells are investigated and the ring ribs were considered very narrow, and the rib forces are considered in radial direction. The conclusion are drawn that with the structural loss factor changing large, the whole pressure level are changed little, but the peak of resonance are slacking down obviously; The shell’s resonance frequency can be changed with irregular ring stiffened cylindrical shell .The work will give some guidelines for noise reduction of this kind of shell.

Abstract: For being convenient for researching the force transmission characteristic and the improvement and use of six-bar slider-crank mechanism, for improving the dynamic work efficiency, for reducing energy consumption, the three-dimensional solid model of the mechanism was established with ADAMS. Each part of the model in ADAMS was set up. Simulation analysis on the working process of the mechanism was achieved. The structure optimization parameters of the mechanism were obtained. The result proves that the locations of revolute joint of rocker and frame, the locations of revolute joint of link and block, the vertical location of revolute joint of upper link and rocker, the horizontal locations of revolute joint of upper link and link are almost no impact on the driving torque of crank. The locations of revolute joint of crank and upper link, the horizontal location of revolute joint of upper link and rocker, the vertical location of revolute joint of upper link and link have less impact on the driving torque of crank. The locations of revolute joint of crank and frame have greater impact on the maximum driving torque of crank.

Abstract: Considering the gap of the contact line of modified involute cylindrical gears influencing on loads, oil film thickness, the friction coefficient was determined on the basis theory of TCA、 LTCA and EHL. so oil film thickness and friction coefficient corresponded with loads on contact line were dispersed, which was used to computed discrete temperature according to the Blok flash temperature formula. and an approach of modified tooth surface optimum design based on the minimum flash temperature was proposed: the modified tooth surfaces was defined as a sum of theoretical tooth and cubic B-spline fit surface based on the uniform grid points created by double parabolas and a straight line and whose normal vector was deduced, besides, used genetic algorithm to optimize the parameter of curve, and get the best modified gear tooth surfaces. the results shows that oil film is thicker in engaging-out, coefficient of friction is contrary, which is responsible for lower flash temperature in engaging-in, besides the flash temperature has little changes in the single tooth meshing zone, and helical gear has a lower flash temperature than spur gear due to higher overlap ratio.

Abstract: This article has carried out systematic research on the multi-tooth meshing problem of involute internal gear pairs with small tooth number difference of normal gear. It firstly establishes the entity assembly model of internal gear pairs with precise tooth profile, then determines the number of multi-tooth meshing teeth pairs with finite element software and finally analyzes the main factors and reason affecting the number of meshing teeth pairs. In the range of tooth number of internal gear equal to 40-200, the conclusion is that when tooth number difference equal to 1 the number of effective meshing teeth pairs is 3-15,when tooth number difference equal to 5 the number of effective meshing teeth pairs is 3-11. The main factors affecting the number of meshing teeth pairs are tooth number and tooth number difference. The fewer tooth number is and the greater tooth number difference is, the fewer the number of meshing teeth pairs is. The reason is that when tooth number is obviously reduced or tooth number difference is obviously increased, the clearance of adjacent gear surface will be greatly increased, which will cause the decrease of the number of meshing teeth pairs. Within the normal value scope of modification coefficient difference of involute internal gear pairs with small tooth number difference, the influence of modification coefficient difference and modification coefficient is very small. When the torque increases, the number of effective contacting teech pairs will keep unchanged. The research in this article provides reference for the calculation of loading capacity of multi-tooth meshing of internal gear pairs with small tooth number difference of normal gear.

Abstract: The machining accuracy grade of cycloid gear in high precision two teeth difference cycloid-pin gear planetary transmission is different to general gear, so it can’t be designed according to the requirement of universal transmission accuracy, this paper presents the design precision grade requirements of high precision cycloid. In the traditional process the two teeth difference profile need gear grinding three times include fixing addendum, which will affect the accuracy of cycloid-pin tooth profile. This paper puts forward the process route of molding grinding. In order to detect the accuracy of two teeth difference cycloid gear tooth profile timely when processing, this paper takes double rod measuring method gives the testing size of cycloid gear tooth profile. This paper adopts the method that the three piece of cycloid gear as a whole to process, which will guarantee the consistency and the same performance of the three pieces of cycloid gear.

Abstract: Contrast analysis of the stub tooth involute gear with 22.5 degree pressure angle, and the existing gear with standard pressure angle has been given in this study. Based on the combination of generating method, numerical calculations and simulations, reasons of undercut phenomena for stub tooth involute gear with 22.5 degree pressure angle are researched and analyzed deeply. Minimum teeth without undercutting for considering the rack cutter’s addendum c*m is given based on the traditional undercutting theory, which also illustrated the validity of theoretical derivation.

Abstract: This paper is aimed at developing a design methodology of powertrain parameters matching for electric vehicles. The vehicles’ dynamics were studied in an attempt to find an optimal torque-speed profile for the electric propulsion system. This study reveals that the motor peak-power characteristic is associated with acceleration and grade ability of vehicles, and the motor rated-power characteristic is related with maximum vehicle velocity. Powertrain parameters of a model vehicle were also designed through theoretical calculation and simulation. To reduce the vehicle mass, a fixed gear ratio transmission is adopted, and the transmission ratio was optimized aimed to improve the energy efficiency. The simulation with chosen driving cycles indicate that parameters matching of the vehicle powertrain are reasonable and can meet the design specification of vehicle power performance and driving range capability.

Abstract: Abstract. Raising torque is one of the import parameters when we design pantograph. how we can calculate raising torque accurately and effectively is what this paper studies on. This article describes the structure of single-arm pantograph briefly , analyses the influen of contact pressure between pantograph and catenary on pantograph’s work, calculates one single arm pantograph’s raising torque by virtual work principle based on establishing mathematical computational geometry model of pantograph, finally, designs the raising torque calculation system using programming language.

Abstract: The motor rotation assembly of machine tools is mainly composed of spindle, rotor and bearings, it is to some extent the most important component, and its dynamic characteristics directly affect the machining accuracy and efficiency. Although the finite element method is effective to solve such dynamic problem, the conventional method generally ignores the influence of assembly tolerance between the spindle and the rotor .This probably would lead to a larger error result. A new method is described to evaluate the results obtained from finite element analysis .Firstly, a finite element mathematical model of motor rotation assembly is established, and then the model is tested by means of modal experiment, finally, the mathematical model results calculated by MATLAB software is compared with that of modal experiment, the results show that this modeling method is accurate and efficient. Furthermore, rotors of different inner diameters are mounted onto the spindle of same size, and then modal experiment and a finite element analysis are applied to obtain the dynamic characteristics of the motor rotation assembly under different assembly tolerances. This research can provide some reference values for the tolerance design of the motor rotation assembly.