No abstract

In order to theoretically research the tooth surface maximum contact stress of a Cylindrical Gear with Variable Hyperbolic Circular-Arc-Tooth-Trace (VH-CATT), the computing formula of maximum contact stress of VH-CATT cylindrical gear is investigated according to Hertz formula in this paper. Insufficient contact fatigue strength will lead to pitting corrosion, plastic deformation of tooth surface and other damages. Therefore, the maximum contact stress of tooth surface must be carried out. The contact stress calculation formula is particularly considering the effect of normal force, total carrying length, synthetical curvature radius, and position angle. The present work establishes analytical solutions to research the effect of different parameters for the contact stress of VH-CATT cylindrical gear incorporating elastic deformation on the tooth surface, and which have shown that the different module, transmission ratio, pressure angle, tooth width, and the cutter head radius have a crucial effect on the contact stress and contact ellipse of VH-CATT cylindrical gear along the tooth width direction. Moreover, a finite element analysis is carried out to verify the correctness of the theoretical computing formula of contact stress of VH-CATT cylindrical gear. By contrast with the theoretical calculated value and the stress value of finite element analysis, its error is very small. It is indicated that the derived formula of contact fatigue strength of VH-CATT cylindrical gear has high accuracy and can accurately reflect the real contact stress value of tooth surface, which is beneficial for research on tooth break reduction, pitting, wear resistance and fatigue life improvement of the VH-CATT cylindrical gear. The study results also have a certain reference value for the design and check calculation of the VH-CATT cylindrical gear.

The transmission error of the gear transmission system is the main factor affecting its transmission performance. The expansion of special applications of elliptic gear transmission system and the improvement of transmission accuracy requirements put forward higher requirements for its transmission performance. Although many works have been presented to study the transmission error of cylindrical gear transmission system, a few works were focused on the transmission error of elliptic gears for the reason of the inconsistency of the tooth profile of the elliptic gear pair, the difficulty of establishing a transmission error model and obtaining the dynamic backlash. To overcome this problem, the theoretical model of the transmission error and backlash of the elliptic gear pair is proposed and established based on the meshing line incremental method. The ellipse gear transmission test-rig is built and the transmission test is carried out on it. Finally, the correctness of the theoretical model is verified. The results show that the dynamic backlash of the elliptic gear pair can be obtained through the bidirectional transmission error curve. The dynamic transmission error has a negative correlation with the speed and has a positive correlation with the load torque. The dynamic backlash shows an increasing relationship with the increase of speed and load torque. The research results of this article can provide a certain theoretical basis for the anti-backlash control of the elliptic gear transmission system and the improvement of transmission performance.

Both plasmon-phonon-polariton (SPP-PHP) modes and phonon-polariton (PHP) modes supported in graphene-coated hexagon boron nitride (h-BN) single nanowire are presented. The field distributions of the lowest 5 order modes of SPP-PHP modes supported in graphene-coated hexagon boron nitride nanowire pairs (SPP-PHP-GHNP) and the lowest 5 order modes of PHP modes supported in graphene-coated hexagon boron nitride nanowire pairs (GHNP) are also demonstrated and analyzed, respectively. The results of numerical calculation show that SPP-PHP-GHNP mode 0 owns the strongest confinement and lowest loss among the lowest 5 order modes of SPP-PHP-GHNP. Furthermore, the field enhancement of SPP-PHP-GHNP mode 0 can reach over 10 by controlling the geometry parameters of GHNP. Meanwhile, the influence of tuning the Fermi level of graphene on the field enhancement is also presented in the paper. The proposed structure may improve the development of graphene-h-BN-based optoelectronic devices.

As an important parameter to distinguish noncircular gear from cylindrical gear, eccentricity is very important for the meshing characteristics and transmission error of noncircular gear. In order to study the transmission characteristics of the elliptic gear, a pair of elliptic gear in the reversing device of a new type of drum pumping was taken as the research object. Based on the analysis of the transmission pressure angle and instantaneous contact ratio of the elliptic gear, the eccentricity error was introduced into the analysis model of transmission error. The influences of the eccentricity on the transmission pressure angle, instantaneous contact ratio, and transmission error were analyzed, and the analysis accuracy is verified by the finite element method. The results show that the eccentricity has a great influence on the transmission pressure angle, instantaneous contact ratio, and transmission error of the elliptic gear, and the eccentricity error has a significant influence on the transmission error. In order to ensure the normal meshing condition of the elliptic gear, the eccentricity should be less than 0.7071, and the maximum instantaneous contact ratio is 1.809. The research results can provide some guidance for the following noncircular spur gear transmission test and transmission error research.