| dc.description.abstract | High-contact ratio spur gear pair are often used in high-load or high-speed applications, due to the absence of axial forces and the reduction in the impact of mesh stiffness resulting from the exchange of gear pairs. Nevertheless, additional considerations must be taken into account when designing spur gear pairs for high contact ratio applications. Firstly, in the case of multi-tooth contact, the load distribution among the tooth pairs will affect the time-variant mesh stiffness. This characteristic can influence transmission noise and vibration at high speeds. Furthermore, the deformation of the gears, shafts, and bearings will also impact the tooth contact characteristics and mesh stiffness of the gear pairs.
The conventional dynamic analysis of gears is based on a systems perspective, which makes it impossible to investigate the contact characteristics of the engaged tooth surface under dynamic loading. Therefore, the objective of this study is to employ computer-aided analysis software, MSC.Marc and MSC.Adams, to conduct a co-simulation of high contact ratio spur gear pairs. This approach is intended to enable an understanding of dynamically loaded tooth contact characteristics of gear pairs. The driving shaft of the gear pair is modeled as cantilever support, while the driven shaft as simple support. The high-contact-ratio gear pairs are analyzed according to the conditions with or without flank modification and shaft misalignment.
In terms of modeling for analysis, five pairs of teeth of the gear were modeled using MSC.Marc for dynamically loaded tooth contact analysis. The motion control of the driving gear is done using several rbe2 elements at different tooth widths, where they are set up as the connection points for co-simulation in order to analyze the influence of the shaft on the gear pairs at high speeds. The inner bore of the driven gear is fitted with a cylindrical rigid body and the centre of the cylinder is set as the connection point. The motion of the driven gear is set to be driven from this point and the torque is applied there. The shafts are dynamically simulated using MSC. Adams. The shaft sections are set up as FE Parts and the connection points are set to the same coordinates as the connection points of the gear sections. Finally, the co-simulation is carried out by using MSC.CoSim in combination with MSC.Adams and MSC.Marc.
Considering the analysis time, the initial condition is a transient velocity change at the time of startup, in order to understand the effect of computer-aided co-simulation through the transient analysis. From the results of the CoSim simulation, it is found that Marc can be analyzed normally, but there are still some problems in the analysis of Adams that have not been overcome, e.g., CoSim can only select and transmit either the velocity or the force data calculated by Adams to Marc; on the other hand, in order to make the calculations more accurate, the number of steps of the analysis of Adams adopts a multiple of that of Marc. However, in the step intervals of Marc, the stiffness value received in the previous step is calculated and presented by Adams independently along the tangential direction of the stiffness curve. This setting causes the Adams calculations to differ from the real situation.
In all analyses, the results begin with a high amplitude, which slowly decrease with time. In the results of the analyses of non-modified gear pairs, the contact patterns are concentrated near the side of the bearing, due to the stiffness of the shaft. In the case of non-modified gear pairs with shaft skew errors, contact on the top of the tooth during the exchange of tooth pairs, results a significant increase in contact stresses. The direction of shaft misalignment and shaft deformation exert a significant influence on the contact pattern. When the direction is identical, the contact pattern will be more concentrated close to of the bearing; conversely, when the direction is opposite, the shaft deformation and shaft error will compensate for each other, resulting in a contact pattern that is analogous to the typical line contact pattern. The impact of shaft inclination error is relatively minor, with no notable alteration in the contact pattern resulting from the error. The results of the analysis of the modified gear pairs demonstrate that the vibration value of the mesh force is relatively minimal, and that the contact pattern remains center on the tooth flank throughout the mesh process. Conversely, the impact of shaft misalignment on the modified gear pair is found to be insignificant. | en_US |