Based on the elastic-plastic model, the tooth surface contact force of helical gear under different loads (400, 1000, 1500, 2000N · m) is considered, as shown in Figure 1.
It can be clearly observed from Figure 1 that when considering the material plastic parameters, when the contact line is in the stage of stable length (stable contact load), the contact force of the contact target helical gear tooth surface is greater than that of the helical gear tooth surface of the elastic model under the same working conditions, while the contact force of the helical gear tooth surface of the elastic-plastic model is increased by about 0.5% compared with the elastic model １１％ 、 １. ８４％ 、 ２. ０１％ 、３. 13%, and the greater the torque, the more obvious the difference. As shown in Figure 2, cut the teeth of driving wheel 2 along the X ⁃ y section, and extract the last surface stress change of the node along the X ⁃ y section under the load of 1500N · m, as shown in Figure 3.
In a certain depth range, the secondary surface stress of the elastic model is always greater than that of the elastic-plastic model, and the secondary surface stress of the two models will decrease with the increase of depth, and the rate of stress reduction of the elastic-plastic model is lower than that of the elastic model; Because the material will produce plastic deformation after being loaded, in this process, part of the energy of the external load is converted into the potential energy between the micro grains of the material, and this potential energy will be converted into plastic deformation and stored in the material, resulting in residual stress. Therefore, with the increase of load, the stress will continue to increase. In order to study the change of subsurface plastic deformation, the plastic deformation regions of X ⁃ y section under four working conditions at the same time are extracted, as shown in Figure 4.
With the increase of load, the plastic deformation area will gradually expand, and the area of the maximum plastic deformation area is also increasing, because when the stress value of helical gear under load reaches the yield strength, the plastic deformation will increase with the increase of load; Therefore, considering the influence of material plastic parameters on the contact characteristics of helical gear tooth surface can not be ignored.
