Study on wear evolution of spur gears considering dynamic meshing stiffness

Wear is an inevitable phenomenon in gear systems and has a great impact on performance and longevity. In view of the fact that the actual variation of meshing stiffness in the double teeth contact region and the nonlinear relationship between meshing stiffness and force are ignored in previous wear prediction studies, a new method with loss-of-lubrication is proposed in this study. A translational-torsional dynamic model is developed for the coupling effect between wear and dynamic characteristics of external spur gears. To obtain more precise dynamic responses, the meshing stiffness and force are coupled with tooth wear, taking into account the structural coupling effect and nonlinear contact. The tooth surface is then discretized, and a wear model is developed based on Archard wear equation, in which the average pressure is used for the engaging point. Experiments and numerical simulations are carried out to analyze the wear pattern and the interaction between wear and dynamic responses. The results show that the progressive wear process is self-adaptive. Meanwhile, the area with the largest wear depth moves slightly from the dedendum and addendum to the pitch line as the wear cycle increases. When the wear depth is at the level of the tooth profile deviation, the influence of wear on meshing stiffness is very small within the single tooth contact region. However, there is a significant decrease in the stiffness of the double teeth contact, and this decrease is related to the wear cycle and torque. At the initial wear phase, as the load increases, the fluctuation of the wear depth within the engaging-in region intensifies and the overall wear depth increases. With the increment of rotate speed, the engaging-in impact makes the fluctuant area of wear depth become larger.