Analysis of fracture characteristics of thin and thick rim asymmetric spur gear based on strain energy release rate

Abstract

Gears are one of the most important components in most mechanical machines, automobiles, and other wind mills. The gears are subjected to repeated fillet stress, which causes them to develop root fracture leading to the failure of the power transmission system. Hence, the gear should be resistant to fracture. Furthermore, reduced weight and size of the gear is necessary to reduce the overall weight of the transmission system. The effect of backup ratio on the fatigue crack behaviour of symmetric and asymmetric spur gear under mix mode fracture is investigated in this study. The strain energy release rate (SERR), T-stress, and stress intensity factors (SIFs) of thick and thin rim asymmetric spur gear under mixed-mode condition are determined. Additionally, the effective SIF and the shape factor are evaluated for all spur gears. It is noticed that the fracture resistance of asymmetric spur gear (ANCR) increases with an increase in rim thickness. Further, an increase in backup ratio increases the stability of the crack and hence retards the crack growth. In addition, the influence of backup ratio on fracture resistance decreases with an increase in drive side pressure angle. Hence, an increase in pressure angle at drive side increases the crack stability, and the resistance towards fracture. The inference of this study gives valuable guidelines for designing asymmetric spur gears to reduce the weight without compromising the service life.