Under the influence of crack shape, the change of mode I stress intensity factor is studied. In the process of research, the semi elliptical initial crack is used. The boundary conditions are as follows: the driving wheel torque is applied 200 N · m, and the minor axis of the semi palm circular initial crack is 1mm. The type I stress intensity factors are calculated respectively when the radius of the long axis is in the range of 1.2-1.8mm. When the major axis radius is 1.2mm, 1.4mm, 1.6mm and 1.8mm respectively, the value of mode I stress intensity factor at the leading edge of tooth root crack is calculated, and the distribution curve is drawn, as shown in the figure.
As shown in the figure, the ki distribution curve within the radius of the long axis of the semi elliptical crack is 1.2mm-1.8mm. It can be observed that the position fluctuation of a in the crack depth will increase with the increase of the long axis radius of the semi elliptical crack, but because the change of Ki: near the tooth surface is not particularly obvious, In this case, the Ki of the whole crack front tends to decrease. When the long axis radius of semi elliptical crack is 1.2mm and 1.8mm respectively, the difference between the maximum and minimum Ki of the former is 325.6mpa · MM1 / 2, but the difference between the maximum and minimum Ki of the latter is only 56mpa · MM1 / 2.