Enlargement of a Circular Hole in Strain Hardening Materials Under Uniaxial Tension

Studying dynamic behavior of planetary gear that has an interal gear whose rim is thin (for example Stoeckicht type planetary gear), we have to consider the deformation of the internal gear. Present report describes the results of an investigation about the influence of the internal teeth on its rim stiffness. Two kinds of experiments were done using twenty-eight steel internal gears (standard spur gear, operating pressure angle 20°) which had different number of teeth, module, rim thickness and radius of center line of rim. On the one hand we took the effect that the teeth increased the stiffness of its rim from measuring the natural frequency of the internal gear in its own plane, on the other we took it from the relationship between the magnitude of the force and deflection when static force was applied to the radial direction of the internal gear. So the internal gears were replaced by rings of equivalent stiffness. Therefore the stiffness of the rim section in the internal gear including the teeth was described as the equivalent ring thickness with stiffness. This thickness was expressed by one experimental equation as the function of number of teeth and ratio of radius of center line of rim to rim thickness.