Derivation of Kinematic Relations and Finite Element Stress Analysis of Flexspline in a Harmonic Drive Gear Box

This article investigates the kinematic relationships in a harmonic drive gear box with a fixed circular spline. According to the results, the ratio of vertical to horizontal deflection of the flexspline is constant for all values of the applied load and it only depends on geometric dimension of the flexspline. The difference in gear teeth of the flexspline and that of circular spline can only take values of 2. According to the results, flexspline deflection reveals similar trends with that of a cylindrical shell. This manifests itself in terms of a correlation factor Cf, through which one can find flexspline deflection ratio using cylindrical shell results. This factor can play an important role in design of flexspline. Using the proposed design curves, one can calculate the required force for a full engagement of gear teeth.