Calculation of displacement of neutral layer of flexspline in harmonic reducer considering axial deformation

ZHAO Bin, FAN Yuan-xun
（School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210000, China）

Abstract: Aiming at the problem of complicated deformation of flexspline in harmonic reducer and lack of accurate displacement calculation method， the calculation method of displacement of each point on the neutral layer of the flexspline considering the axial deformation was studied. A method to simplify the force model of the flexspline with a circle of radial load was proposed. The displacement function expression was constructed through the Green function. The undetermined coefficients in the displacement function were solved by the boundary conditions at both ends of the cylinder, the continuous condition of the internal force and the mutation of shear force at the load. The undetermined coefficients were corrected according to the displacement coordination of the cylinder and its bottom. According to the finite element simulation calculation results, the displacement components of the points on the neutral layer of the flexspline cylinder in various directions were extracted, and the theoretical calculation results were verified. The results indicate that the distribution of the theoretical calculation results of displacement is basically consistent with the finite element results, and the maximum amplitude error is 6.7%. This method can quickly and effectively calculate the deformation of the flexspline.
Key words: harmonic reducer; flexspline; displacement of the neutral layer; finite element analysis