Elastic deformation characteristic of the flexspline in harmonic drive

The paper presents a method to describe the spatial deformation of a cup-type flexspline, in which the spatial deformation of the flexspline is separated into a set of deformed curves on the cross sections vertical to the axis. Based on this method, the deformation function of the neutral layer of a flexspline deformed only by wave generators, such as a cam, roller, as well as disk type wave generators, is investigated. To investigate elastic deformation characteristic of a flexspline under the load condition, a finite element contact analysis parametric model is established by ANSYS Parametric Design Language (APDL). Using this model, a spatial elastic deformation of a cup-type flexspline with any parameters can be solved. The examples indicate that elastic deformation of the flexspline has spatial characteristic, linear variation characteristic along axial direction under no-load condition, non-linear variation characteristic under load condition, and the load is heavier, the distortion (or skewness) of the flexspline is severer. By means of double cubic spline function, the deformation function with discrete data is fitted. The work in the paper lays on groundwork for further kinematics analysis.