Contact analysis for short harmonic reducer in robotic joints

To reveal contact stress and deformation distribution of short harmonic reducer in robotic joints under different loads, an unloaded surface to surface contact finite element model between flexspline and wave generator is established. The boundary condition of the engagement between flexspline and rigid spline is evaluated according to the experimental engaging force formula. The stress and deformation of the flexspline are solved by precondition conjugate gradient method, and the relationship with varying loads are analyzed. It is found that the deformation and stress increments on the flexspline ring cross section increase geometrically with heightened load, and the distributions of the deformation and stress increments remain unchanged. The conclusions are compatible with the cases of unloaded flexspline deformation, flexspline destruction and axial stress distribution under load.