Tooth effects on assembling bending stress of flexible tooth rim in harmonic drive

•Tooth root thickness and tooth dedendum arc radius are equally important on affecting the bending stiffness of tooth rim.•Dedendum arc radius is the main factor of stress concentration.•Tooth effects depend on the size of root thickness and dedendum arc radius relative to the radial thickness of tooth rim.•Stiffness coefficient changes linearly with relative dedendum arc radius and relative root thickness.•Stress concentration factor varies parabolically with relative dedendum arc radius and exponentially with relative root thickness.