抄録
Fatigue failure patterns of a three-dimensional, extremely thin-walled spur gear used in a harmonic drive device are introduced in this paper. In order to solve strength design problem of this extremely thin-walled spur gear, mechanics models and responsive finite element methods are developed to do contact analyses, tooth load distribution and flexible bearing ball load calculations of the devices through 18 years of efforts of the author. Tooth load distribution and flexible bearing ball load are calculated by the presented contact analysis methods and stress analyses of the extremely thin-walled spur gear are conducted by using three-dimensional finite element method. The calculated stresses include bending stresses at the tooth root, contact stresses on tooth surfaces and structural stresses of the extremely thin-walled gear body itself. Contact stresses of the bearing balls are calculated by substituting bearing ball loads into Hertzian formula. Many experimental results and practical design experiences of the author show that the calculated results are reasonable. Finally, based on the fatigue failure patterns of the harmonic drive devices, strength design methods of every failure pattern are presented hi this paper.
