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CSME 2019/10
Volume 40 No.5
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471-480
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Stress Calculation and Fatigue Life Evaluation on Cup-Type Flexspline under Bending and Torsion in Harmonic Drive
Ligang Caia, Qiushi Hua, Zhifeng Liua, Congbin Yanga and Tao Zhanga
aInstitute of Advanced Manufacturing and Intelligent Technology, Beijing University of Technology, Beijing 100124, China.
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Abstract:
This paper describes a composite method of calculating multi-tooth root stress and evaluating fatigue life of flexspline (FS) in harmonic drive (HD). In order to accurately describe the stress state of the flexible gear root, a mathematical method combined with simulation method is applied. FS is divided into two parts, the cup part and the teeth part, according to the type of stress. On the cup part, the stress is caused by the support of the wave generator (WG). The bending stress is analyzed using differential equations and appropriately set boundary conditions. The theoretical analysis of meshing teeth in a harmonic drive is brought into the finite element model of FS that is deformed by the outer contour of the wave generator. The simulation is conducted under the action of torque and the meshing generated stress is obtained. Finally, the stress spectrum of the tooth root is acquired according to the flexural and torsion stress, while the maximum radial, the circumferential and shear stress are obtained. After applying the fourth strength theory to calculate the Von-Mises stress, the safety factors of several materials are compared according to the S-N curve and fatigue limit formula.
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Keywords: Harmonic drive, Flexspline, Multi-tooth meshing, Fatigue life evaluation.
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©
2019
CSME , ISSN 0257-9731
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