Failure Analysis of a Flexspline of Harmonic Gear Drive in STC Industrial Robot: Microstructure and Stress Distribution

Abstract

The failure process and failure mechanism of the flexspline in harmonic reducer system after 500h operation were analyzed. The microstructure, element composition and mechanical properties of flexspline were studied by optical microscope (OM), scanning electron microscope (SEM), atomic emission spectrometry (AES), infrared carbon sulfur analyzer and microhardness tester. The stress distribution of the key parts of the flexspline was calculated by LS-DYNA finite element simulation software. The results revealed that the main reason for the failure of the flexspline was the local micro crack and the variation of the dimensional accuracy, the essential reason was grain and ferrite phase inappropriately. In addition, the stress of the failed flexspline was concentrated near the crack, the maximum stress was increased by 26%, which compared well with empirical conclusion. This work can offer a reference for the further improvement of the flexspline.