A combined numerical and optical analysis of failure attributes in polymer nanocomposite gears

Abstract

This section conducted an experimental gear test to investigate the failure modes of polyoxymethylene (POM) spur gears. The gear tests involved applying a constant range of different torques, covering both subcritical and above-critical loading ranges for POM gears. The failure mechanisms were evaluated by analyzing captured images at the point of failure using a 2D digital microscope and studying the wear microstructure of the gears using scanning electron microscopy. The findings revealed that at 6, 8, and 10Nm torque levels, the failure modes included tooth pitch cracking, plastic deformation, and wear. However, beyond a torque of 10Nm, a significant material flow was observed. This was attributed to the combination of a substantial increase in tooth temperature at high torque levels and the poor thermal conductivity of POM gears, resulting in a decrease in gear tooth strength and a consequent drastic flow of material induced by thermal effects. Furthermore, the stress analysis of the POM gears was performed using finite element analysis, and the results were compared to analytical models for validation and further understanding. © 2025 Elsevier B.V., All rights reserved.