Load-bearing analysis of polymer nanocomposite gears using a temperature-based step loading technique: Experimental and numerical study

Abstract

The load-bearing characteristic of polyoxymethylene (POM)/carbon black (CB)/CaCO3 ternary nanocomposite gears were assessed using a temperature-based step loading approach. An online temperature measuring system was integrated into the gear test rig to continuously measure the gears’ bulk temperature. Dynamic mechanical thermal analysis (DMTA) was performed to explore a correlation between the viscoelastic characteristics, failure, and wear behavior of nanocomposite gears. The step loading test results showed that the load-bearing capacity was incremented from 7 Nm for pure POM to 10 Nm for POM/CB/3CaCO3 ternary nanocomposite gear. The finite element analysis of gears indicated that the maximum contact stress was different for those with similar critical torque. It was suggested that the maximum contact stress could complement the step loading technique in defining the load-carrying capacity of polymer-based gears. The failure analysis indicated the impediment of tooth cracking and thermal bending in ternary nanocomposite gears. The scanning electron microscopy (SEM) micrographs showed a much smoother tooth worn surface with minor traces of surface cracks and plastic flow for ternary nanocomposites, assigned to the promoted wear resistance, elastic response, and lower hysteretic self-heating due to the synergetic reinforcing effects of CB and nano-CaCO3.