Gear life and failure mode versus meshing stress in polyacetal/carbon black nanocomposite gears

• Published in: Engineering failure analysis 2022-01, Vol.131, p.105859, Article 105859
• Main Authors: Mohsenzadeh, R., Shelesh-Nezhad, K., Chakherlou, T.N., Yaghini, H.H.
• Format: Article
• Language: English
• Subjects: Carbon black; Critical load; Failure mode; Nanocomposite gear; Stress-life curve; Tooth temperature
• ISSN: 1350-6307; 1873-1961
• DOI: 10.1016/j.engfailanal.2021.105859

•A new approach based on temperature-monitoring was employed to determine the polymer gear critical load.•The incorporation of carbon black nanoparticles improved the gear load capacity and life.•An experimental–numerical approach was presented to predict the gear life versus contact stress. The life and failure mode of polyoxymethylene (POM) and POM/carbon black (CB) spur gears were assessed under different torque levels. A new experimental approach was performed to obtain the transition torque of polymer based gears by employing the online temperature monitoring and step-loading. The gear life versus contact stress was experimentally investigated and a life prediction model was proposed. Dynamic mechanical thermal analysis (DMTA) assessment was employed to determine the viscoelastic behavior of gear materials. The POM/CB gears exhibited improved load capacity, heat performance and service life. The POM/CB gear material demonstrated higher storage modulus and lower hysteresis heating as compared to pure POM gear material. The addition of CB nanoparticles switched the failure mode from fracture to tooth thinning and tooth tip plastic deformation at lower levels of torque (6, 8 and 10 Nm). At higher torque levels (12 and 14 Nm), the POM/CB gears showed 52% and 65.2% increases in the service life, compared to the pure POM gears, and finally failed under thermal material flowing.