Influence of gearbox oil on 3D printed carbon fiber reinforced polymer

This study builds upon prior research investigating the effects of gearbox oil on filament wound carbon fiber reinforced polymer (CFRP) materials. Here, short carbon fiber composite material was examined, motivated by the intention to use such materials in vehicle gearboxes. Automotive sector faces pressures to reduce CO 2 emissions, therefore car manufacturers explore possibilities to implement CFRP into their gearboxes for parts such as shafts or casings to save weight, and also improve NVH behavior. Also, e-bike manufacturers aim to use polymers with short carbon fibers for making gears in their gearboxes. The important caveat to using these materials in gearboxes is the operating environment which is oil. While numerous studies have explored the influence of water on CFRP mechanical properties, research on the effects of oil remains scarce. Our experiment, conducted on 3D printed specimens, revealed predominantly positive effects of 60°C oil on the material’s ultimate tensile strength, with increases ranging from 2 to 10% depending on printing orientation, and on Young’s modulus, which increased by 7% in the longitudinal direction but decreased by 5% in the transversal direction. Interestingly, there was no significant change in glass transition temperature, and only negligible and inconsistent diffusion behavior was observed.