Optimum interface shape and vibration test for a new transmission helical gear composed of steel and aramid/phenol composite

Hybrid gears made of fiber-reinforced polymeric composite material and steel are recently attracting electric vehicle designers' attention due to their possible advantages such as lightweight and reduced vibration transfer for automotive transmissions. In this study, polymeric composite material is placed in-between the steel teeth and a central hub region in the radial direction of the hybrid helical gear. The partial usage of polymeric composite material for the high torque gear is expected to reduce the transmissibility of vibration from teeth to hub as well as the weight of a transmission gear-train. Using the finite element method, optimization, and vibration tests, a composite hybrid helical gear satisfying strength and vibration characteristics is successfully developed in this study. The reduction in acceleration of the hybrid gear is observed by comparing to that of a 100 % steel gear. From a point of view in damping ratio, the composite hybrid gear can make reduction of vibration by 42.3 %. To secure the bonding strength between steel and composite parts, the design optimization for the complicated bulgy and hollow interface region is performed by considering complex dimensions.