Integrated finite element and experimental vibration analysis for reliable electric vehicle gearbox design

Electric vehicle (EV) gearboxes need to be light but strong and must handle a large amount of force while working at speed. They also need to stay stable when moving. This study shows a method to test and design EV gearboxes. The gearboxes considered have a 9:1 speed change. The finite element analysis is carried out, and it is revealed that the gearbox assembly undergoes a maximum displacement of 11.5 mm. The reported global housing displacement was verified against structural FEA results. While ISO 6336–1:2019 provides shaft deflection criteria for gear alignment, these do not directly apply to housing deformation. Local gear tooth deflection was found to be < 0.5 mm, which is within acceptable meshing limits. The modal analysis estimated two natural frequencies at 820 Hz and 1340 Hz. The operating excitation band of the gearbox lies between 65 and 300 Hz, corresponding to shaft rotational speeds. The Stage 2 gear-mesh frequency (130 Hz) falls within this band, while Stage 1 gear-mesh frequency (1170 Hz) lies above it. Neither the fundamental gear-mesh frequencies nor their harmonics coincide with the identified modal frequencies, confirming that resonance is avoided within the tested operating conditions. These findings indicate that the gearbox design is dynamically stable and reliable within the tested operating conditions, with experimental validation showing close agreement to FEA predictions (maximum error 3%). The frequencies obtained by FEA and the experimental method are found to be close to each other, with a maximum error of 3%. However, the results are subject to boundary condition assumptions and experimental setup constraints.