An initial bifurcation analysis of an EV pickup truck

Vehicles with a beam axle setup, such as trucks, can experience a problem known as “axle tamp”, where the rear axle and wheels undergo a potentially damaging self-sustaining vibration in the vertical, longitudinal and torsional directions. As the automotive industry continues the move towards electrification, it is unknown to what extent adding electric motor(s) to the powertrain changes the problem. The nonlinear nature of the problem make analysis difficult without an efficient method such as bifurcation analysis used in this research. The results characterize an axle tramp region in the electric-drive truck model which is compared to a car with internal combustion engine (ICE). The bifurcation analysis proves to be an efficient way to identify the instability leading to axle tramp, and the harmonically forced bifurcation analysis reveals a further region of tramp not previously observed.