Design optimization of the propeller shaft and transfer case for high-speed 4WD vehicles

Nowadays, vehicle enthusiasts often vary their driving patterns, ranging from driving at very high speeds to off-roading. Due to these driving patterns, 4WD vehicle demand is continuously growing day by day. A 4WD vehicle used to have better traction control with enhanced stability. The 4WD vehicle performance and reliability at high speed are critically influenced by driveline stiffness and natural frequency. Driveline stiffness and natural frequency are very critical parameter for high-speed vehicles, that significantly influenced by the propeller shaft and transfer case. This study focuses on the design optimization of the transfer case and critical frequency of propeller shafts to enhance vehicle performance at high speeds. The analysis begins with a comprehensive study of the factors affecting power transfer path, transfer case stiffness, critical frequency, including material properties, propeller shaft geometry and the boundary conditions. Advanced computational methods are employed to model the dynamic behavior of the powertrain to identify the natural frequency of the transfer case and propeller shaft. The design parameters are modified by using optimization method to cross the critical frequency outside of the vehicle's operating speed range. This include modifying of the power transfer path of the transfer case, propeller shaft material and diameter to achieve the required frequency and stiffness of the driveline systems. The optimized design is validated with a 4WD vehicle for safe operating frequency and resonant vibrations of driveline systems at high speed. The results indicate that the significant improvement in the transfer case and propeller shaft performance to reduce the driveline vibration and increase the durability of the systems.