Design Optimization of the Propeller Shaft and Transfer Case for High-Speed 4WD Vehicles

Nowadays, vehicle enthusiasts often vary the driving patterns, from high-speed driving to off-roading. This leads to a continuous increase in demand for four-wheel drive (4WD) vehicles. A 4WD vehicle have better traction control with enhanced stability. The performance and reliability of 4WD vehicles at high speeds are significantly influenced by driveline stiffness and natural frequency, which are largely affected by the propeller shaft and transfer case. This study focuses on the design optimization of the transfer case and the propeller shafts to enhance the vehicle performance at high speeds. The analysis begins with a comprehensive study of factors affecting the power transfer path, transfer case stiffness, and critical frequency, including material properties, propeller shaft geometry, and different boundary conditions. Advanced computational methods are employed to model the dynamic behavior of the powertrain, identifying the natural frequency of the transfer case and propeller shaft. Design parameters are modified by using optimization methods to ensure the critical frequency is outside the vehicle's operating speed. The modification involves to power transfer path of the transfer case, as well as the material and diameter of the propeller shaft. The optimized design is validated with a 4WD vehicle to ensure safe operating frequency and minimize resonant vibrations in the driveline systems at high speeds. The results indicate that the significant improvements in the performance of the transfer case and propeller shaft, reducing driveline vibrations and enhancing system reliability.