Effect of directional anisotropy on the mechanical properties and finite element analysis of a pickup truck’s crankshaft

The study investigates the effect of directional anisotropy on the mechanical properties of a forged steel crankshaft. Finite element analysis was conducted to determine the most efficient mechanical strength and safety factor related to directional anisotropy.Comprehensive experimental analyses, including tensile testing, hardness measurements, chemical composition analysis, and microstructural observation, were conducted on specimens extracted from the crank webs. The specimens were designed to be specified at 0, 45, and 90 directions, respectively.The mechanical results of ultimate tensile strength and yield strength obtained in the 0 direction showed the highest value, while the 90 direction showed the lowest values. The maximum variation gap was 9.1% of ultimate tensile strength and 7.8% of yield strength. The distribution values of hardness results showed a narrow variation in all specimens. The microstructure was observed using an optical microscope, revealing no significant differences in phase structures among all specimens. A scanning electron microscope showed a fracture phenomenon. The specimens of 45 and 90 directions showed both dimple and cleavage patterns. In addition, the finite element simulation results showed that the critical location on the crankpin geometry was at the web fillet area due to the highest stress, which resulted in a violation of the Von Mises stress criterion. Attention should be paid to optimising material design for enhanced safety.The influence of directional anisotropy on the mechanical properties of forged steel crankshafts remains limited by its focus on in-house expertise in the manufacturing process, which may not accurately represent all crankshaft designs or materials. Future research should explore a broader range of forged steel grades, conduct preliminary stress analysis, and examine anisotropic effects to enhance the precision of crankshaft design.Metallographic and fractographic analyses offered significant practical insights for the design and optimisation of forged steel crankshafts. Additionally, finite element analysis can indicate the influence of stress on the mechanical part by correlating microstructural features and failure mechanisms, providing insights that can effectively guide the limiting crankshaft performance to extend service life.The study provides unique insights into how microstructural and stress variations influence the crankshaft’s ability to endure operational stresses. The values underscore the critical role of FEA utilisation and advanced quality control strategies in enhancing the reliability, efficiency, and precision of future crankshaft development, ultimately contributing to improved performance and durability in automotive applications.