Failure Analysis of Crankshaft with Variations of Defect Locations Using the Finite Element Method

Crankshaft is a critical component in an internal combustion engine, operating under cyclic bending and torsional loads, making it susceptible to fatigue failure, particularly in regions with high stress concentration and pre-existing defects. Therefore, this study aimed to investigate the effect of defect location on the failure mechanism of the crankshaft using the Finite Element Method (FEM). The analysis was performed using ANSYS Student version of Mechanical on both defect-free and defective models. Defects were introduced at the crankpin fillet, main journal fillet, and oil hole. The material was specified as ASTM A536 Grade 80-55-06. The evaluated parameters included von Mises stress, strain, and Mode I stress intensity factor (KI). The simulation results showed that the maximum von Mises stress in the defect-free model was 364.18 MPa, which is below the material yield strength of 379.2 MPa. In contrast, defective models produced KI values ranging from 45 to 57 MPa√m, all exceeding the material fracture toughness (KIC) of 32.9 MPa√m. The highest KI value, 57 MPa√m, occurred at the main journal fillet with a crack depth of 0.6 mm. The results indicate that increasing crack depth elevates the likelihood of crack propagation and subsequent fatigue failure. Defect location exerts a significant influence on crankshaft failure behavior, and FEM provides an effective approach for predicting crack propagation in engine components.