The Failure Analysis of Crankshaft of Four Cylinder Diesel Engine Using Numerical Method

Crankshaft is one of the main components of a combustion engine, and it is designed to be used for continuous rotation. Therefore, this study aims to analyze the crankshaft failure of a jeep with a four-cylinder diesel engine which was used to transport 4 tons of logs on rough terrain and uneven roads for 12 months. The process involved modeling the crankshaft with the initial defect followed by the application of the finite element method to determine the value and distribution of stresses occurring on the crankshaft and around the location of the initial defect. The stress values obtained were later used to calculate the stress intensity factor (KI), and the value obtained was compared with the fracture toughness (KIC) value. The simulation results and stress intensity factor (KI) calculated showed a concentration of stress in the area of the initial defect as indicated by the average value of the stress intensity factor recorded to be 293.13944 MPa √m from the simulation, while the fracture toughness of the material is 91.73 ± 3.34 MPa √m. This means KI > KIC at the crack tip, and this causes further propagation starting from the initial defect. The results simply showed that the crack propagation due to loading and the value of stress concentration at the crack tip area is the cause of the crankshaft failure. This is associated with the repeated loading characterized by beach mark patterns on the fractured surface.