Modeling and Stress Analysis of Single Cylinder Four Stroke Single Engine Crankshaft by Using Finite Element Method for Improving Fatigue Life

Abstract

The complicated, mass-produced internal combustion engine (ICE) crankshaft transforms the pistons' reciprocating motion into a rotating motion. This study investigates the possibility of increasing the fatigue life of a single-cylinder engine crankshaft by altering its geometry. Boundary conditions were applied during the finite element analysis (FEA) using ANSYS to determine the lifespan, maximum stress points, and essential areas of the original and optimized crankshafts. The fillet areas between the crank web and crankshaft journal exhibited the highest stress, and the leading cause of failure was fatigue, which started in this area of the journal. Geometry optimization reduced the crankpin fillet radius and changed the crankpin diameter, resulting in a 15% decrease in stress and a 62.55% increase in crankshaft lifespan. The crankpin diameter adjustment alone was responsible for a further 25.88% reduction in stress. Von-Mises stress, shear stress, and crankshaft life were computed using the outputs of the ANSYS program. As such, the fatigue life of the crankshaft was significantly increased by the adjustments made to the crankpin fillet diameter and radius.