Failure Analysis of Crankshaft using Finite Element approach

Chetan Kahate, Ashok Keche

The fatigue phenomenon occurs due to repetitive loading on components like crankshaft of IC engine. Fatigue due to combined bending and torsion is most common reason of failure of crankshaft. The objective of this work is to evaluate fatigue life of alloy steel made crankshaft. The crankshaft under study was investigated for failure zone in pin web fillet region. The process wise investigation was made to find out the root cause of fracture occurred in failure zone. The root cause was found to be low surface finish in the pin web fillet region. It  caused the undesired stresses in the failure zone. It is observed that due to bad surface finish the fatigue life of existing crankshaft was drastically reduced. The crankshaft is modeled and stresses are analyzed using finite element software. The fatigue life of crankshaft subjected to pure bending and pure torsion loading is obtained during actual testing. The possibility of using fatigue test data from pure bending and pure torsion loading is explored in present work to estimate the fatigue life due to combined loading. In the present study the attempt has been made to improve the surface finish of crank shaft. It is observed that the surface finish is improved 35/% by changing the guide shoe material of crank shaft assembly. The results obtained from simulations are then correlated with experimental results of loading.