International Journal of Engineering Research in Electronics and Communication Engineering

Fatigue Life Prediction of Crankshaft of Pulsar 180 Engine

Author : Puneetha B ¹ Dr. Narasimhe Gowda ²

Date of Publication :7th October 2016

Abstract: The crankshaft of the engine is a most critical part in the engine as it is a heavy structure with complicated geometry. During working due to repetitive bending and shear stresses are usual stresses induced in the crankshaft, which are solely responsible for the crankshaft failure by fatigue. Thus, the assessment of the fatigue strength and life evaluation of the crankshaft assumes a vital part in the design and development of the crankshaft, taking into account of its safety and reliability during the operation. The Pulsar 180 DTS-i engine is considered for analysis which is made up of forged alloy steel 41Cr4Mo[1]. However, the analysis is also carried out by changing the material grey cast iron SAE J431 G2500 to compare the results. The static strength and fatigue failure criteria of the crankshaft are predicted analytically using S-N approach and modified Goodman theory. The 3D geometric model of crankshaft is created by reverse engineering. The FE model of the crankshaft is then developed using ANSYS Workbench. The investigation of the static structural strength and fatigue life is done utilizing ANSYS Workbench desktop software code and are validated with analytical solutions. Fatigue lives of the crankshaft for both forged alloy steel and grey cast iron are predicted based Von-Mises theory (Distortion Energy theory) and Maximum Principal Stress theory and are compared. Also the variation of fatigue lives of both forged alloy steel and grey cast iron crankshafts with different values of mean stress are predicted and compared. The evaluated results are graphically presented and discussed. There was a close agreement between the results in the Von-Mises stress obtained by analytical and FEA, which was 258 MPa by the analytical calculations and 248.11 MPa from the FE analysis and maximum stress obtained by both analytical and FE analysis were less than the ultimate tensile strength 1020 MPa of the material AISI 4140 alloy steel. The fatigue life of the forged alloy steel Crankshaft is 66% higher than the grey cast iron Crankshaft. And also the fatigue life increases with increase in the value of mean stress

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