Buckling analysis and material selection of connecting rod to avoid hydro-lock failure

Abstract

Recently, weight reduction of the engine component are demanded for the purpose of higher efficiency. For decreasing the weight of the connecting rod by considering lighter material, buckling strength of the rod plays an important role as it acts as a column. The current study is concerned with the buckling failure and material selection of a 645E3B engine connecting rod. The failure of the rod is because of low buckling safety factor (BSF) and higher compression ratio due to the sudden locking of the piston in case of hydro-lock phenomenon. Hydro-lock phenomenon occurs when excess amount of fuel-air mixture insert into the combustion chamber or because of water leakage into the combustion chamber. A theoretical procedure has been presented and finite element analysis has been adopted for this study. It includes calculating the buckling load as well as stress using merchant-rankine approach and slider-crank mechanism approach. Then the impact load on the connecting rod is calculated. A suitable geometrical model has been created using SOLIDWORKS. To validate the model, modal analysis of the rod has been done by using ANSYS 18.0. Consequently, buckling modes are obtained and critical buckling loads are calculated. Also, stresses have been obtained for the existing connecting rod and aluminium alloy connecting rod under critical buckling load. Finally it has been concluded that when the connecting rod fails due to hydro lock, merchant-rankine approach is inappropriate for buckling load calculation and the buckling strength of aluminium alloy rod is much lower than the forged steel rod. So it can’t be used for heavy duty diesel engine. The results of this work gives essential information for the connecting rod design against buckling failure in heavy duty diesel engines.