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Strength and durability of commercial vehicle structure is of prime importance to users while quicker time to market and least material cost are demands of competitive world. This requires assessment not just with simplistic loadcases but robust and accurate predictions closely co-relating real proving ground conditions. This paper demonstrates systematic approach of first road load predictions using MBD model, then stress analysis using FE model and finally life prediction using fatigue solver. MBD model was built using flex body, air suspensions with rigid links and tires with FTire characteristics. Same model ran on various virtual proving grounds and load history at various joints were extracted. Then inertia relief stress analysis with unit loads were carried out in Nastran and output stresses were mapped against load history in fatigue solver.

The conventional methods of connecting rod design consider the centre of gravity (CG) position at 2/3rd distance from connecting rod small end. The connecting rod CG position decides the reciprocating and rotating mass distribution. The reciprocating force impacts inertia stresses at the connecting rod small end while rotating force impacts the inertial stresses, minimum oil film thickness (MOFT) and peak oil film pressure (POFP) at the connecting rod big end. This paper work has analyzed connecting rod design in view of three probable causes of CG position variation as due to dimensional changes to sustain higher loading, manufacturing process variation and high speed of turbocharged (TC) engine. Total nine load cases have been considered for study of these causes. As well, CG variation impact is analyzed at big end bearings for MOFT and POFP.