Finite Element Analysis and Cross Section Optimization of an Automotive Connecting Rod

This study examines the effect of I-section web reinforcement on the static response of an automotive connecting rod for a representative 1.6-litre petrol engine. Two SAE 4340 steel geometries with web thicknesses of 5 mm and 7 mm were modelled in SolidWorks 2023 and analysed in ANSYS Workbench 19.2. All other specified dimensions were held constant. Separate compressive and tensile load cases of 31,863 N and 10,073 N were derived from the engine parameters. The numerical model used quadratic solid elements and local refinement at the shank-to-boss fillets. For the baseline compressive case, the standard and fine meshes produced peak von Mises stresses of 178.4 MPa and 174.7 MPa, a reported difference of 2.1%. Increasing the web thickness reduced peak compressive stress from 178.4 MPa to 151.2 MPa and peak tensile stress from 58.6 MPa to 49.3 MPa, corresponding to reductions of 15.2% and 15.9%. Maximum compressive deformation decreased from 0.0523 mm to 0.0441 mm, while the compressive yield safety factor increased from 2.63 to 3.11. Tabulated component masses were 0.312 kg and 0.328 kg. The comparison supports web reinforcement as a means of reducing static stress, but does not establish a globally optimal section. Reported analytical buckling margins require reconciliation of calculation inconsistencies before they can support a design decision.