The design of connecting rod I-beam section has great influence on lightweight and buckling properties and the optimal design can hardly be obtained based on the usual empirical design. A new optimization method of obtaining the optimal solution was proposed which used sensitivity analysis to get optimal design parameters and built Isight optimization model with NLPQL algorithm. DOE method was used to determine samples to find the design parameters that had a large contribution to buckling stress and area. Then an optimization model was built according to the selected parameters and the calculation was conducted based on the minimum cross section area and the buckling safety factor of no less than 1.1. The optimal solution was finally achieved and the safety factor could reach 1.1 with the least increase of weight. Finite element method was used to calculate the combustion pressures that the connecting rod could bear and the comparison before and after the optimization was conducted. The results showed the yield pressure improved by 14% and the ultimate pressure improved by 16%. Accordingly, the validity of optimization method was verified.
