Design optimization of a connecting rod for energy savings

Abstract A connecting rod must be designed with high reliability, ensuring sufficient strength to remain rigid under loading while being lightweight to minimize inertia forces. These forces arise when the rod and piston decelerate, reverse direction, and accelerate at the end of each stroke. In this study, a numerical shape optimization procedure was implemented in conjunction with a three-dimensional finite element model to optimize the geometry and volume of a stainless-steel connecting rod. The objective was to minimize the maximum von Mises stress under both tensile and compressive loading conditions while simultaneously reducing the rod’s volume. The results indicate that modifying the connecting rod’s shape – specifically by increasing the outer radii of the crankpin and piston-pin ends and incorporating a hollow tapered slot in the shank section – significantly enhances performance. This optimized design reduces maximum von Mises stress by approximately 6 % under tensile loading and 45 % under compressive loading. Additionally, the new design decreases the connecting rod’s volume by 10.5 %, leading to a reduction in overall weight. Consequently, this weight reduction lowers fuel consumption costs and decreases the manufacturing cost of the connecting rod. Ultimately, this optimization process contributes to lighter engine components, reducing inertia forces, lowering overall engine weight, enhancing efficiency, and promoting energy savings.