Pareto Optimal Balancing of Four-bar Mechanisms Using Multi-Objective Differential Evolution Algorithm

Four-bar mechanisms are widely used in the industry especially in rotary engines. These mechanisms are usually applied for attaining a special motion duty like path generation; their high speeds in the industry cause an unbalancing problem. Hence, dynamic balancing is essential for their greater efficiency. In this research study, a multi-objective differential evolution algorithm is used for Pareto optimization balancing of a four-bar planar mechanism while considering the shaking moment and horizontal and vertical shaking forces as objective functions. This is necessary since the high magnitude of shaking forces and moment affect the fatigue life of the mechanism. The design variables are both kinematic and dynamic parameters of the moving links. The Pareto charts of five-objective optimization exhibit a large number of non-dominated points, which provide more choices for optimal balancing design of the planar four-bar mechanism. A comparison of the results obtained from this study with those reported in the literature shows a significant decrease in shaking forces and shaking moment.