Optimal transmission angle and dynamic balancing of slider-crank mechanism with joint clearance using Pareto Bi-objective Genetic Algorithm

Abstract

Following errors in manufacturing process and hinge movement, clearance occurs in the joints of mechanisms. Together with noise, vibration and abrasion caused by impact forces between the mechanism’s joints, this phenomenon also results in dynamic imbalance and reduced transmission quality. In the present study, these effects are mitigated properly. Since slider-crank mechanisms are widely used in internal combustion engines, the associated kinematic and dynamic equations are presented in this study considering clearances in crank and sliding pins. Moreover, the Lagrangian equation minimization method is utilized to simulate clearance angles and their derivatives. Besides, bi-objective functions are defined regarding optimization, one as the sum of shaking forces and shaking moment and the other as the transmission angle of the slider-crank mechanism. Then, the optimization process is performed using multi-objective genetic algorithm. The length of the links and the position of their mass center were subsequently considered as the design variables. The optimization results were illustrated through the Pareto front. Comparing the outcomes of this study with the main mechanism as well as the findings of previous studies, wherein only the transmission angle had been optimized without considering the necessary dynamic balance, revealed the superiority of the obtained results.