OPTIMAL KINEMATIC SYNTHESIS OF 4-BAR PLANAR CRANK-ROCKER MECHANISMS FOR A SPECIFIC STROKE AND TIME RATIO

摘要

Optimal synthesis of mechanisms is a successful approach for mechanism design to satisfy all the desired characteristics of the designed mechanism. The 4-bar crank-rocker mechanism has wide industrial applications and its synthesis is of increasing importance. The optimal design problem in this ease is a constrained multi-dimensional problem. Powell optimization technique is used to minimize a special objective function combining the mechanism stroke and time ratio. 3 functional constraint functions are used to perform a successful optimization process leading to satisfying the requirements of a successful operation of the mechanism. The mechanism kinematical functions are derived in a dimensionless form. The results are tabulated for an easy reference to them without any calculations. Power law models are fitted to the optimization results. It was possible to obtain a mechanism stroke between 20 and 55 degrees and a time ratio between 1.05 and 1.204 for a transmission angle in the range 45 to 135 degrees. A comparison is conducted between the optimal design results using the tabulated normalized dimensions and the optimal values using the proposed power law models.