Dimensional synthesis of a stephenson III six-bar slider-crank function generator using genetic algorithm

: Since recently, two-degree-of-freedom adjustable mechanisms have been widely used in many applications, such as variable displacement pumps and variable compression ratio engines. To design such an adjustable mechanism, a proper single-degree-of-freedom mechanism that can be transformed into a two-degree-of-freedom mechanism may first be synthesized, then links and joints can be added to modify the mechanism into an adjustable mechanism. This paper deals with the dimensional synthesis of a Stephenson HI six-bar slider-crank function generator, which is usually modified into an adjustable mechanism by adding one link and one joint. For this, displacement analysis equations were derived for the Stephenson III six-bar slider-crank mechanism, and a genetic algorithm was used to determine the dimensions of the mechanism that approximately satisfies a set of prescribed piston joint positions.