Publicación: DYNAMIC SYNTHESIS OF A CRANK-ROCKER MECHANISM MINIMIZING ITS JOINT-FORCES
Fecha
2019
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MECHANISMS AND MACHINE SCIENCE
Resumen
DYNAMIC JOINT-FORCES IN A MECHANISM PRODUCE VIBRATION AND WEAR, DECREASING ITS LIFE SPAN. MANY STUDIES HAVE BEEN CARRIED OUT ON OPTIMIZATION OF MECHANISMS DYNAMIC BEHAVIOUR; HOWEVER, FEW OF IT ARE FOCUSED ON THE REDUCTION OF JOINT-FORCES. THEREFORE, THIS WORK PRESENTS A METHOD TO OBTAIN THE LINK LENGTHS OF FUNCTION GENERATION FOUR-BAR LINKAGES, MINIMIZING THE MAXIMUM DYNAMIC FORCE IN THE JOINTS. THE STUDY ASSUMES THAT THE CRANK ROTATES WITH CONSTANT ANGULAR VELOCITY AND THE ROCKER MOVES A HIGH AMOUNT OF INERTIA BETWEEN TWO POSITIONS. HENCE, THE MECHANISM MASS AND INERTIA IS CONSIDERED NEGLIGIBLE. THE EQUATIONS OF MOTION ARE SET UP TOGETHER WITH DEAD-CENTER CONSTRUCTION METHOD AFTER ALT. TO ANALYZE THE BEHAVIOUR OF THE JOINT-FORCES, ALL THE EQUATIONS ARE PARAMETRIZED, FINDING OUT THAT THE MAXIMUM JOINT-FORCE IS MINIMIZABLE FOR EVERY TASK GIVEN. THE MINIMIZATION OF THE JOINT-FORCES IS ACHIEVED BY USING SIMPLE ALGORITHMS AS BISECTION AND REGULA-FALSI ILLINOIS. THE RESULTS SHOW THAT THIS METHOD REDUCES THE MAXIMAL JOINT-FORCE BY A MEAN VALUE OF 8.5%, WITH RESPECT TO THE DEAD-CENTER CONSTRUCTION METHOD WITH TRANSMISSION ANGLE MINIMIZATION. MOREOVER, FOR SOME TASKS, THE FORCE REDUCTION COULD REACH UP TO 60%. FURTHERMORE, THIS METHOD SOLVES THE PROBLEM OF NULL-LENGTH CRANK AND ROCKER FOR CENTRIC CRANK-ROCKER MECHANISMS, GENERATED BY THE TRANSMISSION ANGLE MINIMIZATION.
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REACTION FORCES, FUNCTION GENERATOR, FOUR-BAR LINKAGE
