Modeling and Simulation of a Screw-Worm Gear Mechanical Transmission to Achieve its Optimal Design under Imposed Constraints

Abstract

This work deals with the modeling and simulation of a screw-worm gear mechanical transmission, abbreviated screw-jack, to achieve its optimal design under imposed constraints. Optimal design is sought under two different conditions: to maximize the screw-jack’s efficiency (energy saving) and to minimize its overall size (compact design). Several different models of buckling for the screwed shaft are taken into account by introducing a variable coefficient of fixity. Different strength theories of failure for the screwed shaft are taken into account, according to the type of material used, by introducing a variable weighting coefficient of the shear stress relative to the normal stress in evaluation of the equivalent stress. Variation of the mechanical transmission’s efficiency and its overall size versus the coefficient of fixity and the shear stress weighting coefficient are presented and discussed.