An investigation the effects of geometric tolerances on the natural frequencies of rotating shafts

This paper presents the effects of geometric tolerances on the rotating shafts natural frequencies. Due to modeling the tolerances, a code is written in MATLAB 2013 software that produces deviated points. Deviated points are controlled by different geometric tolerances, including cylindricity, total run-out and coaxiality tolerances. Final surfaces and models passing through the points are created using SolidWorks 2013 software and finally modal analysis is carried out with the FE software. It is observed whatever the natural frequency is higher or the geometric tolerances are greater, the real and ideal shafts natural frequencies are more distant. Also difference percentage between ideal and real frequencies is investigated. The results show that the percentage value is approximately constant for every mode shapes

Multiobjective optimization for force and moment balance of a four-bar linkage using evolutionary algorithms

In this study, force and moment balance of a planar four-bar linkage is implemented using evolutionary algorithms. In the current problem, the concepts of inertia counterweights and physical pendulum are utilized to complete balance of all mass effects, independent of input angular velocity. A proposed multiobjective particle swarm optimization, and non-dominated sorting genetic algorithm II are applied to minimize two objective functions subject to some design constraints. The applied algorithms produced a set of feasible solutions called pareto optimal solutions for the design problem. Finally, a fuzzy decision maker is utilized to select the best solution among the obtained pareto solutions. The results show that optimal solutions minimize the weights of applied counterweights and eliminate both shaking forces and moments transmitted to the ground, simultaneously