Nabeel T. Alshabatat and Koorosh Naghshineh
Natural frequency, dimple, genetic algorithm, finite element analysis, modal analysis
In this paper, the natural frequencies of a beam, with different boundary conditions, are enhanced by creating cylindrical dimples on its surface. These dimples alter the local stiffness in the beam while keeping its mass the same. This method is cost-effective in comparison with other structural dynamics modification methods (SDM) because it is a one-step manufacturing method and because it enhances the dynamic behaviour of beam structures without additional weight or additional joints. The natural frequencies of dimpled beam are calculated by finite element method. In particular, ANSYS package is used in building the dimpled beam models for modal analysis. The effect of dimple location and size on the beam fundamental frequency is investigated. The simulation results indicated that creating dimples on simply supported and free–free beams decreases their fundamental frequencies, while creating dimples on clamped beams may increase their fundamental frequency. The optimal designs of dimpled beams are presented. The proposed method couples the finite element method for the modal analysis with an optimization technique based on genetic algorithm (GA). The optimization results show that dimpling technique is an effective technique to optimize the natural frequencies. The proposed technique is experimentally validated. The experimental results show a good agreement with the simulation results.
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