Conference Papers

Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/28506

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Author: search.filters.author.Rao, R.Subject: search.filters.subject.Active Vibration Isolation

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    Experimental investigations of structurally pre-stressed actuator based active vibration isolation system
    (American Institute of Physics Inc. subs@aip.org, 2020) Divijesh, P.; Rao, M.; Rao, R.; Dheeraj; Sushith
    Active Vibration Isolation is considered to be one of the most effective methods to reduce the undesirable vibrations generated in any mechanical system. Stacked piezoactuators are suitable actuators used for variety of applications such as micro and nano positioning applications because of their high stiffness and fast response. However in order to provide optimal preloading force to the stacked actuators for longer lifetime and better performance with dynamic applications these stack actuators are structurally pre-stressed. In the present work, an active vibration isolation system is designed and developed using two structurally pre-stressed actuators namely source actuator and isolator actuator where source actuator is used for generating vibrations and the isolator actuator to nullify the generated vibrations. Initially the transfer function of the MLA 10x10x20 stack actuator was identified using its known parameters and was modeled in MATLAB/ Simulink to estimate the simulated displacement for a particular voltage at different frequencies. The simulated displacements were then compared with experimental displacements for different frequencies and the results were plotted. The experimental displacements of both source actuator and isolator actuator were found at different frequencies and was compared with the simulated displacements for a particular voltage and the results were plotted. Finally active vibration isolation experiments were carried out using the proposed set up for a particular voltage at different frequencies and the percentage of vibration isolation achieved was also estimated. © 2020 Author(s).
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    Implementation of structurally pre-stressed piezo actuator based active vibration isolation system for micro milling
    (Elsevier Ltd, 2023) Divijesh, P.P.; Rao, M.; Rao, R.; Jain, N.; Prabhu, P.
    This paper presents the implementation of a structurally pre-stressed piezo actuator based active vibration isolation system incorporated with tool based micromachining setup for analyzing and comparing the milled pocket depth surface before and after isolation. A carbide micro end mill tool with 1 mm diameter and 4 flutes has been used for carrying out pocket milling experiments with and without vibrations on copper work pieces having 3 mm thickness. The machining parameters selected were spindle speed of 16,000 rev/min with 64 mm/min feed rate and 50 lm depth of cut. Two sets of pocket milling experiments were carried out using the proposed vibration isolation setup one with vibration and the other without vibration. In the first set of experiment, the source actuator was actuated for generating vibrations during pocket milling whereas in the second set of experiment, both source and isolator actuators were actuated for nullifying the vibrations generated during pocket milling. The macroscopic lens output images of the pocket depth surfaces before and after isolation were then compared corresponding to various actuation voltages at different frequencies using the proposed vibration isolation setup. Based on the macroscopic lens output images it was observed that the milled pocket depth surface obtained by actuating only source actuator showed distinct rings wherein the ring count matched with frequency and feed rate that has been provided during machining. However, the milled pocket obtained by actuating both source and isolator actuators resulted in surface characteristics with less pronounced rings similar to that of regular machining. Also the rings that has been formed showed more defined edges with the increase in actuator voltage indicating that these distinct patterns were caused due to the vibrations generated by the source actuator alone and not other factors. © © 2023 Elsevier Ltd. All rights reserved.