TY - CHAP AU - Nankali, A AU - Lee, Y S AU - Kalmár-Nagy, Tamás TI - Targeted Energy Transfer for Suppressing Regenerative Instabilities in a 2-DOF Machine Tool Model T2 - ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference PB - American Society of Mechanical Engineers (ASME) CY - New York, New York SN - 9780791855997 PY - 2013 PG - 5 DO - 10.1115/DETC2013-13510 UR - https://m2.mtmt.hu/api/publication/2902448 ID - 2902448 N1 - WoS: a befoglaló címe: PROCEEDINGS OF THE ASME INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCES AND COMPUTERS AND INFORMATION IN ENGINEERING CONFERENCE, 2013, VOL 8 AB - We study targeted energy transfer (TET) mechanisms by applying a nonlinear energy sink (VES) to suppress regenerative instabilities in a 2-DOF planar machine tool model. With the help of a numerical continuation tool, DDEBIFTOOL, we show that the tool instability is generated through a subcritical Hopf bifurcation in this simplified tool model. Studying modal energy exchanges reveals that only one of the DOFs is predominant, which may lead to the standard single-DOF machine tool model. Then, we apply an ungrounded NES to the 2-DOF tool model such that the NES interacts only with the dominant mode, which turns out to be more efficient than applying the NES to the other insignificant mode. Simple numerical simulations and bifurcation analysis demonstrate that the three typical TET mechanisms can be identified - That is, recurrent burstouts and suppression, and partial and complete suppression of tool instability. LA - English DB - MTMT ER - TY - CHAP AU - Nankali, Amir AU - Surampalli, Harsheeta AU - Lee, Young S AU - Kalmár-Nagy, Tamás TI - Suppression of Machine Tool Chatter Using Nonlinear Energy Sink T2 - ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference PB - American Society of Mechanical Engineers (ASME) CY - New York, New York SN - 9780791854785 PY - 2012 SP - 1215 EP - 1223 PG - 9 DO - 10.1115/DETC2011-48502 UR - https://m2.mtmt.hu/api/publication/2835955 ID - 2835955 N1 - DETC2011-48502 AB - Suppression of regenerative instability in a single-degree-of-freedom (SDOF) machine tool model was studied by means of targeted energy transfers (TETs). The regenerative cutting force generates time-delay effects in the tool equation of motion, which retained the nonlinear terms up to the third order in this work. Then, an ungrounded nonlinear energy sink (NES) was coupled to the SDOF tool, by which biased energy transfers from the tool to the NES and efficient dissipation can be realized whenever regenerative effects invoke instability in the tool. Shifts of the stability boundary (i.e., Hopf bifurcation point) with respect to chip thickness were examined for various NES parameters. There seems to exist an optimal value of damping for a fixed mass ratio to shift the stability boundary for stably cutting more material off by increasing chip thickness; on the other hand, the larger the mass ratio becomes, the further the occurrence of Hopf bifurcation is delayed. The limit cycle oscillation (LCO) due to the regenerative instability appears as being subcritical, which can be (locally) eliminated or attenuated at a fixed rotational speed of a workpiece by the nonlinear modal interactions with an NES (i.e., by means of TETs). Three suppression mechanisms have been identified; that is, recurrent burstouts and suppressions, partial and complete suppressions of regenerative instabilities in a machine tool model. Each suppression mechanism was characterized numerically by time histories of displacements, and wavelet transforms and instantaneous energies. Furthermore, analytical study was performed by employing the complexification-averaging technique to yield a time-delayed slow-flow model. Finally, regenerative instability suppression in a more practical machine tool model was examined by considering contact-loss conditions. LA - English DB - MTMT ER - TY - JOUR AU - Dombóvári, Zoltán AU - Barton, David AU - Wilson, Eddie AU - Stépán, Gábor TI - On the Global Dynamics of Chatter in the Orthogonal Cutting Model JF - INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS J2 - INT J NONLINEAR MECH VL - 46 PY - 2011 IS - 1 SP - 330 EP - 338 PG - 9 SN - 0020-7462 DO - 10.1016/j.ijnonlinmec.2010.09.016 UR - https://m2.mtmt.hu/api/publication/1454448 ID - 1454448 N1 - Funding Agency and Grant Number: Hungarian Scientific Research Foundation OTKAOrszagos Tudomanyos Kutatasi Alapprogramok (OTKA) [K68910]; HAS-BUTE Research Group on Dynamics of Machines and Vehicles Hungarian-Spanish Intergovernmental S&T Cooperation Programme [OMFB-01265/2007]; OPENAER project; Great Western Research fellowship; EPSRCEngineering & Physical Sciences Research Council (EPSRC) [EP/E055567/1] Funding text: Z D and G S were supported by the Hungarian Scientific Research Foundation OTKA Grant no K68910 HAS-BUTE Research Group on Dynamics of Machines and Vehicles Hungarian-Spanish Intergovernmental S&T Cooperation Programme Grant no OMFB-01265/2007 and the OPENAER project (CENIT program of CDTI) D A W B was supported by a Great Western Research fellowship R E W was supported by EPSRC Grant EP/E055567/1 Export Date: 28 November 2019 CODEN: IJNMA Export Date: 29 November 2019 CODEN: IJNMA AB - The large-amplitude motions of a one degree-of-freedom model of orthogonal cutting are analysed. The model takes the form of a delay differential equation which is non-smooth at the instant at which the tool loses contact with the workpiece, and which is coupled to an algebraic equation that stores the profile of the cut surface whilst the tool is not in contact. This system is approximated by a smooth delay differential equation without algebraic effects which is analysed with numerical continuation software. The grazing bifurcation that defines the onset of chattering motion is thus analysed as are secondary (period-doubling, etc.) bifurcations of chattering orbits, and convergence of the bifurcation diagrams is established in the vanishing limit of the smoothing parameters. The bifurcation diagrams of the smoothed system are then compared with initial value simulations of the full non-smooth delay differential algebraic equation. These simulations mostly validate the smoothing technique and show in detail how chaotic chattering dynamics emerge from the non-smooth bifurcations of periodic orbits. © 2010 Elsevier Ltd. All rights reserved. LA - English DB - MTMT ER - TY - CHAP AU - Kalmár-Nagy, Tamás TI - Practical Stability Limits in Turning T2 - ASME 2009 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference PB - American Society of Mechanical Engineers (ASME) CY - New York, New York SN - 9780791849019 PY - 2010 SP - 669 EP - 678 PG - 10 DO - 10.1115/DETC2009-87645 UR - https://m2.mtmt.hu/api/publication/2836007 ID - 2836007 N1 - WoS: a befoglaló címe: PROCEEDINGS OF ASME INTERNATIONAL DESIGN ENGINEERING TECHNICAL CONFERENCES AND COMPUTERS AND INFORMATION IN ENGINEERING CONFERENCE, VOL 4, PTS A-C Cited By :4 Export Date: 9 July 2024 Correspondence Address: Kalmár-Nagy, T.; Department of Aerospace Engineering, , College Station, TX 77843, United States; email: asme@kalmarnagy.com LA - English DB - MTMT ER - TY - JOUR AU - Kalmár-Nagy, Tamás AU - Stépán, Gábor AU - Moon, FC TI - Subcritical Hopf bifurcation in the delay equation model for machine tool vibrations JF - NONLINEAR DYNAMICS J2 - NONLINEAR DYNAM VL - 26 PY - 2001 IS - 2 SP - 121 EP - 142 PG - 22 SN - 0924-090X DO - 10.1023/A:1012990608060 UR - https://m2.mtmt.hu/api/publication/106051 ID - 106051 N1 - Export Date: 29 November 2019 CODEN: NODYE AB - We show the existence of a subcritical Hopf bifurcation in the delay-differential equation model of the so-called regenerative machine tool vibration. The calculation is based on the reduction of the infinite-dimensional problem to a two-dimensional center manifold. Due to the special algebraic structure of the delayed terms in the nonlinear part of the equation, the computation results in simple analytical formulas. Numerical simulations gave excellent agreement with the results. LA - English DB - MTMT ER -