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    Decomposition of process damping ratios and verification of process damping model for chatter vibration
    (ELSEVIER SCI LTD, 2012) Turkes, Erol; Orak, Sezan; Neseli, Suleyman; Yaldiz, Suleyman
    In the previous study, by the same authors, titled "A new process damping model (PDM) for chatter vibration (Measurement, 44 (8) (2011) 1342-1348)", a new approach has been presented for obtaining process damping ratios (PDRs). This PDM has been constituted on the basis of the shear angle (phi) oscillations of the cutting tool and the alteration of the penetration forces when they penetrate into the wavy surface. Variation and quantity of PDR are predicted by reverse running analytical calculation procedure of traditional Stability Lobe Diagrams (SLDs). In this study, firstly, how the PDM in previous study results with different materials such as AISI-1050 and Al-7075 are examined. Then, two problems are solved: how much of the total PDR of cutting system is caused by the tool penetration and how much is caused by (phi) oscillation? Finally, verification of PDR values and PDM are performed by energy equations. (C) 2012 Elsevier Ltd. All rights reserved.
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    Linear analysis of chatter vibration and stability for orthogonal cutting in turning
    (ELSEVIER SCI LTD, 2011) Turkes, Erol; Orak, Sezan; Neseli, Suleyman; Yaldiz, Suleyman
    The productivity of high speed milling operations is limited by the onset of self-excited vibrations known as chatter. Unless avoided, chatter vibrations may cause large dynamic loads damaging the machine spindle, cutting tool, or workpiece and leave behind a poor surface finish. The cutting force magnitude is proportional to the thickness of the chip removed from the workpiece. Many researchers focused on the development of analytical and numerical methods for the prediction of chatter. However, the applicability of these methods in industrial conditions is limited, since they require accurate modelling of machining system dynamics and of cutting forces. In this study, chatter prediction was investigated for orthogonal cutting in turning operations. Therefore, the linear analysis of the single degree of freedom (SDOF) model was performed by applying oriented transfer function (OTF) and \tau decomposition form to Nyquist criteria. Machine chatter frequency predictions obtained from both forms were compared with modal analysis and cutting tests. (C) 2010 Elsevier Ltd. All rights reserved.
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    Modelling of dynamic cutting force coefficients and chatter stability dependent on shear angle oscillation
    (SPRINGER LONDON LTD, 2017) Turkes, Erol; Orak, Sezan; Neseli, Suleyman; Sahin, Mumin; Selvi, Selcuk
    Productivity of high-speed turning operations is limited by the onset of self-excited vibrations known as chatter. Unless avoided, chatter vibrations may cause large dynamic loads damaging the machine spindle, cutting tool or workpiece and leave a poor surface finish behind. Cutting force magnitude is proportional to the thickness of the chip removed from the workpiece. This paper presents a new procedure to determine dynamic cutting force coefficients (DCFC) required for process simulation by mechanistic modelling. In this study, a two degree of freedom complex dynamic model of turning with an orthogonal cutting system is considered. The complex dynamic system consists of a dynamic cutting system force model based on shear angle (phi) oscillations and penetration forces caused by the tool flank's contact with the wavy surface. The dynamic cutting force coefficients are identified by operating a series of cutting tests at the desired frequency, while changing phi oscillations and penetration forces. It is shown that the process damping coefficient increases as the tool is worn, which increases the chatter stability limit in cutting. The chatter stability of a dynamic cutting process is solved using the Nyquist law and time domain simulation (TDS) techniques and compared favourably against experimental results at low cutting speeds. Finally, comparisons among the proposed mechanistic model and experimental results show a good agreement with the analytically established SLD and, thus, validate the effectiveness of the proposed model.
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    A new process damping model for chatter vibration
    (ELSEVIER SCI LTD, 2011) Turkes, Erol; Orak, Sezan; Neseli, Suleyman; Yaldiz, Suleyman
    This paper presents a new analytical process damping model (PDM) and calculation of Process Damping Ratios (PDR) for chatter vibration for low cutting speeds in turning operations. In this study a two degree of freedom complex dynamic model of turning with orthogonal cutting system is considered. The complex dynamic system consists of dynamic cutting system force model which is based on the shear angle (phi) oscillations and the penetration forces which are caused by the tool flank contact with the wavy surface. Depending on PDR, the dynamic equations of the cutting system are described by a new mathematical model. Variation and quantity of PDR are predicted by reverse running analytical calculation procedure of traditional Stability Lobe Diagrams (SLD). Developed mathematical model is performed theoretically for turning operations in this study and simulation results are verified experimentally by cutting tests. (C) 2011 Elsevier Ltd. All rights reserved.