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Shock and Vibration
Volume 18, Issue 1-2, Pages 333-341
http://dx.doi.org/10.3233/SAV-2010-0606

Energy-Based Analysis of Ultrasonically Assisted Turning

G.A. Volkov,1 V.A. Bratov,2 A.A. Gruzdkov,3 V.I. Babitsky,4 Y.V. Petrov,2 and V.V. Silberschmidt4

1St.-Petersburg State University, St.-Petersburg, Russia
2Institute for Problems of Mechanical Engineering RAS, St.-Petersburg, Russia
3St.-Petersburg State Technological Institute, St.-Petersburg, Russia
4Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leics., LE11 3TU, UK

Received 29 January 2010; Revised 12 August 2010

Copyright © 2011 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The process of ultrasonically-assisted turning (UAT) is a superposition of vibration of a cutting tool on its standard movement in conventional turning (CT). The former technique has several advantages compared with the latter, one of the main being a significant decrease in the level of cutting forces. In this paper the effects observed in UAT are analysed employing ideas of dynamic fracture mechanics. The active stage of loading duration depends heavily on ultrasonic frequency and the cutting speed; he application of the fracture criterion based on the notion of incubation time makes it possible to calculate a dependence of this duration on its threshold amplitude. An estimation of energy, necessary to create a threshold pulse in the material, is made by solving the contact Hertz problem. The obtained time dependence of energy has a marked minimum. Thus, the existence of energy-efficient loading duration is demonstrated. This explains the decrease in the cutting force resulting from superimposed ultrasonic vibration. The obtained results are in agreement with experiments on ultrasonic assisted machining of aluminium and Inconel 718 alloy.