Abstract: To reach the best momentary values of the machining process performances (concerning productivity, precision, surface quality etc.) it is necessary to continuously monitor the deviations from the programmed values of the cutting process parameters (caused especially by instability) and to counteract them. This is possible only if we have a technological system’s dynamics model to express the relation between the machining process input parameters and their consequences regarding the stability. Such a model may be developed by starting from the equations characterizing the physical process or by identification. During the last decades, several models were suggested and, more or less, validated in practice. They all have two major inconvenient: i) the machining process and the machining system are treated separately and ii) they cannot give information about the position of the system’s current functioning point relative to its stability limit. By assuming the potential chaotic character of the cutting process dynamics, we made investigations concerning the possibility of identifying the dynamics of both machining process & system, considered together as a unique entity. There are more, well known, chaotic classic models: logistic, Henon, Lorenz etc. After thoroughly analyzing them, we chose the logistic (one-dimensional) model as the most appropriate to be used for characterizing the cutting force (or the acceleration) variation during a cutting process and thus, to identify the machining process & system dynamics. By online monitoring the momentary value of the logistic model control parameter and by comparing it to a critical value, the position of the system’s current functioning point relative to its stability limit may be known.

Brief Biography of the Speaker:
Gabriel Frumusanu graduated a 5 years Mechanical Engineering degree program at "Dunarea de Jos" University of Galati (1987); PhD in Industrial Engineering - at "Dunarea de Jos" University of Galati (1999); Training stages at: "Ecole des Mines de Paris", CEMEF, Sophia-Antipolis – France (1992); "Universita degli Studi di Padova", Padua – Italy (1997); "Ecole Nationale Superieure des Artes et Metiers", Angers – France (2002). Research fields: numerical modeling of manufacturing processes and surfaces generation; cutting processes dynamics; metals cold forming (deep drawing, extrusion, orbital volumetric cold forming). Professional experience: 1988 – 1990 – Engineer responsible of equipments maintenance at Cold Rolling Mill from Galati Iron and Steel Company; 1990 – 2000 – Assistant-professor at "Dunarea de Jos" University of Galati, Manufacturing Science and Engineering Department; 2000 – 2004 – Associate-professor, in the same department; 2004 up to present – Professor, in the same department.
Prof. Frumusanu participated in over 20 research projects supported by Romanian Ministry of Education and Science; author / co-author of over 20 scientific or didactic books; over 100 scientific papers written or co-authored, published to International / National Conferences proceedings (Spain, France, Hungary, Israel, Moldavia) and Journals. Invited professor at "Universita degli Studi di Padova", Padua – Italy (2006). Member of professional and scientific associations: Romanian Association for Non-Conventional Technologies - ARTN, Romanian Association of Managers and Engineers - AMIER, Romanian Association of Tensometry - ARTENS; Expert of Romanian National University Research Council - CNCSIS and of Romanian Agency for Quality Assurance in Higher Education - ARACIS.