Povestea unei Şcoli de Lubrificaţie din Politehnica Bucureşteană„DIFUZIUNI” LA NIVEL NAŢIONAL ŞI INTERNA -ŢIONALÎn afară de membrii echipei de cercetare care mi-au fostsau îmi sunt doctoranzi am atras mulţi alţi studenţi, din ţarăsau străinătate în aria Lubrificației prin colaborări/coordonărila proiectul de diplomă, la tezele de master sau doctorat.Este o listă lungă, greu de reconstitut, dar îmi amintesctotuşi de: N. Galperin şi M. Groper de la TECHNION dinIsrael, P.Keane, B. McGroder, H. Parker şi J. Wagner de laUniversitatea din Pittsburgh, Z.C. Peng de la LSU din BatonRouge, F. Orgerit, N. Brunetiere şi A. Fătu de la Universitateadin Poitiers, S. Deaconu de la CFD Research Corp.,Huntsville, Diana A. Ladoş conferenţiar la Worcester PolytechnicInstitute și A. Minculescu, inginer la HoneywellGarrett (ultimii patru foşti studenţi din Politehnica dinBucureşti) precum și M.Alexandrescu de la Universitateade Nord din Baia Mare.ÎN LOC DE CONCLUZIILubrificaţia, alături de Frecare și de Uzare, este parte aTribologiei, domeniu ultra-multidisciplinar, uneori eteroclit.Lubrificaţia ca soluţie de reducere drastică a frecării, dar şide răcire, pompare, amortizare, vibrare, de transmitere a puteriietc. poate fi percepută la prima vedere, ca o aplicaţie comodăa Mecanicii Fluidelor. Aparenţele înşeală, căci filmulde lubrifiant, dorit sau nedorit, este extrem de subţire încomparaţie cu dimensiunile curente din problemeleMecanicii Fluidelor. Conştientizând acest lucru se poateînţelege complexitatea şi dificultatea Lubrificaţiei prinaceea că: Vîscozitatea variază cu temperatura şi presiunea; Grosimea filmului depinde de rigiditatea si permeabilitateafrontierelor; Curgerea cavitaţională şi/sau schimbarea de fază seasociează cu existenţa unui interstiţiu divergent, şi/sau cuvariatia temperaturii și a presiunii; Impurităţile lubrifiantului contează; Dilatarea părţilor solide ale cuplei trebuie luate înconsiderare şi aşa mai departe.Toate cele precizate mai inainte impun o abordare multidisciplinarăși aceasta a fost caracteristica Şcolii deLubrificaţie nucleate de mine în Politehnica din Bucureşti şiîn colaborarile mele internaţionale.Întotdeauna temele de studiu atât pentru doctoranzii meicât şi pentru colaborările din străinătate au fost generate demine.Într-o lume în care modelările sunt preponderent numerice,am păstrat viu, analiticul, analogia şi fenomenologia,abordări care încep să fie uitate. N-am uitat, cum auspus-o și alții că „cel mai bun calculator este cel dintreurechi!”. Această caracteristică m-a făcut să le fiu complementarşi necesar celor dotaţi cu mai multă aparatură delabo rator sau tehnică de calcul. Asta s-a întâmplat în Israel,Franţa, USA, ba chiar şi în Japonia.Cărţi publicate / Published BooksNATIONAL AND INTERNATIONAL “DIFFUSIONS”Besides the members of the Lubrication Group, whoare or have been my PhD students, I redirected the interestof many other Romanian or foreign students toward the Tribologyarea through collaboration/guidance at their work forDiploma thesis, master degrees or PhD thesis. It’s a verylong list, quite difficult to rebuild; however I remember: N.Galperin and M. Groper from TECHNION Israel, P.Keane,B. McGroder, H. Parker and J. Wagner from University ofPittsburgh, Z.C. Peng from LSU of Baton Rouge, F. Orgerit,N. Brunetiere and A. Fătu from University of Poitiers, S.Deaconu from CFD Research Corp., Huntsville, Diana A.Ladoş, Assisstant Professor at Worcester Polytechnic Instituteand A. Minculescu, research engineer at HoneywellGarrett (the latter four, former students of University PO-LITEHNICA of Bucharest), as well as M. Alexandrescufrom North University of Baia Mare.INSTEAD OF CONCLUSIONSLubrication, alongside with Friction and Wear, representsa part of Tribology that can be defined as a multidisciplinaryscience, sometimes heterogeneous. As a solution fordrastic friction reduction, as well as for cooling, pumping,damping, vibration, power transmission etc., Lubricationcan be considered at first glance as a simplified approach ofFluid Mechanics. Appearances are deceptive, because, desiredor not, the lubricant film is extremely thin in comparisonwith the typical dimensions used in Fluid Mechanics.When this aspect comes forward then the difficulty and complexityof Lubrication can be understood, with all its complexitems: Variation of viscosity with temperature and pressure; The film thickness dependence on the stiffness andpermeability of the solid boundaries; Cavitation and/or phase changes are associated withthe existence of a divergent gap, and/or with the temperatureand pressure variation; Lubricant impurities must be taken into consideration; The thermal expansion of the rigid boundaries mustbe also consideration, and so on;All these require a multilateral approach which representsthe particular feature of the Lubrication School nucleatedby me in the University POLITEHNICA ofBucharest and by international cooperation.I have always generated the subjects for my PhD studentsas well for my foreign collaborations.I keep alive the analytical, the analogy and the phenomenology,approaches which may easily be forgotten in aworld of numerical modeling. I have not forgotten the words“the best computer is the one you have between your ears!”.This quality made me complementary and needful to mypartners better equipped for experimental work and more familiarwith computers. This has been proven in Israel,France, USA, and even in Japan. V.N. Constantinescu, A. Nica, M.D. Pascovici, Gh.Ceptureanu, Şt. Nedelcu, SLIDIG BEARIGS, New York,Allerton Press. Inc., 1985. (publicată iniţial în limba romană,la Ed. Tehnică, în 1980) M.Gafiţanu, D.Pavelescu, M.D.Pascovici ş.a. ORGAEDE MAŞII, Vol.I, Ed. Tehnică, Bucureşti, 1981 I.Drăghici, M.D.Pascovici, A.Jula ş.a., ÎDRUMAR DEPROIECTARE Î COSTRUCŢIA DE MAŞII, Vol.I, Ed.Tehnică, Bucureşti, 1981 M.D. Pascovici, LUBRIFICAŢIA - Prezent, perspective,Ed. Tehnică, Bucureşti, 1985 M.D. Pascovici, T. Cicone, TRIBOLOGY – textbook, LitoUPB, 2001 M.D. Pascovici, T. Cicone, ELEMETE DE TRIBOLO-GIE, Ed. BREN Bucureşti 2002 T. Cicone, M.D. Pascovici, APLICAŢIILE LUBRIFI-CAŢIEI, Ed. PRINTECH Bucureşti 2006 T. Cicone, M.D. Pascovici, ETAŞĂRI CU PERII, Ed.BREN Bucureşti 2007 C: Bălan, L. Hamnelid, J.M. Franco, M. Britton, P.T.Callaghan, D. Bonneau, Al.V. Rădulescu, A. Marin THERHEOLOGY OF LUBRICATIG GREASE, pp. 79-105, 115–137, European Lubricating Grease Institute Publications, 2000 J. Frene, T. Cicone, FRICTIO I LUBRICATED CO-TACTS cap. 8.4. din LEMAITRE HADBOOK OF MATERI-ALS BEHAVIOR MODELS, Academic Press, 200114
Vizualizarea vaporizării în filme subţiri (13 microni) cu aplicaţii laetanşările frontale realizată în cadrul programului post-doc de cătreT.Cicone la Univ. din Poitiers (2 nd World Tribology Conference, Viena2001)Vizualization of vaporisation in thin films (13microns) with aplicationto mechanical face seals done during a Post Doc work by T. Cicone atthe University of Poitiers (2 nd World Tribology Conference, Vienna 2001)Lucrări publicate în reviste cotate ISIPapers Published in ISI (ranked) JournalsM.D. Pascovici (1970) The Circumferential Temperature Distributionof Complete J. Bearings, Wear,16,1-2,143-147M.D. Pascovici (1974) Experimental Study of the Influenceof Heat Transfer on the Temperature Distribution in a LubricantFilm, Wear,29,1,59-67M.D. Pascovici (1974) Temperature Distribution in the LubricantFilm of Sliding Bearings under Intensive Lubricantwall.Heat Transfer Conditions, Wear, 29,4,277-286M.D. Pascovici (1976) An Application of the Principle ofUnchanging Form by Wear in Natural Joints, Wear, 37,1,191-192M.D. Pascovici (1978) A Simple Method for the Computationof Lubricant Film Maximum Temperature, Wear, 49,391-392M.D. Pascovici (1978) Computation of the Residual Torqueof Oil Cooled Disk Clutches, Wear, 50,383-386M.D. Pascovici (1981) Fluid Friction Torque Variation WithSliding Speed, Wear,73,387-389M.D. Pascovici, Al.V. Rădulescu (1987) The Grease SqueezeFilm, Wear,116,261-266M.D. Pascovici, I. Etsion (1992) A Thermo-HydrodynamicAnalysis of a Mechanical Face Seal, ASME J. of Tribology,114,2,639-645I. Etsion, M.D. Pascovici (1993) A Thermo-HydrodynamicAnalysis of a Misaligned Mechanical Face Seals, STLETrib.Trans., 36,4,589-596M.D. Pascovici, M.M. Khonsari, J.Y. Jang (1995) On theModeling of a Thermomechanical Seizure, ASME J. of Tribology,117,4, 744-747I. Etsion, I., M.D. Pascovici (1996) Phase Change in a MisalignedMechanical Face Seal, ASME J. of Tribology,118,1,109-115I. Etsion, M.D. Pascovici (1996) Hydrodynamic Effects onthe Boiling Interface in a Misaligned Two-Phase MechanicalSeal – A Qualitative Study, STLE Trib.Trans.,39,4,922-928M.D. Pascovici, I. Etsion (1996) The Accuracy of the IscoviscousSolution of the Reynolds Equation in MechanicalSeals, IMechE-J. of Engng. Tribology, 210,152-156I. Etsion, M.D. Pascovici, L. Burstein (1997) The Boiling Interfacein a Misaligned Two-Phase Mechanical Seal, ASMEJ. of Tribology, 119,2,265-272I. Etsion, M.D. Pascovici (1997) Vaporization in Face SealsOperating with Liquid Mixtures, STLE Trib.Trans., 40,4,694-700J.Y. Jang, M.M. Khonsari, M.D. Pascovici (1998) ThermohydrodynamicSeizure: Experimental, Theoretical Analysis,ASME J. of Tribology, 120,1,8-15J.Y. Jang, M.M. Khonsari, M.D. Pascovici (1998) ModelingAspects of a Rate-Controlled Seizure in an Unloaded J. Bearing,STLE Trib.Trans., 41,4,481-488M.M. Khonsari, M.D. Pascovici, B.V. Kucinschi (1999) Onthe Scuffing Failure of Hydrodynamic Bearings in the Presenceof on Abrasive Contaminant, ASME J. of Tribology,121,90-96Al.V. Rădulescu, F. Vasiliu (1999), A Simplified CalculusMethod for a Grease-Lubricated Rayleigh Step Bearing”, LubricationScience, 11,3,271-284C.V. Suciu, O. Bonneau, D. Brun-Picard, J. Frene, M.D. Pascovici(2000) Study of a Novel Squeeze Film Damper, VibrationGenerator, ASME J. of Tribology, 122,1,211-218B.R. Kucinschi, M. Fillon, J. Frene, M.D. Pascovici (2000)A Transient Thermohydrodynamic Study of Steadily LoadedPlain J. Bearing Using Finite Element Method Analysis,ASME J. of Tribology, 122, 1, 2000, 219-226M.D. Pascovici, M.M. Khonsari (2001) Scuffing Failure ofHydrodynamic Bearings Due to an Abrasive ContaminantPartially Penetrated in the Bearing Over-Layer, ASME J. ofTribology, 123,2,430-433T. Cicone, M.D. Pascovici, B. Tournerie (2001) NonisothermalPerformance Characteristics of Fluid Film MechanicalFace Seals, IMechE-J. of Engng. Tribology, 215, 2001, 35-44C.V. Suciu, T. Iwatsubo, M.D. Pascovici (2002) Analysis ofa Torsional Fluid Film Vibrator, ASME J. of Tribology,124,3,480-485M.D. Pascovici, T. Cicone (2003) Squeeze-film of unconformal,compliant, layered contacts, Trib. Int., 36,11,791-799Z.C. Peng, M.M. Khonsari, M.D. Pascovici (2003) On thethermoelastic instability of a thin-film-lubricated sliding contact:a closed-form solution, IMechE-J. of Engng. Tribology,217,197-204Al.V. Rădulescu, F. Vasiliu (2003) Theoretical Study of theBi-dimensional Grease Flow Process in the Regions with Discontinuities,Lubrication Science, 15,2,163-171B.R. Kucinschi, K.J. DeWitt, M.D. Pascovici (2004), Thermohydrodynamic(TEHD) analysis of a grooved thrustwasher, ASME J. of Tribology, 126,2,pp.264-274V.G. Marian, M. Kilian, W. Scholz, (2007) Theoretical andexperimental analysis of a partially textured thrust bearingwith square dimples, IMechE-J. of Engng. Tribology, 217,197-204, 221,7,771-778T. Cicone, M.D. Pascovici, A. Minculescu (2008) A simplifiedthermoelastohydrodynamic model for a parallel surfaceslider, Trib. Int. 41,947–953M.D. Pascovici, T. Cicone, V. Marian (2009) Squeezeprocess under impact, in highly compressible porous layers,imbibed with liquids, Trib. Int., 42,1433–1438M.D. Pascovici, T. Cicone, M. Fillon, M. Dobrica (2009) Analyticalinvestigation of a partially textured parallel slider”,IMechE-J. of Engng. Tribology, 223,151-158The history of a Lubrification School from the University Politehnica of Bucharest15