f7c4d160-7c07-402b-ab32-234bc9d2aad620211115045003993naun:naunmdt@crossref.orgMDT DepositInternational Journal of Geology1998-449910.46300/9105http://www.naun.org/cms.action?id=28304720214720211510.46300/9105.2021.15https://www.naun.org/cms.action?id=23318PetruCârdeiComputer engineering INMA Bucharest, RomaniaAlexandrosAlexiouFaculty of Mechanics University of Craiova Craiova, RomaniaMirceaBădescuFaculty of Mechanics University of Craiova Craiova, RomaniaValentinVladuŃScientific Director INMA Bucharest, RomaniaNicolaeConstantinSoil Laboratory INMA Bucharest, RomaniaEugenMarinSoil Laboratory INMA Bucharest, RomaniaThe paper presents a point of view on the main sources that can generate some optimal points in the energy field of the agricultural machines working processes. It looks like a possible source of the existence of optimal points in the energetic field of work processes of agricultural machinery and equipment, are the coefficients of friction and specific resistance to deformation of soil. In the news models these coefficients became nonlinear functions. Similar forms are given for all three coefficients and is shown the existence of optimal points. They make some considerations about this method and include results obtained using it.111520211115202125293https://www.naun.org/main/NAUN/geology/2021/a062004-003(2021).pdf10.46300/9105.2021.15.3https://www.naun.org/main/NAUN/geology/2021/a062004-003(2021).pdfA. Sandru, M. Badescu, L. Sandru, Reducing energy consumption through rational use of agricultural aggregates, Romanian Writing Publishing, Craiova, 1982. N. N. Letosnev, Agricultural Machinery, State Agro-Forestry Publishing House, Bucharest, 1959. C. Dobrescu, Optimization of parameters of the agricultural aggregates to reduce energy consumption, Editorial propaganda agricultural machinery, Bucharest, 1981. A. Sandru, S. Popescu, I. Cristea, V. Neculăiasa, Exploitation of agricultural machinery, Didactic and Pedagogic Publishing House, Bucharest, 1983. D. Toma, T. Neagu, I. Florescu, S. Lepşi, Agricultural Tractors, Didactic and Pedagogic Publishing House, Bucharest, 1978. Ş. Căproiu, V. Scripnic, M. Segărceanu, D. Toma & all, Dictionary of agricultural mechanics, CERES Publishing House, Bucharest 1972. 10.1088/0305-4470/30/17/015F., J. Elmer, Nonlinear dynamics of dry friction, J. Phys. A:Math. Gen. 30 (1997) 6057-6063. M. Rădoi, E. Deciu, Mechanics, . Didactic and Pedagogic Publishing House, Bucharest, 1981. 10.1038/nature02750M. Urbakh, J. Klafter, D. Gourdon and J. Israelachvili, The nonlinear nature of friction, Nature, vol. 430, 2004 , pp. 525-528. 10.1006/jsvi.2001.3818M. Vaishya and R. Singh, Sliding friction-induced non-linearity and parametric effects in gear dynamics, Journal of Sound and Vibration, 248(4), 2001, pp. 671-694. L.,R.Ray, Nonlinear Tire Force Estimation and Road Friction Identification: Simulation and Experiments, Automatica, vo. 33, issue 10, 1997, pp. 1819-1833. C. Makkar, Nonlinear modelling, identification, and compensation for frictional disturbances, A thesis presented to the graduate school of the University of Florida in partial fulfilment of the requirements for the degree of master of science, University of Florida, 2006. 10.21236/ada330640T., A. Shugar, Numerical modelling of steady-state plo/soil interaction, Technical Report TR-2081-SHR, Naval Facilitiues Engineering Service, Port Hueneme, California 93043-4370, 1997. W., R. Gill, Soil Dynamics in Tillage and Traction, Agricultural Research Service USDA, 1968. 10.1016/s0022-4898(99)00006-3U. A. Rosa, D. Wulfsohn, Constitutive model for high speed tillage using narrow tools, Journal of Terramechanics 36, pp. 221-234, 1999. V. A. Meca, P. Cârdei, Studies and Researches for Unifying the Resistance Expression of machines Designed to Soil Tillage With Applications in the Working Regime Optimisation, INMATEH, vol. 36, pp. 21-26, 1/2012. P. Cârdei, A. Meca, G. Kostandinov, Soil farm machinery mode of operation:from the optimisation to the basis (1), INMATEH, vol. 37, pp.13-20, 2012. P. Cârdei, G. Kostandinov, Soil farm machinery mode of operation:from the optimisation to the basis (2), INMATEH, vol. 37, pp. 21-30, 2012; P. Cardei, R. Sfîru , I. Pirnă, M. Bădescu, S. Boruz, S. Lazar, Studies and researches on energetic optimisation of fodder harvesting combines-unidimensional models, INMATEH, vol. 38, pp. 5-14, 2012. P. Cardei, R. Sfîru , I. Pirnă, M. Bădescu, S. Boruz, At. Atanasov, Studies and researches on energetic optimisation of fodder harvesting combines-two idimensional models, INMATEH, vol. 38, pp. 15-22, 2012.