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CNAA / Theses / 2005 / June /

Contribuţii teoretico-experimentale la studiul fiabilităţii pieselor şi îmbinărilor utilajului agricol recondiţionate cu compozite pe bază de polimeri

Author: Marian Grigore
Degree:doctor habilitat of engineering
Speciality: 05.20.03 - Exploitation and Maintenance of Agricultural Machinery and Food Industry
Scientific consultant: Victor Şeremet
doctor habilitat, associate professor (docent), Technical University of Moldova
Scientific council:


The thesis was presented on the 9 June, 2005
Approved by NCAA on the 22 September, 2005


Adobe PDF document0.56 Mb / in romanian


In the thesis work is solved an actual scientific problem and namely the improvement of the theoretical bases concerning the of systems calculation boarding and of the provision of parts reliability of the machines and joints, restored wits polymeric covering. The research was carried out on base of the investigation of tribosystems restored with polymeric composites that presents great interest both for users of farm machinery and for repair production.

The first chapter deals with the motivation of the use of polymeric composite material in repair production. The state of the question of investigation as to reliability of the farm machinery as a whole and separate parts restored with polymeric covering is considered. The given analysis of the main theses of reliability and the theoretical bases of the repair of the farm machinery and the theoretical basis of the repair of the farm machinery and of processing industry are listed. The questions of the engineering from the standpoint rating of the provision of quality to recovering the parts of the machines and their joints are considered a significant place is dedicated to critical analysis of the methods of the fixing compozite polymeric covering and of the material themselves used both in repair production and in other branches of national economy. Problems of investigation are given at the end of the chapter.

The Second chapter is dedicated to theoretical aspect of the reliability parts and of machines restored with polymeric covering. On base of the structural analysis of dimension of inaccuracy of joins, restored with polymeric covering, and methods of the provision of calculation of to accuracy metal-polymer joints were formulated theoretical bases for calculation of clearance and tightness of the interfaces consisting of one metallic part and the second with restored polymeric covering. Scientific novelty of the theoretical propositions consists in the fact that that for the first time were used the mathematical equations for calculation of accuracy of the joints take also were into account all the significant factors, that appear on length of the whole life cycle of the product, including the specific inaccuracy of the parts restored with polymeric covering. The calculation of accuracy of the joints is founded on the decision of the problem marginal limiting of polymeric layer, upshot from possible deformation, making uze of Green functions.

The third chapters deals with methods and means of investigation of the physicomechanical characteristics of the polymeric covering, as well as the assessment of the factors of reliability of restored parts and their joints.

In IV-VI chapters are given the results of the experimental-analytical investigations the reliability level of the tribosystems restored with polymeric covering in the process of their designing, reconstruction and usages. On the base of the experimental studies, is designed difinite recommendations were made coarsening the reliability level of the joints, restored with polymeric covering, depending on material of the covering, dimension of accuracy, conditions of contacting surfaces, nature of the joints. The investigations were carried out in laboratory and working conditions.

In conclusion of the work, on the basis of carried outexecuted experimental-analytical investigations, are given recommendations on development of the technological processes of the recovering of the worn-out parts with polymeric covering, the main findings are systematized, noted the personal contribution of the author, is noted practical and scientific usefulness of the results of investigation, recommendations on implementation in production of the obtained results and their technical-economic assessment are presented.