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Increasing the availability and maintainability of couplings with clearance restored with polymer composite materials

Author: Ţapu Veaceslav
Degree:doctor of engineering
Speciality: 05.20.03 - Exploitation and Maintenance of Agricultural Machinery and Food Industry
Scientific consultant: Grigore Marian
doctor habilitat, professor, Agrarian State University of Moldova
Institution: Agrarian State University of Moldova
Scientific council: DH 60-05.20.03-27.03.08
Agrarian State University of Moldova


The thesis was presented on the 26 December, 2011
Approved by NCAA on the 16 February, 2012


Adobe PDF document0.59 Mb / in romanian


Reliability, Composite materials, Maintenance, Wear.


The paper consists of an introduction, four chapters, general conclusions and recommendations, bibliography containing a list of 178 sources, 3 annexes, 112 pages (they don’t include the bibliography), 24 figures and 7 tables. The obtained results are published in 13 scientific papers.

Field of study– technical.

The purpose and objectives of dissertation. The purpose is to increase the availability and maintainability of couplings with clearance in the field of agricultural machinery and other related fields. The researches were focused on the following main objectives of dissertation: analysis of current state of researches regarding the insurance of availability and maintainability of tribological metal-polymeric couplings; elaboration of research schemes and organization of the experimental laboratory; continue researches in order to improve the quality of couplings with clearance reconditioned with polymer composite materials for difficult lubricating conditions and establishing the limit state and catastrophic state of the couplings with clearance restored with porous polymer composite materials; elaborating the technological reconditioning process of wear parts and implementing the results obtained in the dissertation.

Scientific novelty of obtained results. The scientific novelty of dissertation consists in solving an important scientific problem submitted in the dissertation and namely Demonstrating the efficiency of applying polymeric composite materials with a porous structure of the surface layer with the purpose to increase the availability and maintainability of restored couplings with clearance as components of the agricultural machinery and machinery of processing industry.

Theoretical significance consists in determining the dynamics of wear and certain physico-mechanical properties of metal-polymeric couplings with clearance depending on the operating conditions, polymer composite materials’ constitution, technological parameters of application and formation of polymer coatings, and characteristics of the contact surfaces and nature of joint.

Applied value of dissertation is provided by theoretical-experimental recommendations regarding the availability and maintainability of metal-polymeric couplings with clearance restored with porous polyamide-epoxidic composite materials; the positive effect of implementing the obtained results in the production process; using the results obtained in dissertation in improving the training process of students of agricultural engineering specialities and other related specialities.

Implementation of scientific results. The results obtained in dissertation were implemented in the production process in the Technological Experimental Station “Pascani”, Technological Station “Codru” and Didactic Experimental Station “Chetrosu”. The results of implementation have been approved by the Ministry of Agriculture and Food Industry of the Republic of Moldova.