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Contributions to research on dynamics of precessional planetary transmissions

Author: Sochirean Anatolie
Degree:doctor of engineering
Speciality: 05.02.02 - Theory of machines and machine elements
Scientific adviser: Valeriu Dulgheru
doctor habilitat, professor, Technical University of Moldova
Scientific council:


The thesis was presented on the 28 November, 2008
Approved by NCAA on the 26 February, 2009


Adobe PDF document1.14 Mb / in romanian


CZU 621.833.6

Adobe PDF document 11.66 Mb / in romanian
186 pages


precessional motion, gearing, gear wheel, model, dynamics, kinetostatical, CAD, CAE, Autodesk Inventor, Solid Works, Motion Inventor, Motion Works, MathCAD


In order to valorize, on a large scale, precessional planetary transmissions, which are mechanical transmissions relatively complex on kinematical and dynamic levels, it is necessary to carry out supplementary fundamental research. The doctoral thesis contains the results of theoretical and experimental research on precessional planetary transmissions carried out in the period 1999-2008. The analysis of the state-of-the-art in the field of planetary transmissions with multiple gearing, as a whole, and of the precessional planetary transmissions, in particular, has demonstrated the need for a study in the field of the dynamic load which appears in the precessional gearing and for the design of constructive procedures able to reduce their influence on the bearing capacity and on the vibroactivity of precessional planetary transmissions. For maximum consideration of the influence of dynamic load on thebearing capacity in the design phase it is strictly necessary to define the calculation method for precessional gearing. In this respect the author made a number of original contributions to the definition of dynamicity factor of the load by designing a series of nomograms in order to justify the selection of this factor. The results of complex research (analytical and CAE models) on the influence of basic geometrical parameters on the value and character of linear velocity variation, angular and linear accelerations of the teeth contact point subject to a precessional cycle have an important role in the prognostication of the precessional planetary transmissions dynamics behaviour at the design phase.

New research methods for precessional planetary transmissions dynamics and for the action upon transmission bearings which allow for rapid optimization of the gearing geometry in the phase of design and of the bearing capacity of precessional planetary transmissions bearings. The design concept of precessional planetary transmissions has been developed. It will give the possibility to carry out basic research on 3D models of precessional planetary transmissions kinetostatics. In the result of theoretical and experimental research, that has been carried out, a series of driving mechanisms have been designed based on precessional planetary transmissions, which have been partially valorized.