A review on modelling and dynamic analysis of viscoelastic rotor systems

Purpose The purpose of this study is to bring down collective information about various issues encountered in modelling of rotor systems. Design/methodology/approach The most important and basic part of “rotor dynamics” is the study related to its different modelling techniques which further involves the analysis of shaft for understanding the system potential, competence and reliability. The issues addressed in this study are classified mainly into two parts: the initial part gives out a vast overview of significant problems as well as different techniques applied to encounter modelling of rotor systems, while the latter part of the study describes the post-processing problem that occurs while performing the dynamic analysis. Findings The review incorporates the most important research works that have already placed a benchmark right from the beginning as well as the recent works that are still being carried out to further produce better outcomes. The review concludes with the modal analysis of rotor shaft to show the importance of mathematical model through its dynamic behaviour. Originality/value A critical literature review on the modelling techniques of rotor shaft systems is provided from earliest to latest along with its real-time application in different research and industrial fields.

Research of wear resistance of a covering of shafts of the turbocharger of the diesel engine restored by means of a gas-dynamic spraying

The analysis of tribological researches on the most perspective way of restoration of a primary resource of engines by means of a gas-dynamic spraying is resulted in article. It was found that to reduce the coefficient of friction and increase the wear resistance of the coating is theoretically justified the use of copper-zinc powders brand C-01-11, applied by gas-dynamic spraying. It is established that the physical and mechanical properties of the coatings (roughness, microhardness, friction coefficient) on the restored turbocharger meet the requirements of the manufacturer. The coefficient of friction in the connection, the rotor shaft (reduced powder with copper and zinc), with a plain bearing (made of tin-lead bronze Bros - 10 - 10) is 20 % less than in the connection where the rotor shaft is made of steel 40. The total wear in the bearing assembly with the restored gas-dynamic sprayed rotor shaft is 20 % lower than in the assembly where the rotor shaft is restored by the basic technology. The technology of restoration of a surface of a shaft of a rotor of the turbocompressor, under the bearing of sliding (gas-dynamic spraying) which increases its resource by 23 % in comparison with basic technology of repair of a shaft of a rotor is developed. This allows you to increase its operating time with the established regulatory and technical documentation for overhaul of the engine. A stand for testing diesel turbochargers with recovery technology has been developed, which allows to determine the parameters and characteristics of diesel engine turbochargers in different periods of operation, running-in and adjustment. Tests on the stand showed that turbochargers with restored rotor shafts according to the proposed technology after 2000 operating hours increase all performance by 13 % more than turbochargers repaired by the basic technology. Operational tests have shown that turbochargers repaired using the proposed technology have an operating time of 989 moto-hours more than turbochargers repaired with existing technology

Method of modeling the electrical capacity of the measuring transducer

To diagnose the eccentricity of the rotor shaft of an electric machine, a device is proposed, the sensitivity of which does not depend on fluctuations in the parameters of the network and the load of the electric machine, since the displacement of the rotor is monitored using capacitive sensors located evenly around the circumference of each end of the shaft. Diagnostic results are assessed according to two valid criteria. The device allows to determine not only the value of the eccentricity of the rotor, but also the direction of the displacement of the rotor. Keywords: electric machine, rotor eccentricity, method for modeling electrical capacity. [email protected]

Dynamic Analysis of the Rod-Fastened Rotor Considering the Characteristics of Circumferential Tie Rods

The research on the dynamic performance of the rod-fastened rotor (RFR) has always been a hotspot. However, the structural complexity of RFR has brought significant challenges to the dynamic study of the RFR. The tie rods provide preload for the rotor shaft segment, while the coordinate deformation of the tie rods will occur during the process of vibration. In addition, the tie rods and the rotor shaft segments are structurally connected in parallel. These factors all will influence the dynamic performance of the RFR. In this paper, for a RFR system, the vibration equation of the RFR considering all factors of the tie rods is deduced in detail. The influence of various factors on the dynamic performance of the rotor is investigated. Results show that the preload directly affects the dynamic performance of the RFR system. When the preload is small, the tie rod has a larger influence on the natural frequencies of the rotor. However, when the preload force reaches a certain value, the influence of the tie rod on the natural frequencies of the rotor is almost negligible. The research results provide a theoretical reference for the understanding of and further research on RFR.