Commonly applied theories of self-excited vibrations in machine tools are prevailingly based on frequency domain analysis of linear models, and in most cases only focus on evaluation of stability limits of strictly linear systems. In this way the behaviour of more stable or more unstable systems cannot be studied and analyzed. Neither is it possible to study certain important nonlinear effects because of limitations connected with the classical representation of systems only in the frequency domain. Evaluation of stability by analysing nonlinear systems in the time domain has not been applied until recently. The paper shows a new approach based on an interpretation of self-excited vibration systems as nonlinear servo-systems. With this approach linear and nonlinear systems of any degree of stability can be studied using a combination of frequency and time-domain methods. This can considerably contribute to better understanding of complex phenomena in various regimes and specific situations.
This article covers the development of the synthesis of the zinc coatings with dispersed polytetrafluorethylene particles (zinc–polytetrafluorethylene composite coatings). The technology was based on zinc electrolytic plating in weakly acid bath. After optimising the parameters of the technology according to the results of coating analyses by infrared spectroscopy and tribological measurements, it was possible to prepare zinc coatings with homogenously incorporated polytetrafluorethylene. This ensured significantly lower friction coefficient of these coatings in comparison with pure zinc coating. The corrosion resistance and self-lubrication character of zinc–polytetrafluorethylene coatings is promising in potential replacement of existing multi-layered zinc coating systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.