This article explores two models of internal friction in porous materials and ultrafine-grain composite materials. The high-temperature background is described by two straight sections based on the dependence of the internal friction value on the reverse temperature or frequency of vibrations.

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Questions of ensuring reliability and safety of operation of complex technical systems are relevant during the operation of power equipment of thermal plant (TPP). The paper presents a generalized statistical analysis of defects and damages over the past 15 years in the control systems of steam turbines of types ET (extraction turbine) and IET (industrial extraction turbine), with an installed capacity of 50 to 135 MW. As a result of the calculation study, the main cause-and-effect relationships of the resulting defects that lead to an emergency stop of the turbines were identified. This paper presents the results of the analysis of defects in steam turbine control systems and provides recommendations for eliminating and preventing unplanned downtime due to an emergency shutdown of turbine units.