Abstract
The aim of this paper is to propose a methodology for the modelling, testing, and the parameter identification of viscoelastic supports for rotating machines at the component and system level. Although the use of this type of dampers is common in rotordynamic applications, the strict dependence on the working frequency of the material parameters makes their behavior hard to predict and recommends grounding the design on experimental data of the characteristics. A dedicated test rig is adopted to characterize the supports and validate the modelling approach at component level. A parameter identification procedure is carried out from the experimental results to extract the mechanical properties of the supports. To this end, a Genetic Algorithm (GA) is adopted to search the most fitting values of damping and stiffness of the reference model. The choice of GA is motivated by the need of adopting a technique that can be easily implemented on industrial control units, being that the dedicated machine is supposed to be used in production lines for testing procedures. The results are obtained in terms of complex stiffness as a function of the frequency and are then translated in classical stiffness and damping components that are commonly used in rotordynamics. Afterwards, they are introduced in the model of a turbo-molecular pump adopted as a case study to evaluate the correctness of the proposed methodology at system level at stand-still and with the pump in rotation. The proposed approach is effective, showing a good match between the numerical model and the experimental results even with a relatively low order model of the viscoelastic supports and on a complex rotordynamic system.
Highlights
Vibrations in mechanical structures are typically caused by structural issues like effects of the material fatigue damage and wear, and are the cause of loss of performance and reliability.In rotordynamics, these negative consequences are emphasized and strongly influence and constrain most of the design phases
The objective of this paper is to propose a methodology to identify the behavior of viscoelastic dampers and to predict the rotordynamic behavior of shafts supported by them
The proposed procedure is tested on the two different dampers that have been installed in the compressor side (CS) and in the shaft end side (SES) of the turbo-molecular pump that is used for the experimental validation at the system level, as reported in the final section of this paper
Summary
Vibrations in mechanical structures are typically caused by structural issues like effects of the material fatigue damage and wear, and are the cause of loss of performance and reliability. In the oil and gas industry, and in aerospace, solutions based on active/semi-active hydraulic systems, electrorheological [1,2], and magnetorheological [2] solutions have been proposed for the adaptation of the damping force to the operating conditions These devices cannot avoid drawbacks related to the aging of the fluid and to the tuning that is required for compensating the temperature and frequency effects. Magnetic bearings and dampers witnessed a steady growth in applications, like vacuum pumps, compressors for air conditioning, turbo-compressors in oil and gas industry, turbines for energy recovery, and storage, such as kinetic energy storage systems (KESS) and compressed air energy storage (CAES) [3,4,5,6] They allow for contactless operation and lack the need of lubrication and oil supply systems. The close correlation between model response and experimental data at standstill, and with the shaft at full speed, demonstrates the effectiveness of the approach at system level
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
