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Investigatiom of friction on a beam-blades model
Půst, Ladislav ; Veselý, Jan ; Horáček, Jaromír ; Radolfová, Alena
Results of measurements of damping and friction properties of a couple of turbine blades modeled by a couple of cantilever prismatic beams with perpendicular branches provided by friction surfaces made of material T671- Böhler or coating of wolfram carbide are presented. The dependences of energy lost, coefficients of dry friction and equivalent linear damping coefficients on amplitudes of vibrations, on frequency in the range 10 – 40 Hz and on normal forces were shown. Revided regression relation can be used at damping elements designed of turbine blades.
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Computational model of a blade couple conected by a damping element
Půst, Ladislav ; Horáček, Jaromír
Couple of turbine blades is analysed on a simplified computational model of two cantilevers undamped beams connected on its free ends by a damping element, which is either linear one or has Coulomb friction characteristic. The end of one beam is excited by harmonic force. Derived expressions for amplitudes of vibrations are completed by response curves records. The model of combined dry and viscous damping but corresponds to the experimental results. A more exact computational model with eccentric frictional contacts and a structural modification of blades are proposed as well.
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