A novel method of contactless measurement of turbine vlade vibration during increasing (decreasing) operational speed is presented. The method is based on evaluation of time differences of blade passages along contactless sensors placed on the stator, and substitutional data correction using a numerical model. The method has been verified both numerically and experimentally. For the experimental research on the bladed model wheel of the Institute of Thermomechanics and subsequent applications under operating conditions, two new types of sensors functioning on magnetoresistive and induction principle have been developed. and Obsahuje seznam literatury
The vibrodiagnostic system VDS-UT2 was developed for the investigation of a tram wheel operational vibration and deformation. The system consists of measuring, acquisition and processing tools for monitoring of tram wheels and their operational parameters, e.g. static and dynamic deformation, displacement, velocity, acceleration and temperature. The measuring on a rotating wheel is realized both by telemetric and by top-timing system. Measured data can be remote-observed via Internet connection with the control PC. The acquisition system by Starmans Electronics s.r.o. provides continuous analog and digital data logging. The control PC processes digital logical signals and evaluates time intervals representing circumferential turning angles between disk and rim.. In the contribution, the diagnostic system is described and the measured data including damage analysis are presented. and Obsahuje seznam literatury
This paper presents the procedure for designing electromagnetic bladed wheel excitation. This procedure comes from phase-synchronization of multiple electromagnets distributed around the wheel with a movement of the blade to obtain its resonant vibration. This procedure can be used with merit for dynamic tests of inter-blade couplings. The verification was performed on the tested wheel using two-point electromagnetic excitation of blades under rotation. and Obsahuje seznam literatury
The new test approach for evaluation of thermo-visco-elastic parameters of elastomers is designed, realized and discussed herein. The main attention is devoted to a kinematically excited rubber beam specimen under transient resonant sweep excitation. Mechanical material characteristics, i.e. Young modulus and loss angle, are identified from analytical formulas of frequency function based on measured dynamic loading and response signals. Heat material constants were estimated indirectly by numerical thermo-mechanical FE model and matching numerical and experimental results. The 'sweep' regime tests serve for estimation of thermal and mechanical dependences. Long-term fatigue tests with cyclic resonant loading enable analysis of material degradation, such as hardening and permanent deformations. and Obsahuje seznam literatury
The dynamics of the mistuned model of the tests bladed disc with double perodicity was experimentally investigated. The mistuning arised due to the implemantation of two bunches of blades with damping heads fixed on opposite ends of the diameter. The dry friction effect in the heads was treated. The scale for measurement of the electromagnetic force acting on the disc was designed. It enables to analyse the real electromagnetic excitation of the disc under rotation and evaluation of the FRF characteristics from measured blade responses under rotation. The identified eigenfrequencies and damping constan ts served as indicators for assessment of stiffening and damping effects of the friction couplings in the heads. and Obsahuje seznam literatury