Experimental verification of a dynamic model of a tube roll in terms of subcritical superharmonic vibrations

The non-idealities in a rotor-bearing system may cause undesirable subcritical superharmonic resonances that occur when the rotating speed of the rotor is a fraction of the natural frequency of the system. These resonances arise partly from the non-idealities of the rotor and partly from the non-idealities of the bearings. The superharmonic vibrations of complex rotor-bearing systems can be studied accurately by combining a detailed rotor and bearing model with a multibody simulation approach. The complex rotor-bearing system under investigation is a tube roll of a paper machine supported by a hard-bearing-type balancing machine. Resonances affect the quality of end product and therefore have to be studied in detail. Non-idealities of the rotor-bearing system are measured from the existing structure and the parameters of the real structure are emulated as accurately as possible in the simulation model. The simulation model is verified using the results from experimental modal analysis and the measurement results for the subcritical superharmonic response of the roll. The analogy between the simulation and experimental results of the studied system is substantial.