Vibration analysis of paper machine's asymmetric tube roll

Modelling and measurement of rotor's asymmetry in a paper machine's tube roll is discussed in this study. Due to manufacturing tolerances, the crosssection of the studied tube roll has non-uniform area properties along the length, which causes varying area moments of inertia, i. e. differences in principal moments of inertia. These, in turn, lead to the difference in bending stiffness of the rotor in two perpendicular directions. Measured manufacturing imperfections are incorporated into simulation model. The roll is modeled using Euler-Bernoulli finite beam elements by accounting the effect of deviatoric inertia and stiffness of the asymmetric rotor. The natural frequencies are calculated and mode shapes are observed. The results of the analysis are compared with the corresponding measured frequencies. The agreement between the simulation and experimental results of the studied system can be observed.