Transversal vibration analysis of an axially moving string with unilateral constraints using the HHT method

In this paper, the transversal vibration characteristics of an axially moving string with unilateral constraints were examined using the Hilbert–Huang transform (HHT), due to its wide range of applications. Experiments were conducted on five test cases, and the subsequent analyses were discussed. The experimental results show that the introduction of a guide has the effect of causing low-frequency vibration suppression. The vibration behaviors of the guided segment and the free portion are highly sensitive to the initial tension, the initial clearance between the string and the guide, the transport speed and the guiding length. The details of the string vibrations revealed in this work will be used as a reference for engineering designs and relative system identifications.

► The vibration characteristics of a moving string with constraints are investigated.
► Using HHT, the features of each case are revealed in the time-frequency domain.
► With a long guide, the low frequency components are suppressed substantially.
► The features are sensitive to the guide length, tension, speed and the clearance.