Physical mechanism of ice induced self-excited vibration

摘要

Steady state vibrations of vertical offshore structures induced by crushing failure of level ice were observed on several jacket platforms in Bohai Sea, China. Further analysis of the field data indicates that dynamic ice force is controlled by the structure's motion, in other words, the steady state vibration is self-excited. Yue et al (2009) proposed the physical mechanism of ice induced self-excited vibration based on the mechanical behavior of ice under uniaxial compression in the ductile-brittle transition region. As a matter of fact, the key feature of ice induced self-excited vibration is the loose simultaneousness between the unloading of the ice force and the swing back of the structure. A physical mechanism is presented in this paper to explain this simultaneousness between the unloading of the ice force and the swing back of the structure based on the work of Yue et al (2009).