Semi-active control of tensioner for submerged vertical long cylindrical structure

Long cylindrical structure (LCS) experiences vibrations induced by both cross-flows and structural instability. As the technology of LCS facing more structural safety challenges in deep-water conditions, an appropriate control mechanism to enhance the structural integrity, such as reduce the relative motion in between the LCS and the host platform is now high in demand. This paper studies the mathematical model of structural integration for magneto-rheological (MR) damper with an LCS system. Later, curve fitting method is utilized to determine the characteristic coefficients of MR damper to be used in the equation based on a pseudo-experimental data. Then, the structural integration is regarding as a two degree-of-freedom (2-DOF) system and the efficiency of different control schemes on the tensioner stroke is evaluated. The results indicate that the semi-active control mechanism provides improved performances compared with the passive control and can reduce the complexity and avoid the spillover phenomena inherent form the active control. The anticipated impacts are lead to an advancement of understanding in the controlled dynamics of LCS and extension the applicability of LCS to wider operational limits.