Parametric study of offshore structures with magneto-rheological tuned liquid column damper

The master thesis work involved the implementation of Magneto-rheological tuned liquid damper for the mitigation of undesired vibration caused in offshore structures. The research begins with the study of passive tuned liquid column damper with uniform and non-uniform cross-section, coupled with an offshore structure under random wave force. The results show that increasing the density of the liquid used in the TLCD system gives better results, which provides an opportunity to use fluids with varying density and possibility to modify the conventional passive system into a semi-active damping system. Therefore, the normal fluid is switched with a magnetic fluid which has the ability to change its yield strength under an applied magnetic field. There are two different approaches used in the study to formulate the mathematical model of the semi-active MR-TLCD. The first approach is based on using the magnetic force as an additional stiffness while the second approach is based on using the yield strength of the liquid as an additional damping force in the system. As a result, the efficiency of the semi-active MR-TLCD system was found to be better than the conventional passive TLCD system.