Overall vibration-reduction technology of FPSO topsides based on elastic connection

Objectives In order to decrease the vibration response of topside modules and reduce the transmission of vibration energy from topsides to hull, as well as improving the connection between topsides and hull, this paper proposes an overall vibration-reduction technology is with the topsides connecting elastically to the hull of a floating production storage and offloading (FPSO) unit.

Methods In this vibration-reduction technology, elastomeric bearing pads are utilized to connect the topsides to the hull, and the design loads and inner structure of the pads are determined by predicting the maximum values of the FPSO's acceleration response. The force and corresponding deformation of a specific elastomeric bearing pad are analyzed by the finite element method, and the equivalent stiffness of this pad is obtained as the slope of linear fitting. The vibration response of the topsides and power transmission characteristics of the elastomeric supporting system are then analyzed via numerical simulation and theoretical analysis respectively, with the elastomeric bearing pads replaced with linear springs correspondingly.

Results The vibration responses of the topsides are effectively reduced, with the vibration reduction ratio as high as 30%, while the vibration isolation of the hull can also be effective with the appropriate selection of frequency ratio.

Conclusions This study can provide valuable references for the design and application of the overall vibration reduction of topsides on offshore structures.