Dynamics of a Portable Module Handling System

The paper describes a model of a light module handling system (LMHS) developed for IMR (Inspection, Maintenance and Repair) services typically performed for the seabed-located oil and gas production facilities. In order to describe dynamic performance and loads during the operation, the system is characterized by means of a multi-body model consisting both rigid and flexible links. Using the joint coordinates and homogeneous transformations the dynamics can be described by a set of differential equations of the second order and some constraint equations. The system forms several tree-like structures of bodies. The interaction between them takes place on guiding elements and lifting ropes. An important features of the handling system are flexible guide beams and prongs. The flexibility provided by those elements helps to limit some impact loads during the module docking phase. This functionality is modelled by the rigid finite elements. Lifted objects (subsea modules) are described by a set of special elements defining the hydrodynamic interaction. The work will also show some simulation results reflecting a typical operation.