The load case has been supplied by Quintas and Quintas Offshore.

IDAC’s FEA also met the standards DNV-RP-203 for Fatigue Design of Offshore Steel Structures – August 2005, as required by classification society DNV.

The analysis was conducted in two phases, the first phase the non-linear finite element analysis of the model was done.

IDAC said for the structural analysis the entire rope spool assembly consisted of a spool, a pin and a rope and was modelled in ANSYS Workbench.

The company said that a three-dimensional, nonlinear structural analysis has been employed due to the large deformation of the polyester rope and the frictional contact between the spool rope and spool pin.

FEA intended to probe the structural response of the assembly under the minimum breaking load (MBL) of the rope which will identify the most critical locations, stresses and strains in the spool for the structural and fatigue assessments.

The study found that high stresses beyond yield in the spool were found in the contact area and stresses in other areas remained below the ultimate tensile strength of steel even with the assumed elastic material properties.

IDAC said the design was not likely to fail catastrophically at MBL.

In the second phase, fatigue assessment of the model for a ten year design life, has been studied.

Quintas and Quintas Offshore provided the fatigue load data for the fatigue calculations in accordance with DNV-RP-203.

The spool passed the fatigue assessment as required by Quintas and Quintas Offshore.