Mike Pettit
Ansys Employee

Thanks, I see what you mean.

You can do this in Aqwa Workbench using a stability analysis Hydrodynamic Response system, and the parameter study capability of Workbench. On the Workbench Project Schematic, if you do not already have one, connect a Hydrodynamic Response (HR) system to the Hydrodynamic Diffraction (HD) system, with the HD Solution cell linked to the HR Setup cell.

In the Aqwa Workbench editor, check in the HR Analysis Settings that the Computation Type is set as Stability Analysis (this is the default for the first HR system connected to HD). Right-click on the analysis and Insert > Starting Position.

In the Starting Position object, set the 'Structure' field as appropriate and select the 'Reference Point' as the Connection Point of the mooring line on the structure. Change the 'Definition' from 'Absolute Position' to 'Relative to Geometric Position'. Click the small box next to 'Relative Position X' so that a 'P' shows in the box - this defines the field as an input parameter. (It may make sense to set a different field as your input, depending on the model.)

On the HR Solution, right-click and Insert > Connections > Cable Forces > Whole Cable Forces. In the graph input (named as 'Cable Forces, Whole Cable Forces') select the 'Structure' and 'Connection' as appropriate, and set the 'Component' to 'Tension'.

In the parent graph object (named as 'Parameters vs Iteration Step') click the small box next to 'Initial Value' so that a 'P' shows in the box - this defines the field as an output parameter.

Go back to the Workbench Project Schematic page, and you will see a Parameter Set which links into the Parameters cell of the HR system.

Double-click on this to open the Parameter Set tab. In the Table of Design Points (top-right panel), you can define a series of displacement offsets for the structure position. Once these are defined, click 'Update All Design Points' (top-left). Do not try to interact with Workbench or the Aqwa Workbench editor until the parameter study has finished - the Aqwa editor will open and close itself several times.

Once the design points are updated, the Table of Design Points should show the tensions corresponding to each offset:

You can copy and paste this data for plotting in another program, or you can use the chart function in Workbench: in the Outline of All Parameters table (top-left panel), click Charts. In the Toolbox panel (left-hand side) double-click on Parameters Chart. In the Properties table (bottom-left panel) select the input parameter as the X-Axis, and the output parameter as the Y-Axis. The chart should appear in the bottom-right panel:

I hope this helps - please let me know if you have any other questions.