Reply To: how to create fender between two structures in hydrodynamic diffraction

[Mike Pettit]

Hello,

Just to clarify, are you only running a Hydrodynamic Diffraction analysis? Or are you also going to run a time domain Hydrodynamic Response analysis?

If you are performing Hydrodynamic Diffraction only, the results will provide you with the linear motion response (RAOs) of the spar/torus, which cannot consider the end stops. You can model the PTO stiffness using Connection Stiffness matrices, and you can apply additional damping to the torus. You can set very large values for the RX, RY, RZ stiffnesses to constrain the torus motion with respect to the spar. Any fenders you have defined under Connections will not be considered in the Hydrodynamic Diffraction analysis.

If you are performing a time domain Hydrodynamic Response analysis, you should create fenders at the end stop locations, with the fender stiffness set to the 'Stiffness upper/lower end stop spring' values. The fender sizes and positions should be defined so that there is a 6 m gap between the (uncompressed) fenders. For example, if the fender size is set as 1 m, the fender connection points should be located at +/- 4 m, so that there are 6 metres between the uncompressed fenders.

Mike