Learning Forum

[2020221038]

When passing loads from aqwa to apdl, does the outer contour of the model need to remain exactly the same for both aqwa and apdl? Will a little deviation affect the load transfer? apdl is modelled with shell units and there is an offset problem, is it necessary to keep the shell in the same position as the faces in aqwa? Or is it sufficient to align the actual shape of the shell with the aqwa?

[Mike Pettit]

Hello,

Ideally the outer surfaces of the structural model will be identical to the surfaces in the hydrodynamic model. In particular, the hydrostatic balance may not be correct if the shell thickness would make a significant contribution to the total displaced volume of the structure. However, the load mapping can still be performed even if the models are not exactly identical.

Mike

[2020221038]

The load mapping can still be performed even if the models are not exactly identical. Is it possible to perform a static analysis in this case?

[Mike Pettit]

It will be possible to perform a static analysis. If you are using the Hydrodynamic Pressure add-on in Mechanical, this will issue warning messages if the mass properties are not consistent between the hydrodynamic and structural models, or if there is a significant distance between the surfaces in the two geometries.

Usually we recommend running the static structural analysis with Weak Springs option turned on, which allows you to check the force reaction (imbalance) between the wave loads and the inertial loads. The weak springs forces should be small compared to the self-weight of the structure that you are modelling. If you are satisfied that the force reactions are small enough, you can then turn on Inertia Relief so that the global displacement of the structure is zero.

Mike