Hello,
I'm studying a long, flexible structure, in stillwater.
From my understanding, moses computes bending moment assuming a rigid body (i.e. not accounting the body immersion variations influence on bending moment).
Here attached a sample case demonstrating a simplified configuration: I tried to compare the moses bending moment results (that match exactly an independent result, not considering the flexibility).
moment_flexible.zip
If I consider the flexibility, as expected, the bending moment distributions reduces significantly (green line). Is there a way to consider this effect also in MOSES?
Thanks in advance,
Doug
Hi Doug,
The calculations done in the hydrostatics menu are classic naval architecture. The equations can be found in the standard textbook used for introduction to naval architecture class at university.
Your description sounds like a finite element, or a segmented sections that act independently.
You can try making the sections smaller. That is putting more stations in your vessel.
Or making each section a body and making the connectors have the flexibility. This one seems very complicated.
I am unclear of what the analysis aim is. Those are my suggestions.
Georgina Maldonado
Hello Georgina
The aim of the analysis is studying a long and flexible wave convertor, from the hydrostatics to the hydrodynamics (or better hydroelasticity), in terms of deformations and stresses.
The MOSES results are exact at stations (as shown above), it is not a problem of number of stations. The limit is the assumption of rigid body (as in classic naval architecture).
Could you please point me out cases in which the finite-element solution is performed (considering the flexibility of the equivalent vessel beam)? Is it simple to modify the test case I provided in order to obtain a finite-element solution?
I was also thinking about using connectors but it seems too combersome.
We know that other software (i.e. WAMIT) do perform hydroelasticity. I was interested in knowing if MOSES is able do deal with this kind of problems.
Thanks for all the suggestions
Can you contact me at georgina.maldonado@bentley.com
I looked at your files and I have tried to reproduce your work using rod elements. I would like to know more about what is the lightship at mid span and what is holding the ends in position.
I hope we can continue the conversation there.
Georgina