How to model ship impacting pipe?
How to model ship impacting pipe?
(OP)
I would like your thoughts on how to model a ship impact on an over water pipeline. I want to determine the force and displacement required to rupture the pipe (i.e. the work). I was thinking of a non-linear analysis but am unsure of how to determine at what point a leak would begin. Any ideas?





RE: How to model ship impacting pipe?
Do you already have a particular FEA package that you are using?
Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group
RE: How to model ship impacting pipe?
RE: How to model ship impacting pipe?
As engineers, we tend to look in a book and say, "so that's the yield strength", but you may be dealing with high strain-rate effects (like a car crash for which LS-Dyna is generally the software of choice), temperature effects (depending on where your pipeline is physically located, salt water effects, welding in the pipeline...and I'm sure the materials guys would suggest another consideration or two.
I would also say that you may want to run a few small tests to insure that your analysis techniques are matching reality.
Garland
RE: How to model ship impacting pipe?
The conservative approach would be to model the ship hull as a rigid body that impacts the pipeline. Therefore the pipe absorbs all of the impact energy. The realistic approach is perhaps something less than that. You understand the event and assumptions better than I do so I'll leave that up to you. Stuff like this is really it's own seperate branch of FEA and requires a methodical approach.
Good luck!
-Brian
RE: How to model ship impacting pipe?
If you switch softwares but maintain an implicit solver, you may want to make sure it has some type of kinematic element that doesn't bother calculating stresses. Use these for the ship. You will also need one that transfers inertial loads.
RE: How to model ship impacting pipe?
My thinking was to apply a load to the pipe to displace it incrementally until it ruptures (not sure how I figure out where that point is). Then by plotting the force vs displacement and integrating to get the area I'll have the work done on the pipe which can be equated to the vessel KE.
This is not an exact study and clearly the pipe section in question will be replaced if a vessel ever contacted it. The context is a probability input for a risk analysis.