Watercraft impacting on Water 2

[sharyadi]

Has anybody done analysis on watercraft impacting on water? Assuming a 30 foot boat dropped on water from a height of 15 feet. I don't know where to start - LSDYNA? ABAQUS-EXPLICIT? something else? Advise.

SH

 

[GBor]

If you have Abaqus-Explicit or LS-DYNA, then go for it. If you don't, there are several packages that cost a good bit less that do a very good job of this type of analysis. I'm assuming you don't really care about the water, but are concerned about the boat. There is a product emerging on the market that is fairly inexpensive compared to these, but does offer an explicit solver. Check out AMPS (Advanced Multi-Physics Simulation) at

http://www.ampstech.com.

You can also look at Algor and NEiNastran for implicit solvers.

Find something that will model the water, but not necessarily calculate its stress. I know Algor has "kinematic elements" as well as, I think, "hydrodynamic elements". The kinematic elements aren't included in the stress calculation (speeds up the analysis).

Total cost of the AMPS package even with the explicit solver is amazingly reasonable for the power. Pre-processing a boat hull may be a little difficult, but I'm not a super-user...still learning.

There are several hydrodynamic codes out there, but I'm not sure any of them would handle this. They are usually designed for planing craft "cutting through" waves...

 

[sharyadi]

Thanks GBor. Between LSDYNA and ABAQUS-Explicit which do you recommend. We have both these software, but not sure about the modeling of the water in these two software. I haven't done this before. Someone told me that ABAQUS-Explicit is not reliable for extended time period. Is this true?

I couldnt understand why did you suggest Algor and NEiNastran (implicit analysis) for this time dependent crash?

 

[GBor]

Algor and NEiNastran both have a level of event simulation that is probably sufficient for your needs and they cost less than LS-DYNA or Abaqus Explicit, but since you have LS-DYNA and Abaqus already, I would lean toward LS-DYNA. I don't have experience with either of these, so my opinion is based purely on what I've heard. DYNA seems to be the definitive standard in car crash simulations...I can't see why a "boat crash" would be much different.

As for the water, you could model it as a semi-rigid barrier, or series of semi-rigid barriers, on springs, so that when the boat hits them, the springs dampen the impact. Model these barriers with a relatively small width so that the boat keel would impact the middle barrier which would begin to deflect before the boat impacts the two adjacent barriers and so on...

 

[amorrison]

See thread404-96282

 

[amorrison]

See also thread2-70271