Launching of Jacket structure (ANSYS AQWA)

Hi guys, i am doing a launching of jacket structure using ANSYS AQWA. I ahve faced problem that my jacket and barge passing through each other even though i have insert fenders in deck 14. Anyone can help me please? Thanks in advance and Happy New Year 2016!

 

IDK anything about AQWA and the documentation is available to customers only.

Did you make sure you input the proper initial position of the jacket relative to the deck of the barge? This is something which should be easy to check.

It's not clear if the attached plot is supposed to show the jacket while it's being transported or after the ballasting of the barge has begun in order to launch the jacket.

 

Hi NavalSArtichoke, thanks for your reply. FYI, the initial position has been automatically calculated by ANSYS AQWA, but it still can be re-positioned manually. Do you have any idea how to calculate the proper initial position?

FYI, the case i posted is in even keel condition which is one of my objectives. I will be doing the launching in different angles as well.

 

I'm afraid I'm not familiar with AQWA at all.

When you say the jacket's 'initial position has been automatically calculated by ANSYS AQWA', subject to what final conditions or constraints?

Obviously, there is something not right about this calculation if AQWA puts the jacket thru the middle of the barge, and it's not because there are or are not launch ways described in your model.

Can you manually position the jacket on the barge so that you don't drag the legs thru the deck?

It seems to me, you would place the jacket on the barge, check the draft and trim without ballast, and then add ballast to put the combination into a reasonable transport condition with no trim, if desired. Some programs will allow you to specify the final draft and trim and which tanks to use for ballast, and then the program develops a ballast plan to achieve that desired condition.

 

seems like you have not applied a "contact" to each surface to instruct the elements not to pass through each other.

 

Sorry for confusing you. The photo above shows the condition after I run the simulation.

Below is the condition before the launching of jacket in even keel (without trimming).

Unfortunately after I launch the jacket, it result was that they passing through each other.

Thank you.

 

Hi, thanks for your comment. I have already input the fender option in AQWA to allow both structures contact to each other. But I have no idea why it turns out passing through each other.

Is there any option else besides fender?

Thank you.

 

Is this program even meant for jacket launch? Isn't MOSES more appropriate for this problem?

 

Hi, thanks for asking. Yes, this program can also do launching of jacket and i already succeed in the launching.

Thank you.

 

I'm not sure that the launching of the jacket can be carried out by the simple procedure of sinking the platform. I guess it should also undergo a controlled rotation.
You should also limit the degrees of freedom of the jacket in its movement relative to the platform.

 

I doubt you are going to get a meaningful result using this approach. You need to take into account many other factors including the winch speed to initiate the launch, friction of the jacket on the barge runners, pivoting of the jacket over the rocker arm at the aft end of the barge, etc. You will also want to be checking jacket/barge clearance, bottom clearance after launch as well as barge and jacket strength as it rotates over the rocker. You may well be able to get there using AQWA if you take all theses factors into account in your model but as noted above, MOSES is the software usually used for this. For a thorough description of jacket launch see
http://www.ultramarine.com/hdesk/runs/samples/install/launch.htm

 

Hello, i know this post is a bit old but im currently doing my research using AQWA also for jacket launch. Can i know how you perform the simulation in aqwa? Are you using hydrodynamics response to simulate the lauch? Thanks