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Nonlinear analysis of mooring chain over fairlead

Question asked by Emil A. Edwin on May 6, 2020
Latest reply on Jul 12, 2020 by Emil A. Edwin

I'm currently writing my Msc thesis on fatigue damage in mooring chains.
As a part of the thesis I have to find the hotspot stress in a chain laying over the stern of a anchor handling vessel. (See case2.JPG and chainONfairlead_1.JPG). Alpha and phi is to be the same angle for the picture below.

 Screenshot of chain and vessel stern in SWDesired simulation of chain over vessel stern

I also need to simulate a straight chain under the same tension, to compare stress distributions.

The simulations need to be non-linear, as we expect to see stresses above yield and parts moving (in the chain over stern simulation). The material model uses "Plasticity - von Mises", but for some reason does not start with this when you open solidworks. Material data can be found in Chain.pdf, where dimension is 76mm and steel grade R4.

 

As of now, I have only managed to run a simulation of a straight chain with 3 links and the results here look good. When I've tried to add more links, the simulations have collapsed (error2.jpg).

 

 

 

I am now running a simulation on 4 links with surface to surface connection and a finer mesh. Test is currently running on day 3

 

Underneath is a link to the three different simulation scenarios:

https://drive.google.com/open?id=1UH2qta-K9O621__z5weCVLDTmVItsyv_

 

The one called "StrernTrial.zip" is the simulation most pressing to get results from and my guess, the hardest one to define.

 

I have now been running simulations for a month without getting any results and was hoping you guys might be able to help me out.

This is my last attempt at getting help, before switching to software, which is not preferable as as I will have to learn it from scratch.

 

I really hope someone can help. I will check the forums regularly. I am available on email at almost all times: emilae@stud.ntnu.no.
Meetings over Microsoft Teams is also an opportunity.

Please do not hesitate to contact me if anything is unclear!

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Best regards,
Emil August Edwin

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