When I use links I can see the line almost converges and then fails at one pirticulat node! I am trying to make small changes in order to converge. The third picture was only an expample of what happens when I dont use any links to hold (cable and winch goes through vessel). Regarding vessel object seems to have stiffness, I imported hydrodynamic data from an existing model. I had read this guide a while ago, will try the tips mentioned on this again. Thanks for the reply and the attachement. If your aim is just to determine the layback and touchdown tension, then you may even try the simple option of modeling EndA of the cable as "fixed." This eliminates the need for the winch too as the required tension can be adjusted by increasing/decreasing the length of the catenary. Plus, if your cable gets too noisy during the static run, you may then apply a small damping value to keep the cable robust.Īs you might be aware of, there are still many more ways in which a cable lay analysis could be modeled in OrcaFlex. If the stiffness of the chute is set too high (say 100000 kN) and if your link has just 100 kN, then it is no way going to help in lifting the cable (through the chute) in line to the predefined spline. This is one method.Ĭoming to your method, while using temporary links, it is worth checking the stiffness defined for the links and the chute. In this approach, the links won't be necessary. EndA) toward the vessel and the cable will "fall" on top of the chute rather than coming from the bottom.
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Now, when you run the static analysis, the winch will pull the free end (i.e. the cable end you have on the vessel deck) a few meters away from the chute, say 2m aft and 5m above the chute surface. I am new to this website and this is going to be my first post in a thread!ĭuring the modeling stage, you may try setting the EndA coordinates of the cable (i.e. I am not sure if you are still up with this analysis. So was wondering if someone knew some tips or tricks around this. So I was wondering if there was an easier way to just tell my line to follow a specified path or close to that specified path.īut it works some times and other times it just finds coordinates on the under side of my chute or just through the vessel. So if I want to get results for 10 conditions it will take quite a long time.
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If I vary the tension in the winch, I have to change the values of the Links as well, which is trial and error method and its quite laborious. My cable is fixed to a winch (all on my vessel). But at the end to keep my cable(line in orcaflex) above the chute, they just used temporary links to hold it over the chute and at the end of the simulation I have to make sure the links have 0 tension in them.
I did get in touch with the support and they gave me quite a good explanation about my problem.
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I have also tried all possible methods and tips from the user manual as well.Īnd your right, it needs a lots of careful setup :/
If anyone could help me please do let me know. I have tried using links to hold the cable above the chute but it ends up falling through the vessel or under the chute.
The cable starts to find nodes within the vessel and under the chute and other places. When i start varying the tension all the problems start. What happens is initial condition my model converges and the cable find the nodes perfectly over the chute. Hence the winch either pulls in cable or pays out according to tension. I want to vary the tension in the winch and check the corresponding tensions and touchdown. I connect one end of the cable to a winch and the other anchored with enough slack in it. Now first I set my cable to follow a spline and over the chute which is on my aft deck. I am a fairly new user to Orcaflex but I have a good understanding of FEM.īasically I am trying to model a subsea cable and find the tension and other values of the cable.
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I would be glad for some help regarding the software Orcaflex.
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