Learning Forum

[MMES]

Greetings for you all,

I have a few questions regarding my simple model of S lay pipeline laying.

• Why is my model so "bouncy" ? I tried using acceleration wih tabular data (you can see what I tried in the model) instead of standard earth gravity, but unsuccessfully

• Im not quite sure if I am using right contact approach with defined like that in the model. Should I try with bigger pinball radius ?

• I incorporated tensioner force, but I am not quite sure if I noticed anything different with that introduced in the model (different with the curvature of the pipeline)
• I want to plot a graph with water depth on Y axis and with horizontal distance on X axis so as to check the touch down point and difference with different set ups but I didn't found I way of doing so 
• Would it be better to introduce springs (on positions which i defined in the geometry, not in the model) on possible contact areas with the ground ? And which way would be the best of doing so ?

Link of my model:

https://we.tl/t-qLe9UgTKfJ

[peteroznewman]

From the title of the discussion, I expected to see a planar surface for the ground, not a line body.  Why use a line body?  Is the cross-section very wide to make it like a planar surface?  I don't understand. Please clarify what you are trying to simulate.

[MMES]

I am trying to simulate a simple S lay, and getting the bended S shape of the pipe due its own weight. I extruded a plate as a flat seabed and used a line body for the pipeline.

Cross section of the pipe is :

• outer diameter 1,42m
• inner diameter 1,1748m

 

[peteroznewman]

You might need to add the Stinger to help form the S bend.

 

[MMES]

Thats true and that is my next step, but currently I am trying to finish all the things in this phase.

I' m having problems plotting deformed shape (horizontal distance) along water depth (y axis), but not quite sure how to manage that.

 

[MMES]

For example, how to create a graph like this for my problem (using path geometry or something similar ?)

[peteroznewman]

Nodes have an Initial position with X,Y,Z coordinates that can be output from the mesh.

Deformation has X,Y,Z displacements relative to the Inital position that can be output.

The Final position in X,Y,Z coordinates of the node = Inital position + Deformation.

[MMES]

Could this simulation be done within 2D environment ? Are beam/pipe elements supported within 2D analysis ?

 

[peteroznewman]

Changing 3D solid elements to 2D plane elements results in a large reduction in node count which speeds up the solution.

Beam elements already have few nodes in the model so there is no great need to reduce the node count.

You can add a Displacement BC to all the nodes to set 3 of the DOF on each node to 0 to make it a planar problem. If the beam S-bend is in the X-Y plane, then the Z, RotX and RotY DOF can be set to 0 and the beam will bend only in the X-Y plane and the model will solve slightly faster because the number of unknowns was cut in half. The real benefit is the solution may be more stable because the pipe can't go sideways anymore, however, that may be less realisitic.