## General Mechanical

#### I would like to ask which of you has done research on buckling restraint of submarine pipelines？

• sr1993
Subscriber

I would like to ask which one of you has done research on buckling control of submarine pipelines, for example, using sleepers to control buckling. I have built a model, but it cannot reach the experimental buckling amplitude, which is puzzling to me.

The pipe is 6 meters long and rests on sleepers

• HuiLiu
Ansys Employee
How does the result look like, buckling mode, critical load etc? Also what's the BC and loading definition? The sleeper seems to be extremely narrow, so how is the mesh on these pieces?n
• sr1993
Subscriber
First of all, thank you for answering my questions, thank you for your patience, and I will introduce some of my models.The following figure is the model data of the experimentnThe following is my ansys model diagram，There is a sleeper with a height of 2mm in the middle, and the seabed plane is a rigid plane. Units 170 and 177 are used when the pipeline contacts the seabed, and units 170 and 176 are used when the submarine pipe contacts the sleeper. The initial bending degree caused by the sleeper in the middle of the pipeline is simulated by a formula.nThe following is my comparison chartnI don't understand why the uplift degree of my model pipe is lower than the experimental value. I am puzzled, but there is nothing I can do.n
• sr1993
Subscriber

How does the result look like, buckling mode, critical load etc? Also what's the BC and loading definition? The "sleeper" seems to be extremely narrow, so how is the mesh on these pieces?https://forum.ansys.com/discussion/comment/96869#Comment_96869

First of all, thank you for answering my questions, thank you for your patience, and I will introduce some of my models.The following figure is the model data of the experimentnnThe following is my ansys model diagram，There is a sleeper with a height of 2mm in the middle, and the seabed plane is a rigid plane. Units 170 and 177 are used when the pipeline contacts the seabed, and units 170 and 176 are used when the submarine pipe contacts the sleeper. The initial bending degree caused by the sleeper in the middle of the pipeline is simulated by a formula.nnThe following is my comparison chartnnI don't understand why the uplift degree of my model pipe is lower than the experimental value. I am puzzled, but there is nothing I can do.n
• HuiLiu
Ansys Employee
To clarify, you are doing a nonlinear static analysis, not eigenvalue buckling, right? From the graph you shared, looks like both buckling load and post buckling behavior are not the same as your test result. In general if you need to compare FEA results with experimental data, make sure the setup in FEA model realistically reflect the physical test. For example, material properties, boundary conditions (say if you have some fixed support, is it rigidly fixed in your experiments as well?), etc.umerically, you might want to check to see if you have stabilization energy activated, and if it is too high. The regular Newton-Raphson method will need stabilization to be able to converge a solution upon buckling and post buckling. n
• sr1993
Subscriber

To clarify, you are doing a nonlinear static analysis, not eigenvalue buckling, right? From the graph you shared, looks like both buckling load and post buckling behavior are not the same as your test result. In general if you need to compare FEA results with experimental data, make sure the setup in FEA model realistically reflect the physical test. For example, material properties, boundary conditions (say if you have some fixed support, is it rigidly fixed in your experiments as well?), etc. Numerically, you might want to check to see if you have stabilization energy activated, and if it is too high. The regular Newton-Raphson method will need stabilization to be able to converge a solution upon buckling and post buckling.https://forum.ansys.com/discussion/comment/97671#Comment_97671

Hello, teacher, if you can, I hope I can add some of your WeChat, I will ask you at a fixed time, I will pay a reward, I hope you can agree, my WeChat is songrixuan.n