abaqus pre-tension

[a126z]

In the Abaqus system shown in the figure, three analysis steps are set up: step1, step2, and step3. In the step1 static analysis step, a pretension is applied to the top of six anchor cables. In the step2 static analysis step, net buoyancy is applied while the pretension remains unchanged, and their effects cancel each other out. In step3, the analysis becomes a dynamic implicit analysis, with wave forces applied while maintaining the pretension and net buoyancy.

Question: Why does the displacement of the system become very large after the simulation ends? When only wave forces are applied, the system's displacement is about 0.6m. However, after applying pretension, net buoyancy, and wave forces, the system displacement reaches 4m. The problem is that when only the first two analysis steps are calculated, the system displacement is already close to 0.

 

[a126z]

When applying a pretension of, for example, 1e6 N to anchor cables in ABAQUS CAE, should one use 'bolt loads' or 'Defining an initial stress'? Or neither of these? The results mentioned above were obtained using the method of creating and editing bolt loads.

 

[FEA way]

It depends on how the cables are modeled. Probably the best way would be to model them with axial connector elements and just stretch them in the first step.