Multi-Step Analysis

[Ariyan1]

Dear Colleague,

I have a silly question. I would like to do multi-step analysis for a monopile of offshore wind turbine . The first step is static analysis where I need to obtain the stresses and displacements. Next I want to couple the buckling analysis to the first step. I have define the second step however when I run the simulation I get the following error message:

DIFFERENTIAL STIFFNESS MATRIX IS COMPLETELY NULL. THE EIGENPROBLEM CANNOT BE SOLVED. IN A *BUCKLE ANALYSIS THE MOST LIKELY CAUSE IS THAT A NONZERO LOADING PATTERN WAS NOT SPECIFIED VIA *BOUNDARY, *CLOAD, *DLOAD, ETC

I have tried to use the restart attributes but I could not make it work.

Any help would be greatly appreciated.

Regards,

Ariyan

 

[Mustaine3]

And have you applied a load in the buckling step?

 

[Ariyan1]

Hi Mustaine3,

Thanks for your reply.

Yes I have applied the load for the buckling step. The only way to make the simulation work was replacing the first step by linear perturbation-buckle otherwise it does not let me to have the two step in conjunction with each other.

Thanks for your help in advance.

Regards,

Ariyan