Elastic shear buckling load using eigen value

[ElakiyaT]

Dear All,
I am simulating Lipped channel beam in shear. I am using linear perturbation BUCKLE analysis (eigen value solver). when I give the load as displacement induced loading, I am getting the eigen values but when I give the load as forced induced loading, it is showing the error as stated below.

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,. SEE Eigenvalue Buckling Prediction IN THE Abaqus/Standard USERS MANUAL.

Please advice.
Thank you.

 

[FEA way]

How is the reference point connected with the beam ? Why are there 2 loads ?

Can you share the file ?

 

[ElakiyaT]

Hi,
Thank you for your reply.
I am modelling three point bending test of lipped channel beam. Beam will be loaded at the shear center.
I have attached the cae file. Please have a look.

https://files.engineering.com/getfi...42-bdf2-25e51606b423&file=15025AR1-3point.cae

Thank you.

 

[ElakiyaT]

when I give the load in z direction. it's not showing error. But I have to give the load in -y direction

https://files.engineering.com/getfi...2f-5b696c9ef724&file=15025AR1-3point-2020.cae

 

[FEA way]

There's a boundary condition fixing the displacement of that middle reference point in the Y direction, so the force applied there can't work.

 

[ElakiyaT]

Yeah. I got it. Now It's working. Thank you