Abaqus warning, max ratio parameter

[Tinni1]

Hello,

I am conducting a post-buckling analysis of a Cold-formed steel column in Abaqus. The column is connected to a small length of track sections at the top and bottom with screws. the track is connected to the loading plates and base support with 4 nos M8 bolts at the top and bottom. I have modeled these bolts with solid elements and used solid elements to model part of the track sections around the bolt hole, based on guidance provided in the literature.


While running the analysis I got the below warning:


For a self-contact surface, the facets of the elements in the element set WarnElemFacetThickPt63d-Step1 are thicker than 0.6 times the edge or diagonal length of the facets. Use the MAX RATIO parameter on *SURFACE to allow automatic rescaling of the contact thicknesses where necessary for this surface. Refer to the status file for further details.

Could anyone tell me what is the procedure to use this MAX RATIO parameter on the *SURFACE in Abaqus?

The end boundary condition of my model looks like the below:

Many thanks!

 

[FEA way]

You are using contact pairs in Explicit, right ? You can add MAX RATIO to the *SURFACE keyword and specify a value or leave the default one (0.6). This way the contact thickness of selected facets might be adjusted automatically to meet the condition.

 

[Tinni1]

Many thanks for your response!

Yes, I am using contact pairs in Explicit.

I just added the MAX RATIO to the *surface keyword. I suppose it should be added only to the specific surface shown in the warning message, and not to all the surfaces ?

I am not much familiar with the keywords in Abaqus. That's why adding the image of the keyword part where I added the MAX RATIO.

Could you please confirm, if this is the correct way to do it? Many thanks!

Also, it would be great if direct me to any reference, where I could learn about the basics of using keywords in Abaqus.

 

[FEA way]

Try adding it to the surface based on elements referenced in the warning message first. Then check if the message still appears (you can run a datacheck to do this). I would advise switching to general contact unless there's a reason not to use it in your case.

The best source of information about keywords in Abaqus is the Keywords guide in the documentation. Once you get familiar with it and with the Abaqus keyword interface, it will become an essential part of your work.

 

[Tinni1]

Thank you so much!