Time increment required is less than the minimum required

[spintwo]

Hello All,

I have a recurring error that is prohibiting any analysis on an punch indentation test (aximsymmetric).

I tried using an adaptive mesh and for some reason abaqus is removing it upon submitting it to the program. Can someone help me with this? I'm out of ideas (i've been poring through the message files...)

Any clues on BreastDimd?

Thanks in advance!

 

[spintwo]

There is a particularly peculiar part of the analysis -- upon aborting, I look at the partial attempted solution and if I zoom very closely into the beveled corner of the indenter and the substrate immediately underneath it, I see the substrate actually going through the rigid body...

I believe this may be related but I'm not sure in what way...

Thanks in advance

 

[GregLocock]

I think you need to read up on penetration algorisms

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[spintwo]

Any good recommendations?

 

[GregLocock]

The documentation for your program will probably give the equation they have used, and some guidance on how to tune the various constants.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[spintwo]

I think I have identified the problem to be a local instability due to too much deformation.

When I limit my displacement boundary condition (what I'm using as the defining act for my rigid body punch-indentation test), the model runs with no problem. When I try a displacement of about 2% of the total height of the specimen, but when I try to get to 5% or 10%, I get "too many increment" and "the increment needed was smaller than the minimum allowed" errors that make the analysis abort. I believe that there may be softening or rupture occurring near the edges of the indenter?

I was wondering how can I get these larger deformations to continue? Can I specify manually just a larger yield stress for this substrate [deformed] material? Should I attempt a Riks method static analysis? If I make the material ultimately stronger, shouldn't these errors disappear?

 

[TomaszK]

Do you try to change minimum increment size in job defining? Sometimes 1e-5 is to low. For steel properties sometimes 1e-7, 1e-8 is proper, especially with contacts.