Restart analysis error: unknown instance name

[mQmichelle]

Hi there,

I am trying to run a 3D model, it contains contact, so I decide to run the model with very small load and additional boundary condition in order for the contact to work first, then try to restart the analysis with the real load and deactivate the additional boundary condition.

I have successfully completed the first model with restart request at frequency=1, then I copied the first model and adding a new step to deactivate the BC and modify the load. When I try to run the restart analysis, it shows an error: Unknown instance name "column pin". Column pin is one of the part in the assembly.

I have no idea why this error coming up, I tried to run the restart analysis without any change, it shows the same error, and I tried to change the restart model to full analysis (with extra step for real load and deactivate BC), it shows no error message.

Did I miss any step for restart analysis???

 

[IceBreakerSours]

Wait a minute: Why do you even need a *Restart?

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[mQmichelle]

If I apply all the load in one step, it won't converge, even with very small increment, I thought it maybe because the contact isn't working at the first place, so I try to apply additional boundary condition for the contact to work first, I got the idea from the internet, is this right??

 

[IceBreakerSours]

I didn't think about this earlier but I see why *Restart would be recommended in contact. However, given the nature of your posts, I think you must establish whether contact really is the cause of your problems.

Now, if contact is the source of your troubles, then bringing the two bodies into contact with a displacement boundary condition (in the first step) is a good idea assuming the transient response is not much of a concern. But if you are interested in the transient response, then it is better to incorporate the appropriate physics which will bypass such issues.

"Abaqus/Standard 2D example: forming a channel" in the Getting Started with Abaqus: Interactive Edition and "Contact Difficulties and Diagnostics" in the Abaqus Analysis User's Guide (version 6.14) are excellent resources. Version 6.14, in particular, has another excellent example that talks about various contact energies in depth: Energy computations in a contact analysis.

Documentation is available online, if you do not have it.

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[mQmichelle]

I will read the example first, thanks for your information and help.

 

[IceBreakerSours]

I should also suggest user forums on LinkedIn and Yahoo Groups are very active as well.

But, your best friend will always be the documentation - which, arguably, happens to be the best in the world of FEA. So take a ton of time, if that's what it takes, to read it patiently/carefully/ and sometimes over and over again; it is one good habit to have.

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