When do ABAQUS recognize contacts ?

[ymn]

Hello,

Let us say I have a model of a ball and a square plate. I throw the ball towards the plate and let us say there is 10 mm gap between them. When will ABAQUS recognize the contact between them, is there a specific number like for example: when their distance become 1 mm or something ? Also, what should be the motivation of dividing this case into 2 steps, first one for closing gap and recognition of contact, second for impact. Does it make the analyse more accurate or easy to converge or something else ?

Thanks

 

[FEA way]

Abaqus uses so called penetration function (h - distance between surfaces, negative when they are separated). For h < 0 no constraint is applied since there's no contact. For h=0 constraint is enforced and contact pressure is applied.

Such approach (separate step to establish contact) is often used but pretty much only in static analyses where initial gaps are undesirable and the analyst wants to make sure that all parts in the model are properly connected. It's not necessary to do it in impact analyses.

 

[ymn]

Got it, thank you @FEA way

 

[IceBreakerSours]

Firstly, read the documentation. RTFM was the best advice I got when I first started.
Secondly, Abaqus does NOT know/care about units. That is, the logic it uses internally, is based on dimensionless quantities.
Third, I do not think if you are ready to jump into the deep end of the pool, but I personally like Vladislav Yastrebov's notes on contact a lot so try this link.

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