Contact types 1

[mdama]

Could anyone bring physical examples of when to use different types pf contacts like bonded, frictionless, frictional, no separation?
And in bonded contact, when we talk about linear analysis, how does that exactly mean?

 

[NRP99]

-Bonded contact is used when you have no relative sliding or gap separation between two bodies/their contacting surface. In Abaqus, it is usually achieved by tie constraint.
-Frictionless contact is used when you have sliding which is frictionless like very smooth/machined surface sliding on each other. E.g. the friction in ball bearings is lot lesser than normal steel on steel (μ=0.15 to 0.3). We can consider the ball bearings as frictionless(μ=0.001 to 0.003)
-The everyday problems are frictional problems since even though there is lubrication or very high surface finish/polished surface, there will still small amount of sliding friction is present. Steel on steel is one example where frictional contact is used.
-No separation is nothing but there is no separation (normal to contacting surface or normal gap between the surface will always maintained zero) but there is sliding between bodies which can be frictionless.

The bonded contact means the two bodies are integral (no relative sliding and normal gap=0 between contacting surface never changes. Whatever force are applied to body 1 will be transmitted to body 2) hence it can be considered that the two bodies becomes one body and your nonlinearity due to contact is removed. This is nothing but linear analysis.

 

[FEA way]

This is actually nomenclature used by Ansys. Abaqus has a very different approach to contact types. The behavior is considered separately in the normal and tangential directions. You can replicate the contact types known from Ansys in Abaqus but also do much more than that. If you are looking for a direct equivalent of bonded contact, check tied contact in Abaqus. Tie constraint allows you to achieve pretty much the same goal but is somewhat different since it doesn’t impose contact constraints.

By default separation in contact is allowed but you can check the No separation box to prevent it.

By default contact is frictionless but you can define the Coulomb friction model in various ways (optional dependency on slip rate and so on). You can also choose rough friction which is basically no sliding contact known from some other FEA software.

All in all, contact has a lot of options and possibilities in Abaqus. Currently, general contact is what specifically distinguishes Abaqus in terms of contact modeling, no other software has such a complex algorithm of contact detection.