The bonded contact is a special type of contact which allows no relative dispacement between two connected solid bodies. This type of contact constraint is used to glue together different solids of an assembly. The two surfaces that are in contact are classified as master and slave. Every node in the slave surface(slave nodes) is tied to a node in the master surface(master node) by a constraint.
For implementing a bonded contact,click on the Contacts and then Add Contact Constraint condition to create a new contact constraint. Select type to Bonded Contact. You can now assign the faces or sets that should be tied together via the assignment boxes. For numerical purposes you have to choose one of these selections as master and the other one as slave. During the calculation, the degrees of freedom of slave nodes are constrained to the master surface.
When running contact analyses, you can define position tolerance manually or set it to Off. When tolerance is set to Off, all the slave nodes will be tied to the master surface whatsoever. Therefore, if the larger surface is used as a master surface, one master node will be tied to multiple slave nodes leading to artificial stiffness in the slave surface.
You should be very careful while assigning a surface as slave or master. If a larger surface is chosen as slave (or surface with higher mesh density),the computation time will increase significantly and it might also result in wrong solution, especially when no specific tolerance criteria is provided.