1、 Defining contact pairs in ABAQUS/Standard
After the selection of contact pair surfaces, three key factors must be determined when creating a contact formulation:
⑴ the contact discretization;
⑵ the tracking approach; and
⑶ the assignment of ―master‖ and ―slave‖ roles to the respective surfaces.
1.1the contact discretization
ABAQUS/Standard offers two contact discretization options: a traditional ―node -to-surface‖ discretization and a true ―surface -to-surface‖ discretization.
1.1.1 Node-to-surface contact discretization
Traditional node-to-surface discretization has the following characteristics:
⑴ The slave nodes are constrained not to penetrate into the master surface; however, the nodes of the master surface can, in principle, penetrate into the slave surface
⑵ The contact direction is based on the normal of the master surface.
⑶ The only information needed for the slave surface is the location and surface area
associated with each node; The direction of the slave surface normal and slave surface curvature are not relevant.Thus, the slave surface can be defined as a group of nodes— a node-based surface. ⑷ Node-to-surface discretization is available even if a node-based surface is not used in the
contact pair definition
Fig.1 Node-to-surface contact discretization
1.1.2 Surface-to-surface contact discretization
To stress accuracy, surface-to-surface discretization considers the shape of both the slave and master surfaces in the region of contact constraints.
Surface-to-surface discretization has the following key characteristics:
⑴ Contact conditions are enforced in an average sense over the slave surface, rather than at discrete points (such as at slave nodes, as in the case of node-to-surface discretization). Therefore, some penetration may be observed at individual nodes; however, large, undetected penetrations of master nodes into the slave surface do not occur with this discretization.
⑵ Surface-to-surface discretization is not applicable if a node-based surface is used in the contact pair definition.