Connection Contact
Connection Contact
Mesh independent spotweld beams/solids and adhesive solids (connections in PRIMER) are tied to their respective panel shells using tied contacts in Ansys LS-DYNA. For solids the preferred contact is *CONTACT_TIED_NODES_TO_SURFACE, for beams it is *CONTACT_SPOTWELD. These constrained contacts give the correct shear stiffness for a weld connection. Penalty (_OFFSET) contacts will generally not give adequate stiffness - vehicle models can show 10% underestimate of torsional stiffness when penalty contact is used for all spotwelds.
Modelling constrained contacts: Constrained contacts require rigorously correct modelling as they are incompatible with other forms of constraint and may interfer with one another. For example, if a *CONSTRAINED_NODAL_RIGID_BODY attaches to a node of a shell to which a spotweld beam is attached by *CONTACT_SPOTWELD, the spotweld will be released. Similarly, if a piece of foam is tied to a panel by a constrained tied contact, spotwelds cannot be attached to the same shells by a *CONTACT_SPOTWELD. The best solution to this problem is to transfer the nodes which will not tie out of the constrained contact to an _OFFSET contact.
PRIMER's function has been designed to create spotweld/adhesive contact(s) with automated deployment of _OFFSET contact where necessary.