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Download PRIMER 10.0 user manual
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User manual Version 10.0, June 2011 PRIMER 6.10.9 Connection contact Mesh independent spotweld beams/solids and adhesive solids (connections in Primer) are tied to their respective panel shells using tied contacts in 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 CONNECTION > CONTACT function has been designed to create spotweld/adhesive contact(s) with automated deployment of _OFFSET contact where necessary. 6.10.9.1 Checking the connection contact Connection contact is checked in a variety of contexts. • when you run a model check - to report connections in error • whenever connections are put onto the table - so their status is reported correctly • using CONNECTION > CHECK > CONNECTIVITY • using CONNECTION > CONTACT All use the same checking function and will report error code for each connection such as • NOTCONNECTED - nodes or shells are missing from the contact definition • NOT TIED - node and shell are in contact but fail to tie, usually because they are too far away • NOT STICKING - constraint clash prevents contact from working • BAD CONTACT - contact type is invalid The results of model check are displayed in a tree view. The drop-down allows easy transfer of connections to the table, e.g. for re-making. Details on the table provides useful information about the error. Page 6.181
