Displacement check against elements (CHECK_ELGR)

Limit node growth with CHECK_ELGR. Element surfaces/lines can be defined as limiting surfaces/lines in order to check node displacements against any contour. This option offers more flexibility than the check for the absolute displacement or the check against geometric primitives.

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DVCON_BEAD

The limiting surfaces are formed by beam, shell or solid structures. The limiting surfaces are generated in the FE preprocessor and loaded via the interface (FEM_INPUT) in the optimization preprocessor.

The parameter 

    
      CHECK_ELGR = elgr_name

specifies an element group whose elements may not be penetrated (contact condition) by the nodes of the node group (ND_GROUP parameter).

Activation of the element check represents a collision control. If a node attempts to penetrate an element, the node displacement is scaled back so that the affected node remains on the side of the element where it is intended to be. If the element group is not already defined in inputdeck, it must be defined with GROUP_DEF before it can be referenced with CHECK_ELGR.

Up to six CHECK_ELGR parameters can be defined in every DVCON_BEAD command. They are executed in the order of their declaration within the DVCON_BEAD command.

Tip: To simplify the definition of the contact check it is useful to divide the limiting surfaces by assigning various element property numbers (or materials). This simplifies the selection and assembly of groups in the optimization preprocessor.

Important:
  1. All nodes of the selected node group are checked against all elements of the element group, elgr_name. To keep the number of control conditions within limits, only those nodes and elements that have the potential for penetration should be checked against one another. The groups should be correspondingly defined.
  2. The nodes (ND_GROUP parameter) and the elements (CHECK_ELEM parameter) should have a definite minimum distance in the initial model in order to verify on which side of the element a node must remain.
  3. If the elements being used in the check are loaded with the ADD_FILE parameter (FEM_INPUT), take care that node or element IDs are not used twice as SIMULIA Tosca Structure cannot process duplicated IDs.