Design variables (DV_BEAD)

Design variables that are usable in bead optimization setups are introduced. Valid are all nodes of shell elements.

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DV_BEAD

In bead optimization shell models may be modified by moving the nodes perpendicular to the shells. Only nodes which are members of a shell element may be used as design nodes. Nodes for solid elements cannot be design nodes.

Define a Design variable in Tosca ANSA® environment

  1. Choose DESIGN AREA in the Task manager and select Edit.
  2. In DV_BEAD dialog, select the node group of design nodes.



Define a Design variable in Tosca Structure.gui

  1. Choose Command > DV_BEAD in Tosca Structure.pre.
  2. In the DV_BEAD dialog, select a node group and assign an ID_NAME for further reference to the definition.
Important:

  • For BEAD_CONTROLLER the nodes are only moved in the positive direction of the shells determined by the element definition in the FE analysis. For BEAD_SENSITIVITY the nodes may move in both the positive (GROW) as well as the negative (SHRINK) normal direction.
  • If you want to have nodal movement in negative normal direction and want to use BEAD_CONTROLLER invert the optimization displacement direction by defining a negative SCALE factor in the OPT_PARAM command. This has no effect for BEAD_SENSITIVITY.

The following figure shows the optimization displacement direction for bead optimization:
  • BEAD_SENSITIVITY is restricted to use only certain shell elements. Please consult the table below:

Valid element types for sensitivity based bead optimization

Abaqus element type

MSC Nastran® element type

Shell elements

SHELL_TRIANG_3

S3

S3R

STRI3

CTRIA3

CTRIAR

SHELL_TRIANG_6

  

CTRIA6

CTRIAX6

SHELL_QUAD_4

S4

S4R

CQUAD4

CQUADR

CSHEAR

SHELL_QUAD_8

S8R

CQUAD8