Design Variables (DV_BEAD)

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

This page discusses:

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DV_BEAD

In bead optimization, shell models might be modified by moving the nodes perpendicular to the shells. Only nodes that are members of a shell element might be used as design nodes. Nodes for solid elements cannot be 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 might move in both the positive (GROW) as well as the negative (SHRINK) normal direction.
  • If you want to have nodal movement in the 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:

Supported Elements attached to Bead Sensitivity Design Nodes using SENS_CALC_MODE = TOSCA.

BEAD_SENSITIVITY is restricted to use only certain shell elements. When using Tosca sensitivities, the element types below are supported.

Valid element types for sensitivity-based bead optimization

Abaqus element type

ANSYS® element type

MSC Nastran® element type

Shell elements

SHELL_QUAD_4

S4

S4R

SHELL143

SHELL181

SHELL41

SHELL43

SHELL63

CQUAD4

CQUADR

CSHEAR

SHELL_QUAD_8

S8R

SHELL93

CQUAD8

SHELL_TRIANG_3

S3

S3R

STRI3

CTRIA3

CTRIAR

SHELL_TRIANG_6

CTRIA6

CTRIAX6

Supported Elements attached to Bead Sensitivity Design Nodes using Abaqus.

When running with Abaqus as a solver using bead sensitivities, Tosca does not calculate the sensitivities on its own by default, but retrieves the sensitivity values from the solver. The table below shows the supported elements.

Valid element types for sensitivity-based

nodal optimization with Abaqus sensitivities.

Abaqus element type

SHELL_QUAD_4

S4

S4R

SHELL_QUAD_8

M3D8

S8R

SHELL_TRIANG_3

S3

S3R