In the optimization task editor, click the
Advanced tab.
Toggle on Growth direction opposite to shell
normal to reverse the direction of the nodal displacement that forms
the bead.
By default, the direction in which the nodes are moved to form the
bead is determined from the stress state of the model at the start of the
optimization—the first cycle. Alternatively, you can specify that the
optimization determines the direction in which the nodes are moved after every
design cycle.
By default, an internally computed value will be used for the bead
width. Alternatively, you can specify the absolute value of the width of the
bead.
Specify the number of iterations the bead optimization will perform.
The number of iterations modifies the step size of the optimization. The
default value is 2.
Specify the following Penalty Conditions:
- Minimum stress
ratio
-
Enter the value of the minimum von Mises stress ratio to prevent
Abaqus/CAE
from optimizing regions with very low stresses.
Abaqus/CAE
does not apply bead optimization in the regions where the von Mises stress is
less than the value computed from the specified ratio multiplied by the highest
von Mises stress in the design area (0.0 < Minimum stress
ratio < 1.0). The default value is 0.001.
- Maximum
membrane stress ratio
-
Enter the value of the maximum membrane stress ratio to prevent
Abaqus/CAE
from optimizing regions in a predominately membrane, or inplane, stress state
(the introduction of a bead in a region under a predominately membrane stress
state may make the structure softer).
Abaqus/CAE
does not apply bead optimization in regions where the membrane stress is
greater than the constant value computed from the maximum bending stress in the
original model divided by the specified ratio (0.0 < Maximum
membrane stress ratio). The default value is 1.0.
Specify the following Mesh Smoothing Parameters:
- Curve smooth
-
Enter the relative value of the radius defining a region of high
curvature.
The introduction of a bead during the optimization can squeeze nodes
together and result in small elements. For even higher degrees of curvature and
large bead heights, the nodes can begin to overlap causing the analysis to
fail. To prevent the collapse of the mesh,
Abaqus/CAE
can modify how it moves nodes while creating a bead in a region of high
curvature. High curvature is defined as the radius calculated by multiplying
the Curve smooth value and the average element edge length
in the design area. High values of Curve smooth and,
hence, a large radius encompassing many elements, can be computationaly
expensive. The default value is five times the average element length.
- Node
smooth
-
By default, the value for Node smooth is 0.25 ×
bead width. Alternatively, you can specify the
absolute minimum in-plane distance between neighboring nodes during the
creation of a bead. Values between 0.0 and 0.5 × bead
width are allowed.
Node smoothing is applied to prevent sudden changes in displacement of
neighboring nodes, especially near the boundary between the design area and the
rest of the model or where active design variable constraints are restraining
the displacement of nodes.
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