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vk.com/club152685050Rezoning | vk.com/id446425943

difficult to determine when material is unstable, you can check the strain values, stress states, and convergence patterns. A sudden convergence difficulty could mean that material is no longer stable. The program also issues a warning at the beginning of the solution indicating when hyperelastic material could be unstable, although such a warning is very preliminary and applies only to cases involving simple stress states.

Unstable Structures

For some geometries and loads, a deformation may cause a "snap-through," or local buckling. Such behavior can also manifest itself as a mesh distortion, but one that rezoning cannot repair. The effect is usually easy to detect by closely checking the deformed region or the load-versus- time (displacement) curve.

Numerical Instabilities

A condition of numerical instability can occur when a problem is nearly overconstrained. The constraints can include kinematic constraints such as applied displacements, CP, and CE, and volumetric constraints introduced by fully incompressible material in mixed u-P elements. In many cases, numerical instability is apparent even in the early stages

of an analysis.

For a successful rezoning, the new mesh must be of a higher quality than the old mesh. If the new mesh is not better than the original mesh, rezoning cannot improve convergence, and can even worsen convergence problems.

4.2. Rezoning Requirements

Rezoning is available for 2-D and 3-D analyses. All multiframe restart files must be available.

Following are the supported analysis types, elements, materials, loads, boundary conditions, and other rezoning requirements:

Support Category

 

Requirements

 

 

 

Solid elements

PLANE182 -- B-bar method only (KEYOPT(1) = 0).

 

PLANE183

 

• For both PLANE182 and PLANE183, all stress states (KEYOPT(3)) are al-

 

 

lowed: plane strain, plane stress, axisymmetric, and generalized plane

 

 

strain. Pure displacement formulation (KEYOPT(6) = 0) or mixed u-P for-

 

 

mulation (KEYOPT(6) = 1) is allowed.

 

SOLID185 -- B-bar method only (KEYOPT(1) = 0). Pure displacement for-

 

 

mulation (KEYOPT(6) = 0) or mixed u-P formulation (KEYOPT(6) = 1) is

 

 

allowed in a nonlayered configuration (KEYOPT(3) = 0).

 

SOLID186

 

SOLID187

 

SOLID285

Contact ele-

TARGE169

ments

 

 

 

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of ANSYS, Inc. and its subsidiaries and affiliates.

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Rezoning Requirements

Support Category

Requirements

 

 

CONTA171 and CONTA172 with any of the following valid KEYOPT settings:

KEYOPT (1) = 0

KEYOPT (2) = 0, 1, 3, 4

KEYOPT (3) = 0

KEYOPT (4) = 0, 1, 2

KEYOPT (5) = 0, 1, 2, 3, 4

KEYOPT (7) = 0, 1, 2, 3

KEYOPT (8) = 0

KEYOPT (9) = 0, 1, 2, 3, 4

KEYOPT (10) = 0, 2

KEYOPT (11) = 0

KEYOPT (12) = 0, 1, 2, 3, 4, 5, 6

KEYOPT(14) = 0

 

TARGE170

 

CONTA173 and CONTA174 with any of the following valid KEYOPT set-

 

 

tings:

 

 

KEYOPT (1) = 0

 

 

KEYOPT (2) = 0, 1

 

 

KEYOPT (4) = 0, 2

 

 

KEYOPT (5) = 0, 1, 2, 3, 4

 

 

KEYOPT (7) = 0, 1, 2, 3

 

 

KEYOPT (8) = 0

 

 

KEYOPT (9) = 0, 1, 2, 3, 4

 

 

KEYOPT (10) = 0, 2

 

 

KEYOPT (11) = 0

 

 

KEYOPT (12) = 0, 1, 2, 3, 4, 5, 6

 

 

KEYOPT(14) = 0

Surface-effect

SURF153 and SURF154

elements

 

 

 

 

Only normal and tangential pressures applied on SURF153 and

 

 

SURF154 are supported. (That is, rezoning support is available only

 

 

for pressure on faces 1 and 2 for SURF153 and pressure on faces 1,

 

 

2 and 3 for SURF154.)

Contact pair

Rigid-flexible -- Target elements and pilot node cannot be remeshed.

behavior

 

 

 

• Flexible-flexible contact.

 

Self-contact.

Materials

Most structural materials are supported. The exceptions are:

 

 

- CAST (cast iron)

 

 

- CONCR (concrete)

- CZM (cohesive zone)

- DMGE and DMGI (damage),

Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information

 

of ANSYS, Inc. and its subsidiaries and affiliates.

91