Block Format Keyword
/CLUSTER - Cluster of Elements for Spotweld/Connection Modeling
Description
Describes an assembly of brick or spring elements for post-processing and failure control.
Format
(1)
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(2)
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(3)
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(4)
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(5)
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(6)
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(7)
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(8)
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(9)
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(10)
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/CLUSTER/ELEM_TYPE/cluster_ID/unit_ID
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cluster_title
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group_ID
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skew_ID
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Ifail
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Fn_fail1
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a1
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b1
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Fs_fail
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a2
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b2
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Mt_fail
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a3
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b3
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Mb_fail
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a4
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b4
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Field
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Contents
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SI Unit Example
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ELEM_TYPE
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Cluster element type keyword
BRICK: cluster of brick elements
SPRING: cluster of spring elements
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cluster_ID
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Cluster identifier
(Integer, maximum 10 digits)
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unit_ID
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Optional unit identifier
(Integer, maximum 10 digits)
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cluster_title
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Cluster block title
(Character, maximum 100 characters)
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group_ID
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Element group identifier
(Integer)
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skew_ID
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Skew identifier
(Integer)
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Ifail
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Failure model option
Default = 0 (Integer)
= 0: No global failure criterion
= 1: Unidirectional failure, element is deleted if force or moment in one direction reaches the limit value
= 2: Unidirectional failure, element is deleted if forces and moments in all directions reach the limit values
= 3: Multi-directional failure (Comment 8)
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Fn_fail
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Failure force in normal direction (tension)
Default = 1.0e30 (Real)
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Fs_fail
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Failure force in tangent direction (shear)
Default = 1.0e30 (Real)
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Mt_fail
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Failure moment in normal direction (torsion)
Default = 1.0e30 (Real)
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[N * m]
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Mb_fail
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Failure moment in tangent direction (bending)
Default = 1.0e30 (Real)
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[N * m]
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a1 - a4
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Multi-directional failure scale factors (only used if Ifail =3)
Default = 1.0 (Real)
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b1 - b4
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Multi-directional failure exponents (only used if Ifail =3)
Default = 1.0 (Real)
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| 1. | The cluster of elements are used for connection (spotweld, welding line, glue, and so on). |
| 2. | The cluster of elements may only be defined with groups of solid (8 node bricks) or spring elements. |
| 3. | For bricks, cluster of elements works with LAW59 and LAW83 only. Solid elements of cluster should be interconnected. |
| 4. | For springs, cluster of elements works with TYPE13. |
| 5. | The number of elements in cluster group is limited to 100. |
| 6. | All cluster elements must have the same orientation (Z local coordinate for solids, X local coordinate for springs, or direction from first to second node). |
| 7. | Only one layer of element in the normal (thickness direction) is allowed to define a cluster. |
| 8. | When global force/moment failure criterion FAIL is reached, all elements in the cluster are deleted. |
| 9. | Cluster elements may have local failure criteria (/FAIL associated to brick element material law or failure parameters defined in spring property). These local criteria are independent of global force failure criterion defined in /CLUSTER. |
| 10. | Failure criterion FAIL is calculated, as follows: |
Unidirectional local, Ifail=1:
Unidirectional general, Ifail=2:
Multi-directional, Ifail=3:
| 11. | Local coordinate system: |
| • | If skew_ID is defined, the skew Z-axis defines normal direction in local coordinate system, tangent plane will be defined by skew X and Y axis. |
| • | If skew_ID = 0, the normal direction in local coordinate system is defined by the vector between geometrical centers of nodes on bottom and top side. |
| 12. | Available post-processing options: |
/ANIM/VECT/CLUST/FORCE - force vector in global coordinates
/ANIM/VECT/CLUST/MOM - moment vector in global coordinates
/TH/CLUSTER - forces and moments in global or local coordinates
| 13. | Output for TH: Forces and moments in global and local coordinate system, failure criterion FAIL. |
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See Also:
/TH/CLUSTER
Skew and Frame (/SKEW & /FRAME)
Example 22 - Ditching
