/MERGE/RBODY

Block Format Keyword Defines the merging of entities to a master rigid body.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/MERGE/RBODY/merge_ID
merge_title
master_ID m_type slave_ID s_type Iflag          

Definitions

Field Contents SI Unit Example
merge_ID Rigid body merge identifier.

(Integer, maximum 10 digits)

  
merge_title Rigid body merge title.

(Character, maximum 100 characters)

  
master_ID Master rigid body identifier.

(Integer, maximum 10 digits)

  
m_type Master rigid body type flag.
=0
Set to 1.
=1 (Default)
Master is an /RBODY.

(Integer)

  
slave_ID Slave rigid body identifier.

(Integer, maximum 10 digits)

  
s_type Slave entity type flag.
= 0
Set to 1.
= 1 (Default)
Slave is an /RBODY.
= 2
Slave is a node ID.
= 3
Slave is a node group (/GRNOD) identifier.

(Integer)

  
Iflag Merge option flag. 2
= 0
Set to 2.
= 1
Mass and inertia of the slave entity is ignored. The merged rigid body will use the properties defined in the master rigid body.
= 2 (Default)
Mass and inertia of the slave entity is added to the master rigid body. The master node position is moved to the merged rigid body new center of gravity.
= 3
Mass and inertia of the slave entity are added to the master rigid body. The master node position is not moved, due to merging.

(Integer)

  

Comments

  1. Line 1 can be repeated to define multiple rigid body merges within one block.
  2. All slave rigid body nodes (slave and master) become slave nodes of the master rigid body.
  3. Before merging, the inertia, mass, and center of gravity of each slave and master rigid body is calculated based on their /RBODY properties. Next, the slave entities are merged to the master rigid body and new rigid body properties are calculated based on the Iflag option.
  4. For s_type =2 (node_ID) and =3, (/GRNOD), the slave entities can only be defined in one /MERGE/RBODY and not in any /RBODY.
  5. The master rigid body defined in a /MERGE/RBODY can be defined as a slave rigid body in another /MERGE/RBODY. However, complex hierarchies should be avoided, as they can become difficult to debug.
  6. All kinematic conditions, initial velocity, and gravity loading applied to the slave rigid body master node are ignored.
  7. The slave rigid body sens_ID, Skew_ID, Ispher, Ikrem, surf_ID, and Ioptoff options are ignored. The merged rigid body will use the flags defined in the master rigid body.
  8. The merged rigid body can be activated or deactivated with /SENSOR or using the /RBODY/ON or /RBODY/OFF Engine option.
  9. If a slave rigid body is defined in a time history output (/TH/RBODY), the master rigid body will automatically be included in the time history output, instead of the slave rigid body.
  10. /MERGE/RBODY cannot be used with a rigid body that is the master surface of an /INTER/TYPE21 contact.