/SECT/CIRCLE

Block Format Keyword A circle section is used to output the force and moment of a cross section defined by a circular disc.

The nodes and elements that define the section are automatically selected by intersecting the groups of elements with a disc.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/SECT/CIRCLE/sect_ID/unit_ID
sect_title
node_ID1 node_ID2 node_ID3   ISAVE   Δ t α
file_name
grbric_ID   grshel_ID grtrus_ID grbeam_ID grsprg_ID grtria_ID Ninter   Iframe
Input read only if Ninter > 0
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
int_ID1 int_ID2 int_ID3 int_ID4 int_ID5 int_ID6 int_ID7 int_ID8 int_ID9 int_ID10
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
XM YM ZM        
Dir_X Dir_Y Dir_Z        
R            

Definitions

Field Contents SI Unit Example
sect_ID Section identifier

(Integer, maximum 10 digits)

  
unit_ID Unit Identifier

(Integer, maximum 10 digits)

  
sect_title Section title

(Character, maximum 100 characters)

  
node_ID1 Node identifier N1 defining the local output system of the section.

(Integer)

  
node_ID2 Node identifier N2 defining the local output system of the section.

(Integer)

  
node_ID3 Node identifier N3 defining the local output system of the section.

(Integer)

  
ISAVE Saving or reading the section data from file_name flag.
=0
Do not save any data.
=1
Save section displacements in the section cut file.
=2
Save section displacements, resultant force, and moment components in the section cut file.
=100
Read and apply the section data as loads to the model.
=101
Read and apply the section data as loads to the model. Also output in the time history the difference between the applied section resultants (force and moment) and the simulation’s calculated section results.
This option requires that the section data was created using the ISAVE =2 option.

(Integer)

  
Δ t Time step for saving the data used with ISAVE =1 or 2.

Default = time step of the simulation (Real)

 [ s ]
α Exponential moving average filtering constant (0 < α < 1). Smaller values result in more filtering.

Only used when applying the displacements to a section using ISAVE= 100 or 101.

Recommended value =0.62832 (refer to Filter in the User Guide)

Default = No filtering (Real)

  
file_name Root name of the file which contains the flag output. The section file will be named file_nameSC01.

Default = Runname (where Runname is the prefix to the Engine file, Runname_0001.rad)

(Character, maximum 100 characters)

  
grbric_ID Brick group identifier.

(Integer)

  
grshel_ID Shell group identifier.

(Integer)

  
grtrus_ID Truss group identifier.

(Integer)

  
grbeam_ID Beam group identifier.

(Integer)

  
grsprg_ID Spring group identifier.

(Integer)

  
grtriag_ID Triangle group identifier.

(Integer)

  
Ninter Number of interfaces

(Integer)

  
Iframe Flag defining the center of the local system used in the calculation of the section forces and moments. 3
The section output is in the local system with the center defined as:
=0
Origin of the local section system.
=1
Geometrical center of the section.
=2
CoG of the section.
=3
Global system point (0,0,0).
The section output is in the global system with the center defined as:
=10
Origin of the local section system.
=11
Geometrical center of the section.
=12
CoG of the section.
=13
Global system point (0,0,0).

(Integer)

  
int_ID1, int_ID2, ..., int_IDn Optional interface identifiers, if Ninter > 0.

(Integer)

  
XM X coordinate of center of the disc (Point M).

(Real)

 [ m ]
YM Y coordinate of center of the disc (Point M).

(Real)

 [ m ]
ZM Z coordinate of center of the disc (Point M).

(Real)

 [ m ]
Dir_X X coordinate of normal vector to the disc.

(Real)

 [ m ]
Dir_Y Y coordinate of normal vector to the disc.

(Real)

 [ m ]
Dir_Z Z coordinate of normal vector to the disc.

(Real)

 [ m ]
R Radius of the disc.

(Real)

 [ m ]

Comments

  1. The elements groups defined will be intersected by the defined disc. The section nodes are created from the nodes of those intersected elements, which are on the upside (z > 0) of the plane of the disc.


    Figure 1.
  2. The forces and moments from the sections will be stored in the time history file and requested using /TH/SECTIO.
  3. The local force and moment output system of the section is defined using 3 nodes. These three nodes should be nodes on the section plane, so their position is updated when the section moves. When using the Cross-Section Assistant in HyperMesh to create the section, the 3 nodes are automatically selected.
    Local system is defined as:
    • Nodes node_ID1 and node_ID2 define the local x-axis of the section.
    • Nodes node_ID1, node_ID2, and node_ID3 define the local plane xy of the section.
    • The local y-axis is defined by projecting node_ID3 perpendicular to the local x-axis.
    • The intersection of the local x- and y-axis is then the origin of the system.
    • Last, the section normal is the local z-axis which is perpendicular to the xy plane.
    • The center of the section can be redefined using the Iframe option. Refer to Force and Moment Computation in the User Guide for further details.
  4. Sections can also be used in a cut modeling method where section forces and displacements are saved from a full model and then applied in a second cut model. In the full model, the section information is saved using the ISAVE =1 or 2 option. Then in the cut model, the same section nodes and element groups are defined and the section displacements are applied to the cut model using ISAVE =100 or 101. The cut model is then used to study a detailed area of the full model.
  5. Recommendations:
    • Define Iframe =2 or 12, the center is the CoG of the section.
    • Time history output GLOBAL and LOCAL in /TH/SECTIO.