ANSYS Interface

RBE3 elements are different from Nastran RBE3 elements. In ANSYS, the RBE3 card is used to distribute the force/moments from the master node to a set of slave nodes. Whereas in Nastran, these elements define the rigid body motion. In HyperMesh, the RBE3 card is mapped as a RBE3 element. Therefore, when creating the RBE3 elements in HyperMesh for the template, the following points should be noted:

• When a RBE3 element is created in HyperMesh, the DOFs are defined for the master as well as for the slave nodes. However, since the slave node DOFs are not applicable in , they are not exported.
• By default, when a RBE3 element is created in HyperMesh, the same weight factor that is applied at the master node is also applied on all the slave nodes. The Update subpanel in the RBE3 panel allows you to modify the weight factors for the individual slave nodes. Since the master node weight factor is not applicable in ANSYS, it is not exported.
• The RBE3 elements created in HyperMesh using other solver templates, such as Nastran, are exported according to template terminology.

Exportation of the SLAVE# Array:

*DIM,SLAVE#,ARRAY,      NS,       1,       1
*SET,SLAVE#(       1,       1,       1),  ID_1  
*SET,SLAVE#(       2,       1,       1),  ID_2  
*SET,SLAVE#(       3,       1,       1),  ID_3
.
.
.
*SET,SLAVE#(      NS,       1,       1),  ID_NS

Where,

#

HyperMesh element ID of the RBE3

NS

Number of slave nodes within the RBE3

ID_1, ID_2, ID_3,…,ID_NS

IDs of the slave nodes

Exportation of the WEIGHT# Array:

*DIM,WEIGHT#,ARRAY,      NS,       1,       1
*SET,WEIGHT#(       1,       1,       1),  WF_1
*SET,WEIGHT#(       2,       1,       1),  WF_2
*SET,WEIGHT#(       3,       1,       1),  WF_3
.
.
.
*SET,WEIGHT#(      NS,       1,       1),  WF_NS

Where,

#

HyperMesh element ID of the RBE3

NS

Number of slave nodes within the RBE3

WF_1, WF_2, WF_3,…,WF_NS

Weighting factors corresponding to each slave node

Each RBE3 element is written using a RBE3 card with the following format:

RBE3, Master_ID, DOF, SLAVE#, WEIGHT#

Where,

Master_ID

ID of the master node

DOF

Degrees of freedom checked in the RBE3 panel for RBE3 elements with ID #. DOF is exported as follows:

U

If ux is checked

UY

If uy is checked

UZ

If uz is checked

ROTX

If rotx is checked

ROTY

If roty is checked

ROTZ

If rotz is checked

UXYZ

If ux, uy, and uz are checked

RXYZ

If rotx, roty, and rotz are checked

ALL

If all are checked

If a combination of DOFs not listed above are checked, several RBE3 cards will be exported for the same element. For example, if ux, uy, and roty are checked, three RBE3 cards will be exported.

RBE3, Master_ID, UX, SLAVE#, WEIGHT#
RBE3, Master_ID, UY, SLAVE#, WEIGHT#
RBE3, Master_ID, ROTY, SLAVE#, WEIGHT#

SLAVE#

Name of the slave node ID array

WEIGHT#

Name of the weighting factor array

• The operations performed in HyperMesh can also be saved as a compact HyperMesh binary file using the File > Save As option.
• Bolt simulation configuration files are available in the ANSYS profile. In the Bolt panel, you can create general bolt, bolt with one or two washers, bolt with spider option and clips.
• Use the Mass Calc panel (Tool page) to determine the mass of your finite element model. Select the ansys.tpl template file through the Import tab. The mass calculation is supported for the following element type numbers: 1, 2, 3, 4, 5, 8, 10, 13, 16, 18, 20, 21, 23, 24, 25, 28, 31, 32, 33, 41, 42, 43, 44, 45, 46, 51, 53, 54, 55, 57, 58, 60, 61, 62, 63, 64, 67, 69, 70, 71, 75, 77, 78, 80, 82, 83, 87, 90, 91, 92, 93, 95, 96, 97, 98, 99, 107, 116, 117, 118, 119, 120, 121, 143, 145, 147, 148, 150, 152, 153, 154, 157, 162, 163, 164, 173, 174, 180, 181, 182, 183, 185, 186, 187, 191
• Each operation in HyperMesh results in an ASCII command that is added to a command.cmf file. This file is useful if your computer shuts down while working in HyperMesh. You can restore your previous work by reading this file with the command function, which can by found by clicking File > Run > Command File. You can delete this file if it requires too much disk space.

  The command.cmf file can also be used to store repetitive HyperMesh operations. If you deal with the same set of geometrical and material properties, you can record the creation of these collectors, such as steel plate, foam solids and aluminum rods, into series of command files and read them as needed.

• The ANSYS template is associated with the Composites panel. Using this panel for laminated elements, such as SHELL99, enables the following:
  Element orientation by two methods:

  • By system assigns a system to the element (set ESYS for the element).
  • By vector projects a vector on the element plane. A coordinate system, in which the x-axis is parallel to the defined vector, is created and assigned to the element as ESYS.
  • The by system axis and by angle options are not available for this template.
  • Visualization of the element orientation
  • Visualization of the ply direction on a layer-by-layer basis. Visualizes the angles defined in the R card with respect to the element orientation.
• If you change KEYOPT3 for MASS21 and KEYOPT6 for BEAM23 elements, make sure you do so on the component as well as on property collector.
• When you click the card image button while creating a property collector, the GENERAL card is shown at the end of the list. This card is used to card edit the properties that are not used by any element.
• The ANSYS connectivity for a second order (3-node) line element (such as BEAM189 or SURF153), is as follows: End-node-I, End-node-J and Mid-node-K. However, for creation of a bar3 element in HyperMesh (using the bar panel/bar3 subpanel), pick node A, node B, and node C in the following order: End-node-I, Mid-node-K and End-node-J, respectively. The ANSYS template will export the bar3 element using the ANSYS connectivity.
• Apply loads in local coordinate systems (ANSYS NROTAT card) using HyperMesh with the following methods:
  • The Forces panel and the Moments panel allow you to apply loads in a local coordinate system by using the local system option.
  • The set analysis option in the Systems panel, Assign subpanel can be used to assign a node to a coordinate system. A load applied to that node would be displayed correctly after exportation and importation of the ANSYS deck.
  If both options of applying loads in local coordinate systems are used for the same node, the first method (via the Forces and Moments panels) takes precedence.

The following items are supported under this feature:

• Import pressure load applied on BEAM3, BEAM4, BEAM23, BEAM44 elements. Import restrictions are explained below.
• Use the Pressure panel to apply SFBEAM load on beam elements.
• Export pressure load applied on BEAM elements in HyperMesh as SFBEAM load in ANSYS solver deck. The Export feature is explained in detail below.

SFBEAM is the keyword command in ANSYS decks to apply pressure load on BEAM elements. This command line has following arguments:

SFBEAM,ELEM,LKEY,Lab,R5.0,DIOFFST,DJOFFST

ELEM

Element ID and Lab is always pres(pressure).

LKEY

Load key number which determines the face of the beam where the pressure load is applied.

Refer to the ANSYS solver documentation for information on the face of the beam and corresponding LKEY number as it changes from BEAM to BEAM.

• The HyperMesh-ANSYS interface presently supports the following LKEY values for each BEAM element. You can import SFBEAM load with these LKEYs.

  Table 1.

  ELEMENT TYPE	SUPPORTED LKEYs
  BEAM3	1, 3, 4
  BEAM4	1, 2, 4, 5
  BEAM23	1, 3, 4
  BEAM24	1, 2, 4, 5
  BEAM44	1, 2, 4, 5
  BEAM54	1, 3, 4
  BEAM188	1, 2, 4, 5
  BEAM189	1, 2, 4, 5

• DIOFFST, DJOFFST, which define offset values for pressure value at node I and J, are not supported in HyperMesh.
• SFLOAD, which applies a pressure load that varies across the length of the beam, is not supported in HyperMesh 9.0. Only pressure load with constant value can be imported.

• You can apply a pressure load in HyperMesh on any bar2, bar3 and rod, elements. Only the pressure loads which are applied on supported BEAM element types can be exported.
• If no option for direction is selected, pressure is applied on ‘element – y’ direction by default. You can use the options available in the Pressure Load panel to specify the direction of the load.
• The ANSYS solver allows pressure on beam elements in only specified faces of the elements, as mentioned by LKEYS. In other words, pressure on beam elements is applied in element co-ordinate system. Keep this in mind before determining the direction of the pressure.
• You cannot apply a pressure load that varies across the length of the BEAM even though it is allowed in the ANSYS Solver.
• Load offsets at node I and J are not supported.

• Pressure on beams is exported as SFBEAM cards.
• Pressure only applied on BEAM3, BEAM4, BEAM23, BEAM44, BEAM54, BEAM188, BEAM189 elements will be exported.
• Pressure applied in any arbitrary direction is resolved in to corresponding element systems, and relevant LKEYs will be assigned while exporting. When you import the deck back to HyperMesh, you will see resolved loads.