Export ANSYS File: Entities

Description

Nodes

Straus7 exports nodes and node attribute associated user-defined coordinate systems using the N command for the Batch (1 File) and Unblocked CDB formats, the NRRANG and NREAD commands for the Batch (3 File) format, and the NBLOCK command for the Blocked CDB format. For each entry, Straus7 writes the node number and position in global Cartesian coordinates.

Nodal Coordinate Systems

Straus7 exports rotation angles to align the nodal coordinate system with attribute assigned user-defined coordinate systems. Applicable attributes include node rotational mass, node restraint, node force and node moment. The node rotational mass attribute takes precedence over the node restraint, node force and node moment attributes with nodal coordinate system assignment. The nodal coordinate system may be defined from a Cartesian, cylindrical, spherical or toroidal coordinate system in terms of an equivalent Cartesian coordinate system at that particular location.

Elements

Straus7 exports elements using the EN command for the Batch (1 File) and Unblocked CDB formats, using the ERRANG and EREAD commands for the Batch (3 File) format, and using the EBLOCK command for the Blocked CDB format. Elements are exported in blocks according to their material reference number, element type, real set, section ID and element coordinate system number. The material reference number, element type, real set, section ID and element coordinate system number are defined explicitly for the Batch (1 File) format prior to each block using the MAT, TYPE, REAL, SECNUM and ESYS commands respectively. For the Batch (3 File), Unblocked CDB and Blocked CDB formats, the material reference number, element type, real set, section ID and element coordinate system number are defined within each element specification using the EREAD, EN or EBLOCK commands respectively.

Node Numbering

Node numbers are preserved when exporting to an ANSYS file. Additional reference nodes generated by Straus7 for beam/pipe element local axis orientation are numbered consecutively following the highest node number. For example: if there are 250 nodes with an additional 30 reference nodes generated by Straus7, the ANSYS file will contain nodes numbered 1-250, and additional reference nodes numbered 251-280.

Element Numbering

Straus7 exports node translational/rotational masses, pinned/rigid links, beam elements, plate elements and brick elements using a global numbering system. Numbering begins from 1, and is consecutive in order of structural masses, pinned/rigid links, beams, plates and bricks. For example: if there are 15 structural masses, 30 pinned/rigid links, 120 beams, 55 plates and 25 bricks, the ANSYS file will contain structural mass elements numbered 1-15, pinned/rigid links numbered 16-45, beams numbered 46-165, plates numbered 166-220 and bricks numbered 221-245.

Beam, Plate and Brick Non-Structural Mass Attributes

Beam non-structural mass, plate face non-structural mass and brick face non-structural mass attributes are not load case dependent in ANSYS. Straus7 exports beam non-structural mass and plate non-structural mass attributes in accordance with the selected Pre-load/Non-structural Mass Load Case. Beam non-structural mass and plate face non-structural mass attributes are exported as real set data distributed mass values for ANSYS element types SHELL28, SHELL41, SHELL43, BEAM44, SHELL91, SHELL93 and LINK180. Brick non-structural mass attributes are ignored.

Beam2, Beam3

Straus7 exports beam element types Beam2 and Beam3 using the ET command and associated element option keys using the KEYOPT command. The element type is specified according to the beam type, nonlinear tables and assigned attributes.

Spring-Damper

Spring-damper elements are exported using the COMBIN14 element type for linear stiffness values, and COMBIN39 for nonlinear stiffness values given by Axial Force vs Displacement or Torque vs Twist tables (the Axial Force vs Displacement table takes precedence over the Torque vs Twist table for nonlinear table assignment). Lateral stiffness and lateral damping values and Axial Force vs Velocity tables for the spring-damper element are ignored.

Cable

Cable elements are exported using the LINK180 element type. Truss element behaviour is assumed for cable elements.

Truss

Truss elements are exported using the LINK180 element type. Axial Stress vs Strain tables are supported for this element type.

Cutoff Bar

Cutoff bar elements are exported using the LINK180 element type. Truss element behaviour is assumed for cutoff bar elements.

Point Contact

Zero gap and Normal gap point contact elements are exported using the CONTAC52 element type.

Beam

Beam elements are exported using the BEAM44 element type when beam translational and rotational end release attributes are assigned, and BEAM188 when beam translational and rotational end release attributes are not assigned. Beam translational and rotational end releases with partial end releases are exported as fixed or full release according to the Partial End Release option. Axial Stress vs Strain tables are supported for the BEAM188 element type. Moment vs Curvature tables are ignored.

User-Defined

User-defined beam elements are exported using the MATRIX27 element type.

Pipe

Pipe elements are exported using the PIPE18 element type.

Connection

Connection elements are exported using the COMBIN14 element type for linear stiffness values, and COMBIN39 for nonlinear stiffness values given by Force vs Displacement or Moment vs Rotation tables for axial and torque stiffness (the Force vs Displacement table takes precedence over the Moment vs Rotation table for nonlinear table assignment). Shear and bending stiffness values for the connection element are ignored.

Default

If a beam element is not assigned a property, the BEAM44 element type is assumed.

Reference Nodes

For element types that require a reference node (BEAM188, PIPE18), Straus7 will generate a reference node for export if one is not already defined.

Beam Principal Axis Angle

For beam and pipe elements, the beam principal axes may be specified for the BEAM44, BEAM188 and PIPE18 element types by the reference node. If a reference node is not defined for the BEAM44 element type, a -90 degree rotation angle is specified such that the Straus7 principal axis system is consistent with the default ANSYS local axis system.

Tri3, Quad4

Straus7 exports plate element types Tri3 and Quad4 using the ET command and associated element option keys using the KEYOPT command. The element type is specified according to the plate type, material and Export Heat Transfer selection.

Plane Stress

Plane Strain

Axisymmetric

Plate/Shell

Shear Panel

The shear panel plate element type is exported using the SHELL28 element type for Tri3 elements, and SHELL43 element type for Quad4 elements.

Membrane

Tri6, Quad8, Quad9

Straus7 exports plate element types Tri6, Quad8 and Quad9 using the ET command and associated element option keys using the KEYOPT command. The centre node is ignored for Quad9 elements. The element type is specified according to the plate type, material and Export Heat Transfer selection.

Plane Stress

Plane Strain

Axisymmetric

Plate/Shell

Shear Panel

The shear panel plate element type is exported using the SHELL93 element type.

Membrane

Default

If a Tri6, Quad8 or Quad9 plate element is not assigned a property, or the plate type and material are not supported, the SHELL93 element type is assumed.

Tetra4, Pyra5, Wedge6, Hexa8

Straus7 exports brick element types Tetra4, Pyra5, Wedge6 and Hexa8 using the ET command and associated element option keys using the KEYOPT command. The element type is specified according to the brick material and Export Heat Transfer selection.

Heat Transfer

Heat transfer properties only are exported if the Export Heat Transfer option is selected. Heat transfer properties are exported using the SOLID70 element type for Tetra4, Wedge6 and Hexa8 elements, and using the SOLID62 element type for Pyra5 elements.

Drucker-Prager (Isotropic)

Isotropic materials with the Drucker-Prager yield criterion are exported using the SOLID62 element type.

Isotropic, Orthotropic, Anisotropic, Rubber

Isotropic, orthotropic, anisotropic and rubber materials are exported using the SOLID185 element type for Tetra4, Wedge6 and Hexa8 elements, and using the SOLID62 element type for Pyra5 elements. For an isotropic material, the von Mises yield criterion is assumed. Nonlinear Stress vs Strain tables are supported for the SOLID185 element type.

Fluid

Fluid materials are exported using the FLUID80 element type.

Default

If a Tetra4, Pyra5, Wedge6 or Hexa8 brick element is not assigned a property, the SOLID62 element type is assumed.

Tetra10, Pyra13, Wedge15, Hexa16, Hexa20

Straus7 exports brick element types Tetra10, Pyra13, Wedge15, Hexa16 and Hexa20 using the ET command and associated element option keys using the KEYOPT command. The mid-side nodes are ignored for Hexa16 elements. The element type is specified according to the brick material and Export Heat Transfer selection.

Heat Transfer

Heat transfer properties only are exported if the Export Heat Transfer option is selected. Heat transfer properties are exported using the SOLID90 element type.

Drucker-Prager (Isotropic)

Isotropic materials with the Drucker-Prager yield criterion are exported using the SOLID95 element type.

Isotropic, Orthotropic, Anisotropic, Rubber

Isotropic, orthotropic, anisotropic and rubber materials are exported using the SOLID186 element type for Pyra13, Wedge15, Hexa16 and Hexa20 elements, and using the SOLID187 element type for Tetra10 elements. For an isotropic material, the von Mises yield criterion is assumed. Nonlinear Stress vs Strain tables are supported for the SOLID186 and SOLID187 element types.

Default

If a Tetra10, Pyra13, Wedge15, Hexa16 or Hexa20 brick element is not assigned a property, the SOLID95 element type is assumed.

Links

Straus7 exports the following links using the CE command.

Straus7 exports Pinned links as an element of the ET command element type MPC184 (KEYOPT(1) = 0).

Straus7 exports XYZ Rigid links as an element of the ET command element type MPC184 (KEYOPT(1) = 1). XY-plane, YZ-plane and ZX-plane rigid links are exported using the CE command.

Heat Transfer

If the Heat Transfer option is selected, the temperature degree of freedom only is exported for links using the CE command.

See Also