ESURF
ESURF, XNODE, Tlab, Shape
Generates elements overlaid on the free faces of selected
nodes.
XNODENode number that is used only in the following two cases:
XNODEis a single extra node number (ID) used for generating SURF151 or SURF152 elements when KEYOPT(5)=1.XNODEis a single pressure node number (ID) used for generating HSFLD241 or HSFLD242 elements.There is no default.
XNODEmust be specified for the above cases. IfXNODE= P, graphical picking is enabled and all remaining command fields are ignored (valid only in the GUI). A parameter or parametric expression can be substituted forXNODE.TlabGenerates target, contact, hydrostatic fluid, and 3D thermal surface effect elements, with correct direction of normals.
This option is valid only with TARGE169, TARGE170, CONTA172, CONTA174, CONTA177, HSFLD241, HSFLD242, and SURF152 elements.
TOP
—
Generates target and contact elements over beam and shell elements, or hydrostatic fluid elements over shell elements, or SURF152 over SHELL294 elements, with the normals the same as the underlying beam and shell elements (default).
BOTTOM
—
Generates target and contact elements over beam and shell elements, or hydrostatic fluid elements over shell elements, or SURF152 over SHELL294 elements, with the normals opposite to the underlying beam and shell elements.
If target or contact elements, hydrostatic fluid elements, and 3D thermal surface effect elements (SURF152) are defined on the same underlying shell elements, you only need to use this option once to orient the normals opposite to the underlying shell elements.
REVERSE
—
Reverses the direction of the normals on existing selected target elements, contact elements, hydrostatic fluid elements, and 3D thermal surface effect elements (SURF152).
If target or contact elements, hydrostatic fluid elements, and 3D thermal surface effect elements (SURF152) are defined on the same underlying shell elements, you only need to use this option once to reverse the normals for all selected elements.
ShapeUsed to specify the element shape for target element TARGE170 (
Shape= LINE or POINT) or TARGE169 elements (Shape= POINT).(blank)
—
The target element takes the same shape as the external surface of the underlying element (default).
LINE
—
Generates LINE or PARA (parabolic) segments on exterior of selected 3D elements.
POINT
—
Generates POINT segments on selected nodes.
Notes
The ESURF command generates elements of the currently active element type overlaid on the free faces of existing elements. For example, surface elements (such as SURF151, SURF152, SURF153, SURF154, or SURF159) can be generated over solid elements (such as PLANE55, SOLID70, PLANE182, SOLID185, or SOLID272, respectively).
Element faces are determined from the selected node set (NSEL) and the load faces for that element type. The operation is similar to that used for generating element loads from selected nodes via the SF,ALL command, except that elements (instead of loads) are generated. All nodes on the face must be selected for the face to be used. For shell elements, only face one of the element is available. If nodes are shared by adjacent selected element faces, the faces are not free and no element is generated.
Elements created by ESURF are oriented such that their surface load directions are consistent with those of the underlying elements. Carefully check generated elements and their orientations.
Generated elements use the existing nodes and the active MAT, TYPE, REAL,
and ESYS attributes. The exception is when Tlab = REVERSE. The reversed target and contact elements
have the same attributes as the original elements. If the underlying
elements are solid elements, Tlab = TOP
or BOTTOM has no effect.
When the command generates a target element, the shape is by default the same as that of the underlying element. Issue ESURF,,,LINE or ESURF,,,POINT to generate LINE, PARA, and POINT segments.
The ESURF command can also generate the 2D or 3D node-to-surface element CONTA175, based on the selected node components of the underlying solid elements. When used to generate CONTA175 elements, all ESURF arguments are ignored. (If CONTA175 is the active element type, the path uses ESURF to generate elements.)
To generate SURF151 or SURF152 elements that have two extra nodes from FLUID116 elements, KEYOPT(5) for SURF151 or SURF152 is first set to 0 and ESURF is issued. Then KEYOPT(5) for SURF151 or SURF152 is set to 2 and MSTOLE is issued. For more information, see Using the Surface Effect Elements in the Thermal Analysis Guide.
For hydrostatic fluid elements HSFLD241 and HSFLD242, the ESURF command generates triangular (2D) or pyramid-shaped (3D) elements
with bases that are overlaid on the faces of selected 2D or 3D solid
or shell elements. The single vertex for all generated elements is
at the pressure node specified as XNODE. The generated elements fill the volume enclosed by the solid or
shell elements. The nodes on the overlaid faces have translational
degrees of freedom, while the pressure node shared by all generated
elements has a single hydrostatic pressure degree of freedom, HDSP
(see HSFLD241 and HSFLD242 for more information about the pressure node).