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发表于 2003-1-15 10:56:15
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来自 黑龙江哈尔滨
回复： 【推荐】积分鼓励，做弹簧划分网格
我在HELP中COPY的一点有关内容，与该题有关，希望和我一样
没用过该命令的同学，看过后，都能试着做一下。我也在试着做。
我想这个命令做螺纹时同样适用。
VEXT, NA1, NA2, NINC, DX, DY, DZ, RX, RY, RZ — Generates additional volumes by extruding areas.
PREP7:Volumes
MP ME ST DY PR EM EH FL PP ED
NA1, NA2, NINC
Set of areas (NA1 to NA2 in steps of NINC) that defines the pattern to be extruded. NA2 defaults to NA1, NINC defaults to 1. If NA1 = ALL, NA2 and NINC are ignored and the pattern is defined by all selected areas. If NA1 = P, graphical picking is enabled and all remaining command fields are ignored (valid only in the GUI). A component name may also be substituted for NA1 (NA2 and NINC are ignored).
DX, DY, DZ
Increments to be applied to the X, Y, and Z keypoint coordinates in the active coordinate system (DR, Dθ, DZ for cylindrical; DR, Dθ, DΦ for spherical).
RX, RY, RZ
Scale factors to be applied to the X, Y, and Z keypoint coordinates in the active coordinate system (RR, Rθ, RZ for cylindrical; RR, Rθ, RΦ for spherical). Note that the Rθ and RΦ scale factors are interpreted as angular offsets. For example, if CSYS = 1, RX, RY, RZ input of (1.5,10,3) would scale the specified keypoints 1.5 times in the radial and 3 times in the Z direction, while adding an offset of 10 degrees to the keypoints. Zero, blank, or negative scale factor values are assumed to be 1.0. Zero or blank angular offsets have no effect.
Notes
Generates additional volumes (and their corresponding keypoints, lines, and areas) by extruding and scaling a pattern of areas in the active coordinate system.
If element attributes have been associated with the input area via the AATT command, the opposite area generated by the VEXT operation will also have those attributes (i.e., the element attributes from the input area are copied to the opposite area). Note that only the area opposite the input area will have the same attributes as the input area; the areas adjacent to the input area will not.
If the areas are meshed or belong to meshed volumes, a 3-D mesh can be extruded with this command. Note that the NDIV argument on the ESIZE command should be set before extruding the meshed areas.
Scaling of the input areas, if specified, is performed first, followed by the extrusion.
In a non-Cartesian coordinate system, the VEXT command locates the end face of the volume based on the active coordinate system. However, the extrusion is made along a straight line between the end faces. Note that solid modeling in a toroidal coordinate system is not recommended.
Caution: Use of the VEXT command can produce unexpected results when operating in a non-Cartesian coordinate system. For a detailed description of the possible problems that may occur, see Solid Modeling in the ANSYS Modeling and Meshing Guide.
If the area that is being extruded (used as the pattern for the resulting volume) with the VROTAT, VEXT, VOFFST, or VDRAG command is meshed (or belongs to a meshed volume), that mesh will be used as a pattern for the mesh of the volume that is created (see Extruding Meshed Areas). (Compare these commands to the VSWEEP command, which is described in Sweeping Volumes.)
If you are interested in extruding your mesh, follow these steps:
Mesh the area that is to be extruded, dragged, offset, or rotated (using MESH200 elements).
Select an appropriate 3-D element type [ET] (match the shape and number of nodes to the MESH200 element). Activate the selection [TYPE].
Specify the desired number of element divisions in the extruded, rotated, or offset direction (NDIV argument on ESIZE command). If using VDRAG, specify the number of element divisions on the drag path line(s) (LESIZE or ESIZE,,NDIV).
Issue the VROTAT, VEXT, VOFFST, or VDRAG command.
Concatenated areas [ACCAT] or areas that have concatenated lines [LCCAT] cannot be extruded. You can get around the concatenated line limitation by first meshing the area(s), then deleting the concatenated lines, and finally extruding the area(s) into meshed volume(s).
If element attributes have been associated with the pattern area via the AATT command, the opposite area generated by the VDRAG, VEXT, VOFFST, or VROTAT operation will also have those attributes (i.e., the element attributes from the pattern area are copied to the opposite area). Note that only the area opposite the pattern area will have the same attributes as the pattern area; the areas adjacent to the pattern area will not.
Use the following command to make the generation of meshed volumes from 2-D models easier:
Command(s):
Use the following command to make the generation of meshed volumes from 2-D models easier:
Command(s):
EXTOPT
GUI:
Main Menu> reprocessor> Modeling> Operate> Extrude> Elem Ext Opts
Main Menu> Preprocessor> Meshing> Mesh> Volume Sweep> Sweep Opts
EXTOPT controls options relating to the generation of volume elements from area elements using the VEXT, VROTAT, VOFFST, VDRAG, and VSWEEP commands. It enables carry-over of material attributes, real constant attributes, and element coordinate system attributes of the pattern area elements to the created volume elements (except for VSWEEP as noted below).
The EXTOPT control options include the following:
When using VEXT, VROTAT, VOFFST, or VDRAG, you can set controls to carry-over material attributes, real constant attributes, and element coordinate attributes of the pattern area elements to the meshed volume elements. (When using VSWEEP, since the volume already exists, use the VATT command to assign attributes before sweeping.)
When using VEXT, VROTAT, VOFFST, or VDRAG, you can set controls to carry-over particular attributes (materials, real constants or element coordinate systems) of the pattern area elements to the generated volume elements or you can set controls to use particular attributes (material, real constants or element coordinate systems) of the current MAT, REAL, and ESYS command settings for the generated volume elements.
You can set controls to set the number of element divisions and spacing ratio in the direction of volume generation.
When using VEXT, VROTAT, VOFFST, or VDRAG, you can set controls to clear the pattern area mesh when volume generations are done. (When you are using VSWEEP, if selected, the area meshes on the pattern (source), target, and/or side areas clear when volume sweeping is done.)
The carry-over of the attributes of the pattern area elements saves you time that would otherwise be required to prepare the 3-D model extrusion of multiple areas with differing attributes.
Figure 5.13. Extruding (and Scaling) Meshed Areas Into Meshed Volumes
5.2.5.3. Sweeping Volumes
To fill an existing unmeshed volume with elements by sweeping the mesh from an adjacent area throughout the volume:
Command(s):
VSWEEP
GUI:
Main Menu> Preprocessor> Meshing> Mesh> Volume Sweep> Sweep
When you use the VROTAT, VEXT, VOFFST, and VDRAG commands to extrude a meshed area into a meshed volume, ANSYS creates the volume and the volume mesh simultaneously. In contrast, you use the VSWEEP command in an existing unmeshed volume. Thus VSWEEP is particularly useful when you are importing a solid model that was created in a CAD program.
For detailed information about volume sweeping, see Generating a Volume Mesh By Sweeping of this manual, as well as the description of the VSWEEP command in the ANSYS Commands Reference. |
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