The process of discretizing geometry into a collection of elements is called meshing. The collection of finite elements representing the geometry is called the finite element mesh. The simplest way to create a finite element mesh is to use a finite element pre-processor, such as Altair HyperMesh.
The mesh consists of nodes (grid points) and elements. In OptiStruct, the GRID card provides the coordinates of a node (grid point) in relation to a user-defined coordinate system or the basic coordinate system. The format of a GRID card is shown below:
Example: Grid point ID 101 - has coordinates 1.0, 1.0, 0.0 relative to the basic coordinate system.
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GRID |
101 |
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1.0 |
1.0 |
0.0 |
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Elastic element cards begin with the letter C. There is a wide range of element types available in OptiStruct (See the Elements section on the List of Bulk Data Entries (by function)); the majority of these reference one or more nodes and a geometric property card, in the manner shown in the following examples:
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Example: Rod element - Element ID 79 - connecting nodes 44 and 45 - references property ID 3. |
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CROD |
79 |
3 |
44 |
45 |
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Example: 4-noded quadrilateral element - Element ID 23 - connecting nodes 101, 102, 103 and 104 - referencing property ID 2. |
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CQUAD4 |
23 |
2 |
101 |
102 |
103 |
104 |
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Example: 20-noded hexahedral element - Element ID 179 - connecting nodes 70 through 89 - referencing property ID 4. |
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CHEXA |
179 |
4 |
70 |
71 |
72 |
73 |
74 |
75 |
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76 |
77 |
78 |
79 |
80 |
81 |
82 |
83 |
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84 |
85 |
86 |
87 |
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89 |
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