Table 1‑2 lists the four methods available in Patran to create finite elements.

The IsoMesh method is the most versatile for creating a finite element mesh. It is accessed by selecting:

IsoMesh will mesh any untrimmed, three- or four-sided set of biparametric (green) surfaces with quadrilateral or triangular elements; or any triparametric (blue) solids with hedahedral, wedge or tetrahedral elements.

Mesh density is controlled by the “Global Edge Length” parameter on the mesh form. Greater control can be applied by specifying a mesh seed which can be accessed by selecting:

Mesh seeds are applied to curves or edges of surfaces or solids. There are options to specify a uniform or nonuniform mesh seed along the curve or edge.

Paver is used for any trimmed (red) surface with any number of holes. Paver is accessed in the same way as IsoMesh except the selected Object must be Surface. Mesh densities can be defined in the same way as IsoMesh. The mesh seed methods are fully integrated and may be used interchangeably for IsoMesh and Paver. The resulting mesh will always match at common geometric boundaries.

TetMesh is used for any solid, and is especially useful for unparametrized or b-rep (white) solids. TetMesh is accessed the same way as IsoMesh, except the selected Object must be Solid. Mesh densities can be defined in the same way as IsoMesh. The mesh seed methods are fully integrated and may be used interchangeably for IsoMesh and TetMesh. The resulting mesh will always match at common geometric boundaries.

Multi-point constraints (MPCs) provide additional modeling capabilities and include a large library of MPC types which are supported by various analysis codes. Perfectly rigid beams, slide lines, cyclic symmetry and element transitioning are a few of the supported MPC types available in Patran.

Translate, rotate, or mirror nodes and elements.

Create a solid mesh by either extruding or arcing shell elements or the face of solid elements.

The Finite Element application’s Renumber option is provided to allow direct control of node and element numbering. Grouping of nodes and elements by a number range is possible through Renumber.

Create database associations between finite elements (and their nodes) and the underlying coincident geometry. This is useful when geometry and finite element models are imported from an outside source and, therefore, no associations are present.

Meshing creates coincident nodes at boundaries of adjacent curves, surfaces, and⁄or solids. Equivalencing is an automated means to eliminate duplicate nodes.

To use your computer effectively, it is important to number either the nodes or the elements in the proper manner. This allows you to take advantage of the computer’s CPU and disk space for the analysis. Consult your analysis code’s documentation to find out how the model should be optimized before performing Patran’s Analysis Optimization.

Sometimes it is difficult to determine if the model is valid, such as, are the elements connected together properly? are they inverted or reversed? etc. This is true--even for models which contain just a few finite elements. A number of options are available in Patran for verifying a Finite Element model. Large models can be checked quickly for invalid elements, poorly shaped elements and proper element and node numbering. Quad element verification includes automatic replacement of poorly shaped quads with improved elements.

The Finite Element application’s Show action can provide detailed information on your model’s nodes, elements, and MPCs.

Modifying node, element, and MPC attributes, such as element connectivity, is possible by selecting the Modify action. Element reversal is also available under the Modify action menu.

Deleting nodes, elements, mesh seeds, meshes and MPCs are available under the Finite Element application’s Delete menu. You can also delete associated stored groups that are empty when deleting entities that are contained in the group.