When the nodes of the model have been generated, the next step is to define the elements. The region is subdivided into triangular elements by considering four nodes that form a quadrilateral such as the area in Fig. 4. The interior quadrilaterals can be left as elements or they may be further divided into triangular elements by inserting the shortest diagonal into each interior quadrilateral. The length of the two diagonals are calculated and compared. The elementary quadrilateral is then subdivided into two triangular elements using the shortest diagonal. This procedure is repeated until all sets of four nodes havebeen analysed. Division using the shortest diagonal is preferable because elements close to an equilateral shape produce more accurate results than long narrow triangles.
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Fig. 4. A set of four nodes divided into two triangular finite elements. |
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