DATA SET 8: ELEMENT INCIDENCES

Element incidences for NEL elements are needed if KSTR = 0. Usually, a total of NEL records are needed. However, if a group of elements appear in regular pattern, automatic generation is made. Each record contains the following variable and is FREE-FORMATTED. All variables are specified regardless of problem dimensionality. For example, for a quadrilateral element in two dimensions, specify IE(MI,1) to IE(MI,4) with positive integers or node numbers and set IE(MI,5) to IE(MI,8) to zero. This latter set of zeros are required and are used to identify the shape of the element. Similar rules apply to line elements (two nodes) in one dimension, triangular elements (three nodes) in two dimensions, tetrahedrons (four nodes), pentahedrons (six nodes), and hexahedrons (8 nodes) in three dimensions.

1. MI = Global element number of the first element in a sequence,

2. NSEQ = NSEQ subsequent elements will be automatically generated,

3. MIAD = Increment of MI for each of the NSEQ subsequent elements,

4. IE(MI,1) = Global node number of the first node of element MI.

5. IE(MI,2) = Global node number of the second node of element MI.

6. IE(MI,3) = Global node number of the third node of element MI.

7. IE(MI,4) = Global node number of the fourth node of element MI.

8. IE(MI,5) = Global node number of the fifth node of element MI.

9. IE(MI,6) = Global node number of the sixth node of element MI.

10. IE(MI,7) = Global node number of the seventh node of element MI.

11. IE(MI,8) = Global node number of the eighth node of element MI.

12. IEMAD = Increment of IE(MI,1) through IE(MI,8) for each of the NSEQ elements.

NOTE: A line with twelve 0's must be used to signal the end of this data set.

Note that node numbers are entered into the IE(,) array according to the following convention. For one-dimensional problems, the nodes should be numbered consecutively. Node numbers of quadrilateral and triangular elements should be entered counterclockwisely. In three dimensions, the first four nodes of a hexahedron start from the front, lower, left corner and progress around the bottom element surface in a counterclockwise direction. The other four nodes begin from the front, upper, left corner and progress around the top element surface in a counterclockwise direction. Similar convention is used for pentahedrons. For tetrahedrons, the three nodes at the base of the elements should be entered counterclockwisely first and the top node the last. For all other positions in array IE(,) that are not used, zero should be entered.

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