Elements that are defined in one configuration can be degenerated or collapsed to create other configurations, while still preserving the number of nodes and element type in the original configuration. For example, the HyperMesh Qaud4 element can degenerate into a Tria3 element, but when exported, the four nodes and quadrilateral element information is written in the solver deck.
Degenerated brick elements are either Hex8 or Hex20 elements, collapsed into a wedge element (Penta6 or Pet15). Penta6 (Element configuration 206) is a 3D, 1st order, triangular prism shape element with a 6 noded order as shown in Figure 1. Hex8 (Element configuration 208) is a 3D, 1st order, brick shape element with a 8 noded order as shown in Figure 2. The Degenerated Brick (Element configuration 206) option is a 3D, 1st order, triangular prism shape element with a 8 noded order as shown in Figure 3.
Standard node order for a 1st order, penta6 element will be 1, 2, 3, 4, 5, 6. In cases of Degenerated Brick elements, the node order will be 1, 2, 2, 4, 5, 6, 6, 8, with nodes 2 and 6 being repeated during export. The same node repetition method is used for a 2nd order, degenerated brick element, but nodes 2 and 6 will be repeated twice and node 18 will be repeated once (1, 2, 2, 4, 5, 6, 6, 8, 9, 10, 2, 12, 6, 14, 15, 16, 17, 18, 18, 20).
Figure 1: Element Configuration 206, 6-noded penta |
Figure 2: Element Configuration 208, 8-noded hexa |
Figure 3: Element Configuration 206, 8-noded penta |
Since the 8-noded, hexa element is degenerated into a 8-noded penta element, the 1st order brick element option is added under the 6-noded penta (Element configuration 206) and the 2nd order brick element option is added under the 15-noded penta (Element configuration 215).