Eight-node brick element (C3D8 and F3D8)

The C3D8 element is a general purpose linear brick element, fully integrated (2x2x2 integration points). The shape functions can be found in [36]. The node numbering follows the convention of Figure 53 and the integration points are numbered according to Figure 54. This latter information is important since element variables printed with the *EL PRINT keyword are given in the integration points.

Figure 53: 8-node brick element

Figure 54: 2x2x2 integration point scheme in hexahedral elements

Although the structure of the element is straightforward, it should not be used in the following situations:

• due to the full integration, the element will behave badly for isochoric material behavior, i.e. for high values of Poisson's coefficient or plastic behavior.
• the element tends to be too stiff in bending, e.g. for slender beams or thin plates under bending. [74].

The F3D8 element is the corresponding fluid element.