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### Twenty-node brick element (C3D20 and F3D20)

The C3D20 element is a general purpose quadratic brick element (3x3x3 integration points). The shape functions can be found in [33]. The node numbering follows the convention of Figure 46 and the integration scheme is given in Figure 47.

This is an excellent element for linear elastic calculations. Due to the location of the integration points, stress concentrations at the surface of a structure are well captured. However, for nonlinear calculations the elements exhibits the same disadvantages as the C3D8 element, albeit to a much lesser extent:

- 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. [68].

The F3D20 element is the corresponding fluid element.

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**Contents**guido dhondt 2012-10-06