CTETRA 1st-order (4-noded) Element Checks

The following qualities of the CTETRA 1st-order element are checked:

The aspect ratio of a CTETRA 1st-order element is defined as the maximum of the aspect ratio of its four triangular faces. Each face is treated as a CTRIA3 element.

The face skew angle of a CTETRA 1st-order element is defined as the maximum of the skew angles of its four triangular faces. Each face is treated as a CTRIA3 element.

The same vertex angle check is performed for all of the faces, and each is treated as a triangular (CTRIA3) or quadrilateral (CQUAD4) element. The minimum and maximum values reported for the element.

The collapse of a CTETRA 1st-order element is defined as the minimum of four values, each calculated as the ratio between the distance from a vertex to its opposing face, and the square root of the area of the opposing face.

collapse = MIN (hi / sqrt(Ai)       i = 1,2,3,4

The reported value is normalized by 1.2408, which gives the equilateral tetra a collapse value of 1. As the tetra collapses, the collapse value approaches 0.

An edge angle is the absolute value of the angle between two faces sharing a common edge subtracted from 90 degrees. The edge angle (EA) of a CTETRA 1st-order element is defined as the maximum of its six edge angles.

EA = MAX | 90 - ANGLE(Nki, Nli)     i = 1, ..., 6

Where, Nki and Nli are the normal vectors of faces k and l that have a common edge i.

 

CTETRA 2nd-order (10-noded) Element Checks

The following qualities of the CTETRA 2nd-order element are checked:

This quality is calculated using only the corner nodes. Its definition is the same as that used for the CTETRA 1st-order element.

This quality is calculated using only the corner nodes. Its definition is the same as that used for the CTETRA 1st-order element.

This quality is calculated using only the corner nodes. Its definition is the same as that used for the CTETRA 1st-order element.

This quality is calculated using only the corner nodes. Its definition is the same as that used for the CTETRA 1st-order element.

This quality is calculated using only the corner nodes. Its definition is the same as that used for the CTETRA 1st-order element.

The hoe normal and tangent offsets of the CTETRA 2nd-order element are defined as the maximum of the hoe normal and tangent offsets of its 6 edges, respectively. See the definition of hoe normal offset of 3-node edge.

The hoe normal and tangent offsets of the CTETRA 2nd-order element are defined as the maximum of the hoe normal and tangent offsets of its 6 edges, respectively. See definition of hoe tangent offset of 3-node edge.

 

CTETRA Default Bounds

The values used for warning and error checks may be adjusted by the ELEMQUAL bulk data entry, but validity checks are hard-coded.

See Also:

Element Quality Check