LOCAL_TRIADS Switch: Display of Element Local Axes

LOCAL_TRIADS switch: Display of element local axes

Solid, shell, thick-shell, beam and interface elements all have local coordinate systems, and you can display "local" triads of their axes using this switch. The figure below left shows examples of local triads on solids, and the figure below right, on beams and shells.

The method used to compute element local axes is given in the following section:

Solids	Transforming Directional Solid Results to the Element Local System	In all cases D3PLOT generates local axes from the element topology alone. Note that it does NOT currently "know" about any local material axes, beta angles or ply directions. From D3PLOT 13.0 onwards a local ply X axis can also be plotted (see Ply local X axis ).
Thin shells	Thin shell coordinate systems
Thick shells	Frame of Reference: Computing the Local Coordinate System
Beams	"Basic" Components for All Beams
Segments	Contact segments use the same method as thin shells.

An easier way of spotting reversed outward normals of shells and interface segments

The local Z axes (outward normals) of shells and interface segments are important in some contexts. For shells averaging across adjacent elements with top and bottom surfaces flipped gives misleading contours, and for interface segments some types of contact surface cause problems if their outward normals face the wrong way.

Therefore, as well as being able to display local triads, you can plot their OUTWARD_NORMAL components in CT continuous-tone plots. This plots normals that face you in magenta, and those that face away from you on blue. It makes it easy to spot elements that face the wrong way: certainly it is easier than hunting for reversed local Z axes using triads!