Plot > Average Box

Calculates the weighted average value for all selected contour points.

You will be prompted to select the two corners of the window by picking each with a single mouse click. Only those contour points enclosed in the window will be included. To view the location of the actual contour points enable display of trajectories (Plot > Options > Trajectories). The contour points are located where the trajectories are drawn.

The averaging is done by multiplying each selected value by the area of its associated surface or grid patch, then summing these. This result is presented as the "Weighted Sum". The "Average" is determined by dividing the weighted sum by the total area.

All values are accumulated as vector components. Principal stresses are determined from the weighted mean of the Cartesian components. Displacement, flow and surface shear components are determined from the weighted mean of the vector components.

Note that for stresses, the "Weighted Sum" is actually the total force acting on the surface.

If you multiply by the shear modulus, the "Weighted Sum" of the plastic shear displacement (ride) is actually the Seismic Moment.

Complex polygonal shapes can be defined using Plot > Polygon Box.