The "Approximate Principal Strains"-component expects as input a reference model (input-plug "Model") and the same model in a deformed configuration (input-plug "def.Model"). The deformed model can be the output of a "ModelView"-component. Hand over a list of points to the input-plug "Point" where principal strain directions shall be computed. For each point in this list the following two steps are applied: First those three nodes of the reference model that do not lie on a line and have minimum distance to the given point are determined. Second the strains in the sides of the thus found triangle determine the principal strain directions -- plane stress is assumed. The conversion of first (output-plug "VT1") and second principal strains (output-plug "VT2") to vectors occurs in such a way that they align with the average displacement of the triangle that defines the corresponding strain-state. The size of the vectors emanating from "VT1" and "VT2" can be scaled by providing a factor in the input-plug "Scale".