To specify or characterize a product to be expected under a specified load, create not only a corresponding characterized product but also a method for characterizing the product.

Over many defined plotters and field points 9 a product composed of nonlinear piezoelectric material 1, a distribution of characteristic linear modules is generated. Each of the modules is defined as the inclination of a broken line stretching from a zero reference point to a point corresponding to the plot or the field point 9 with respect to each of the plots and the field points 9, in one pertaining characteristic curve 10.