Fracture resistance curves (R-curves) with normalised axes

Data from the literature have been re-analysed and are presented here as further evidence supporting the proposed modification to the abscissa of a fracture resistance or R-curve in order that a unique curve is obtained for a given material. Results are also detailed, from geometrically similar pieces and from a regime of fully plastic plane strain, that give a unique R-curve without normalisation. Yet other data which are in or near a plane stress fracture mode do not fall within any of the above categories and are argued to require scaling on the ordinate.