Method for the local evaluation of non-linear expansion paths and their associated limit strain of at least one metallic sheet material formed by a forming process by means of a limit shape curve

摘要

The invention relates to a method for the local evaluation of non-linear expansion paths and their associated limit expansions of at least one metallic sheet metal material formed by a forming process by means of at least one limit shape change curve. For the improved prognosis of failure points, the following method steps are carried out: for a component of at least one metallic sheet material, the nonlinear expansion paths that occur during the forming process are determined at selected component points by means of a forming simulation program and visually represented in a strain diagram by the two inplane In the strain diagram, through the experimentally determined failure points of the metallic sheet material, as a limit strain curve, the 0-FLC defining the material of the metallic sheet material is placed for each point within the strain gauge Strain diagram is given an associated comparative stress-strain ellipse as φ-isoline, which is also shown in the strain diagram, at least one non-linear strain path is shown in d in the expansion diagram, wherein a strain portion of the non-linear strain path representing a pre-strain forming an actual strain increment is displaced in the strain diagram along the comparative ellipse until the direction of effect of the strain extension representing a follow elongation passes through the zero point of the strain diagram, the new pre-strain point is determined on the basis of which the pre-strain and the following elongation accumulating accumulates up to 0-FLC and the failure point of the metallic sheet material of the component is predetermined.