According to exemplary embodiments of the present invention, using a
fracture limit stress line obtained by converting a hole expansion ratio
into a stress as a criterion for a fracture, the risk of fracture in a
material can be evaluated quantitatively by comparing the relationship
between data obtained from a numerical analysis using a finite element
method and the fracture limit stress line. Thus, when determining a
fracture limit in a stretch flange portion in a thin plate in a process
including one or more deformation path variations, it is possible to
obtain the fracture limit curve easily and efficiently and predict the
fracture with high accuracy, and the risk of fracture upon press forming
or crash can be evaluated.