Bending simulation method

A simulation method for virtually bending a workpiece, comprising:

• a) setting a workpiece condition of the workpiece to be bent, a tool condition and a target folding angle;
• b) obtaining a first target stroke amount of a punch according to the workpiece condition, the tool condition and the target folding angle;
• c) deforming the workpiece virtually, corresponding to a virtual descent of the punch by the first target stroke amount, and obtaining a deformation image of the workpiece after a spring-back according to an elastoplasticity finite-element method based upon the workpiece condition, the tool condition and the target folding angle;
• d) determining whether a folding angle of the deformation image coincides with the target folding angle by comparing the folding angle and the target folding angle;
• e) when the folding angle and the target folding angle do not coincide in workpiece linear data showing a relationship between the target stroke amount and the folding angle of said deformation image under said first target stroke amount, automatically calculating, based upon the first target stroke amount considering the spring-back of the workpiece, a second target stroke amount so that the folding angle of the deformation image approaches the target folding angle by obtaining an intersection between a straight line obtained by differentiating at a point corresponding to the first target stroke amount and said target folding angle and setting a value located between a target stroke amount corresponding to said intersection and the first target stroke amount as the second target stroke amount;
• f) setting the first target stroke amount equal to the second target stroke amount;
• g) repeating steps c)-f) until the folding angle and the target folding angle coincide;
• and
• h) outputting information including the target stroke amount, spring-back amount, applied pressure and deformation shape.