Abstract: Forming limit diagrams (FLD-s) deliver quantitative, graphical information concerning the ultimate ductility material my display under various strain conditions and boundary criterion of material failure in a deep drawing process. FLD-s are commonly obtained by usage of special samples – the so-called Nakazima’s bands. This method is realized in general as a circle grid is printed on the sheet surface and its deformation is measured after the forming. Different deformations transform the circles to ellipses, exhibiting a different eccentricity. A software system for quantitative determination the changes in lengths of both major and minor axes of ellipses, is presented in this report. The grid deformed images are captured in computer memory by a digital camera, equipped with a mechanical piece, allowing the camera optical axis to maintain orthogonal upon each local area of specimen surface. An interactive way of operator-computer work is proposed for ellipses geometry analysis. The two axes of each ellipse of interests are measured and data derived are presented graphically, and recorded in a data base as well. Using this information the main deformations of samples are calculated after that.

Keywords: deep drawing, plastic deformations, forming limit diagrams.

ACM Classification Keywords: C.4 Performance of systems- Measurement techniques

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A SOFTWARE SYSTEM FOR DETERMINATION OF FORMING LIMIT DIAGRAMS

Georgi Stoilov, Jordan Genov, Vasil Kavardzhikov, Jordan Kovachev