METHOD OF EVALUATION OF CRITICAL STRAIN DURING LOCAL SHEET STAMPING Russian patent published in 2008 - IPC G01N3/28 

FIELD: mechanic.

SUBSTANCE: the invention relates to the machine engineering. The peripheral zones of the sample are preliminary pressed down and a spherical pit is pulled until a neck forms or the sample breaks. Before the beginning of deformation, two kinds of grade grid, square and radial, are applied to the work piece. During processing of the grade grids, the radial one is used to determine the direction of the main axes of the deformation tensor, and the square grid is used to determine the deformation intensity near the neck being formed or the destruction area. The cell dimensions for calculations are taken from its unfolded pattern tangent to the outer surface of spherical pit in the point of intersection of the cell diagonal lines.

EFFECT: increased accuracy of determining of critical strain of material deformation.

3 cl, 6 dwg