A NONSTANDARD SYMMETRY-BREAKING PHENOMENON IN SHEET-METAL STRETCHING

Mathematical models for stamping of metal blanks are based upon the ph ysical principles of equilibrium of forces, material constitutive laws and constraints resulting from contact between the blank and the pres s itself. We investigate singularities in the differential algebraic e quation (DAE) resulting from one such model. In particular, the inabil ity of numerical integrators to preserve anticipated symmetries in its solution as time advances is shown to be due to singularities on or c lose to the solution curve.