Patent ID: 8190408

Claim:
A method of numerically predicting surface imperfection in a stoning operation of a stamped sheet metal part using a finite element method (FEM) mesh model comprising: receiving, in a computer system, a FEM mesh representing a stamped sheet metal part, the FEM mesh containing a plurality of nodes and a plurality of two-dimensional finite elements, wherein each of the two-dimensional finite elements are defined by corner nodes and edges between each adjacent pair of corner nodes; selecting a stoning direction with respect to the FEM mesh, the stoning direction corresponding to one of a stoning operation's directions; establishing a group of neighboring elements for each of the two-dimensional finite elements intersected by the stoning direction; creating a continuous smooth surface in a group-to-group scheme using the group of neighboring elements established earlier; and examining the continuous smooth surface's cross-section in the stoning direction to determine whether there is a surface imperfection, wherein the cross-section information is stored in a storage device and graphically displayed to a monitor upon a user's instruction.