| 主权项 |
1. A method of conducting a time-marching simulation of scrap trimming operations in sheet metal forming comprising:
receiving, in a computer system having an application module installed thereon, a finite element analysis (FEA) model containing a plurality of finite elements to represent a stamped sheet metal before one or more scrap portions being cut away and a definition of a trimming operation setup that includes respective computerized models for at least one trim steel, at least one trim post and at least one other die structure, the computerized model for each trim steel containing a set of cutting-edge nodes representing said trim steel's cutting edge and a corresponding trim vector defining said each trim steel's cutting direction; establishing, with the application module, at least one trim line on the FEA model by projecting each set of cutting-edge nodes onto the FEA model in accordance with the corresponding trim vector, at least one finite element being crossed by the at least one trim line as a result; creating, with the application module, a series of node-pairs along the at least one trim line at intersections with edges of the at least one crossed finite element, each node-pair including two nodes with same coordinates and said two nodes being connected in all degrees of freedoms (DOFs) with a numerical constraint; modifying, with the application module, the FEA model by splitting said at least one crossed finite element into two or more new finite elements such that each new finite element is properly sized to ensure numerical stability and said each new finite element being defined using one of the two nodes in a corresponding node-pair to ensure no finite element straddles the at least one trim line; dividing, with the application module, the modified FEA model's finite elements into first and second groups separated by said at least one trim line, the first group representing a trimmed portion modeled with rigid finite elements while the second group representing said one or more scrap portions modeled with deformable finite elements; and conducting, with the application module, a time-marching simulation of trimming operations using the modified FEA model along with the received definition of the trimming operation setup, at each solution cycle during the time-marching simulation, the numerical constraint of one or more of the node-pairs that are determined to be reached by one of the cutting-edge nodes is released, and numerically-simulated structural behaviors of said one or more scrap portions are obtained as said second group of finite elements deforms in response to the released numerical constraint, and in response to contacts with said at least one trim steel, with said at least one trim post and with said at least one other die structure. |
