Numerically estimating a pre-stamped shape of a workpiece used for manufacturing a product/part with deep draw metal stamping

1. A method of obtaining a pre-stamped shape of a workpiece used for manufacturing a product/part comprising:

receiving, in a computer system having at least a finite element analysis (FEA) based application module installed thereon, a three-dimensional (3-D) mesh model representing a 3-D geometry of a product or part manufactured with deep draw metal forming process, the 3-D mesh model containing a plurality of nodes connected by a plurality of shell finite elements;

modifying, with the application module, the 3-D mesh model by converting a quadrilateral shell finite element to triangular shell finite elements;

calculating, with the application module, respective averaged nodal curvatures of the nodes of the 3-D mesh model based on the 3-D geometry;

creating, with the application module, a two-dimensional (2-D) mesh model by unfolding the 3-D mesh model to a plane while maintaining all of the corresponding triangular shell finite elements between the 2-D mesh model and the 3-D mesh model as similar triangles; and

obtaining, with the application module, an estimated pre-stamped shape of a workpiece used for manufacturing the product or part by iteratively updating the 2-D mesh model with a set of internal nodal forces of the triangular shell finite elements based on deformations with respect to the corresponding triangular shell finite elements of the 3-D mesh model and with a set of nodal force adjustments based on the respective averaged nodal curvatures, whereby the shape of the converged 2-D model is the estimated pre-stamped shape of the workpiece.

2. The method of claim 1 , said calculating the respective averaged nodal curvatures further comprises:

calculating, with the application module, an averaged edge curvature of an edge that is shared by two adjacent triangular shell finite elements for all edges in the 3-D mesh model; and

calculating, with the application module, the averaged nodal curvature at each node in the 3-D mesh model by averaging respective averaged edge curvatures of all edges connected to said each node.

3. The method of claim 2 , wherein the averaged edge curvature is calculated as a function of respective geometric centers of the two adjacent triangular shell finite elements and the share edge's mid-point.

4. The method of claim 1 , said creating the two-dimensional (2-D) mesh model further comprises solving a set of simultaneous equations for two unknown nodal coordinates at each node of the 2-D mesh model, the simultaneous equations being set up from theorems of similar triangles for the corresponding triangular shell finite elements between the 3-D mesh model and the 2-D mesh model.

5. The method of claim 1 , said obtaining the estimated pre-stamped shape of the workpiece used for manufacturing the product or part further comprises:

(b) obtaining, with the application module, a set of projected nodal positions by projecting all nodes of the 3-D mesh model onto the plane, on which the 2-D mesh model is located;

(c) adjusting, with the application module, the set of internal nodal forces by adding a nodal force adjustment at each node of the 2-D mesh model, the nodal force adjustment being a function of the averaged nodal curvature in a direction defined by said each node of the 2-D mesh model and the corresponding projected nodal position;

(d) determining, with the application module, whether the 2-D mesh model has converged; and

if not converged, updating, with the application module, the 2-D mesh model due to the set of internal nodal forces and repeating (b)-(d);

otherwise, designating the 2-D mesh model as the estimated pre-stamped shape of the workpiece.

6. A system for obtaining a pre-stamped shape of a workpiece used for manufacturing a product/part comprising:

a memory for storing computer readable code for at least a finite element analysis (FEA) based application module;

at least one processor coupled to the memory, said at least one processor executing the computer readable code in the memory to cause the application module to perform operations of:

receiving a three-dimensional (3-D) mesh model representing a 3-D geometry of a product or part manufactured with deep draw metal forming process, the 3-D mesh model containing a plurality of nodes connected by a plurality of shell finite elements;

modifying the 3-D mesh model by converting a quadrilateral shell finite element to triangular shell finite elements;

calculating respective averaged nodal curvatures of all nodes of the 3-D mesh model based on the 3-D geometry;

creating a two-dimensional (2-D) mesh model by unfolding the 3-D mesh model to a plane while maintaining all of the corresponding triangular shell finite elements between the 2-D mesh model and the 3-D mesh model as similar triangles; and

obtaining an estimated pre-stamped shape of a workpiece used for manufacturing the product or part by iteratively updating the 2-D mesh model with a set of internal nodal forces of the triangular shell finite elements based on deformations with respect to the corresponding triangular shell finite elements of the 3-D mesh model, and with a set of nodal force adjustments based on the respective averaged nodal curvatures, whereby the shape of the converged 2-D model is the estimated pre-stamped shape of the workpiece.

7. The system of claim 6 , said calculating the respective averaged nodal curvatures further comprises:

calculating an averaged edge curvature of an edge that is shared by two adjacent triangular shell finite elements for all edges in the 3-D mesh model; and

calculating the averaged nodal curvature at each node in the 3-D mesh model by averaging respective averaged edge curvatures of all edges connected to said each node.

8. The system of claim 7 , wherein the averaged edge curvature is calculated as a function of respective geometric centers of the two adjacent triangular shell finite elements and the share edge's mid-point.

9. The system of claim 6 , said creating the two-dimensional (2-D) mesh model further comprises solving a set of simultaneous equations for two unknown nodal coordinates at each node of the 2-D mesh model, the simultaneous equations being set up from theorems of similar triangles for the corresponding triangular shell finite elements between the 3-D mesh model and the 2-D mesh model.

10. The system of claim 6 , said obtaining the estimated pre-stamped shape of the workpiece used for manufacturing the product or part further comprises:

(b) obtaining a set of projected nodal positions by projecting all nodes of the 3-D mesh model onto the plane, on which the 2-D mesh model is located;

(c) adjusting the set of internal nodal forces by adding a nodal force adjustment at each node of the 2-D mesh model, the nodal force adjustment being a function of the averaged nodal curvature in a direction defined by said each node of the 2-D mesh model and the corresponding projected nodal position;

(d) determining whether the 2-D mesh model has converged; and

if not converged, updating the 2-D mesh model due to the set of internal nodal forces and repeating (b)-(d);

otherwise, designating the 2-D mesh model as the estimated pre-stamped shape of the workpiece.

11. A non-transitory computer readable medium containing instructions which, when executed in one or more processors, perform a method of obtaining a pre-stamped shape of a workpiece used for manufacturing a product/part, the method comprising:

receiving a three-dimensional (3-D) mesh model representing a 3-D geometry of a product or part manufactured with deep draw metal forming process, the 3-D mesh model containing a plurality of nodes connected by a plurality of shell finite elements;

modifying the 3-D mesh model by converting a quadrilateral shell finite element to triangular shell finite elements;

calculating respective averaged nodal curvatures of all nodes of the 3-D mesh model based on the 3-D geometry;

creating a two-dimensional (2-D) mesh model by unfolding the 3-D mesh model to a plane while maintaining all of the corresponding triangular shell finite elements between the 2-D mesh model and the 3-D mesh model as similar triangles; and

obtaining an estimated pre-stamped shape of a workpiece used for manufacturing the product or part by iteratively updating the 2-D mesh model with a set of internal nodal forces of the triangular shell finite elements based on deformations with respect to the corresponding triangular shell finite elements of the 3-D mesh model, and with a set of nodal force adjustments based on the respective averaged nodal curvatures, whereby the shape of the converged 2-D model is the estimated pre-stamped shape of the workpiece.

12. The non-transitory computer readable medium of claim 11 , said calculating the respective averaged nodal curvatures further comprises:

calculating an averaged edge curvature of an edge that is shared by two adjacent triangular shell finite elements for all edges in the 3-D mesh model; and

calculating the averaged nodal curvature at each node in the 3-D mesh model by averaging respective averaged edge curvatures of all edges connected to said each node.

13. The non-transitory computer readable medium of claim 12 , wherein the averaged edge curvature is calculated as a function of respective geometric centers of the two adjacent triangular shell finite elements and the share edge's mid-point.

14. The non-transitory computer readable medium of claim 12 , said creating the two-dimensional (2-D) mesh model further comprises solving a set of simultaneous equations for two unknown nodal coordinates at each node of the 2-D mesh model, the simultaneous equations being set up from theorems of similar triangles for the corresponding triangular shell finite elements between the 3-D mesh model and the 2-D mesh model.

15. The non-transitory computer readable medium of claim 12 , said obtaining the estimated pre-stamped shape of the workpiece used for manufacturing the product or part further comprises:

(b) obtaining a set of projected nodal positions by projecting all nodes of the 3-D mesh model onto the plane, on which the 2-D mesh model is located;

(c) adjusting the set of internal nodal forces by adding a nodal force adjustment at each node of the 2-D mesh model, the nodal force adjustment being a function of the averaged nodal curvature in a direction defined by said each node of the 2-D mesh model and the corresponding projected nodal position;

(d) determining whether the 2-D mesh model has converged; and

if not converged, updating the 2-D mesh model due to the set of internal nodal forces and repeating (b)-(d);

otherwise, designating the 2-D mesh model as the estimated pre-stamped shape of the workpiece.