# Towards an Automated Design Evaluation Method for Wire Arc Additive Manufacturing
## 4 Results on Example Geometries  
We used an example bar part with several design flaws (left-hand side) and corresponding corrections (right-hand side) to demonstrate and verify our implementation (see Figure 7). The smallest wall thickness measures 1 mm (not manufacturable) while the largest wall thickness is around 29 mm, and leads to a mass accumulation. The part exhibits 13 concave and 13 convex edges, rounded with a radius of at least 5 mm on the right-hand side and, conversely, sharp-edged on the left-hand side. In the center, a tapered slot was introduced with an angle of 11\({}^{\circ}\) and a maximum opening of 10 mm to test the detection of small angles and small clearances. The implementation classifies most elements properly and reveals all intended design errors in our example. However, our implementation of the shrinking ball algorithm reports minor convergence issues. In our test example for 99 out of 50,014 points (\(\approx\)2.0%), the iteration aborted by reaching the maximum number of iterations instead of meeting the empty sphere criteria. Nonetheless, for most of these elements, the results were still valid, since the last iterations all yielded the same values. The resulting approximated medial surfaces for the inner and outer 3D-MAT, respectively, are presented in Figure 8a,b. The center points are color-coded from blue to red for small to large radii. While the results look mostly as expected like a local symmetry plane of the geometry, the right-hand side of the outer medial surface shows loosely spread center points around the rounded edges. This originates from the surface discretization: on a perfectly round continuous surface, every tangent sphere would have an infinite radius and thus the center point would be infinitely far away from the surface (as is the case for the plane surfaces). However, through the surface discretization, the triangle's normal vectors are deviated and the tangential spheres intersect with adjacent triangles, resulting in non-infinite sphere radii. Figure 9a-f show the results of the manufacturability evaluation; critical elements are highlighted in their severity from yellow to red. The wall thickness and clearance rule properly detect the corresponding design flaws and do not highlight any false positives. Only the thin wall element does not appear as a plane face but is spotted, which relates to irregular angle results in that region, which are used as a classification filter. Figure 7: Example bar part to verify our implementation. Design flaws on the left-hand side, and corresponding corrections on the right-hand side. All dimensions are indicated in millimeters. The edge rules generally show the same results as the thickness and clearance rules. However, the critically thin wall is classified as edge, which is caused by the same angle-related issue as reported above. On interpreting the results, it has to be noted that the  
Figure 8: Approximations of the medial surfaces of the example part. The center points of the inscribed spheres are color-coded by their radius in millimeters. Figure 9: Evaluation results on the example part. For each feature, non-manufacturable faces are highlighted with a color scale from yellow to red with ascending constraint violation. upper left rounding radius has the same value as the radius limit; therefore, they would be manufacturable. Furthermore, the bottom layer edges would be manufacturable too, despite being highlighted properly according to the defined rule. Since in the WAAM process a part is built up on a base plate, it is possible to manufacture sharp edges on the base layer. Nevertheless, since our implementation has no information on the part's build orientation, this detail cannot be considered. The low angle between the middle bars and the radius gradients is detected as well. However, while the angle shows clear results, the gradient classification shows issues. The thin wall is again falsely included, and some elements were not filtered out in the transitions from corner to wall.