# An Optimization Workflow in Design for Additive Manufacturing
## 2 Design Workflow
Once the optimized part is modeled, it is necessary to perform an additional FE analysis to mechanically validate the final model. This step is mandatory in topology optimization because during the modeling phase weak zones could arise, especially if manual remodeling is adopted. After that, process-related considerations are done. Process planning deals with all the necessary operations needed once the AM production technology and machine have been selected. The orientation of the part inside the manufacturing machine, the generation of the supports (if needed), and the generation of the print path strategy affect the quality of the printed part, i.e., the surface texture and the mechanical properties [26], the material and energy consumption, and the production time [62; 63; 64]. Then, process simulation helps to predict residual stress and geometric distortion of the printed parts, avoiding time-consuming and expensive experimental campaigns based on trial and error. The evaluation of residual stresses and thermal distortions allows compensating the geometrical CAD model obtaining parts with the desired dimensional specifications and mechanical properties, reducing the probability of defects that lead to crack initiation, propagation, and failure both during the printing and the utilization of the product, especially when dealing with metallic components [65]. Process simulation methods that concentrate not only on metals AM techniques [66; 67; 68; 69] but also on material extrusion [70; 71] and powder bed fusion [72; 73] of polymers can be found. If the FE analysis fails to validate the component or if the manufacturing process simulation highlights dimensional deformation and residual stresses higher than requirements, it is necessary to remodel the part or to step back to the optimization phase, changing the boundary conditions of the model. When all these steps are successfully completed, the part is ready to be produced. The component is optimized for the intended use and it is likely to not encounter manufacturing issues during the printing phase. An important consideration is whether to use the topology optimization or the size optimization approach. One option could be to apply both and compare the solutions, choosing the one that best suits the application, but it is computationally demanding. Some a priori thoughts can help to decide as well. If the part is metallic, the struts of the lattice could act as internal supports, heat dissipators, and prevent thermal warping. Furthermore, being less bulky, the lattice structure could present lower residual stress. The mechanical validation of a lattice structure requires high computational resources and it is time consuming due to the high number of 3D elements needed to mesh the structure; at the same time, while the FE validation analysis is mandatory for the topology optimized part because the manual remodeling phase can introduce weak areas, it is less necessary for the lattice structure model because the diameters of the beams were previously optimized through a FE analysis and in the presented mesh modeling approach the optimized value is adopted at the middle of the beam, whereas the diameter tends to increase towards the nodal points.