## 5 Applicability on Various Technologies
### Additive Manufacturing for Optronics Parts  
This second study emphasizes the potential opportunities offered by switching to a new mode of mechanical design, namely a \"Design By Additive Manufacturing\" (DBAM), with an application in the aeronautics and defense fields. A global design approach in five steps, created as a modular framework, is suggested to be introduced in this new methodology [52]. The study was conducted by a team of designers from a financing company, composed of three people of various qualifications and experience. **Step I1:** The main lever targeted in this study is to try and manage the complexity of assemblies as early as the design phase. If complexity is reduced, benefits are expected in terms of lower assembly costs and improvements to the reliability of final products. **Step I2:** The technology identified to cope with this lever is additive manufacturing. This choice of technology has a direct impact on the design phase: a reliable design needs to be considered as soon as possible in terms of the way it will be manufactured in order to enhance the time to market of the product. A new manufacturing technology implies a major change in the way the parts are designed, and in this case on the whole design methodology. **Step I3:** The study relies on a single part, denoted \"4 mirrors head\". This choice was made because of the complexity of the assembly (five parts) relative to the small size of the product (about 1 dm\({}^{3}\)). Being an embedded component of a mobile device, some design parameters, such as weight and stiffness for example, need to be as enhanced if possible. In the same way, over 20 different functions are defined for the final product or its direct neighborhood. The objective of the design is to increase the number of functions the final assembly can fulfill. **Step P4:** The indicators defined in this step are quite simple: the number of components of the final assembly to optimize the main lever, number of functions fulfilled by the assembly, weight, and stiffness to optimize its embedded behavior and some other product performance criteria in order to validate its behavior in any circumstance. **Step P5:** The team of designers created a first assembly, manufactured using classical machining. This product was composed of five components and was able to fulfill 16 functions at 260 g. This was chosen as the lower bound of the study, as it was the result of the best performance from the engineers of the company with the tools at their disposal before additive manufacturing. **Step P6:** This step is not documented in this study. During design processes, this is generally an implicit step, performed in parallel with an evaluation of the functional requirements specifications. The optimal solution is a virtual assembly of the only material necessary to achieve the expected functionalities, without considering the physical or technological constraints necessary for the use or manufacture of the product. **Step S7:** This step is mostly built around the use of the DBAM methodology: knowledge synthesis, product specification, concept generation, control, and finally design and evaluation using computer-aided design. A design loop for topological optimization, using a Finite element simulation, was also used in order to generate the shapes for the best compromise between weight and stiffness. The result is a single part, fulfilling 20 functions, at a weight of 245 g.  
**Step S8:** The simulation phase was developed by making some prototype parts in SLA and polymer. These prototypes were designed to evaluate the notions of ergonomics and perform some mountability tests. The reliability aspect was not explicitly tested. These prototypes also validated the coherence between CAD-defined shapes and actual shapes obtained by additive manufacturing with this specific design. **Step 19:** The preparation of implementation was performed thanks to the first prototypes of the final part on the actual machine, made in SLM and aluminum AS7G06.