## 4 PBF-LB/M Process
### Design
#### 4.1.2 Structural Optimization
By enhancing the structural design, they achieved a stiffness increase of over 30% above the minimum requirement while reducing the weight from 1.60 to 0.94 g. This improvement represents a substantial performance enhancement along with a weight reduction exceeding 40% compared to the conventionally manufactured component [122,123]. The second primary strategy for achieving lighter structures is latticing. Lattice structures are composed of repeating unit cell elements in three-dimensional space. Thanks to AM, lattices offer numerous advantages: they enhance object strength, reduce mass by using less material, lower production costs by shortening build times, decrease fuel usage through lighter component weight, and minimize material waste. To design lightweight structures with high mechanical performance, natural structures such as cork, sea urchins, honeycombs, and trabecular bone are often used as models. The three most common families of lattice structures are: surface-based lattices, strut lattices (periodic and stochastic), and planar-based lattices. Architected materials are precisely engineered structures designed to achieve specific, controlled physical responses. This class of materials exhibits novel or customized behaviors through the interaction of their intrinsic material properties and carefully designed geometries. Lattice structures are a subset of architected materials, consisting of repeating networks of interconnected nodes and beams (or other structural elements), often optimized for mechanical performance. By utilizing lattice-based designs, these materials can precisely manipulate thermal, electromagnetic, mechanical, or biological properties. Architected materials enable fine-tuning of a component behavior by modifying its geometry at the mesoscale, such as in auxetic materials, which exhibit a negative Poisson ratio, rather than relying solely on changes to the material microstructure [124, 125, 126]. Employing lattice structures facilitates component lightweighting, effectively reducing part weight while preserving structural integrity. Latticing provides the means to decrease solid mass without compromising performance. Additionally, lattices can be fine-tuned to construct high-energy or shock-absorption structures. For instance, auxetic lattice structures, characterized by their negative Poisson ratio, exhibit excellent behavior in  
Figure 6: Examples of topology-optimized structures manufactured by PBF-LB/M: (**a**) the Light Rider, the first 3D-printed electric motorcycle by APWorks [121] and (**b**) an optimized antenna bracket for RUAG Sentinel satellites [123]. energy absorption and damping. Moreover, lattice structures inherently offer a large surface area, making them ideal for heat transfer and particularly advantageous for thermal management and heat exchanger applications [127]. Figure 7 depicts various applications of lattice structures, including heat exchangers (a), orthopedic implants (b), and vibration isolation (c). With the synergic use of TO and latticing, the highest levels of lightweightness, and thus sustainability and efficiency, can be achieved. A case study where TO and latticing were used for the structural optimization of the VEGA space launcher connector support made of aluminum alloy Al7075 is illustrated in Figure 8[117]. The optimized configurations resulted in a weight reduction of up to 63%. The latticing design strategy, which includes incorporating grid structures into the holes produced by the optimization process, was adopted to enhance manufacturability. In particular, grid structures were used on topology-optimized configurations, which strongly reduced the amount of support needed. This optimization also resulted in a weight reduction of connector supports by about 57% compared to the main component [117]. Figure 8: Case study of VEGA space launcher connector support optimization by TO and latticing [117].