## 4 PBF-LB/M Process
### Design
#### 4.1.2 Structural Optimization
\"\({\rho_{i}}\)\" is the density of the ith element, and the parameter \"P\" denotes the penalization factor, with a range of 1 < \(P\)\(\leq\) 3. \"\(k_{0}\)\" signifies the stiffness of the ith element before penalization. Components designed through TO often include free forms and intricate shapes that are complex or impossible to manufacture with traditional production methods. However, these designs are ideally suited to the PBF-LB/M process, which offers more flexibility in design rules and can efficiently reproduce complex geometries without incurring additional costs [113; 114]. The advantages of combining topology optimization with AM technology can be categorized into saving both money and time by using reduced material and avoiding additional costs. By reducing the weight, the TO can lower fuel consumption and emissions, increase payload and range, and enhance the maneuverability and agility of the aerospace or mobility industry [115]. However, the practical adoption of these optimized designs depends not only on their performance benefits but also on the ability to manufacture them efficiently and cost-effectively. The complexity of topology-optimized and lattice structures can pose challenges in production, particularly in ensuring dimensional accuracy, minimizing defects, and achieving consistent mechanical properties. Process parameters, material selection, and advanced post-processing techniques play a crucial role in overcoming these hurdles. While the initial design phase, computational simulations, and extended production times may lead to higher upfront costs, these can be offset by long-term benefits such as material savings, improved efficiency, and enhanced performance throughout the component lifecycle. In fact, this approach aids in overcoming design challenges, particularly in creating lightweight components for many industrial fields such as automotive and aerospace. Several case studies on the TO of aerospace components, such as the connector support of the VEGA space launcher, a typical lever component from civil aircraft, a housing part from fan cowl structures, and a jet engine bracket, demonstrate mass reductions ranging from 20 to 60% [116; 117]. Also, several case studies on the topology optimization of automotive components have shown significant improvements. For example, brake calipers achieved a 41.6% mass reduction, the steering upright became 9% lighter than the reference component, and the optimized automotive knuckle part exhibited a stiffness increase of more than 2.5 times compared to the original design [118; 119; 120]. Furthermore, this approach is particularly appreciated when combined with the use of lightweight, high-performance alloys. To cite an outstanding example, APWorks has developed the world first 3D-printed motorcycle utilizing PBF-LB/M technology and the patented Scalmalloy(r) material [121]. This innovative creation, illustrated in Figure 6a, known as the Light Rider, stands out as an exceptionally lightweight model, weighing just 35 kg [46]. Its 6 kW electric motor propelsit from zero to 80 km/h within seconds, demonstrating impressive acceleration. The motorcycle frame, a mere 6 kg, contributes to its remarkable 30% weight reduction compared to conventionally manufactured e-motorcycles. APWorks employed an algorithm to design the Light Rider's optimized structure, achieving a minimal weight while ensuring frame robustness to endure everyday driving demands and stresses. RUAG Space has developed an optimized antenna bracket, measuring 40 cm in length, for Sentinel satellites using PBF-LB/M with AlSi10 Mg (Figure 6b). Engineers redesigned and optimized this part using Altair ProductDesign which is SIMP-based software 2023, followed by production utilizing an EOS M400 machine.