Lattice materials represent one of the utmost applications of additive manufacturing. The promising synergy between additive processes and topology optimization finds full development in achieving components that comprise bulky and hollow areas, as well as intermediate zones. Yet, the potential to design innovative shapes can be hindered by technological limits. The article tackles the manufacturability by laser-based powder bed fusion (L-PBF) of aluminum-based lattice materials by varying the beam diameter and thus the relative density. The printing accuracy is evaluated against the distinctive building phenomena in L-PBF of metals. The main finding consists in identification of a feasibility window that can be used for development of lightweight industrial components. A relative density of 20% compared with fully solid material (aluminum alloy A357.0) is found as the lowest boundary for a 3-mm cell dimension for a body-centered cubic structure with struts along the cube edges (BCCXYZ) and built with the vertical edges parallel to the growth direction to account for the worst-case scenario. Lighter structures of this kind, even if theoretically compliant with technical specifications of the machine, result in unstable frameworks.

Lattice structures, whose manufacturing has been enabled by additive technologies, are gaining growing popularity in all the fields where lightweighting is imperative. Since the complexity of the lattice geometries stretches the technological boundaries even of additive processes, the manufactured structures can be significantly different from the nominal ones, in terms of expected dimensions but also of defects. Therefore, the successful use of lattices needs the combined optimization of their design, structural modeling, build orientation, and setup. The article reports the results of quasi-static compression tests performed on BCCxyz lattices manufactured in a AlSi7Mg alloy using additive manufacturing. The results are compared with numerical simulations using two different approaches. The findings show the influence of the relative density on stiffness, strength, and on the energy absorption properties of the lattice. The correlation with the technological feasibility points out credible improvements in the choice of a unit cell with fewer manufacturing issues, lower density, and possibly equal mechanical properties.

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This paper presents a comparison between the experimental investigation and the Finite Element (FE) modal analysis of an automotive rear subframe. A modal correlation between the experimental data and the forecasts is performed. The present numerical model constitutes a predictive methodology able to forecast the experimental dynamic behaviour of the structure. The actual structure is excited with impact hammers and the modal response of the subframe is collected and evaluated by the PolyMAX algorithm. Both the FE model and the structural performance of the subframe are defined according to the Ferrari S.p.A. internal regulations. In addition, a novel modelling technique for welded joints is proposed that represents an extension of ACM2 approach, formulated for spot weld joints in dynamic analysis. Therefore, the Modal Assurance Criterion (MAC) is considered the optimal comparison index for the numerical-experimental correlation. In conclusion, a good numerical-experimental agreement from 50 Hz up to 500 Hz has been achieved by monitoring various dynamic parameters such as the natural frequencies, the mode shapes, and frequency response functions (FRFs) of the structure that represent a validation of this FE model for structural dynamic applications.

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