Effective Mechanical Properties of AlSi7Mg Additively Manufactured Cubic Lattice Structures

Abstract

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.

Architected Materials for Additive Manufacturing: A Comprehensive Review

“…More specifically, the size effect influences the mechanical properties through a specific scaling law formula. According to the existing literature [ 19 , 20 , 21 ], the effective mechanical properties of every architected material are dependent on the applied relative density in exponential relation via the aforementioned scaling laws. Furthermore, lattice structures, with intense exponential relation ( n > 2) between the mechanical properties and relative density, reveal low stiffness and strength with an extensive plateau after the yield point at the stress–strain diagram; this mechanical response is defined as bending-dominated behavior [ 22 , 23 ].…”

On the Technological Feasibility of Additively Manufactured Self‐Supporting AlSi10Mg Lattice Structures

“…[21] New approaches are proposing the adoption of neural networks that allow tuning the desired mechanical response in much shorter computational times. [22] Simulation is addressed in many studies today [10,18,[23][24][25] with a special attention to the development of plastic and damage models.…”

“…[14] The need for a standard characterization protocol for the assessment, preliminary to mechanical testing, of the lattice dimensions and microstructure, is well recognized in literature. [20] The authors' previous contributions [23,27] reported the manufacturability and numerical/experimental compressive behavior of body-centered cubic unit cells, with the addition of reinforcement beams in the X, Y, and Z directions (BCCxyz, Figure 1a). It emerged that horizontal beams (i.e., the beams along X and Y DOI: 10.1002/adem.202201074…”

“…The authors’ previous contributions [ 23,27 ] reported the manufacturability and numerical/experimental compressive behavior of body‐centered cubic unit cells, with the addition of reinforcement beams in the X, Y, and Z directions (BCCxyz, Figure a). It emerged that horizontal beams (i.e., the beams along X and Y directions) encountered severe production difficulties, due to their nonself‐supporting nature, if specimens are produced with the Z beams aligned to the build direction of the PBF machine.…”

“…[ 28 ] For applications where the direction of loads under operating conditions is well predicted, the BCCz cell may represent a solution with an efficient distribution of mass that avoids defective, little load‐bearing, horizontal struts. [ 23 ] In the present study, technological feasibility of BCCz cells is analyzed in terms of 1) actual density as compared to the nominal one; 2) dimensional accuracy, separately for different orientations and error sources, up to the calculation of the international tolerance (IT) grade; and 3) presence/absence of defects, cracks, and irregular shapes. Output quality is evaluated for varying beam diameter, cell size, and relative density.…”