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The degree to which lattice structure fabricated by additive manufacturing (AM) processes matches the original solid model depends on a number of factors, some of which include type of AM process, machine characteristics, and powder utilized. Although some thresholds on dimensions or orientation for 3D-printed simple bars or plates are available in...
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... A wide range of common strut-and surface-based lattices were considered. The thresholds of 0.4 and 0.3 mm were used for strut diameter and wall thickness (recommended by Ref. [21]). Table 1 summarizes dimension and topology of the samples and corresponding volume fractions (relative density). ...
... Table 1 summarizes dimension and topology of the samples and corresponding volume fractions (relative density). To achieve homogeneous geometry, the samples are oriented two 45° around two axes and printed on one corner [21]. Large structural support is considered to avoid thermal distortion and residual stress. ...
Lattices are popular choice for energy absorption. This work is an attempt to extend the application of metallic lattices beyond this application. If enough energy is absorbed at low impact loads, it would revolutionize their application as protective structures. Significant number of tests were conducted to determine energy and impact absorption property/capacity for several topologies and densities at different rates. A suitable parameter representing impact was discussed, and energy-impact diagrams were developed for optimum performance. An optimum design point was identified to benefit fully from plateau behavior leading to high energy absorption at low impact densification stress. The results demonstrated that surface-based lattices absorb higher energy at identical weight compared to strut-based counterparts, but at the cost of imposing higher level of stress (impact) to the object. In comparison, FCC and gyroid show the best performances by absorbing specified energy at the lowest impact loads among their strut- and surface-based counterparts, respectively. FCC is selected as the best topology for low-impact-load applications, while Schwarz D is the best choice for high-energy applications. Some practical cases are studied to demonstrate the application of developed diagrams for protecting humans and goods in the event of an impact.
... In general, the initial part of both load-displacement curves is non-linear and concave. This is due to the deformation of debris left on the surface or flattening of slightly distorted face-plates [11]. As it can be observed in Fig. 3 a, the FCC sample collapses in a layer-by-layer manner. ...
... An EOS M270 was used to print samples from Ti6AlV4 powder with the process parameters recommended by the manufacturer. Ref. [11] examined a wide range of strut-and surface-based lattices and determined 0.4 mm and 0.3 mm as the thresholds for strut diameter and wall thickness, respectively. To reach to homogeneous geometry, the samples were oriented two 45° around two axes and printed on one corner. ...
... To reach to homogeneous geometry, the samples were oriented two 45° around two axes and printed on one corner. Large structural support was considered to avoid thermal distortion and residual stress [11]. ...
Collapse mechanism dictates plateau behavior for a lattice. Sharp large drops in this region are due to formation of diagonal shear bands. They may ruin energy absorption capacity of lattice. This paper is an attempt to evaluate the possibility of improving collapse mechanism in favor of energy absorption. A significant number of tests were conducted to investigate the influence and effectiveness of changes in cell topology, solid material properties, and relative density. It was demonstrated that alteration of solid material properties (through heat treatment) as well as relative density can affect fluctuations in the plateau region significantly. This has been possible through replacing shear bands with normal layer failure, or through thickening the shear band and smoothening the transitions. One of the practical achievements for this study is that the best energy absorption performance was obtained at relative density ranging from 20 to 30%. At this range, the specific absorbed energy (energy per unit weight) reaches its maximum peak for all examined lattices. However, magnitude of the peak is highly dependent on the lattice topology. This highlights the superiority of lattices as engineered structures over conventional metallic foams. Among the wide range of examined strut- and surface-based lattices, face-centered cubic (FCC) and Schwarz D lattices performed the best for weight-sensitive energy absorption applications.
... Microscope images in conjunction with image processing software offer an alternative noncontact measurement approach. High-resolution microscope images of the part can be captured and processed using specialized software such as ImageJ [11,12]. The software employs image analysis algorithms to extract planar dimensional information such as distances, angles, and feature sizes. ...
Due to its exceptional electrical and thermal conductivity, pure copper is frequently employed in industry as the base metal for thermal management and electromagnetic applications. The growing need for complicated and efficient motor designs has recently accelerated the development of copper additive manufacturing (AM). The present work aims to improve the power density of the copper laser powder bed fusion (Cu-LPBF) coil by increasing the slot-filling factor (SFF) and the electrical conductivity. Firstly, the dimensional limitation of Cu-LPBF fabricated parts was identified. Sample contouring and adjusting beam offset associated with optimum scan track morphology upgraded the minimum feature spacing to 80 μm. Accordingly, the printed winding's slot-filling factor increased to 79% for square wire and 63% for round wire. A maximum electrical conductivity of 87% (IACS) was achieved by heat treatment (HT). The electrical impedance of full-size Cu-LPBF coils, newly reported in this study, was measured and compared with solid wire. It can reflect the performance of Cu-LPBF coils (power factor) in high-frequency applications. Furthermore, surface quality benefited from either sample contouring and HT, where the side surface roughness was lowered by 45% and an additional reduction of 25% after HT.
