Lightweight Metal Cellular Structures Fabricated via 3D Printing of Sand Cast Molds

Abstract

Cellular structures offer high specific strength and can offer high specific stiffness, good impact absorption, and thermal and acoustic insulation. A major challenge in fabricating cellular structures is joining various components. It is well known that joints, either welded or bolted or bonded with an adhesive, serve as stress concentrators. Here, we overcome this shortcoming by the use of metal casting into 3D printed sand molds for fabricating cellular structures and sandwich panels. Furthermore, the use of 3D printing allows for the fabrication of sand molds without the need for a pattern, and thus enables the creation of cellular structures with designed mesostructure from a bevy of metal alloys. We use the finite element method to numerically analyze the energy absorption capabilities of an octet truss cellular structure created with the proposed manufacturing process and that of a solid block of the same material and area density as the cellular structure. In the numerical simulations, mechanical properties collected through experimental quasi-static compression testing are employed. It is found that indeed the cellular structure absorbs considerably more impact energy over that absorbed by a solid structure of the same weight.

Casting of complex structures in aluminum using gypsum molds produced via binder jetting

“…In particular in case of thinner parts as the D_CA_60_5 and D_CA_60_7.5 geometries to a fragmentation of the part itself. This fragmentation is coherent with the weakness measure from (Snelling et al , 2015) and (Kim et al , 2018) in case of the lattice structure demonstrators. However, the focus was on the gypsum resistance to complex part production, and the results confirm that its application in the sand casting process could be investigated.…”

“…In particular in case of thinner parts as the D_CA_60_5 and D_CA_60_7.5 geometries to a fragmentation of the part itself. This fragmentation is coherent with the weakness measure from (Snelling et al , 2015) and (Kim et al , 2018) in case of the lattice structure demonstrators.…”

Additive manufacturing as an emerging technology for fabrication of microelectromechanical systems (MEMS)

“…Source: Reprinted with permission from Snelling et al 142 Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.…”

Investigation of process parameter effect on anisotropic properties of 3D printed sand molds

“…A minimum nominal strength is required for an easy manipulation of the mold and good dimensional accuracy of the casting. This rigidity should be obtained with a minimum 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 binder resolution (XR = 140 µm), that means small Loss-On-Ignition values, to reduce the off-gassing that hinders the filling of the sand mold cavity [5,13,14,29].…”