Abstract:Sandwich structures are frequently used in automotive, aerospace and marine industries, as they provide adequate functional properties. The two-dimensional regular hexagonal cell shape, i.e. honeycomb is the most used core structure in sandwich panels. Recently, a new type of cellular structures composed of lattice struts has been proposed, as they combine high stiffness, strength and energy absorption with low weight. The main purpose of this research is to investigate the effect of the lattice topology on t… Show more
“…2,[12][13][14][15][16] Truss or lattice cores have received considerable attention because, in comparison with the honeycomb, they may exhibit superior buckling resistance, at low relative density. 13,16,17 Intensive research was carried out by several researchers to study the mechanical behavior of cellular materials or of honeycomb sandwich panels under different loading conditions. 2,10,11,13,[18][19][20][21][22][23] The most widely studied and used core is the conventional honeycomb made by the repetition of equal hexagonal cells.…”
The aerospace, automotive, and marine industries are heavily reliant on sandwich panels with cellular material cores. Although honeycombs with hexagonal cells are the most commonly used geometries as cores, recently there have been new alternatives in the design of lightweight structures. The present work aims to evaluate the mechanical properties of metallic and polymeric honeycomb structures, with configurations recently proposed and different in-plane orientations, produced by additive and subtractive manufacturing processes. Structures with configurations such as regular hexagonal honeycomb (Hr), lotus (Lt), and hexagonal honeycomb with Plateau borders (Pt), with 0°, 45°, and 90° orientations were analyzed. To evaluate its properties, three-point bending tests were performed, both experimentally and by numerical modeling, by means of the finite element method. Honeycombs of two aluminum alloys and polylactic acid were fabricated. The structures produced in aluminum were obtained either by selective laser melting technology or by machining, while polylactic acid structures were obtained by material extrusion using fused filament fabrication. From the stress distribution analysis and the load–displacement curves, it was possible to evaluate the strength, stiffness, and absorbed energy of the structures. Failure modes were also analyzed for polylactic acid honeycombs. In general, a strong correlation was observed between numerical and experimental results. The results show that the stiffness and absorbed energy increase in the order, Hr, Pt, Lt, and with the orientation through the sequence, 45°, 90°, 0°. Thus, Lt structures with 0° orientation seem to be good alternatives to the traditional honeycombs used in sandwich composite panels for those industrial applications where low weight, high stiffness, and large energy-absorbing capacity are required.
“…2,[12][13][14][15][16] Truss or lattice cores have received considerable attention because, in comparison with the honeycomb, they may exhibit superior buckling resistance, at low relative density. 13,16,17 Intensive research was carried out by several researchers to study the mechanical behavior of cellular materials or of honeycomb sandwich panels under different loading conditions. 2,10,11,13,[18][19][20][21][22][23] The most widely studied and used core is the conventional honeycomb made by the repetition of equal hexagonal cells.…”
The aerospace, automotive, and marine industries are heavily reliant on sandwich panels with cellular material cores. Although honeycombs with hexagonal cells are the most commonly used geometries as cores, recently there have been new alternatives in the design of lightweight structures. The present work aims to evaluate the mechanical properties of metallic and polymeric honeycomb structures, with configurations recently proposed and different in-plane orientations, produced by additive and subtractive manufacturing processes. Structures with configurations such as regular hexagonal honeycomb (Hr), lotus (Lt), and hexagonal honeycomb with Plateau borders (Pt), with 0°, 45°, and 90° orientations were analyzed. To evaluate its properties, three-point bending tests were performed, both experimentally and by numerical modeling, by means of the finite element method. Honeycombs of two aluminum alloys and polylactic acid were fabricated. The structures produced in aluminum were obtained either by selective laser melting technology or by machining, while polylactic acid structures were obtained by material extrusion using fused filament fabrication. From the stress distribution analysis and the load–displacement curves, it was possible to evaluate the strength, stiffness, and absorbed energy of the structures. Failure modes were also analyzed for polylactic acid honeycombs. In general, a strong correlation was observed between numerical and experimental results. The results show that the stiffness and absorbed energy increase in the order, Hr, Pt, Lt, and with the orientation through the sequence, 45°, 90°, 0°. Thus, Lt structures with 0° orientation seem to be good alternatives to the traditional honeycombs used in sandwich composite panels for those industrial applications where low weight, high stiffness, and large energy-absorbing capacity are required.
“…The results of FEA, theoretical and experiments are compared as shown in Figure 21, revealed that the elastic FEA results showed the lower flexural deformation of the sandwich panel concerning the experimental results 78,79 knowing the FEA based on elastic analysis and that perfect bonding between the layers are assumed. It is obvious that experimental results demonstrated higher deformation than the FEA due to the interfacial adhesion incompatibility between dissimilar printed layers in addition to the delay occurred during printing the second material printing sequence.…”
This paper aims to investigate experimentally and using finite element analysis the performance of using three-dimensional printing technology to produce a composite sandwich panel that is made of the high-flexible core as well as with high stiffness upper and lower surfaces made of a glass fiber reinforced composite filament. There are many advantages of using sandwich structures in many applications, especially the aerospace field, where the high stiffness to strength and the lightweight is the most preferred in such applications. The conventional manufacturing methods that are used to produce sandwich panels are limited to particular core geometry, whereas manufacturing a composite core is not possible by these traditional production methods. So by using additive manufacturing technology, it becomes more applicable to design a combination of different geometries and materials to achieve properties that have never been made before, especially combining flexibility and high energy absorption keeping high strength to failure. A central deflection to a length of 0.26 is observed within the elastic zone, a remarkable ratio in beams that reflects the three-dimensional printed sandwich beams’ capability with a highly flexible core to absorb energy that would open doors for many industrial applications that is attributed to the lowest flexural rigidity (167E-3Pa · m4) of the sandwich by using the TriHex infill pattern. In contrast, the Gyroid infill structure could afford the highest central load (0.264 kN). At the peak load applied on the sandwich beam, a maximum error of 5.4% is estimated by finite element analysis lower than the experimental values.
“…A lot of research has been done on the performance of different types of cores and various classifications have been presented by researchers. Figure 3 shows the main types of sandwich cores: foam [19,20], z-pinned [21], corrugated [22,23], lattice [24,25], balsa [26,27], cork [28,29], and composite [30,31]. Figure 3.Classification for sandwich cores.…”
In recent years, concerns about environmental pollution have led to the development of natural fiber sandwich structures as alternatives to petroleum-based ones. This paper reviews various studies on sandwich structures composed of non-wood cellulose-nature fibers. These fibers mainly include flax, hemp, jute, kenaf, sisal, coir, and bamboo. The studies are classified based on the type of fibers, the components in which they are used, and experimental tests/numerical investigations. Furthermore, a few suggestions for future research in the field of eco-friendly sandwich structures are made.
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