3D FDM production and mechanical behavior of polymeric sandwich specimens embedding classical and honeycomb cores

Abstract

Desktop 3D FDM (Fused Deposition Modelling) printers are usually employed for the production of nonstructural objects. In recent years, the present authors tried to use this technology also to produce structural elements employed in the construction of small UAVs (Unmanned Aerial Vehicles). Mechanical stresses are not excessive for small multirotor UAVs. Therefore, the FDM technique combined with polymers, such as the ABS (Acrylonitrile Butadiene Styrene) and the PLA(Poly Lactic Acid), can be successfully employed to produce structural components. The present new work is devoted to the production and preliminary structural analysis of sandwich configurations. These new lamination schemes could lead to an important weight reduction without significant decreases of mechanical properties. Therefore, it could be possible, for the designed application (e.g., a multifunctional small UAV produced via FDM), to have stiffener and lighter structures easy to be manufactured with a low-cost 3D printer. The new sandwich specimens here proposed are PLA sandwich specimens embedding a PLA honeycomb core produced by means of the same extruder, multilayered specimens with ABS external layers and an internal homogeneous PLA core using different extruders for the two materials, sandwich specimens with external ABS skins and an internal PLA honeycomb core using different extruders for the two materials, and sandwich specimens where two different extruders have been employed for PLA material used for skins and for the internal honeycomb core. For all the proposed configurations, a detailed description of the production activity is given.Moreover, several preliminary results about three-point bending tests, different mechanical behaviors and relative delamination problems for each sandwich configuration will be discussed in depth.

Honeycomb Sandwich Specimens Made of PLA and Produced Via 3D FDM Printing Process: An Experimental Study

“…The proposed lamination sequence should give a marginal increase of the total weight and a consequential important increasing of the bending stiffness. In Brischetto et al (2018), several sandwich configurations were preliminary investigated by considering honeycomb or homogeneous cores and different combinations of PLA and ABS for the skins and the cores. One of the most promising configuration was that here investigated in depth.…”

Characterization of the Mechanical Properties of FFF Structures and Materials: A Review on the Experimental, Computational and Theoretical Approaches

“…FFF parts can be used in a wide range of applications, namely Unmanned Aerial Vehicle (UAV) [12], dentistry [13], electrochemical batteries [14], lattice and cellular materials [15,16,17], sandwich structures [18], tissue engineering scaffolds [11,19,20], and even in parts for 3D printers [21]. Even the food industry has explored the fused deposition process for food, for instance, to print with pasta, pork, pizza dough, chocolate, etc.…”

Mechanical Performances of Lightweight Sandwich Structures Produced by Material Extrusion-Based Additive Manufacturing

“…Further, researchers [ 18 ] have focused their studies on understanding the influence of different sandwich structures (with three different core shapes, hexagon, triangle, and square shapes) taking into account the following parameters: nature of core shape, number of infill shapes, and orientation of cores and the way the dynamic behavior of sandwich structures is influenced. Preliminary studies investigated the manufacture and testing of mechanical performance (bending and tensile) of honeycomb core sandwich structures [ 19 , 20 , 21 ], printed with different materials (PLA and ABS) and using different filling techniques. An initial investigation into the manufacture of continuous carbon fiber sandwich structures without the addition of supports has been carried out [ 22 ].…”