Experimental Characterization of Composite-Printed Materials for the Production of Multirotor UAV Airframe Parts

Abstract

In this paper, the characterization of 3D-printed materials that are considered in the design of multirotor unmanned aerial vehicles (UAVs) for specialized purposes was carried out. The multirotor UAV system is briefly described, primarily from the aspect of system dynamics, considering that the airframe parts connect the UAV components, including the propulsion configuration, into a functional assembly. Three additive manufacturing (AM) technologies were discussed, and a brief overview was provided of selective laser sintering (SLS), fused deposition modeling (FDM), and continuous fiber fabrication (CFF). Using hardware and related software, 12 series of specimens were produced, which were experimentally tested utilizing a quasi-static uniaxial tensile test. The results of the experimental tests are provided graphically with stress-strain diagrams. In this work, the focus is on CFF technology and the testing of materials that will be used in the production of mechanically loaded airframe parts of multirotor UAVs. The experimentally obtained values of the maximum stresses were compared for different technologies. For the considered specimens manufactured using FDM and SLS technology, the values are up to 40 MPa, while for the considered CFF materials and range of investigated specimens, it is shown that it can be at least four times higher. By increasing the proportion of fibers, these differences increase. To be able to provide a wider comparison of CFF technology and investigated materials with aluminum alloys, the following three-point flexural and Charpy impact tests were selected that fit within this framework for experimental characterization.

Keywords: additive manufacturing; continuous fiber fabrication; fiberglass reinforcement; material experimental characterization; multirotor UAV airframe parts; uniaxial tensile test.

Figure 1

Multirotor UAV platform: (a) quadrotor heavy-lift prototype; (b) hexarotor 3D model.

Figure 2

Examples of 3D-printed airframe parts.

Figure 3

SLS technology—schematic overview.

Figure 4

AM technologies—schematic overview: (a) FDM; (b) CFF.

Figure 5

Test specimen (ISO 527-2 [45] standard test specimen for uniaxial quasi-static tensile testing)—G-code generation in a slicer.

Figure 6

Additive manufacturing and experimental measurements flow chart.

Figure 7

Experimental equipment: (a) SHIMADZU AG-X; (b) performing quasi-static uniaxial tensile stress on the test specimen.

Figure 8

S09 test specimen with concentric fiber reinforcement.

Figure 9

CFF—fiber reinforcement angles.

Figure 10

Integrated experimental procedure for material characterization.

Figure 11

Stress–strain diagram for specimen 1 (S01) series experimental measurements.

Figure 12

Stress–strain diagram for S02 experimental measurements.

Figure 13

Stress–strain diagram for S03 experimental measurements.

Figure 14

Stress–strain diagram for S04 experimental measurements.

Figure 15

Stress–strain diagram for S05 experimental measurements.

Figure 16

Stress–strain diagram for S06 experimental measurements.

Figure 17

Stress–strain diagram for S07 experimental measurements.

Figure 18

Stress–strain diagram for S08 experimental measurements.

Figure 19

Stress–strain diagram for S09 experimental measurements.

Figure 20

Stress–strain diagram for S10 experimental measurements.

Figure 21

Stress–strain diagram for S11 experimental measurements.

Figure 22

Stress–strain diagram for S12 experimental measurements.

Figure 23

Mean values of the maximum stress regarding PLA and PETG materials.

Figure 24

Mean values of the maximum stress regarding default print parameters for PLA, PETG, PA 12, and Onyx materials.

Figure 25

Mean values of the maximum stress regarding CFF technology using Onyx and fiberglass reinforcement.

Figure 26

Three-point flexural test—equipment and test execution.