PSI - Issue 41

N.A. Fountas et al. / Procedia Structural Integrity 41 (2022) 638–645 Author name / Structural Integrity Procedia 00 (2019) 000–000

641

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The “dog bone” geometry for the experimental specimens were 4mm thick as per ASTM D638 and fed to SolidWorks ® CAD environment in STL format. A Craftbot ® Plus 3D printer was employed to fabricate the specimens. Its platform is made of aluminum, thus providing the capability for printing specimens using different types of material. The maximum volume of the vat was 250 x 200 x 200 (mm), whilst the PS was up to 200 mm/sec. The material under study was the commercially available NEEMA 3D™ WOOD PLUS consisting of 30 % coconut wood fibers / additives, and 70 % pure PLA polymer. The filament diameter was 1.75 mm. The density was 1.2 g/cc (ASTM D1505), the melting point for the material is between 140-150°C, and the nozzle's diameter was 0.4mm. Fig.1a shows the geometry of the experimental specimen and Fig.1b the printing process.

Fig. 1. (a) “Dog bone” tensile test specimen as per the ASTM D638 (b) Printing process in Craftbot® Plus 3D printer.

The experimental results in terms of tensile tests according to the systematic design of experiments that L18 mixed level design suggests, are presented in Table 2.

Table 2. Experimental results according to L18 mixed level Taguchi OA design.

FFF parameters

Objective

Experiment no.

NT ( o C)

LT (mm)

RDA (deg.)

PS (mm/sec)

UTS (MPa)

1 2 3 4 5 6 7 8 9

0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3

180 180 180 200 200 200 220 220 220 180 180 180 200 200 200 220 220 220

0

30 40 50 30 40 50 40 50 30 50 30 40 40 50 30 50 30 40

17.420

7.043 5.480

45 90

15.410 10.240

0

45 90

7.745

16.920 12.580 10.010 16.920 12.145 15.420 12.080 10.010 15.210 12.007 10.150 8.970

0

45 90

10 11 12 13 14 15 16 17 18

0

45 90

0

45 90

0

45 90