PSI - Issue 34

Atefeh Rajabi Kafshgar et al. / Procedia Structural Integrity 34 (2021) 71–77 Atefeh Rajabi Kafshgar et al./ Structural Integrity Procedia 00 (2021) 000 – 000

74

4

Where n and Y i are the number of orthogonal arrays and response variable, respectively.

Table 2. Orthogonal array and the mechanical properties' value Num# A B C D Ultimate Tensile Stress (MPa)

Elongation at Break (%)

Modulus of Elasticity (GPa)

Yield Strength (MPa)

Toughness (J)

1 2 3 4 5 6 7 8 9

20 200 90 0.1 20 200 45 0.2 20 220 90 0.2 20 220 45 0.1 40 200 90 0.1 40 200 45 0.2 40 220 90 0.2 40 220 45 0.1 60 200 90 0.1 60 200 45 0.2 60 220 90 0.2 60 220 45 0.1

20.71 17.67 19.79 21.36 24.18 22.24 26.14 25.31 26.23 25.22 28.67 29.43

3.33 4.40 3.69 4.33 4.08 4.49 3.59 4.56 4.28 5.51 4.45 4.40

1.04 0.72 0.93 0.89 0.95 0.91 1.19 1.06 1.22 1.00 1.20 1.21

17.27 10.96 14.14 12.78 14.49 15.18 20.07 17.76 19.05 15.99 19.42 21.27

0.46 0.74 0.47 0.58 0.59 0.89 0.53 0.65 0.76 1.19 0.77 0.85

10 11 12

Fig. 2 shows the result and suggestions of the Taguchi method for stress, elongation, elastic modulus, strength, and toughness values, reprehensively. Graphs show the mechanical properties' behavior in different levels of printing factors. It can be seen that “Infill Density” has a significant effect on all outputs. According to Fig. 1, raster angle and layer thickness have less effect on the UTS value. Moreover, the results show that besides infill density, layer thickness has a significant effect on elongation at break and toughness values as well. It is achievable from the results that increasing the infill density, extrusion temperature, and raster angle and decreasing layer thickness improves the UTS, modulus of elasticity, and yield strength of the PLA 3D printed tensile test sample.

(c)

(a)

(b)

(d)

(e)

Fig. 2. Mean effect plots for SN ratio for (a) Ultimate Tensile Stress, (b) Elongation at Break, (c) Modulus of Elasticity, (d) Yield Strength, (e) Toughness obtained from the Taguchi method applied for the results of tensile strength tests made of 3D printed PLA material.

Thus, the best treatment combination for the UTS, modulus of elasticity, and yield strength is infill density of 60%, extrusion temperature of 220 o C, and raster angle of 90 o , and layer thickness of 0.1mm. On the other side, the best treatment combination for elongation at break and toughness is obtained with an infill density of 60%, extrusion temperature of 200 o C, raster angle of 45 o , and layer thickness of 0.2mm. The best level of factors for each mechanical property is also summarized in Table 3. The result describes that 60% infill density is the best level of infill destiny parameter but there is no unique printing configuration that optimizes all mechanical properties.