PSI - Issue 61

Jose Beltra Mira et al. / Procedia Structural Integrity 61 (2024) 156–163 Author name / Structural Integrity Procedia 00 (2024) 000–000

158

3

PLA

(a)

(b)

W = 30 mm B = 6 mm

W = 40 mm B = 8 mm

W = 50 mm B = 10 mm

(c)

Fig. 1. (a) Example CT specimens, (b) example experimental setup, and (c) example data collection from CT tests.

properties. Note that the samples here were printed using the same rolls of material used to print the compact tension samples used in this study.

ABS

PLA

PC

Flat ±45°

Flat 0/90°

Horiz ±45°

Horiz 0/90°

Flat ±45°

Flat 0/90°

Horiz ±45°

Horiz 0/90°

Flat ±45°

Flat 0/90°

Horiz ±45°

Horiz 0/90°

1000 1200 1400

1000 1200 1400

1000 1200 1400

0 200 400 600 800

0 200 400 600 800

0 200 400 600 800

Force (N)

Force (N)

Force (N)

0 0.1 0.2 0.3 0.4 0.5 0.6

0 0.1 0.2 0.3 0.4 0.5 0.6

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Strain (mm)

Strain (mm)

Strain (mm)

Fig. 2. Examples of force-deflection curves for each of the 12 cases. One curve for each was randomly selected for each combination from the five replications of the experiment.

Table 2. Calculated material properties over five replications of the experiment. These properties will be used to calculate K Q and the sample dimensions required for plane strain.

Yield Stress (MPa)

Elastic Modulus (GPa)

Elongation at Yield (%)

n

Material

Mean

Stdev

Mean

Stdev

Mean

Stdev

ABS 20 32.36 PC 20 54.23 PLA 20 47.84

4.54 9.17 5.79

2.01 2.36 2.97

0.19 0.15 0.34

1.96 3.11 2.47

0.09 0.78 1.84

3. Results After completing three replications of each test ( n = 27), the mean and standard error SE = σ/ √ n from each factor combination was calculated. These data are shown in Table 3 and Figure 3 below. The conditional fracture toughness K Q was calculated from the collected data and basic properties, as shown in Table 4. In order to establish if any of the samples met the requirements of ASTM D5045 for plane strain condition and can be used as K IC values, the minimum sample dimensions (thickness B , crack length a , and ligament L = ( W − a )) were calculated and are also shown in Table 4 below. Given the actual versus minimum ligament length, crack length a , and the sample thicknesses B , it is clear that none of the samples met the criteria [ B , a , L = ( W − a )] > 2 . 5( K Q /σ y ) 2 of this standard for K IC and therefore will be referred to as K Q values for the remainder of this study. Note that the values of σ y came from the property calculations shown in Table 2.