PSI - Issue 56

Cosmin Florin POPA et al. / Procedia Structural Integrity 56 (2024) 176–183 Popa Cosmin-Florin/ Structural Integrity Procedia 00 (2019) 000–000

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The shear specimens were produced in two configurations: the first with two layers contour and the second without contour. Both configurations were printed with the same raster orientation at 0 degrees. Six specimens of each type were printed, as depicted in Fig. 1. Fig. 1 a) displays a specimen without a contour, revealing an irregular outline and rough filament ends. In contrast, Fig. 1 b) illustrates a specimen with a contour, displaying a smooth surface without any roughness. These observations highlight the influence of contour presence, on the final surface quality of the 3D printed PETG specimens.

Fig. 1 The printed specimens a) without contour and b) with contour.

Fig 2 The test setup used for the experiment.

The specimens were measured before the painting, the dimensions are shown in Table 1.

Table 1 The specimen dimensions Specimens without contour

Specimens with contour

Specimen

Width

Thickness

Specimen

Width

Thickness

P1 P2 P3 P4 P5 P6

5.10 4.99 5.00 4.89 5.03 4.78

6.35 6.29 6.32 6.29 6.33 6.35

P1c P2c P3c P4c P5c P6c

5.09 5.06 5.11 5.02 5.03 5.06

6.35 6.35 6.36 6.38 6.37 6.38

. The Dantec Q-400 Digital Image Correlation (DIC) system comprises two 5-megapixel greyscale cameras strategically positioned on either side of the red-light source, precisely at the center of the specimen. For illumination, Dantec HILIS LED technology was employed, ensuring better precision in measurements. Data acquisition was facilitated through a trigger unit, offering both analog and digital input/output channels. Instra4D software was employed for data processing and visualization purposes. First, to conduct the tests, a meticulous calibration procedure was executed to ensure the accuracy of the measurements. Calibration involved the use of a BNB 9x9 plate. During these tests, the Global Residual was determined to be 0.240. Image capture occurred at a rate of 1 Hz, for each camera. To optimize visibility and minimize reflectivity, the specimens were meticulously prepared. They were coated with multiple layers of white paint until the surfaces achieved complete whiteness. Subsequently, a light-speckle pattern, created using black paint, was applied over the area of interest on the specimens. The tests were performed on the Zwick tensile machine with a 5 kN load cell. The specimens were clamped in each half of the specimen, remaining in the interest area of the specimen. The specimen was loaded with a speed of 5 mm/min in displacement control. The collection of the necessary strain data was accomplished through the use of DIC