PSI - Issue 72

E.B. Galkina et al. / Procedia Structural Integrity 72 (2025) 222–228

224

a

b

Fig. 1. Manufacturing technology of the studied samples: (a) 3D printer Designer XL Pro S2; (b) scheme of the FDM/FFF printing method.

Fig. 2. The scheme of the samples for measuring residual strains, mm.

The studied materials include three thermoplastic polymers commonly used in FDM 3D printing: acrylonitrile butadiene styrene (ABS), polylactide (PLA), and polyethylene terephthalate glycol (PETG). The main printing parameters for each material are presented in Table 1.

Table 1. The main technological parameters of 3D-printing for the studied materials № Material Nozzle temperature, °С Bed temperature, °С

Layer height, mm

Print speed, mm/min

Fan speed, % Chamber cooling, %

1 2 3

PLA

210 235 250

60 70

100

PETG

20

0

0.2

40

ABS

105

0

Residual strain measurements in the samples were performed using optical backscatter reflectometry with an OSI-D reflectometer. A detailed description of the OBR operating principle, its features, and applications can be found in works (Katrenova et al. (2024), Xu et al. (2024)). Residual strain measurements are conducted in several stages: 1. Strain registration using distributed FOS starts before embedding the optical fiber into the material under study. 2. Fiber placement and fixation occur after pausing the printing process at a predetermined height. The optical fiber is secured in two designated slots (through-holes):  In the first slot, the optical fiber is fixed without additional coatings, except for a protective polyimide coating, which remains functional up to 300°C. This optical fiber section is exposed to both mechanical strain and temperature variations.  In the second slot, the optical fiber which has a diameter of 0.15 mm is enclosed in a Teflon tube with an inner diameter of 0.5 mm. One end of the Teflon tube extends outside the sample, where it is bonded with the optical fiber using an adhesive joint. This configuration ensures temperature transmission while preventing mechanical strain transfer to this section of the optical fiber, thereby enabling temperature compensation for strain readings on the first fiber section according to the following ratio:

( cK      T

)

(1)