PSI - Issue 72

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

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where T  — spectral shift measured in a section of optical fiber that does not experience mechanical strain change;  — spectral shift in a section of optical fiber subject to both strain and temperature changes;  — central wavelength of the scan; с — the speed of light; K  — strain sensitivity coefficient. 3. Once the FOS is embedded, the printing process resumes until the next designated pause or until the sample fabrication is complete. 4. After printing, the manufactured sample with embedded fiber-optic sensors remains inside the inactive 3D printer chamber to cool gradually to ambient temperature while FOS readings are recorded. A view of one of the studied samples during the FOS embedding stage is shown in Fig. 3.

Fig. 3. The stage of embedding FOS into PLA sample during manufacturing.

3. Results and discussion Fig. 4 – 6 shows the results of measuring residual strains in parallelepiped samples for PLA, PETG, and ABS, respectively. The obtained data is presented as a set of graphs. In the central part, a two-dimensional heat map illustrates the distribution of strains along the sample length (y-axis) over time (x-axis). The color scale represents the strain levels. In this graph, two dotted lines indicate slices of the strain distribution over time (black dotted line) and along the sample length (red dotted line), with their corresponding graphs positioned at the bottom and to the right of the central graph, respectively.

Fig. 4. Residual strain change in PLA along the length of the sample over time.

Fig. 5. Residual strain change in PETG along the length of the sample over time.