Issue 51

G.S. Serovaev et alii, Frattura ed Integrità Strutturale, 51 (2020) 225-235; DOI: 10.3221/IGF-ESIS.51.18 231 Figure 10 : General view of the experimental setup (a) , microscope (b) . In the Fig. 11 images of polished and unpolished surfaces of a GFRP samples with a 140-times magnification are shown. Figure 11 : Microscopic images of GFRP samples with embedded optical fiber and different surface treatments: polished (upper row), not polished (lower row). For this type of material, surface treatment leads to certain advantages and disadvantages. Thus, an embedded optical fiber is more clearly detected on a polished surface, however, a color gradient is less noticeable when moving from one phase of the composite material to another, which makes it difficult to identify the internal structure. Due to the large differences in height, there are problems with focusing the microscope on an untreated surface and it is not possible to