PSI - Issue 18

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Natalia Kosheleva et al. / Procedia Structural Integrity 18 (2019) 129–134 Author name / Structural Integrity Procedia 00 (2019) 000–000

Fig. 2. GFRP (a) and CFRP (b) samples

In order to assess which type of surface is most suitable for study with an optical microscope, some cross sectional surfaces were polished, and some were left in their original state after the cutting. A comparison of the obtained images showed that the microstructure of the studied samples is better seen on polished surfaces. In the absence of polishing on a number of images, the optical fiber is not visually noticeable or poorly distinguishable. Nevertheless, the study of polished sections together with unpolished ones, on which the relief structure of the sample has been preserved, provides more complete information about the internal structure of the material. The experiment was carried out on a microscope KH-7700 (Fig. 3), which allows to get a magnification up to 7000x. In the experiment an MX (F) -10C lens with an OL-140 adapter and possible magnification up to 140х, 280х, 420х, 560х, 700х was used.

Fig. 3. General view of the experimental setup (a) , microscope (b)

The analysis of the obtained images shows that on the GFRP samples such structural elements of the composite material with a woven reinforcement type as the warp and weft fibers and areas filled with matrix are clearly identified. The image of the internal structure of a GFRP with 140-times magnification is shown in the Fig. 4.