PSI - Issue 18

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

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Fig. 1. The scheme of the woven fabric (2  2 twill)

It is important to ensure the optical fiber integrity during the material manufacturing process, as well as strict adherence to all process parameters: pressure, temperature and time, depending on the brand of material, when creating a smart material such as a polymer composite material with embedded optical fiber. In the study, the following technological process was used. The process of FOSS embedding into PCM included a number of basic operations (Matveenko et al. 2018). At first step, the reinforcing material cutting on the plotter Zund G3 L-2500 was carried out. After that the layers of reinforcing material were laid out on special form-building equipment. The stack of layers for glass-fiber reinforced plastic and carbon fiber-reinforced plastic prepreg consisted of 20 layers. Optical fibers, made from silica core with diameter of 0.124 mm and polyimide protective coating with thickness of 0.012 mm were embedded between 10 th and 11 th layers of reinforcing material. After performing all the operations mentioned above, the polymerization process was carried out in the Langzauner press. During the polymerization process, control of pressure and temperature was carried out by a control computer. After that the technological package was removed. For the curing process the recommended regime according to the specifications of the materials was:  temperature increase to 120  С with a speed of 3  С/min,  holding for 0.4 hours with a temperature of 120°С,  moulding pressure increase to 0.3 MPa,  temperature increase to 180°С with a speed of 3  С/min,  holding for 1.5 hours with a temperature of 180°С,  cooling with a speed of 3°С/min until the temperature is 55°С,  decompression. After the main polymerization process was carried out the temperature of the samples was stabilized within 4 hours at the temperature of 120  С. 3. Microscopic analysis of cross sections of PCM samples with embedded FOSS For each of the materials (GFRP and CFRP), 10 cross-sectional elements were investigated. The photos of the GFRP and CFRP samples are shown in the Fig. 2. The cutting of the samples into pieces was carried out using a round cutter.