PSI - Issue 30

O.V. Startsev et al. / Procedia Structural Integrity 30 (2020) 162–166 M.P.Lebedev et al / Structural Integrity Procedia 00 (2020) 000–000

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Thus, if water is located in macro-damages of PCM in free and capillary condensed states, then its transition into ice with a temperature decrease facilitates an additional increase of internal stresses, while RMS voltage of acoustic emissions are indicators of occurring micro-damages in the polymer matrix and at the matrix-filler interface. 4. Conclusions The influence of a cold climate increases for polymer composite materials containing moisture in capillaries, pores, and microvoids. The accumulated water in polymeric materials when the temperature goes below 0 °C causes an increase in the level of internal stresses. The presented experiments by the method of acoustic emission showed that when the dried and water-saturated samples of glass fiber laminates with small surface defects are cooled, the pulses are within the background noise. Moreover, if the water is localized in macrodamages, then acoustic radiation is observed with a pulse amplitude that is more than two orders of magnitude higher than the background. The results indicate that water localized in macrodamages in a free or capillary condensed state, turning into ice with a decrease in temperature, contributes to an additional increase in internal stresses. Acknowledgements Abdelmola F., Carlsson L.A., 2019. State of water in void-free and void-containing epoxy specimens. Journal of Reinforced Plastics and Composites, 26, 556–566. Bansil R., Wiafe-Akenten J., Taaffe J.L., 1982. Raman spectroscopy of supercooled water. J. Chem. Phys., 76. 2221–2226. D'Arrigo G., Maisano G., Mallamace F., Migliardo P., Wanderlingh F., 1981. Raman scattering and structure of normal and supercooled water. J. Chem. Phys.75, 4264–4270. Filistovich D.V., Startsev O.V., Kuznetsov A.A., Krotov A.S., Anikhovskaya L.I., Dementeva L.A., 2003. Effect of moisture on the anisotropy of the dynamic shear modulus of glass-reinforced plastics. Doklady Physics 48(6), 306–308. Heshmati M., Haghani R., Al-Emrani M., 2017. Durability of CFRP/steele goints under cyclic wet-dry and freeze-thau conditions. Composites Part B. 126, 211–226. Jedidi J., Jacquemin F., Vautrin A., 2006. Accelerated hygrothermal cyclical tests for carbon/epoxy laminates. Composites. Part A. 37, 636–645. Kablov E.N., Startsev V.O., Inozemtsev A.A., 2017. Moisture saturation of structurally similar elements made of polymer composite materials under open climatic conditions and thermal cycling effects. Aviation materials and technologies 2(47), 56–68. (In Russian) Karbhari V.M., 2002. Response of Fiber Reinforced Polymer Confined Concrete Exposed to Freeze and Freeze-Thaw Regimes. Journal of Composites for Construction 6, 35–40. Lopez-Anido R., Michael A.P., Sandford T.C., 2004. Freeze-thaw resistance of fiber-reinforced polymer composites adhesive bonds with underwater curing epoxy. J. of Materials in Civil Engeneering 16, 283–286. Lependin A.A., Polyakov V.V., Salita D.S., 2015. Evolution of statistical characteristics of acoustic emissions during destruction of fiberglass. Letters to Journal of Technical Physics 41, 1–5. (In Russian) Morishige K., Yasunaga H., Matsutani Y., 2010. Effect of pore shape on freezing and melting temperatures of water. J. Phys. Chem. C. 114, 4028–4035. Panin S.V., Startsev O.V., Krotov A.S., 2014. Diagnostics of the initial stage of climatic aging of PCM by change of the coefficient of moisture diffusion. Proceedings of VIAM 7, 1–9. (In Russian) Tsotsis T.K., 1989. Effects of Sub-Freezing Temperatures on Graphite/Epoxy Composite Materials. Journal of Engineering Materials and Technology 111, 438–439. Slavin A.V., Startsev O.V.,2018. Properties of aviation fiberglass and carbon fiber reinforced plastics at an early stage of climatic impacts. Proceedings of VIAM 9, 71–82. (In Russian) Startsev V.O.,2016. Across-the-thickness gradient of the interlaminar shear strength of a CFRP after its long-term exposure to a marine climate. Mechanics of Composite Materials 52(2), 171–176. Startsev O.V., Filistovich D.V., Kuznetsov A.A., Krotov A.S., Anikhovskaya L.I., Dementieva L.A., 2004. Deformability of fiberglass sheets based on adhesive pre-pregs under shear loads in humid environments. Perspektivnyi materialy (Promising Materials) 1, 20–26. (In Russian) Startseva L.T., Panin S.V., Startsev O.V., Krotov A.S., 2014. Moisture diffusion in glass-fiber-reinforced plastics after their climatic aging. Doklady Physical Chemistry 456, 77–81. Sokova S.D., 2010. The choice of electrical insulation materials for repair considering their compatibility and operational characteristics. Bulletin of MSCU 4, 151–156. (In Russian) The reported study was funded by RFBR according to the research project № 18-29-05012. References