PSI - Issue 28

D.A. Bondarchuk et al. / Procedia Structural Integrity 28 (2020) 743–751 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 9. Fatigue curve for material AS4/8552.

6. Conclusions In current research, an extensive numerical investigation of stress concentration phenomena near the tip of the crack and the free edge after cut out of AS4/8552-1 carbon-epoxy multilayered composite was provided. The problem was solved for plane strain case for composite specimen with [0°/90°] lay-up and ideal straight cut along the fiber direction after curing. The behavior of the material during the curing process and the distribution of residual stresses were studied using the developed user subroutine, which was implemented in the ABAQUS. Based on simulation results it can be concluded, that maximum stresses (after cutout) in the sample are close to the ultimate and concentrated in a small area near free edge. There is a possibility of occurrence of micro cracks in the sample during the manufacturing process as well as during a relatively small loading. A slight increase in the G I and G II values at the crack tip during polymerization and a multiple increase of these values after a mechanical cut is shown. The growth of fracture toughness values during the manufacturing process and during cutout is sufficiently small as compared with the static parameters that favour the absence of additional growth of defects. The presence of relatively small defects in the sample or their occurrence during the manufacturing process will not be extended by residual stresses. Obtained by modelling values for stress components are essential and cannot be ignored in consequent structural analysis. The results of the study can be applied for prediction of residual stresses in composite structure by means of simulation and further understanding the nature of fracture of composites. Acknowledgements The research was supported by the Russian Foundation for Basic Research (grant No.18-31-20026, № 20-01 00356). Experimental studies were carried out using the large-scale research facilities «Complex of testing and diagnostic equipment for studying of structural and functional materials under complex thermomechanical loading» PNRPU modernized with funds by The Ministry of science and Higher Education of the Russian Federation (Unique project identifier RFMEFI61920X0017). The funders had no role in study design, data collection and analysis, decision to publish or preparation of manuscript. References Bondarchuk D.A., Fedulov B.N., Fedorenko A.N., Lomakin E.V. The analysis of The analysis of residual stresses in layered composites with [0◦/90◦] layup / D. Bondarchuk, B. Fedulov, A. Fedorenko et al. // PNRPU Mechanics Bulletin. Perm, 2019. no. 3. P. 17–26. Hexply AS4/8552 data sheet. http://www.lookpolymers.com/pdf/Hexcel-HexPly-8552-EpoxyMatrix-AS4-Fiber.pdf. Accessed: 2020-04-17. Boyard N. Heat transfer analysis in polymer composite materials: Forming processes Mechanical engineering and Solid Mechanics. Pdf downloaded from: http://download.polympart.com/polympart/ebook/Heat%20Transfers%20in%20Polymer%20Composite%20Materials%20Forming%20Proces ses.pdf.