PSI - Issue 59

Halyna Krechkovska et al. / Procedia Structural Integrity 59 (2024) 292–298 H. Krechkovska et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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polymer bond of the rod sample within the shell was destroyed by a viscous mechanism by the formation of small dimples (Fig. 4b). These results highlighted the importance of adhesion between the viscous component of the shell (the polymer that bound the glass fibers together into a single unit) and the strong but brittle 10-micron glass fibers. After all, the shell of the composite rod should withstand the load up to the brittle fracture of glass fibers. It was also noted that the fracture of both the glass fibers and the matrix was preceded by their detachment from each other, which was evidenced by secondary cracks along their borders (Fig. 4d). Thus, the adhesion between both shell components (glass fiber reinforcement and polymer matrix) was critical for the initiation of normally oriented fatigue cracks on the surface of the composite rod.

Fig. 4. (a, b) Crack nucleation in fibreglass shell; (c, d) fracture propagation in a fibreglass shell.

Fig. 5. (a) Crack propagation in the carbon fibre core; (b-d) final fracture in the central part of the carbon fibre core (tearing)