Issue 78

D. S. Lobanov et alii, Fracture and Structural Integrity, 78 (2026) 207-219; DOI: 10.3221/IGF-ESIS.78.12

The effect of external service-induced defects on the mechanical properties of fibreglass-reinforced plastic under compression

D.S. Lobanov, E.A. Chebotareva, K.I. Churin Center of Experimental Mechanics, Perm National Research Polytechnic University, Russia

cem.lobanov@gmail.com, https://orcid.org/0000-0003-1948-436X cem.chebotareva@mail.ru, https://orcid.org/0000-0002-6374-6964 eno889@yandex.ru, https://orcid.org/0009-0002-2499-556X

Citation: Lobanov, D.S., Chebotareva E.A., Churin K.I. The effect of external service induced defects on the mechanical properties of fibreglass-reinforced plastic under compression, Fracture and Structural Integrity, 78 (2026) 207-219.

A BSTRACT . Methods have been developed for inducing service-related defects—dents (using flat and spherical indenters) and scratches (using a steel blade)—under controlled impact conditions, based on the combined use of a testing system and an acoustic emission signal recording system. Critical values of loads and displacements have been established for each type of indenter (induced defect). A 4 mm thick STEF model fiberglass laminate was used as the test material. Samples measuring 150 mm × 20 mm × 4 mm were cut from the sheet of material in the warp and weft directions. Simulated external defects were applied to the specimens: a dent at a load of 0.85 times the breaking load, and a scratch at a load of 1 kN and a depth of 0.5 mm. Compression tests (ASTM D 3410/GOST 33519—2015) were carried out on groups of specimens cut along the warp and weft, without defects, and with defects including a cylindrical indentation, a spherical indentation and a scratch. The test results showed that the most dangerous defect is the ball indentation, which leads to a 20% reduction in compressive strength for weft direction samples and a 12% reduction for warp-direction samples. Scratches and cylinder indentations had virtually no effect on the compressive strength values, and the difference in values can be explained by statistical variation. Acoustic emission signals were also recorded and analyzed during the compression testing. K EYWORDS . GFRP, Operational Defects, Scratch, Dent, Mechanical behavior, acoustic emission.

Received: 03.07.2026 Accepted: 12.08.2026 Published: 21.08.2026 Issue: 10.2026

Copyright: © 2026 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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