PSI - Issue 40

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D.S. Lobanov et al. / Procedia Structural Integrity 40 (2022) 258–263 Lobanov D.S., Strungar E.M. / Structural Integrity Procedia 00 (2022) 000 – 000

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Fig. 1. Sketches of specimens with open-hole.

3. Test results and discussion For all series of CFRP specimens, tensile tested according to ASTM D 3039, deformation and loading diagrams were obtained (Fig. 2), mechanical characteristics were determined, and statistical processing was carried out (Table 2) for 10 specimens.

Fig. 2. Typical deformation diagrams of CFRP specimens of various reinforcement schemes during uniaxial tensile testing (according to ASTM D 3039)

Fig. 3 presents loading diagrams for specimens with an open hole tested under ASTM D 5766, which are characteristic of each reinforcement type. Tensile and specimen tests, with an open hole, show that polymeric composite specimens, with orthogonal (type 1) and orthogonal-combined (type 2) interweaving schemes, have a high ultimate load as compared with specimens with inter-layer reinforcement (type 3, type 4) and layered specimens (type 5). For all carbon fiber specimens with different reinforcement types, loading diagrams show breaks related with structural failure. Fig. 4 shows photographs of destroyed specimens of all reinforcement schemes with characteristic damage in the area of the hole. In general, almost all curves in the loading diagram (Fig. 3) are linear. But in some cases, at a later stage of loading, the curves show obvious failures caused by permanent local damage and a decrease in the bearing capacity of the structure (types 1, 2, 3). Analyzing the failure damage of CFRP specimens with a open hole, it can be noted that according to the ASTM D 5766 classification, type 1 specimens were mainly failure by the LGM mechanism. Failure of type 2 specimens occurred by different mechanisms, so one half of them were failed by the LGM mechanism, and the others by the OGM, OMV, SGM, OUU mechanisms. For