PSI - Issue 54

5

Jaroslav Václavík et al. / Procedia Structural Integrity 54 (2024) 294–299 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 4 Tested set-up for 3-point bending test of hollow beams (a) and plastic joints formed after beams bending (upper separate beam, bottom double beam) (b)

a) b) Fig. 4 a) History of load force F depending on the crossbar displacement s for tested separate and doubled hollow beams; b) History of strain measured in front of the end of CFRP plate on the steel

When the profile is filled with foam, a plastic joint is formed at an approx. 20% higher load force; approximately the same increase in deflection of the sample was found. When reinforcing the profile only with a CFRP strip on the bottom side, there was no significant increase in strength. It is interesting that the results are the same for both foams, even though the tensile strength of the polyurethane foam was measured to be approximately 2 times higher than that of the epoxy foam. Using the CFRP plate, the stress at the CFRP ends is increased more than twice up to steel yield point in comparison with non-stiffened beam. Higher strain is in the profile axes in comparison of profile edges. Also the strains on the upper hollow beam side outside the plastic joint have increased twice when using the CFRP plate.