PSI - Issue 52

Wouter De Corte et al. / Procedia Structural Integrity 52 (2024) 99–104 W. De Corte, J. Uyttersprot & W. Van Paepegem/ Structural Integrity Procedia 00 (2019) 000 – 000

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In the first section, the average initial stiffness (determined between 0.05% and 0.15% strain) is equal to 48.8 GPa, while in the second section (determined between 0.5% and 1.0% strain) the stiffness reduces to 11.4 GPa. It is clear that only in the first initial section of the graph the stiffness of the hybrid composite is increased compared to the reference GFRP. The stiffness increase is approximately 120%. This stiffness increase is noticeable up to a strain of 0.2% and an associated stress of 98 MPa. From this point on, the steel will start to yield and will therefore no longer contribute to the stiffness. The average maximum strain at failure is 2.3% and is equal to the ultimate strain limit of the reference GFRP. From this it can be concluded that the ultimate strain is only determined by the properties of the GFRP. However, the average maximum stress has decreased by 21% from 407 MPa for the reference GFRP to 323 MPa for the hybrid composite with Steel A.

0 100 200 300 400 500 0.0% 0.5% 1.0% 1.5% 2.0% 2.5% Stress [MPa] Strain [-] Test 1 Test 2 Test 3 Test 4

0 100 200 300 400 500 0.0% 0.5% 1.0% 1.5% 2.0% 2.5% Stress [MPa] Strain [-] Test 1 Test 2 Test 3 Test 4

Fig. 4. Stress in function of strain for hybrid composite with Steel A (left) and Steel B (right) Fig. 4 (right) shows the stress-strain plot for the hybrid composite with one perforated steel sheet of Steel B. In accordance with the graph of de hybrid composite with Steel A, two sections can also be distinguished for Steel B. The average initial stiffness (determined between 0.02% and 0.05% strain) is 51.6 GPa, while in the second section (determined between 0.5% and 1.0% strain) the stiffness reduces to 14.0 GPa. Also here, the stiffness in the first initial section is increased, in this case by about 130% compared to the reference GFRP. This stiffness increase is noticeable up to a strain of 0.15% and an associated stress of 81 MPa. From this point on, the steel will start to yield and will therefore no longer contribute to the stiffness. The average maximum strain at failure is slightly reduced to a value of 2.1% and the average maximum stress has decreased by 26% to 330 MPa for the hybrid composite with Steel B compared to the reference GFRP.

0 100 200 300 400 500 0.0% 0.5% 1.0% 1.5% 2.0% 2.5% Stress [MPa] Strain [-] Test 1 Test 2 Test 3 Test 4

Fig. 5. Stress in function of strain for hybrid composite with steel wire mesh Fig. 5 shows the stress-strain graph for the hybrid composite with the steel wire mesh. In contrast to Fig. 4, there is no clear apparent stiffness difference with respect to the reference GFRP. The average initial stiffness (determined between 0.02% and 0.05% strain is 19.4 GPa, which is almost 12% lower than the stiffness of the reference GFRP. The average maximum stress and strain at failure are 334 MPa and 2.3%, respectively for the hybride composite. Compared to the reference GFRP, there is no difference in strain, but the ultimate stress has decreased by 18%.