PSI - Issue 44

Annalisa Franco et al. / Procedia Structural Integrity 44 (2023) 2246–2253 Author name / Structural Integrity Procedia 00 (2022) 000–000

2250

5

A summary of the test results for all the tested system is instead reported in Tab. 3. In this table, the maximum load, the elongation at break and the breaking strength are reported for the yarns, while maximum load, elongation at break, tensile strength and modulus (the latter only for the 2 mm/min tests) are reported for the warp direction of the FRP grids, together with the relative average values and coefficients of variation (CoV). Failure in yarns was characterized by diffuse and consecutive rupture of the single filaments constituting the yarn (see Fig. 2(b)), while brittle failure was evidenced in the FRP grids.

Tab. 3. Summary of test results.

YARN

GRID - WARP

Tensile modulus [GPa]

Elongation at break [%]

Breaking strength [N/tex]

Elongation at break [%]

Tensile strength [MPa] 745,5 753,2 835,6 795,3 673,6 632,4 739,3 763,5 710,5 659,1 677,2 765,5 715,2 6,81% 10,20%

Maximum load [N]

Maximum load [N]

Specimen

Specimen

F_Y_2_1 F_Y_2_2 F_Y_2_3 F_Y_2_4 F_Y_2_5 Average

468,9 586,2 454,2 557,4 586,9 530,7

1,62 1,63 1,38 1,41 1,68 1,54 1,33 2,12 1,83 1,67 1,61 1,71

0,20 0,24 0,19 0,23 0,24 0,22 0,24 0,21 0,21 0,25 0,24 0,23 0,24 0,24 0,22 0,25 0,23 0,24 0,30 0,33 0,31 0,30 0,34 0,32 0,33 0,38 0,34 0,40 0,39 0,37

F_W_2_1 F_W_2_2 F_W_2_3 F_W_2_4 F_W_2_5 F_W_2_6 Average F_W_50_1 F_W_50_2 F_W_50_3 F_W_50_4 F_W_50_5 CoV

5710,4 5769,8 6400,5 6091,8 5160,0 4843,8 5662,7 10,19% 5848,4 5442,2 5048,7 5187,6 5863,5 5478,1 6,80%

2,75 2,83 3,82 2,90 2,36 2,30 2,83 2,78 2,58 2,39 2,38 2,70

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28,68 31,71 31,08 32,52 31,62 31,12 4,69%

CoV

12,15%

8,96%

10,66%

19,33%

F_Y_50_1 F_Y_50_2 F_Y_50_3 F_Y_50_4 F_Y_50_5 Average F_Y_200_1 F_Y_200_2 F_Y_200_3 F_Y_200_4 F_Y_200_5 CoV

584,4 507,9 515,7 600,4 576,1 556,9 7,57% 574,4 579,4 516,6 608,6 546,3 565,1 6,19% 182,8 196,8 186,7 178,1 205,6 190,0 5,85% 196,1 227,1 205,2 238,5 235,8 220,5 8,58%

Average

2,566 7,01%

16,99%

8,13%

CoV

2,19

2,1

1,65 1,45

1,6

Average

1,80

CoV

18,17%

4,83%

G_Y_2_1 G_Y_2_2 G_Y_2_3 G_Y_2_4 G_Y_2_5 Average

1,63 1,84 1,79 1,50 1,83 1,74 1,87 1,94 1,76 2,01 1,96 1,91

G_W_2_1 G_W_2_2 G_W_2_3 G_W_2_4 G_W_2_5 Average

3153,5 3217,8 2808,0 3167,5 2953,7 3060,1 5,66% 3640,3 3695,7 3467,3 3618,6 3442,6 3572,9 3,12%

1,74 1,71 1,67 1,80 1,15 1,61 2,03 2,11 2,02 2,08 1,93 2,03

448,1 457,2 399,0 450,1 419,7 434,8 5,66% 517,3 525,1 492,7 514,2 489,2 507,7 3,12%

38,54 35,40 36,51 39,60 38,37 37,69 4,49%

CoV

8,63%

5,75%

CoV

16,34%

G_Y_200_1 G_Y_200_2 G_Y_200_3 G_Y_200_4 G_Y_200_5

G_W_200_1 G_W_200_2 G_W_200_3 G_W_200_4 G_W_200_5

Average

Average

CoV

5,07%

8,46%

CoV

3,38%

The results in terms of average maximum load experimentally obtained for each sample are graphically summarized in Fig. 4. Here, the error bars define the range into which all the experimental results fall. Fig. 4(a) shows the results obtained when testing the yarn of system “F”. One may observe that by passing from a displacement rate of 2 mm/min to 50 mm/min the increase in the average breaking load is 4,93%, while it becomes