PSI - Issue 62

Isabella Mazzatura et al. / Procedia Structural Integrity 62 (2024) 369–376 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

374

6

samples is in the last two columns of Table 2. No treatment on the surface of the sample in correspondence of the single point of measure was applied. A quick visual inspection was performed to exclude any areas with visible imperfections, to avoid executing the tests in damaged areas. In Fig. 5 a picture o f the tests’ execution on a wire is reported.

Fig. 4. Tests' setup.

Fig. 5. Tests' execution.

3.4. Second phase – discussion of the results Table 2 shows the results for each investigated sample ( ‘Sample’) , obtained as average value of conducted measures in each selected point (‘I d. me asure’, σ mean ), and as the overall mean values (σ mean_all ), i.e. considering all the measures performed on a sample. For each kind of considered measures, also Standard Deviation (SD) and Coefficient of Variation (CoV) are reported. From the analyses of the results emerges that: • higher CoVs are associated with the extracted samples. • The stabilized wires always show a residual stress in compression, in between -30 and -190 MPa. • The not stabilized wires show residual stress in tension. • The strands always show a residual stress in tension, in between 120 and 240 MPa. However, as general consideration, it is possible to observe that the entire investigated sample is not large enough to extend the results to a general case.

Table 2. Tests' results. Sample

Id. measure σ mean

SD

CoV

σ mean_all

SD_all CoV_all Type New/extracted

Number of tests

[MPa] [MPa] [MPa] [MPa]

[MPa]

[MPa]

Sample 1 Sample 1_1

149 122 140 -102 -106 -71 -200 -167 -193 -106 -119 -107 -158 -119 -113 -19 -25 -108 -70 -74 -73 -81 -63 -11

37 17 44 34 14 17 16 27 14 12 17 9 24 24 15 28 36 19 38 13 1 7 3 6

25% 14% 32% 34% 14% 24% 8% 5% 14% 13% 10% 16% 2% 5% 21% 1% 40% 48% 9% 23% 60% 127% 61% 120%

137

14

10%

Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire

New - not stabilized 4 New - not stabilized 5 New - not stabilized 6

Sample 1_2 Sample 1_3 Sample 2_2 Sample 2_3 Sample 3_2 Sample 3_3 Sample 4_2 Sample 4_3 Sample 5_2 Sample 5_3 Sample 6_2 Sample 6_3 Sample 6_4 Sample 6_5 Sample 7_2 Sample 7_3 Sample 7_4

Sample 2 Sample 2_1

-93

19

21%

New New New New New New New New New New New New

5 5 4 4 3 4 6 3 3 3 3 3 4 4 2 4 4 4 6 5 5

Sample 3 Sample 3_1

-187

17

9%

Sample 4 Sample 4_1

-111

7

6%

Sample 5 Sample 5_1

-130

24

19%

Sample 6 Sample 6_1

-59

37

63%

Extracted Extracted Extracted Extracted Extracted Extracted Extracted Extracted Extracted

Sample 7 Sample 7_1

-57

32

56%