PSI - Issue 47

G. Morettini et al. / Procedia Structural Integrity 47 (2023) 296–309 Author name / Structural Integrity Procedia 00 (2019) 000–000

304

9

3.2. Method: tensile test All tensile tests, both for standard and notched specimens, were carried out following the ASTM D638 (Inernational ASTM (2015)), ASTM E132 (Inernational ASTM (2004)), and ASTM D5045 (Inernational ASTM (2007)) standards. In particular, an Instron 3382 machine force controlled was used for the tests. The tests were equipped with an Instron W-6280 clip-on extensometer for strain determination. Following the above standards, a machine feed rate of 2 / was used for the tests, and data were acquired at a sampling frequency of 5 . 3.3. Experimental results Standard specimen: real tensile curve From a standard tensile test, monitoring the specimen area evolution it is possible to extrapolate the average results of the real stress-strain curve. In particular, it is possible to calculate a value of the elastic modulus equal to 3500 and an ultimate tensile strength ��� � 62 at � � 0,023 / of elongation. The value of the Poisson's ratio was obtained from literature (Morettini at al. (2022)) �� 0,36 . Consequently, it will also be possible to evaluate the value of the real critical energy density � 0.789 √ � � � � � . With this, all values necessary to implement the ASED method are now available. Notch specimen tensile test Fig.7 shows the graphs of the average values of the tensile test for specimens with a constant section and varying fillet radius. As can be seen from these, the presence of the notch makes the material behavior tend towards brittle. Table3 reports the average results in terms of maximum mean force recorded for each set. These data will be used to make the final comparisons with the theoretical prediction.

Fig. 7. Average values of the tensile test for specimens with a constant section H and different fillet radius (see Table 2 for the geometrical detail of the specimens).

Table 3. Maximum mean force recorded for each set of notch specimens

Set id

1

2

3

4

5o

6

7

8

9

Mean Max Force [N]

2160

2427

2476

2845

3251

3239

3234

3252

3401