**3. Results**

*3.1. Results of the Experimental Study*

Tensile and rupture tests were carried out. Various factors were analyzed, including the loading rate and geometric dimensions of the specimen. As a result of the experiment, the modulus of elasticity was determined for different specimens (Table 2). The elasticity modulus strongly depends on the diameter and thickness of the shunt: for a thickness over 0.5 mm, its value increases several times, and for a thickness less than 0.35 mm, it decreases strongly. The stress–strain curve for a shunt with a diameter of 4.5 mm, wall thickness of 0.35 mm, and length of 20 mm by a rupture test is shown in the Figure 3. The load rate was 30 mm/min and the preload was 0.5 MPa.

**Table 2.** Parameters of samples used in the study.


**Figure 3.** Stress–strain diagram by specimen rupture test.

**Figure 3.** Stress–strain diagram by specimen rupture test. The tensile ultimate strength σ<sup>Y</sup> was also determined (Table 3); its value increases as the specimen diameter increases (Figure 4). The influence of loading rate on tensile strength σ<sup>Y</sup> determination was analyzed. The tensile strength value remained practically unchanged when the load rate application changed from 50 to 250 mm/min. The shape of The tensile ultimate strength σ<sup>Y</sup> was also determined (Table 3); its value increases as the specimen diameter increases (Figure 4). The influence of loading rate on tensile strength σ<sup>Y</sup> determination was analyzed. The tensile strength value remained practically unchanged when the load rate application changed from 50 to 250 mm/min. The shape of the tensile test curve for all specimens was the same. Stress–strain relationships were obtained as a result of tensile tests for two specimens (specimen no. 1, diameter of 5 mm, thickness of

the tensile test curve for all specimens was the same. Stress–strain relationships were obtained as a result of tensile tests for two specimens (specimen no. 1, diameter of 5 mm,

the obtained dependences (Table 4) and stress–strain dependences were plotted (Figure

**Figure 4.** Plot of change in ultimate strength with specimen diameter.

5).

0.5 mm, length of 20 mm; specimen no. 2, diameter of 3 mm, thickness of 0.35 mm, length of 20 mm). The constants for the strain density function were determined from the obtained dependences (Table 4) and stress–strain dependences were plotted (Figure 5). **Figure 3.** Stress–strain diagram by specimen rupture test. The tensile ultimate strength σ<sup>Y</sup> was also determined (Table 3); its value increases as

the specimen diameter increases (Figure 4). The influence of loading rate on tensile


*Materials* **2022**, *15*, x FOR PEER REVIEW 9 of 24


**Figure 4.** Plot of change in ultimate strength with specimen diameter.

**Figure 4.** Plot of change in ultimate strength with specimen diameter.


**Table 4.** Values of hyperelastic models for two samples.
