Issue 27

T.V. Tretiakova et alii, Frattura ed Integrità Strutturale, 27 (2014) 83-97; DOI: 10.3221/IGF-ESIS.27.10 95 (a) (b) Figure 16 : Evolution of axial strain rate fields during the initiation of the ‘necking effect’ (a) and the picture of the fractured flat dog- bone tensile specimen (b) . Figure 17 : Diagrams of axial strain at the post-critical stage (the time period * * 1 6 t t  ). Time max yy  , % av yy  , % max yy   , %/s yy   , %/s * 1 t 36.49 22.93 2.76 0.17 * 2 t 40.65 23.19 2.76 0.17 * 3 t 45.45 23.45 3.70 0.17 * 4 t 51.19 23.71 4.40 0.17 * 5 t 57.93 23.99 4.65 0.17 * 6 t 64.79 24.26 4.80 0.17 Table 5 : Values of strain and strain rate calculated for the time period * * 1 6 t t  . The macroscopic failure of the specimen was at the load level of 4.26 kN, the average value of axial strain of 24.43 % and the local axial strain of 70.44 %. The picture of the flat dog-bone specimen with the crack after tension test is represented in Fig. 16 (b).