PSI - Issue 5

Behzad V. Farahani et al. / Procedia Structural Integrity 5 (2017) 981–988 Behzad V. Farahani et al./ Structural Integrity Procedia 00 (2017) 000 – 000

986

6

1,4

DIC FEM

0,7

Force (kN)

0

0

0,5

1

1,5

2

2,5

Displacement (mm)

(a)

(b)

Fig. 2. (a) DIC problem domain and the interest points in the central section demonstration and (b) reaction force variation correlated with the vertical displacement in the central section of the bi-failure specimen.

(a)

(b)

Fig. 3. AA6061-T6 bi-failure specimen, (a) FEM mesh with the natural and essential boundary conditions demonstration and (b) failure evolution captured for different displacement impositions by DIC test.

Correlating the failure evolution presented in Fig. 3-b and the obtained force/displacement response, shown in Fig. 2-b, it is possible to infer that the first force level fall is related to the first mode of the material failure (caused by tensile effects, high stress triaxiality) and the second drop is subjected to the second failure stage (caused by pure shear, low stress triaxiality) contributing to collapse the material. Nevertheless, the graph underwent some fluctuations after the second failure, as expected, which can be justified to the mechanical vibrations and dynamic effects which the material faced with after breaking down.