PSI - Issue 17

J.P. Pascon et al. / Procedia Structural Integrity 17 (2019) 411–418 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

413

3

The specimen ’s width ( W = 36 mm) and thickness ( t = 9.6 mm), as well as the loading conditions adopted in the experimental work by Torres et al. (2017) were reproduced in the present numerical model and provided in Figure 2. The maximum load is 20.5 kN, which corresponds to a nominal stress of 59.32 MPa. Because of the triple symmetry, only one eighth of the specimen was analysed, imposing zero-displacement conditions along the symmetry planes ( x = 18 mm, y = 0 and z = 0). The initial crack length 2 a varies from 11 to 15 mm. Two load ratios were adopted: R = 0 ( F max = 20.5 kN and F min = 0); and R = -1 ( F max = 20.5 kN and F min = -20.5 kN).

600

500

Stress ,  ( MPa )

400

300

AA6005  at (%)

0,4 0,5 0,6 0,8 0,9 1,2

200

100

0

0,000

0,004

0,008

0,012

0,016

0,020

0,024

Strain , 

Fig. 1. Superimposed stress-strain loops for 6005 alloy with matched lower tips.

Fig. 2. Specimen geometry and loading conditions (dimensions in mm). The hatched part denotes the discretized portion.

The 3D constitutive model employed in the numerical analyses includes a linear elastic response (Hooke’s law) together with the von Mises yield criterion, the associative plastic flow rule and the nonlinear isotropic hardening Swift model. The adopted elastoplastic model is summarized in equations (1) to (5). Equation (1) gives the stress-