Issue 53

R. Harbaoui et alii, Frattura ed Integrità Strutturale, 53 (2020) 295-305; DOI: 10.3221/IGF-ESIS.53.23 303 Table 9: Identification of the anisotropy coefficients for a = 2 by CPB06. Material behavior study  Validation using the Lankford coefficient Based on the identified anisotropic parameters and the experimental Lankford coefficients, the development of the Lankford coefficients based on off-axis angles ψ can be represented. In Figure 8, the experimental Lankford coefficient (EXP) and the curves identified by our behavior model using Cazacu criterion and the curves identified from model using the barlat criterion (Barlat1991) are represented. Figure 8: Evolution of the experimental lankford coefficient compared to those of CPB06 model and Barlat91 model. Figure 8 show a good agreement between the identified results using our identification strategy and the experimental results relating to the Lankford coefficients. We notice that there is an adjustment (a good agreement) between the experimental results and those obtained from the model using the CPB06 criterion. However, the identification using the Barlat91 criterion is not validated by the Lankford coefficient. This improvement is exclusive to structure of studied material: the Barlat criterion is dedicated to face-centered cubic structure such as aluminum alloys [9-10,12]. On the other hand, the Cazacu criterion is developed to model the material behavior with a compact hexagonal structure such as magnesium alloys and titanium alloys [9,15].  Load surface After the identification of the model, the evolution of the load surface can be studied when the material is subjected to four solicitations. Using the identified anisotropy parameters and based on equations (3)-(5) and table 2, the evolution of the load surface under different stresses (EE, WT, SS, ST) is presented in Figure 9. Figure 9: Evolution of the load surface to several tests and solicitations. k C 11 C 12 C 13 C 22 C 23 C 33 Error -0. 02 1 0.2283 0.3197 -1.3154 -2.0016 -2.6882 1.1177e-07 -0.3 1 0.1014 0.0521 -0.9734 0.4437 4.8881 1.1394e-10