Issue 49

G. Meneghetti et alii, Frattura ed Integrità Strutturale, 49 (2019) 82-96; DOI: 10.3221/IGF-ESIS.49.09 89 E XPERIMENTAL EVALUATION OF THE J - INTEGRAL , BASED ON THERMAL MEASUREMENTS n this section, the procedure for the evaluation of J-integral according to Eqn.(18) will be described. In view of this, the evaluation of the (2 , ') p k n  constant is needed. Therefore, two dimensional, plane stress, linear elastic as well as elastic-plastic finite element analyses of the tested specimens were performed in Ansys® 16.2 commercial software, by using 4-node PLANE 182 element. The cyclic curve plotted in Fig. 6 was implemented, along with the Von Mises plasticity rule and the isotropic hardening behaviour. J-integral calculation was based on the domain integral approach implemented in Ansys ® . For more details of FE analyses, the reader is referred to [28]. Once evaluated K I,max and J max from purely elastic and elastic-plastic analyses, respectively, J max,p was calculated from Eqn.(5).  , cc p W evaluated in a control volume R c =0.52 mm versus J max,p is shown in Fig. 7 and it can be seen that a linear relationship can be proposed with (2 , ') 0.869 p k n   in Eqn. (11) and a coefficient of correlation R 2 =0.9976. Figure 6 : Cyclic stress-strain curve of the 4-mm-thick hot rolled AISI 304L stainless steel specimens [28]. Figure 7 : Plastic strain energy included in the control volume V c versus the plastic component of the J integral (  n =applied net-section stress). 0 50 100 150 200 250 300 350 400 450 0 0.002 0.004 0.006 0.008 0.01  a [MPa]  a [m/m] Serie5 cyclic curve xperimental data E=194700 MPa K'=1660 MPa n'=0.29 =274 MPa 0 20 40 60 80 100 Elasto-plastic, plane stress: R 2 =0.9976 [J/m] 10 mm ≤ a ≤ 30 mm 16 MPa ≤  n ≤ 530 MPa J max,p [J/m 2 ] 0 5·10 4 10 5 1.5·10 5 2·10 5 I