Issue 10

A. Pirondi, Frattura ed Integrità Strutturale, 10 (2009) 21-28 ; DOI: 10.3221/IGF-ESIS.10.03 24 Cohesive law Three different kind of cohesive laws were accounted for: i) trapezoidal, ii) triangular and iii) exponential as shown qualitatively i n Fig. 4. The relationship between the parameters of the laws is: i)   0 2 1 1 1 2 m c c c       (4) ii) 0 1 2 m c     (5) iii)   0 1 1 1 1 1 m c e                   (6) where c 1 =  1 /  c e c 2 =  2 /  c . The cohesive energy  0 was taken equal to the fracture toughness measured in [11], that is  0 = G Ic = 550J/m 2 in the case of the ACZ kind of models. The parameters of the different laws were tuned until the peak load of the DCB test was achieved, while keeping also a good correspondance with the overall behaviour. (a) F,  F,  CZ or ACZ (b) F,  F,  CZ or ACZ Figure 3 : FE model of the DCB (a) and of the T-peel (b) joints.  (  )    c  1  2  (  )  m Figure 4 : Outline of the cohesive zone traction-separation laws (Eqns. 4 - 6) .