13th International Conference on Fracture June 16–21, 2013, Beijing, China -4- Table 1 : Experimental results on CT specimens are given for the various WPS cycles. * For LCOIKF cycle, the mean slope ΔK/ ΔT is given. 3. Numerical modeling 3.1 Local approach to fracture As the local approach to fracture needs an accurate description of the stress/strain fields at the crack tip, the mechanical behavior of the material has to be modeled as precisely as possible, as well as the evolution of the characteristics with temperature. Large plastic deformations occur during the pre-loading at the crack tip, producing work-hardening so that finite strain formalism was used. Thus, elasto-visco-plastic constitutive equations were used in order to describe accurately the behavior of the material [8]: where p is the cumulated plastic strain, s the stress deviator and f(σ,p) the yield surface. The parameters determined in previous studies [4,9] are given in Table 2 and allow reproducing accurately both smooth tensile and notched tensile tests up to plastic strains of about 40% (Fig. 3).
RkJQdWJsaXNoZXIy MjM0NDE=