13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- model allows us to consider the friction coefficient within the crack lips, in this first analysis, this friction's value (which highly influences the value of the SIF in second mode) is presently assumed to be equal to zero. The stress state below the interface is very complex, to quantify the crack propagation. An effective SIF value based on the ELBER formalism is addressed: 4− Δ = Imax Ieff K K for R>0 ( .R ) K KImax Ieff 4 4 − + Δ = for -1<R<0 with Imax Imin K K R= Imax Ieff K K Δ = for R<-1 (1) An important aspect of this coupled FEM simulation is the fact that the fretting contact description includes the crack's presence in the contact stress analysis. Indeed, the crack can induce a local pressure's and shear's discontinuity at the contact border which will successively modify the contact loading and finally the crack's propagation process (Fig. 7). Note that such coupled interaction between crack and contact stressing is not considered in usual decoupled approaches involving dislocation methods or weight functions [8]. Figure 7. Illustration of the interaction between the contact stress and the crack's presence in the interface (Q=Q*, case of a normal crack with bp=100 µm)
RkJQdWJsaXNoZXIy MjM0NDE=