13th International Conference on Fracture June 16–21, 2013, Beijing, China -8- stress Sσ providing the start of the scaling transition and the saturation effect as the anomaly of energy absorbing. The microscopic mode of fatigue crack growth is strongly affected by the multiscale slip arrangement, applied stress level and the extent of near tip plasticity. In ductile solids, cyclic crack growth is observed as a process of intense localized deformation in slip bands near the crack tip which leads to the creating of new crack surfaces by shear decohesion. The important feature of cyclic loading conditions, when the onset of crack growth from pre-existing defects can occur, at stress intensity values that are well below the quasi-static fracture toughness. This observation was used as a physical basis for the Paris model, when small scale yielding assumption allowed the formulation of the crack kinetics as m C K dN da = Δ , (4) in the term of the stress intensity factor range defined as min max K K K Δ = − , where max K and min K respectively are the maximum and minimum stress intensity factors, C and mare empirical constants which a functions of material properties and microstructure. This formula predicted the Paris exponent of 4 m≈ in agreement with experiments for most metals [11]. Since the crack growth kinetics is linked to the temporal ability of material to the energy absorbing at the crack tip area the understanding of the saturation nature can be the key factor for the explanation of the 4th power universality. It was shown that the saturation nature can be considered as a consequence of the anomaly energy absorbing in the course of structural-scaling transition in dislocation system with the creation of PSBs and long-range interaction of dislocation substructures. Taking into account that the p- kinetics is given by the 4th order difference in the power in the metastability area the qualitative dependence of the damage rate reads 4 ~ S p A σ & , where Sσ is the saturation stress in the metastability area for * δ δ δ < < C . This result supports the phenomenological law proposed by Paris [11] for the HCF crack growth kinetics. It is interested to note that this channel is very powerful in the sense of the energy absorbing. For instance, similar to the Paris law, the 4th power law 4 A Aσ ε&≈ of the linkage of plastic strain rate pε&on the stress amplitude Aσ was established at the steady-state plastic wave front for several materials experienced shock loading [9, 12]. 6. Defect induced scaling and scaling laws for fatigue crack path With the purpose of understanding of crack behavior near the fatigue crack threshold the replica technique was used to study the correlation between the scaling properties of defect induced roughness and scaling laws of fatigue crack. 3D New View high resolution data of defect induced roughness in the crack process zone (Fig.9a) under fatigue crack path revealed the existence of two
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