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J. Toribio et alii, Frattura ed Integrità Strutturale, 25 (2013) 130-137; DOI: 10.3221/IGF-ESIS.25.19 135 in the crack, and this way enable the opposite crack surfaces to contact prematurely at unloading, i.e., produce PICC. Evidently, this contradicts to Figs. 2 and 5( a,b ), where large displacements and rotations in the crack tip vicinity make material not to fill-in the crack behind the tip and render PICC, but to increment the crack flanks, i.e., they make the crack advance. This gives the reason to consider the suggested PICC origin as an artifact [13], as far as it appears to be not the naturally present feature of a crack under cyclic loading but a product of an analysis method. Figure 5 : Deformations near the crack tip under cyclic loading: ( a ) crack-tip large-deformation patterns with a scheme showing how and where do material "bricks" with their glued local material frames ( , ) x y go by translation and rotation (arrows) from the initial configuration to make the crack grow; ( b ) contour bands of the plastic strain p XX  at the end of the sixth cycle of the route I in deformed solid configuration (undeformed crack tip is seen in the bottom-left corner) to illustrate the contribution of the "bricks" stretching to crack lengthening, but not to its closure; ( c ) scheme of the small-deformation results [13, Fig. 8] used to substantiate the suggested origin of PICC in the supposed filling-in the crack with stretched material behind the tip; the squares shaded in gray and rectangles filled with line pattern represent in ( a ) and ( c ) the same material elements in the initial and deformed states, respectively. C ONCLUSIONS he crack becomes larger after every cycle, i.e., it grows, as suggested the Laird-Smith concept, by means of plastic straining with certain rate ( da/dN ) p . This growth reproduces the key experimental trends of FCG, such as the acceleration with  K and the hindering by overload, which have been repeatedly attributed to the crack closure. Specimen compliance changes, which are frequently considered, following Elber [5], to be the evidences of crack closure, do occur in simulations. Despite all that, no PICC has appeared, and revealed deformation patterns discard its supposed origination from filling-in the crack with plastically stretched material in the wake. It does not matter now whether PICC could occur at substantially larger number of cycles or longer crack growth, or whether local material fracture through bond breaking is a necessary requisite for PICC to arise, but the point is that the supposed consequences of PICC do take place with no closure behind them, thereby bringing doubts about PICC. A CKNOWLEDGEMENTS he authors wish to acknowledge the financial support provided by the following Spanish Institutions: Ministry for Science and Technology (MCYT; Grant MAT2002-01831), Ministry for Education and Science (MEC; Grant BIA2005-08965), Ministry for Science and Innovation (MICINN; Grants BIA2008-06810, and BIA2011-27870) and Junta de Castilla y León (JCyL; Grants SA067A05, SA111A07, and SA039A08). R EFERENCES [1] Overview. Advances in fatigue crack closure measurement and analysis, ASTM STP 1343, R.C. McClung, J.C. Newman, Eds., ASTM International, West Gonshohocken, (1999) XI. [2] Ritchie, R. O., Mechanisms of crack propagation in ductile and brittle solids, Int. J. of Fract., 100 (1999) 55-83. T T