Constitutive behavior of a microcracking brittle solid in cyclic compression |
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Institution: | 1. Université Paris-Est, Laboratoire Navier (UMR 8205 CNRS, ENPC, IFSTTAR), Marne-la-Vallée 77455, France;2. Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle (MSME UMR 8208 CNRS), 5 Boulevard Descartes, Champs-sur-Marne, Marne-la-Vallée 77454, France;1. Department of Civil Engineering, Universidade NOVA de Lisboa, Portugal;2. CEris, ICIST, Department of Civil Engineering, Universidade NOVA de Lisboa, Portugal |
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Abstract: | A constitutive formulation is presented to determine the “driving force” for Mode I fatigue crack growth in notched plates of brittle solids stressed in uniaxial cyclic compression. For the particular case of a microcracking medium, it is demonstrated that residual tensile stresses are induced ahead of the notch during unloading from the maximum far-field compressive stress. We propose that it is this region of residual tensile stresses at the notch-tip which promotes fatigue crack growth in ceramics along the notch plane in a direction normal to the compression axis. The predictions of the analysis are compared with new experimental results on compression fatigue in brittle solids. Specifically, it is shown that the numerical estimates of the near-tip tensile zone size for microcracking ceramics compare favorably with the experimentally measured distance of stable Mode I fatigue crack growth after the first compression cycle. Experimental information on the threshold stress for microcracking, transition stress for the inducement of residual tension during unloading, and the effect of mean stress on fracture, as well as direct observations of microcracks and crack growth in compression fatigue, corroborate the assumptions and implications of the analysis. |
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