Nonlocality of Continuum Approximation of Microcracked Materialsby Zdeněk P. Bažant, Northwestern Univ, Evanston, United States,
Abstract: A continuum with nonlocal damage has recently been shown to be an effective approach for the analysis of strain-softening structures. The basic idea is that only the damage, normally caused by microcracking, is nonlocal, being a function of the averaged strain, while the strain and stress are local continuum properties. Physical justification by micromechanics, however, has been rather limited. In a recent study, it was suggested that the physical source of nonlocality of damage is the fact that the formation and growth of a microcrack depends on the strain energy stored in a nonzero volume of the material surrounding the microcrack, whose release drives the growth of the microcrack. This argument was developed only for a rather idealized, easily tractable case - a uniaxial stress field, a quasiperiodic array of small cracks arranged on a cubic lattice, and neglect of crack interactions. The present presentation shows an improved version of this arguments, as well as another argument that is based on interactions among microcracks.
Subject Headings: Cracking | Stress strain relations | Damage (structural) | Strain hardening and softening | Micromechanics
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