A Statistical Physics Analysis of Rock and Concrete Damage Response

In our thermodynamic approach, crack densities have been treated as a hierarchy of order parameters operating at successively smaller scales (from macroscopic down to microcrack scales). The formulism renormalize surface energy densities due to interaction between microcracks, yields by thermodynami...

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Bibliographic Details
Main Authors: Englman, R, Jaeger, Z
Format: Report
Language:English
Subjects:
APPROXIMATION(MATHEMATICS)
CERAMIC MATERIALS
Ceramics, Refractories and Glass
COALESCENCE
CONCRETE
CRACK PROPAGATION
CRACKS
Crystallography
DAMAGE
DAMAGE ASSESSMENT
DEFECTS(MATERIALS)
DENSITY
ENTROPY
EQUILIBRIUM(GENERAL)
EXTERNAL
FOREIGN REPORTS
FRACTURE(MECHANICS)
FRAGMENTATION
Geology, Geochemistry and Mineralogy
HIERARCHIES
INTENSITY
INTERACTIONS
INTERNAL
LATTIC DYNAMICS
MICROCRACKING
PARAMETERS
PE61102F
PERCOLATION
PHYSICS
POROSITY
RATES
REINFORCED CONCRETE
RELAXATION
RESPONSE
ROCK
SCALE
SHIELDING
SOLIDS
STATISTICAL ANALYSIS
STRESS STRAIN RELATIONS
STRESSES
SURFACE ENERGY
Thermodynamics
THERMOPHYSICAL PROPERTIES
THRESHOLD EFFECTS
WUAFOSR2302C2
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Summary:In our thermodynamic approach, crack densities have been treated as a hierarchy of order parameters operating at successively smaller scales (from macroscopic down to microcrack scales). The formulism renormalize surface energy densities due to interaction between microcracks, yields by thermodynamic self- consistency effective elastic constants (similar to those in effective medium approximations) and stress intensity factors (SIF) in cracked solids and provides thermodynamic definitions for observables (like R-curves and SIF). The fracture behavior under fixed grip or constant stress conditions has been studied numerically. Above a critical strain the material attains an equilibrium non-zero crack density that approaches the percolation threshold asymptotically with increasing strain. The effects of crack crack interactions of anisotropic crack-density and of pre-existing pores have also been studied. Crack propagation in ceramic materials, subject to microcrack formation and coalescence, has been examined with models that differ in the relative time scale involved in the internal relaxation processes and the external loading rate. It was found that when the external loading rate is high, a rising R-curve is obtained, which is primarily due to microcrack shielding.