Equivalent continuum model

Several options are available in FLOTRAN for representing fractured media. The equivalent continuum model (ECM) formulation represents fracture and matrix continua as an equivalent single continuum. Two distinct forms of dual continuum models also are available, defined in terms of connectivity of the matrix. These models are the dual continuum connected matrix (DCCM) and the dual continuum disconnected matrix (DCDM) options. A parallel version of the code, PFLOTRAN, has been developed based on the PETSC parallel library at Argonne National Laboratory. 

Odegard, Gregory M., and Langley Research Center. Equivalent-Continuum Modeling of Nano-Structured Materials. NASA Technical Memorandum, NASA/TM-2001-210863. Hampton, Va. National Aeronautics and Space Administration Langley Research Center available from NASA Center for AeroSpace Information (CASI), 2001. 

Equivalent continuum models of coupled temperature-flow processes of fractured rock masses using FEM (Cai and Han, 1997) ... 

The equivalent continuum model used for the JNC model is developed by combining the crack tensor theory proposed by Oda (1986) and the constitutive model by Barton et al. (1985). This model simulates the anisotropy of the media by crack tensor theory and the non-linear mechanical and hydraulic behavior by the Barton-Bandis (BB) model. Thus, the properties are changed heterogeneously and anisotropically through the excavation process. The constitutive law is incorporated into the coupled THM code, THAMES (Ohnishi, et al., 1985). 

Oda, M., 1986. An Equivalent Continuum Model for Coupled Stresses and Fluid Flow Analysis in Jointed Rock Masses, Water Resour. Res. 22,... 

Oda, M., 1986. An equivalent continuum model for coupled stress and fluid flow analysis and jointed rock masses. Water Resources Research, V. 22, No. 13, pp. 1845-1856. 

FIGURE 2 Equivalent-continuum modeling of eflFective fiber. 

In Odegard s study [48], a method has been presented for finking atomistic simulations of nano-structured materials to continuum models of tfie corresponding bulk material. For a polymer composite system reinforced with SWCNTs, the method provides the steps whereby the nanotube, the local polymer near the nanotube, and the nanotube/ polymer interface can be modeled as an effective continuum fiber by using an equivalent-continuum model. The effective fiber retains the local molecular stractuie and bonding information, as defined by MD, and serves as a means for finking tfie eqniv-alent-continuum and micromechanics models. The micromechanics method is then available for the prediction of bulk mechanical properties of SWCNT/polymer com-... 

This method has been proposed for developing structure-property relationships of nano-structured materials and works as a link between computational chemistry and solid mechanics by substituting discrete molecular structures with equivalent-continuum models. It has been shown that this substitution may be accomplished by equating the molecular potential energy of a nano-structured material with the strain energy of representative truss and continmrm models. 

Because of the approach uses the energy terms that are associated with molecular mechanics modeling, a brief description of molecular mechanics is given first followed by an outline of the equivalent-truss and equivalent-continuum model development. 

Equivalent Continuum Model and Self-Similar Model... 

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