Jorgen
2007-08-28, 18:46
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A new model for predicting the mechanical behavior of semi-crystalline polymers was recently published by J.A.W. van Dommelen, D.M. Parks, M.C. Boyce, W.A.M. Brekelmans, and F.P.T. Baaijens ["Micromechanical modeling of the elasto-viscoplastic behavior of semi-crystalline polymers", J. Mech. Phys. Solids, Vol. 51, pp. 519-541, 2003.]
Their paper describes a new model that combines both crystall plasticity and amorphous plasticity by a hybrid interaction model. The theory they present is micromechanism inspired and detailed, but it is not yet clear how well the model can predict real materials.
Abstract: A micromechanically based constitutive model for the elasto-viscoplastic deformation and texture evolution of semi-crystalline polymers is developed. The model idealizes the microstructure to consist of an aggregate of two-phase layered composite inclusions. A new framework for the composite inclusion model is formulated to facilitate the use of finite deformation elasto-viscoplastic constitutive models for each constituent phase. The crystalline lamellae are modeled as anisotropic elastic with plastic flow occurring via crystallographic slip. The amorphous phase is modeled as isotropic elastic with plastic flow being a rate-dependent process with strain hardening resulting from molecular orientation. The volume-averaged deformation and stress within the inclusions are related to the macroscopic fields by a hybrid interaction model. The uniaxial compression of initially isotropic high density polyethylene (HDPE) is taken as a case study. The ability of the model to capture the elasto-plastic stress-strain behavior of HDPE during monotonic and cyclic loading, the evolution of anisotropy, and the effect of crystallinity on initial modulus, yield stress, post-yield behavior and unloading-reloading cycles are presented.
A new model for predicting the mechanical behavior of semi-crystalline polymers was recently published by J.A.W. van Dommelen, D.M. Parks, M.C. Boyce, W.A.M. Brekelmans, and F.P.T. Baaijens ["Micromechanical modeling of the elasto-viscoplastic behavior of semi-crystalline polymers", J. Mech. Phys. Solids, Vol. 51, pp. 519-541, 2003.]
Their paper describes a new model that combines both crystall plasticity and amorphous plasticity by a hybrid interaction model. The theory they present is micromechanism inspired and detailed, but it is not yet clear how well the model can predict real materials.
Abstract: A micromechanically based constitutive model for the elasto-viscoplastic deformation and texture evolution of semi-crystalline polymers is developed. The model idealizes the microstructure to consist of an aggregate of two-phase layered composite inclusions. A new framework for the composite inclusion model is formulated to facilitate the use of finite deformation elasto-viscoplastic constitutive models for each constituent phase. The crystalline lamellae are modeled as anisotropic elastic with plastic flow occurring via crystallographic slip. The amorphous phase is modeled as isotropic elastic with plastic flow being a rate-dependent process with strain hardening resulting from molecular orientation. The volume-averaged deformation and stress within the inclusions are related to the macroscopic fields by a hybrid interaction model. The uniaxial compression of initially isotropic high density polyethylene (HDPE) is taken as a case study. The ability of the model to capture the elasto-plastic stress-strain behavior of HDPE during monotonic and cyclic loading, the evolution of anisotropy, and the effect of crystallinity on initial modulus, yield stress, post-yield behavior and unloading-reloading cycles are presented.