Abstract:In this work, the GursonTvergaardNeedleman model, commonly used for metallic materials, is applied to the failure of a polymeric material specifically a polyethylene carbon monoxide copolymer, which is an enhanced photodegradable material. GursonTvergaardNeedleman model parameters for this material are obtained using the NelderMead simplex method when correlating experimental and numerical results of both tensile and fracture specimens. Results show that the GursonTvergaardNeedleman model can also be used for … Show more
“…Finally, if going to larger strain we should include damage that might be induced into the polymer. Oral et al. (2012) presents a damage model for polymers that may be adapted into our model.…”
We present unified predictions for the crack onset strain, evolution of crack density, and changes in electrical resistance in indium tin oxide/polymer thin films under tensile loading. We propose a damage mechanics model to quantify and predict such changes as an alternative to fracture mechanics formulations. Our predictions are obtained by assuming that there are no flaws at the onset of loading as opposed to the assumptions of fracture mechanics approaches. We calibrate the crack onset strain and the damage model based on experimental data reported in the literature. We predict crack density and changes in electrical resistance as a function of the damage induced in the films. We implement our model in the commercial finite element software ABAQUS using a user subroutine UMAT. We obtain fair to good agreement with experiments.
“…Finally, if going to larger strain we should include damage that might be induced into the polymer. Oral et al. (2012) presents a damage model for polymers that may be adapted into our model.…”
We present unified predictions for the crack onset strain, evolution of crack density, and changes in electrical resistance in indium tin oxide/polymer thin films under tensile loading. We propose a damage mechanics model to quantify and predict such changes as an alternative to fracture mechanics formulations. Our predictions are obtained by assuming that there are no flaws at the onset of loading as opposed to the assumptions of fracture mechanics approaches. We calibrate the crack onset strain and the damage model based on experimental data reported in the literature. We predict crack density and changes in electrical resistance as a function of the damage induced in the films. We implement our model in the commercial finite element software ABAQUS using a user subroutine UMAT. We obtain fair to good agreement with experiments.
“…Therefore, flow stress constants or GTN constants should be considered differently. Through a study of polymer materials' GTN constants, Oral and Anlas (2012) proposed that unlike general metals, the values; q 1 =3.0, q 2 =1.0, and q 3 =9.0 were more suitable for polymer materials. In this study, q 1, q 2, and q 3 were determined reflecting the proposal.…”
“…Finally, coalescence phase of the microcavities is introduced using the Tvergaard and Needleman model (Oral et al., 2012) in order to consider the effect of void coalescence f c in the numerical implementation where f c represents the porosity at the onset of coalescence and α=(fU-fc)/(fF-fc) is a factor describing the acceleration of the material degradation during coalescence, as shown in Figure 4. f F and f U represent the porosity and the value of f* at failure, respectively.…”
Section: Formulation Of the Micromechanics-based Ductile Damage Model Of The Femur Bonementioning
confidence: 99%
“…f F and f U represent the porosity and the value of f* at failure, respectively. Figure 4.Evolution of porosity model Oral et al. (2012).Figure 5.Return mapping algorithm.…”
Section: Formulation Of the Micromechanics-based Ductile Damage Model Of The Femur Bonementioning
International audienceIn this paper, we propose a new multiscale finite element methodology based on a recently developed micromechanical damage model for the modelling of the human bone behaviour under dynamic loading. The damage is carried out by the framework of the limit analysis based on the MCK (Monchiet, Charkaluk and Kondo) criterion. We first present the methodology allowing the estimation of elastic anisotropic properties of porous media by means of Mori-Tanaka homogenisation scheme. Then, we develop the formulation of the integrated yield criterion derived by considering trial velocity field inspired from the Eshelby inhomogeneous inclusion solution. The obtained micromechanical model is implemented via a User Material routine within the explicit dynamic code LS-DYNA (c). The proposed micromechanical model has been applied successfully for the estimation of the mechanical properties of a human proximal femur under dynamic loading. From the obtained numerical results, it has been shown that the present model has improved the strength prediction of osteoporotic femurs by representing the failure risk in a more realistic approach
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