iMechanica - Comments for "Journal Club for September 2017: Some recent developments in constitutive modeling of glassy polymers"
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Comments for "Journal Club for September 2017: Some recent developments in constitutive modeling of glassy polymers"enDear Rui
http://imechanica.org/comment/29212#comment-29212
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<p><em>In reply to <a href="http://imechanica.org/node/21561">Journal Club for September 2017: Some recent developments in constitutive modeling of glassy polymers</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p>Dear Rui,</p>
<p>Many thanks for your contribution to this journal club issue and I look forward to your future contributions as delineated in your post. The use of modified internal variables have been a very powerful appropach to developing constitutive models for polymers. Thanks for bringing to attention your work and classical work of Tool and others. The furhter challenge perhaps lies in modeling physical phenomena for which a transition of length scales (call it effective field theory applied to thermo-mechanics of nano-heterogeneous metastable media) masks the observed macro-scale phenomena which can be naturally explained by a stochastic description. My hope is that this very limited journal club post attracts the attention to such situations.</p>
<p>Regards,</p>
<p> Alireza.</p>
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</ul>Fri, 15 Sep 2017 13:04:13 +0000Alireza Amirkhizicomment 29212 at http://imechanica.orgDear Alireza,
http://imechanica.org/comment/29201#comment-29201
<a id="comment-29201"></a>
<p><em>In reply to <a href="http://imechanica.org/node/21561">Journal Club for September 2017: Some recent developments in constitutive modeling of glassy polymers</a></em></p>
<div class="field field-name-comment-body field-type-text-long field-label-hidden"><div class="field-items"><div class="field-item even"><p class="MsoNormal"><span>Dear Alireza,</span></p>
<p class="MsoNormal"><span>Thanks for this nice review on the modeling glassy polymers. Indeed, the behaviors of glassy polymers show complex dependence on temperature, rate, thermal history as well as mechanical deformation, which raises a great challenge for developing constitutive models to describe them.</span></p>
<p class="MsoNormal"><span>In addition to the above-mentioned approaches, another approach based on effective temperature has also been developed to describe the nonequilibrium behaviors of amorphous solids. The concept effective temperature originates from Tool’s fictive temperature [1]. By introducing the configurational entropy as a thermodynamic conjugate variable to the effective temperature, a fully consistent nonequilibrium thermodynamic framework has been built [2,3]. Based on the works of the physical community, we have developed a finite deformation continuum mechanics version of the effective temperature theory [4-6]. More importantly, we show that the effective temperature theory can quantitatively capture the dependence of stress response on temperature, strain rate, physical aging, and mechanical pre-deformation [4]. The effective temperature theory can also describe the experimentally measured DSC results, including an increase of enthalpy overshoot with aging, a decrease of enthalpy overshoot with mechanical deformation and the appearance of an undershoot of deformed glassy polymers [6].</span></p>
<p class="MsoNormal"><span>Currently, we are also using the effective temperature to describe the mechanical instability of polymers, such as necking and shear banding. Hope we can obtain some preliminary results in the very near future.</span></p>
<p class="MsoNormal"><span>Rui</span></p>
<p class="MsoNormal"><span>Reference:</span></p>
<p class="MsoNormal"><span>[1] A.Q. Tool, 1946. “Viscosity and extraordinary heat effects in glass”. J. Am. Ceram. Soc. 29, 240.</span></p>
<p class="MsoNormal"><span>[2] T.M. Nieuwenhuizen, 1998. “Thermodynamics of the glassy state: effective temperatures an additional system parameter”. Phys. Rev. Lett.80, 5580.</span></p>
<p class="MsoNormal"><span>[3] E. Bouchbinder, J.S. Langer, 2009. “Nonequilibrium<span> </span>thermodynamics of driven amorphous materials .II. effective-temperature theory”. Phys. Rev. E. 80, 031132.</span></p>
<p class="MsoNormal"><span>[4] R. Xiao, T. D. Nguyen, 2015. “An effective temperature theory for the nonequilibrium behavior of amorphous polymers”, J. Mech. Phys. Solids, 82, 62.</span></p>
<p class="MsoNormal"><span>[5] R. Xiao, T. D. Nguyen, 2016. “A thermodynamic modeling approach for dynamic softening in glassy amorphous polymers”, Extreme Mech. Lett., 8, 70.</span></p>
<p class="MsoNormal"><span>[6] R. Xiao, G. Ghazaryan, T. A. Tervoort, T. D. Nguyen, 2017. <span> </span>“Modeling the energy storage and structural evolution during finite viscoplastic deformation of glassy polymers ”, Phys. Rev. E., 95, 063001.</span></p>
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</ul>Wed, 06 Sep 2017 11:39:16 +0000Rui Xiaocomment 29201 at http://imechanica.org