iMechanica - Comments for "Usermat: Linear viscoelastic model with geometric nonlinearity"
https://imechanica.org/node/19506
Comments for "Usermat: Linear viscoelastic model with geometric nonlinearity"enI am not familiar with the
https://imechanica.org/comment/28118#comment-28118
<a id="comment-28118"></a>
<p><em>In reply to <a href="https://imechanica.org/node/19506">Usermat: Linear viscoelastic model with geometric nonlinearity</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>I am not familiar with the detail of the viscoelastic model and user subroutine Usermat in Ansys. I think two different problems may should be considered.</p>
<p>First, the objectivity of the constitutive law in finite deformation: When you choose an objective constitutive law, the strain measurement and the stress measurement (such as Green strain and PK2 stress) are defined uniquely and are objectivity. Then you calculate the objective strain<span> </span><span>through displacement </span><span>(or rate form through velocity)</span><span> based on the definition, where field displacement is interpolated by nodes displacement in FEM implementation. So the calculated strain in interpolated form is objectivty, and you needn't rotate this varible. If the measurements definition contains the rotation term, the rotation calculation is needed for these measurements or varibles.</span></p>
<p>Second, the deformation assumptions of the layers: As you have mentioned, the shell model generally involves the deformaiton assumptions along the thickness direction. The deformation assumption (especially the stress assumption) usually implemented through modifying the institutive law matrix along the shell thickness direction. Then you need rotate the strain or rotate the constitutiive law matrix to be consistent with the thickness direction.</p>
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</ul>Tue, 23 Feb 2016 02:45:23 +0000tigerzjiecomment 28118 at https://imechanica.orgError | iMechanica