iMechanica - Comments for "Discussion of fracture paper #25 - The role of the fracture process region"
https://imechanica.org/node/23886
Comments for "Discussion of fracture paper #25 - The role of the fracture process region"enDiscussion of fracture paper #25 - The role...
https://imechanica.org/comment/30227#comment-30227
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<p><em>In reply to <a href="https://imechanica.org/node/23886">Discussion of fracture paper #25 - The role of the fracture process region</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>Thank you very much for your interest in our paper and for reading it so thoroughly. I think it's an interesting discussion and reflection. For instance, the fact that the cohesive zone has two independent parameters, the fracture energy and the maximum stress, does not really turn the model into a two-parameter model in the same sense as the K-T or the J-Q models. These other models represent more of the surrounding mechanical state than the two-parameter cohesive zone model is able to account for.</p>
<p>Nailing the cohesive stress, I believe, is a tricky issue. It seems to me that for ductile materials this entity lacks a clear physical interpretation, and therefore tends to play the role of a fitting parameter. Another issue that you raise is whether the present set of parameters is general enough to predict the behavior of considerably longer cracks or for short or even vanishing cracks. Although we have not investigated the predictive ability of the model for these cases, I would expect that the prediction would be far from perfect. One reason is, as you mentioned, that the cohesive zone is taken to be autonomous, that is independent of what is going on around it.</p>
<p>We have actually performed experiments for growing cracks as well (not published yet). These results have not been fully evaluated, but preliminary results indicate that it is, for instance, difficult to predict the behavior for long crack growth using the present approach. Furthermore, it is evident that during crack growth, the rate dependence of the fracture process is very important to capture accurately.</p>
<p>Finally, the question must also be raised if the cohesive zone concept is really the best way to model this kind of crack growth which exhibits a lot of ductility. In the study, we did some preliminary investigations of the fracture surfaces, but I would say that further examinations of the actual fracture process are needed. Such investigations might suggest if, for example, a continuum damage model is a better approach to model fracture of these materials.</p>
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</ul>Tue, 14 Jan 2020 16:28:00 +0000Martin Krooncomment 30227 at https://imechanica.orgError | iMechanica