iMechanica - damage assessment
http://imechanica.org/taxonomy/term/9832
enModal strain energy-based debonding assessment of sandwich panels using a linear approximation with maximum entropy
http://imechanica.org/node/21882
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/76">research</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/11592">sandwich panel</a></div><div class="field-item odd"><a href="/taxonomy/term/9832">damage assessment</a></div><div class="field-item even"><a href="/taxonomy/term/4483">debonding</a></div><div class="field-item odd"><a href="/taxonomy/term/11859">modal strain energy</a></div><div class="field-item even"><a href="/taxonomy/term/11860">linear approximation with maximum entropy</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><img src="http://camlab.cl/wp-content/uploads/2017/11/figure6.png" alt="" width="500" height="235" /></p><p> </p>
<p><strong>Abstract</strong>
</p><p>Sandwich structures are very attractive due to their high strength at a minimum weight, and, therefore, there has been a rapid increase in their applications. Nevertheless, these structures may present imperfect bonding or debonding between the skins and core as a result of manufacturing defects or impact loads, degrading their mechanical properties. To improve both the safety and functionality of these systems, structural damage assessment methodologies can be implemented. This article presents a damage assessment algorithm to localize and quantify debonds in sandwich panels. The proposed algorithm uses damage indices derived from the modal strain energy method and a linear approximation with a maximum entropy algorithm. Full-field vibration measurements of the panels were acquired using a high-speed 3D digital image correlation (DIC) system. Since the number of damage indices per panel is too large to be used directly in a regression algorithm, reprocessing of the data using principal component analysis (PCA) and kernel PCA has been performed. The results demonstrate that the proposed methodology accurately identifies debonding in composite panels.</p>
<p><strong>Keywords</strong>: sandwich panel; damage assessment; debonding; modal strain energy; linear approximation with maximum entropy.</p>
<p><a href="http://camlab.cl/2017/11/21/modal-strain-energy-based-debonding-assessment-of-sandwich-panels-using-a-linear-approximation-with-maximum-entropy/" target="_blank">Get the article</a></p>
<p> </p>
</div></div></div>Tue, 21 Nov 2017 20:41:10 +0000Alejandro Ortiz-Bernardin21882 at http://imechanica.orghttp://imechanica.org/node/21882#commentshttp://imechanica.org/crss/node/21882A novel impact identification algorithm based on a linear approximation with maximum entropy
http://imechanica.org/node/20163
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/76">research</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/11252">impact identification</a></div><div class="field-item odd"><a href="/taxonomy/term/1810">structural health monitoring</a></div><div class="field-item even"><a href="/taxonomy/term/9832">damage assessment</a></div><div class="field-item odd"><a href="/taxonomy/term/2386">maximum entropy</a></div><div class="field-item even"><a href="/taxonomy/term/9834">linear approximation</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p>Paper Accepted for Publication in Smart Materials and Structures</p>
<p>N. Sanchez, V. Meruane, A. Ortiz-Bernardin, “A novel impact identification algorithm based on a linear approximation with maximum entropy.”</p>
<p>ABSTRACT</p>
<p>This article presents a novel impact identification algorithm that uses a linear approximation handled by a statistical inference model based on the maximum-entropy principle, termed linear approximation with maximum entropy (LME). Unlike other regression algorithms as Artificial Neural Networks (ANN) and Support Vector Machines (SVM), the proposed algorithm requires only one parameter to be selected and the impact is identified after solving a convex optimization problem that has a unique solution. In addition, with LME data is processed in a period of time that is comparable to the one of other algorithms. The performance of the proposed methodology is validated by considering an experimental aluminum plate. Time varying strain data is measured using four piezoceramic sensors bonded to the plate. To demonstrate the potential of the proposed approach over existing ones, results obtained via LME are compared with those of ANN and Least Square Support Vector Machines (LSSVM). The results demonstrate that with a low number of sensors it is possible to accurately locate and quantify impacts on a structure and that LME outperforms other impact identification algorithms.</p>
<p>Keywords: Impact identification, structural health monitoring, damage assessment, maximum entropy, linear approximation.</p>
<p><a href="http://camlab.cl/alejandro/publications/a-novel-impact-identification-algorithm-based-on-a-linear-approximation-with-maximum-entropy/" target="_blank">Get the article</a></p>
</div></div></div>Mon, 08 Aug 2016 22:28:15 +0000Alejandro Ortiz-Bernardin20163 at http://imechanica.orghttp://imechanica.org/node/20163#commentshttp://imechanica.org/crss/node/20163A maximum entropy approach to assess debonding in honeycomb aluminum plates
http://imechanica.org/node/16660
<div class="field field-name-taxonomy-vocabulary-6 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/76">research</a></div></div></div><div class="field field-name-taxonomy-vocabulary-8 field-type-taxonomy-term-reference field-label-hidden"><div class="field-items"><div class="field-item even"><a href="/taxonomy/term/4448">sandwich structures</a></div><div class="field-item odd"><a href="/taxonomy/term/4483">debonding</a></div><div class="field-item even"><a href="/taxonomy/term/9615">honeycomb</a></div><div class="field-item odd"><a href="/taxonomy/term/9832">damage assessment</a></div><div class="field-item even"><a href="/taxonomy/term/9833">maximum-entropy principle</a></div><div class="field-item odd"><a href="/taxonomy/term/9834">linear approximation</a></div></div></div><div class="field field-name-body field-type-text-with-summary field-label-hidden"><div class="field-items"><div class="field-item even"><p><strong><font size="2">Abstract</font></strong></p>
<p>
<font size="2">Honeycomb sandwich structures are used in a wide variety of applications. Nevertheless, due to manufacturing defects or impact loads, these structures can be subject to imperfect bonding or debonding between the skin and the honeycomb core. The presence of debonding reduces the bending stiffness of the composite panel, which causes detectable changes in its vibration characteristics. This article presents a new supervised learning algorithm to identify debonded regions in aluminum honeycomb panels. The algorithm uses a linear approximation method handled by a statistical inference model based on the maximum-entropy principle. The merits of this new approach are twofold: training is avoided and data is processed in a period of time that is comparable to the one of neural networks. The honeycomb panels are modeled with finite elements using a simplified three-layer shell model. The adhesive layer between the skin and core is modeled using linear springs, the rigidities of which are reduced in debonded sectors. The algorithm is validated using experimental data of an aluminum honeycomb panel under different damage scenarios.</font>
</p>
<p>
<font size="2"><strong>Keywords:</strong> Sandwich structures; debonding; honeycomb; damage assessment; maximum-entropy principle; linear approximation.</font>
</p>
<p>
<a href="http://camlab.cl/alejandro/publications/a-maximum-entropy-approach-to-assess-debonding-in-honeycomb-aluminum-plates/"><font size="2">Get the article</font></a>
</p>
</div></div></div>Fri, 23 May 2014 19:03:02 +0000Alejandro Ortiz-Bernardin16660 at http://imechanica.orghttp://imechanica.org/node/16660#commentshttp://imechanica.org/crss/node/16660