{"id":61878,"date":"2023-12-19T17:25:02","date_gmt":"2023-12-19T15:25:02","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=61878"},"modified":"2024-02-13T13:06:30","modified_gmt":"2024-02-13T11:06:30","slug":"these-ravi-verma-interaction-des-ondes-ultrasonores-avec-les-defauts-de-frottement-dans-le-contexte-du-controle-non-destructif-des-materiaux","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/agenda\/these-ravi-verma-interaction-des-ondes-ultrasonores-avec-les-defauts-de-frottement-dans-le-contexte-du-controle-non-destructif-des-materiaux.html","title":{"rendered":"THESE Ravi VERMA : Interaction des ondes ultrasonores avec les d\u00e9fauts de frottement dans le contexte du contr\u00f4le non destructif des mat\u00e9riaux\u00a0\u00bb"},"content":{"rendered":"<div id='layer_slider_1'  class='avia-layerslider main_color avia-shadow  avia-builder-el-0  el_before_av_heading  avia-builder-el-first  container_wrap sidebar_right'  style='height: 261px;'  ><div id=\"layerslider_58_1cjag15azcfiy\" data-ls-slug=\"homepageslider\" class=\"ls-wp-container fitvidsignore ls-selectable\" style=\"width:1140px;height:260px;margin:0 auto;margin-bottom: 0px;\"><div class=\"ls-slide\" data-ls=\"duration:6000;transition2d:5;\"><img loading=\"lazy\" decoding=\"async\" width=\"2600\" height=\"270\" src=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1.jpg\" class=\"ls-bg\" alt=\"\" srcset=\"https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1.jpg 2600w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-300x31.jpg 300w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-768x80.jpg 768w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-1030x107.jpg 1030w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-1500x156.jpg 1500w, https:\/\/www.iemn.fr\/wp-content\/uploads\/2019\/01\/sliders_news1-705x73.jpg 705w\" sizes=\"auto, (max-width: 2600px) 100vw, 2600px\" \/><ls-layer style=\"font-size:14px;text-align:left;font-style:normal;text-decoration:none;text-transform:none;font-weight:700;letter-spacing:0px;border-style:solid;border-color:#000;background-position:0% 0%;background-repeat:no-repeat;width:180px;height:30px;left:0px;top:231px;line-height:32px;color:#ffffff;border-radius:6px 6px 6px 6px;padding-left:50px;background-color:rgba(0, 0, 0, 0.57);\" class=\"ls-l ls-ib-icon ls-text-layer\" data-ls=\"minfontsize:0;minmobilefontsize:0;\"><i class=\"fa fa-quote-right\" style=\"color:#ffffff;margin-right:0.8em;font-size:1em;transform:translateY( -0.125em );\"><\/i>ACTUALITES<\/ls-layer><\/div><\/div><\/div><div id='after_layer_slider_1'  class='main_color av_default_container_wrap container_wrap sidebar_right'  ><div class='container av-section-cont-open' ><div class='template-page content  av-content-small alpha units'><div class='post-entry post-entry-type-page post-entry-61878'><div class='entry-content-wrapper clearfix'>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-av_heading-46e5988898e83ebeff44a5f82a605613\">\n#top .av-special-heading.av-av_heading-46e5988898e83ebeff44a5f82a605613{\nmargin:0 0 10px 0;\npadding-bottom:4px;\n}\nbody .av-special-heading.av-av_heading-46e5988898e83ebeff44a5f82a605613 .av-special-heading-tag .heading-char{\nfont-size:25px;\n}\n.av-special-heading.av-av_heading-46e5988898e83ebeff44a5f82a605613 .av-subheading{\nfont-size:15px;\n}\n<\/style>\n<div  class='av-special-heading av-av_heading-46e5988898e83ebeff44a5f82a605613 av-special-heading-h2  avia-builder-el-1  el_after_av_layerslider  el_before_av_hr  avia-builder-el-first'><h2 class='av-special-heading-tag'  itemprop=\"headline\"  >THESE Ravi VERMA : Interaction des ondes ultrasonores avec les d\u00e9fauts de frottement dans le contexte du contr\u00f4le non destructif des mat\u00e9riaux\u00a0\u00bb<\/h2><div class=\"special-heading-border\"><div class=\"special-heading-inner-border\"><\/div><\/div><\/div>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-18u73nj-dad6a947580930e400fc42ba200e80f1\">\n#top .hr.av-18u73nj-dad6a947580930e400fc42ba200e80f1{\nmargin-top:5px;\nmargin-bottom:5px;\n}\n.hr.av-18u73nj-dad6a947580930e400fc42ba200e80f1 .hr-inner{\nwidth:100%;\n}\n<\/style>\n<div  class='hr av-18u73nj-dad6a947580930e400fc42ba200e80f1 hr-custom  avia-builder-el-2  el_after_av_heading  el_before_av_textblock  hr-left hr-icon-no'><span class='hr-inner inner-border-av-border-thin'><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n<section  class='av_textblock_section av-jriy64i8-2f4600354c0449b610997916bbd9b6bc'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" >\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-13ewzjw-68e036126b913e5028f77311dc66b825\">\n.av_font_icon.av-13ewzjw-68e036126b913e5028f77311dc66b825{\ncolor:#bfbfbf;\nborder-color:#bfbfbf;\n}\n.av_font_icon.av-13ewzjw-68e036126b913e5028f77311dc66b825 .av-icon-char{\nfont-size:60px;\nline-height:60px;\n}\n<\/style>\n<span  class='av_font_icon av-13ewzjw-68e036126b913e5028f77311dc66b825 avia_animate_when_visible av-icon-style- avia-icon-pos-left avia-icon-animate'><span class='av-icon-char' aria-hidden='true' data-av_icon='\ue8c9' data-av_iconfont='entypo-fontello' ><\/span><\/span>\n<p><strong>Ravi VERMA<br \/>\n<\/strong><\/p>\n<p>Soutenance :20 d\u00e9cembre \u00e0 13h00<strong><br \/>\n<\/strong>IEMN Amphitheatre - Central Laboratory - Villeneuve d'Ascq<\/p>\n<\/div><\/section>\n<section  class='av_textblock_section av-jtefqx33-628129dba2299b2ecd65ebfc92eac29d'   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><div  class='hr av-kjh3zw-4dff888f744b728a1aca9b3a0971493a hr-default  avia-builder-el-6  avia-builder-el-no-sibling'><span class='hr-inner'><span class=\"hr-inner-style\"><\/span><\/span><\/div>\n<h5><strong><span style=\"color: #800000;\">Jury :<\/span><\/strong><\/h5>\n<ul>\n<li>Dr. Vladislav Aleshin, Chercheur CNRS, IEMN, Lille, Superviseur<\/li>\n<li>Dr. Koen Van Den Abeele, Professeur, KU Leuven, Courtrai, Co-superviseur<\/li>\n<li>Dr. Nathalie Favretto-Cristini, Directrice de Recherche CNRS, LMA, Marseille, Pr\u00e9sidente<\/li>\n<li>Dr. C\u00e9dric Payan, Professeur, LMA, Marseille, Rapporteurs<\/li>\n<li>Dr. Mourad Bentahar, Ma\u00eetre de conf\u00e9rences, Le Mans Universit\u00e9, Rapporteurs<\/li>\n<li>Dr. Christ Glorieux, Professeur, KU Leuven, Courtrai, Examinateurs<\/li>\n<li>Dr. Olivier Bou Matar, Professeur, \u00c9cole Centrale Lille, Lille, Invit\u00e9<\/li>\n<li>Dr. Mathias Kersemans, Professeur, Universit\u00e9 Gent, Invit\u00e9<\/li>\n<\/ul>\n<p><strong>Summary:<\/strong><\/p>\n<p>Cette th\u00e8se porte sur les concepts th\u00e9oriques, les mod\u00e8les et les exp\u00e9riences concernant la propagation des ondes \u00e9lastiques et les vibrations dans les solides contenant des contacts internes (fissures, d\u00e9laminations, etc.) ayant une nature frictionnelle.<br \/>\nUne partie essentielle du travail est li\u00e9e au d\u00e9veloppement d\u2019une m\u00e9thode d\u2019acoustique num\u00e9rique capable d\u2019imiter les ondes \u00e9lastiques dans un environnement contenant des fissures\/contacts de frottement. Ces d\u00e9fauts planaires repr\u00e9sentent une sorte de fronti\u00e8re int\u00e9rieure \u00e0 laquelle il convient d\u2019appliquer des conditions limites appropri\u00e9es. Selon les hypoth\u00e8ses de mod\u00e9lisation, les surfaces des fissures peuvent \u00eatre consid\u00e9r\u00e9es comme planes ou rugueuses. Nous d\u00e9veloppons ici en d\u00e9tail les arguments montrant que la rugosit\u00e9, bien qu\u2019elle introduise une complexification suppl\u00e9mentaire, aboutit finalement \u00e0 une description plus \u00e9l\u00e9gante du contact par rapport aux interfaces planes. En particulier, le contact de surfaces rugueuses isotropes peut \u00eatre repr\u00e9sent\u00e9 efficacement comme un contact entre deux corps axisym\u00e9triques. Cette derni\u00e8re situation ressemble beaucoup \u00e0 la m\u00e9canique de Cattaneo-Mindlin (ou Hertz-Mindlin) dans laquelle deux sph\u00e8res sont excit\u00e9es m\u00e9caniquement par une force oblique.<br \/>\nUn autre \u00e9l\u00e9ment du mod\u00e8le acoustique num\u00e9rique que nous pr\u00e9sentons ici est une description standard par \u00e9l\u00e9ments finis des ondes \u00e9lastiques dans les mat\u00e9riaux solides (unit\u00e9 de m\u00e9canique des solides dans un progiciel FEM commercial). Des efforts techniques ont \u00e9t\u00e9 faits pour int\u00e9grer un mod\u00e8le de contact d\u00e9fini par l\u2019utilisateur comme condition limite dans l\u2019unit\u00e9 de m\u00e9canique des solides. En cons\u00e9quence, un mod\u00e8le complet a \u00e9t\u00e9 obtenu qui incorpore les interactions frictionnelles de contact induites par les ondes, d\u00e9crites \u00e0 partir des premiers principes de la m\u00e9canique des contacts.<br \/>\nUn progr\u00e8s essentiel par rapport aux travaux pr\u00e9c\u00e9dents est li\u00e9 \u00e0 l\u2019application du mod\u00e8le \u00e9labor\u00e9 \u00e0 un cas qui correspond \u00e0 une technique connue d\u2019essais non destructifs acoustiques non lin\u00e9aires. La technique choisie est bas\u00e9e sur l\u2019excitation d\u2019un \u00e9chantillon avec une onde harmonique qui, apr\u00e8s l\u2019ach\u00e8vement d\u2019un r\u00e9gime transitoire, entra\u00eene une r\u00e9ponse purement harmonique d\u2019un \u00e9chantillon intact, alors que la r\u00e9ponse d\u2019un \u00e9chantillon endommag\u00e9 pr\u00e9sentera une anharmonicit\u00e9. Les harmoniques g\u00e9n\u00e9r\u00e9es forment leur propre mod\u00e8le d\u2019onde stationnaire qui peut avoir un maximum clair autour du d\u00e9faut. Dans la pratique, les mesures de signaux de surface sont effectu\u00e9es par vibrom\u00e9trie laser ; notre mod\u00e9lisation repr\u00e9sente donc une tentative d\u2019imiter l\u2019exp\u00e9rience de contr\u00f4le non destructif par vibrom\u00e9trie laser dans des conditions g\u00e9om\u00e9triques simplifi\u00e9es, mais en adh\u00e9rant pleinement \u00e0 son id\u00e9ologie.<br \/>\nLes conditions simplifi\u00e9es sont prises de mani\u00e8re \u00e0 r\u00e9duire le temps de calcul. L\u2019hypoth\u00e8se la plus importante est une g\u00e9om\u00e9trie en 2D qui emp\u00eache imm\u00e9diatement toute comparaison quantitative avec l\u2019exp\u00e9rience. D\u2019autres simplifications sont discut\u00e9es plus en d\u00e9tail ci-dessous. Tout en conservant la m\u00e9thodologie g\u00e9n\u00e9rale proche des principes exp\u00e9rimentaux, nous g\u00e9n\u00e9rons un grand nombre d\u2019images synth\u00e9tiques non lin\u00e9aires d\u2019une fissure isol\u00e9e immerg\u00e9e dans un fragment d\u2019une plaque solide. Nous analysons en d\u00e9tail l\u2019influence des param\u00e8tres g\u00e9om\u00e9triques et physiques du syst\u00e8me dans les cas d\u2019excitations \u00e0 une et deux fr\u00e9quences.<br \/>\nEnfin, nous nous concentrons sur le cas le plus proche des conditions exp\u00e9rimentales r\u00e9elles en termes de g\u00e9om\u00e9trie de l\u2019\u00e9chantillon et de conditions aux limites s\u00e9lectionn\u00e9es. Une comparaison pr\u00e9liminaire entre la th\u00e9orie et l\u2019exp\u00e9rience est pr\u00e9sent\u00e9e.<br \/>\nD\u2019une mani\u00e8re g\u00e9n\u00e9rale, les r\u00e9sultats de cette th\u00e8se pourraient int\u00e9resser les chercheurs impliqu\u00e9s dans des exp\u00e9riences de CND acoustiques non lin\u00e9aires ainsi que ceux qui cherchent des applications de mod\u00e8les de contact semi-analytiques modernes bas\u00e9s sur les principes de Cattaneo-Mindlin.<\/p>\n<h5>Abstract:<\/h5>\n<p>This thesis concerns theoretical concepts, models, and experiments for elastic wave propagation and vibrations in solids containing internal contacts (cracks, delaminations, etc.) having frictional nature. The study is oriented to nondestructive testing and therefore focuses on the case where the material contains few cracks of known configuration, in contrast to microcracked solids in which a statistical ensemble of a large number of internal contacts is present.<br \/>\nAn essential part of the work is related to a development of a method of numerical acoustics capable of imitating elastic waves in an environment containing frictional cracks\/contacts. These planar defects represent a sort of inner boundaries at which appropriate boundary conditions should set. These boundary conditions are set using an original model for frictional interaction based on Cattaneo-Mindlin (or Hertz-Mindlin) mechanics in which two spheres are mechanically excited with an oblique force. The known solutions are extended to the case of rough surfaces and arbitrary in time oblique excitation.<br \/>\nAnother component of the numerical acoustics model we present here is a standard finite element description for elastic waves in solid materials (solid mechanics unit in a commercial FEM package). Some technical efforts have been made to integrate a user-defined contact model as a boundary condition into the solid mechanics unit. As a result, a complete model has been obtained that incorporates wave-induced contact frictional interactions described starting from first principles of contact mechanics.<br \/>\nAn essential progress in comparison to previous works is related to application of the elaborated model to a case that corresponds to a known technique of nonlinear acoustic nondestructive testing. The chosen technique is based on excitation of a sample with a harmonics wave that, after completion of a transient regime, results in a purely harmonic response of an intact sample, whereas the response of a damaged sample will present anharmonicity. The generated harmonics form its own standing wave pattern that can have a clear maximum around the defect. In practice, surface signal measurements are done via laser vibrometry; our modeling therefore represents an attempt to imitate laser vibromenry NDT experiment in geometrically simplified conditions, but fully adhering to its ideology.<br \/>\nThe simplified conditions are taken in a way that reduces the computation time. The most important assumption is a 2D geometry that immediately disables a quantitative comparison to experiment. Other simplifications are discussed below in greater detail. Keeping, however, the general methodology close to experimental principles we generate a large number of synthetic nonlinear images of an isolated crack immersed into a fragment of a solid plate. We analyze in detail influence of geometric and physical parameters of the system in the cases of one- and two-frequency excitations.<br \/>\nFinally, we focus on the case close to real experimental conditions in terms of the sample geometry and boundary conditions selected. A preliminary theory and experiment comparison is presented.<br \/>\nGenerally, the results of this thesis could be of interest for researchers involved in nonlinear acoustic NDT experiments as well as for those who look for applications of modern semi-analytical contact models based on Cattaneo-Mindlin principles.<\/p>\n<\/div><\/section>","protected":false},"excerpt":{"rendered":"","protected":false},"author":20,"featured_media":61885,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[87,65,84,187,318],"tags":[],"class_list":["post-61878","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-agenda-en","category-agenda","category-agenda-en-en","category-annonces-these","category-these-2023"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/61878","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=61878"}],"version-history":[{"count":0,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/61878\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media\/61885"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=61878"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=61878"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=61878"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}