{"id":400,"date":"2021-02-06T12:19:29","date_gmt":"2021-02-06T17:19:29","guid":{"rendered":"https:\/\/web.uri.edu\/nld\/?page_id=400"},"modified":"2026-10-10T13:21:07","modified_gmt":"2026-10-10T17:21:07","slug":"research","status":"publish","type":"page","link":"https:\/\/web.uri.edu\/nld\/research\/","title":{"rendered":"Research"},"content":{"rendered":"\n<div class=\"nld-page-band\" style=\"background:#132433;padding:28px 32px;display:flex;align-items:center;justify-content:space-between;gap:24px;margin:0 0 32px\">\n<div><p style=\"margin:0 0 10px;font-size:13px;line-height:16px;letter-spacing:0.12em;text-transform:uppercase;font-weight:600;color:#A9B6BF\"><span style=\"display:inline-block;width:24px;height:4px;background:#D98A52;vertical-align:middle;margin-right:10px\"><\/span>Nonlinear Dynamics Laboratory<\/p>\n<h1 style=\"color:#F7F6F2;font-size:36px;line-height:42px;margin:0\">Research<\/h1><\/div>\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/web.uri.edu\/nld\/wp-content\/uploads\/sites\/1815\/nld-hero-on-navy.jpg\" alt=\"\" width=\"96\" height=\"96\" style=\"width:96px;height:auto;flex:none\">\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">We study nonlinear dynamics and vibrations through theory, computation and carefully designed experiments. The work falls into four connected themes.<\/p>\n\n\n\n<p style=\"margin:40px 0 8px;font-size:13px;line-height:16px;letter-spacing:0.12em;text-transform:uppercase;font-weight:600;color:#5B6168\"><span style=\"display:inline-block;width:24px;height:4px;background:#B4622A;vertical-align:middle;margin-right:10px\"><\/span>Theme 1<\/p>\n\n\n\n<div class=\"nld-icon-heading\" style=\"display:flex;align-items:center;gap:16px;margin:8px 0 12px\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/web.uri.edu\/nld\/wp-content\/uploads\/sites\/1815\/nld-icon-backbone-curve.jpg\" alt=\"\" width=\"48\" height=\"48\" style=\"width:48px;height:48px;flex:none;margin:0\"><h2 class=\"wp-block-heading\" style=\"margin:0\">Nonlinear normal modes and modal analysis<\/h2><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">We identify nonlinear normal modes experimentally and from data. Our methods track how modal frequencies and shapes change with energy, giving backbone curves and frequency-energy dependence that linear modal analysis cannot capture.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Key papers<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Characteristic value decomposition: A unifying paradigm for data-driven modal analysis. <em>Mechanical Systems and Signal Processing<\/em>, 2025. <a href=\"https:\/\/doi.org\/10.1016\/j.ymssp.2024.111769\">doi:10.1016\/j.ymssp.2024.111769<\/a><\/li>\n\n\n\n<li>Continuation of nonlinear normal modes using reduced-order models based on generalized characteristic value decomposition. <em>Nonlinear Dynamics<\/em>, 2025. <a href=\"https:\/\/doi.org\/10.1007\/s11071-024-10239-0\">doi:10.1007\/s11071-024-10239-0<\/a><\/li>\n\n\n\n<li>Smooth mode decomposition: Theory and its applications in full-field output-only modal analysis. <em>Mechanical Systems and Signal Processing<\/em>, 2023. <a href=\"https:\/\/doi.org\/10.1016\/j.ymssp.2023.110541\">doi:10.1016\/j.ymssp.2023.110541<\/a><\/li>\n\n\n\n<li>Subband decomposition based output-only modal analysis. <em>Journal of Vibration and Acoustics<\/em>, 2023. <a href=\"https:\/\/doi.org\/10.1115\/1.4055135\">doi:10.1115\/1.4055135<\/a><\/li>\n<\/ul>\n\n\n\n<p style=\"margin:40px 0 8px;font-size:13px;line-height:16px;letter-spacing:0.12em;text-transform:uppercase;font-weight:600;color:#5B6168\"><span style=\"display:inline-block;width:24px;height:4px;background:#B4622A;vertical-align:middle;margin-right:10px\"><\/span>Theme 2<\/p>\n\n\n\n<div class=\"nld-icon-heading\" style=\"display:flex;align-items:center;gap:16px;margin:8px 0 12px\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/web.uri.edu\/nld\/wp-content\/uploads\/sites\/1815\/nld-icon-mode-shape.jpg\" alt=\"\" width=\"48\" height=\"48\" style=\"width:48px;height:48px;flex:none;margin:0\"><h2 class=\"wp-block-heading\" style=\"margin:0\">Nonlinear reduced-order modeling<\/h2><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">We build reduced-order models that stay dynamically consistent as amplitude grows, using smooth orthogonal decomposition and manifold-based reduction. The aim is models small enough to analyze and accurate enough to predict.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Key papers<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Persistent model order reduction for complex dynamical systems using smooth orthogonal decomposition. <em>Mechanical Systems and Signal Processing<\/em>, 2017. <a href=\"https:\/\/doi.org\/10.1016\/j.ymssp.2017.04.005\">doi:10.1016\/j.ymssp.2017.04.005<\/a><\/li>\n\n\n\n<li>A new approach to model reduction of nonlinear control systems using smooth orthogonal decomposition. <em>International Journal of Robust and Nonlinear Control<\/em>, 2018. <a href=\"https:\/\/doi.org\/10.1002\/rnc.4238\">doi:10.1002\/rnc.4238<\/a><\/li>\n\n\n\n<li>Robust and dynamically consistent model order reduction for nonlinear dynamic systems. <em>Journal of Dynamic Systems, Measurement, and Control<\/em>, 2014. <a href=\"https:\/\/doi.org\/10.1115\/1.4028470\">doi:10.1115\/1.4028470<\/a><\/li>\n<\/ul>\n\n\n\n<p style=\"margin:40px 0 8px;font-size:13px;line-height:16px;letter-spacing:0.12em;text-transform:uppercase;font-weight:600;color:#5B6168\"><span style=\"display:inline-block;width:24px;height:4px;background:#B4622A;vertical-align:middle;margin-right:10px\"><\/span>Theme 3<\/p>\n\n\n\n<div class=\"nld-icon-heading\" style=\"display:flex;align-items:center;gap:16px;margin:8px 0 12px\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/web.uri.edu\/nld\/wp-content\/uploads\/sites\/1815\/nld-icon-delay-embedding.jpg\" alt=\"\" width=\"48\" height=\"48\" style=\"width:48px;height:48px;flex:none;margin:0\"><h2 class=\"wp-block-heading\" style=\"margin:0\">Signal analysis, damage diagnosis and prognosis<\/h2><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">We use multivariate and nonlinear time-series analysis to track slow damage hidden in fast vibration data. Phase space warping and related methods estimate damage states and predict remaining life in structures and materials.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Key papers<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Ball tree structure-informed phase space warping: a robust algorithm for dynamic degradation tracking under variable speed conditions. <em>Advanced Engineering Informatics<\/em>, 2026. <a href=\"https:\/\/doi.org\/10.1016\/j.aei.2025.104288\">doi:10.1016\/j.aei.2025.104288<\/a><\/li>\n\n\n\n<li>Geometry-informed phase space warping for reliable fatigue damage monitoring. <em>Structural Health Monitoring<\/em>, 2024. <a href=\"https:\/\/doi.org\/10.1177\/14759217231174894\">doi:10.1177\/14759217231174894<\/a><\/li>\n\n\n\n<li>Fatigue life estimation of structures under statistically and spectrally similar variable amplitude loading. <em>Mechanical Systems and Signal Processing<\/em>, 2021. <a href=\"https:\/\/doi.org\/10.1016\/j.ymssp.2021.107856\">doi:10.1016\/j.ymssp.2021.107856<\/a><\/li>\n<\/ul>\n\n\n\n<p style=\"margin:40px 0 8px;font-size:13px;line-height:16px;letter-spacing:0.12em;text-transform:uppercase;font-weight:600;color:#5B6168\"><span style=\"display:inline-block;width:24px;height:4px;background:#B4622A;vertical-align:middle;margin-right:10px\"><\/span>Theme 4<\/p>\n\n\n\n<div class=\"nld-icon-heading\" style=\"display:flex;align-items:center;gap:16px;margin:8px 0 12px\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/web.uri.edu\/nld\/wp-content\/uploads\/sites\/1815\/nld-icon-energy-sink.jpg\" alt=\"\" width=\"48\" height=\"48\" style=\"width:48px;height:48px;flex:none;margin:0\"><h2 class=\"wp-block-heading\" style=\"margin:0\">Vibration absorption, energy transfer and metamaterials<\/h2><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">We design passive nonlinear absorbers and energy harvesters that exploit internal resonance and targeted energy transfer. Current work examines geometry-programmed internal resonance and nonlinear mechanical metamaterials.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Key papers<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Multifaceted vibration absorption of a rotating magnetic nonlinear energy sink. <em>Mechanical Systems and Signal Processing<\/em>, 2025. <a href=\"https:\/\/doi.org\/10.1016\/j.ymssp.2024.112122\">doi:10.1016\/j.ymssp.2024.112122<\/a><\/li>\n\n\n\n<li>Irrational nonlinearity enhances the targeted energy transfer in a rotary nonlinear energy sink. <em>Journal of Computational and Nonlinear Dynamics<\/em>, 2024. <a href=\"https:\/\/doi.org\/10.1115\/1.4065193\">doi:10.1115\/1.4065193<\/a><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-css-opacity\" \/>\n\n\n\n<p class=\"wp-block-paragraph\">The full list is on the <a href=\"https:\/\/web.uri.edu\/nld\/publications\/\">Publications<\/a> page. Our research has been supported by NSF, NIH, the U.S. Army, ONR and AFRL.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Nonlinear Dynamics Laboratory Research We study nonlinear dynamics and vibrations through theory, computation and carefully designed experiments. The work falls into four connected themes. Theme 1 Nonlinear normal modes and modal analysis We identify nonlinear normal modes experimentally and from data. Our methods track how modal frequencies and shapes change with energy, giving backbone curves [&hellip;]<\/p>\n","protected":false},"author":1291,"featured_media":786,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"page-internal-landing.php","meta":{"_acf_changed":false,"footnotes":"","_links_to":"","_links_to_target":""},"class_list":["post-400","page","type-page","status-publish","has-post-thumbnail","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/web.uri.edu\/nld\/wp-json\/wp\/v2\/pages\/400","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/web.uri.edu\/nld\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/web.uri.edu\/nld\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/web.uri.edu\/nld\/wp-json\/wp\/v2\/users\/1291"}],"replies":[{"embeddable":true,"href":"https:\/\/web.uri.edu\/nld\/wp-json\/wp\/v2\/comments?post=400"}],"version-history":[{"count":5,"href":"https:\/\/web.uri.edu\/nld\/wp-json\/wp\/v2\/pages\/400\/revisions"}],"predecessor-version":[{"id":1854,"href":"https:\/\/web.uri.edu\/nld\/wp-json\/wp\/v2\/pages\/400\/revisions\/1854"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/web.uri.edu\/nld\/wp-json\/wp\/v2\/media\/786"}],"wp:attachment":[{"href":"https:\/\/web.uri.edu\/nld\/wp-json\/wp\/v2\/media?parent=400"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}