{"id":1535,"date":"2022-01-22T18:27:40","date_gmt":"2022-01-22T17:27:40","guid":{"rendered":"https:\/\/iop.fnwi.uva.nl\/scm\/wordpress_test\/?p=1535"},"modified":"2026-10-12T21:11:51","modified_gmt":"2026-10-12T20:11:51","slug":"static-friction","status":"publish","type":"post","link":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/2022\/01\/22\/static-friction\/","title":{"rendered":"Static friction"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"1535\" class=\"elementor elementor-1535\" data-elementor-settings=\"[]\">\n\t\t\t\t\t\t\t<div class=\"elementor-section-wrap\">\n\t\t\t\t\t\t\t<section class=\"elementor-section elementor-top-section elementor-element elementor-element-56c53f4c elementor-section-boxed elementor-section-height-default elementor-section-height-default\" data-id=\"56c53f4c\" data-element_type=\"section\">\n\t\t\t\t\t\t<div class=\"elementor-container elementor-column-gap-default\">\n\t\t\t\t\t<div class=\"elementor-column elementor-col-100 elementor-top-column elementor-element elementor-element-4022c990\" data-id=\"4022c990\" data-element_type=\"column\">\n\t\t\t<div class=\"elementor-widget-wrap elementor-element-populated\">\n\t\t\t\t\t\t\t\t<div class=\"elementor-element elementor-element-716a7291 elementor-widget elementor-widget-text-editor\" data-id=\"716a7291\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<style>\/*! elementor - v3.5.5 - 03-02-2022 *\/\n.elementor-widget-text-editor.elementor-drop-cap-view-stacked .elementor-drop-cap{background-color:#818a91;color:#fff}.elementor-widget-text-editor.elementor-drop-cap-view-framed .elementor-drop-cap{color:#818a91;border:3px solid;background-color:transparent}.elementor-widget-text-editor:not(.elementor-drop-cap-view-default) .elementor-drop-cap{margin-top:8px}.elementor-widget-text-editor:not(.elementor-drop-cap-view-default) .elementor-drop-cap-letter{width:1em;height:1em}.elementor-widget-text-editor .elementor-drop-cap{float:left;text-align:center;line-height:1;font-size:50px}.elementor-widget-text-editor .elementor-drop-cap-letter{display:inline-block}<\/style>\t\t\t\t<div style=\"font-size: 18px; line-height: 1.75; color: #43545a; font-weight: 400;\"><!-- INTRODUCTION -->\n<p style=\"margin-bottom: 18px;\">What happens at the microscopic level when two surfaces begin to slide? The transition from <span style=\"color: #10708a; font-weight: 600;\">static to dynamic friction<\/span> plays a crucial role in everything from earthquake dynamics to the stability and wear of mechanical systems.<\/p>\n<p style=\"margin-bottom: 26px;\">Yet a fundamental question remains: why is the force needed to initiate sliding often greater than the force required to keep surfaces moving? Our research investigates the microscopic contact mechanisms behind this transition.<\/p>\n\n<!-- MAIN DISCOVERY HIGHLIGHT -->\n<div style=\"background: #F0F6F8; border-left: 4px solid #10708A; border-radius: 8px; padding: 24px 26px; margin: 28px 0;\">\n<div style=\"font-size: 12px; font-weight: bold; letter-spacing: 1.2px; color: #10708a; margin-bottom: 10px;\">A SURPRISING DISCOVERY<\/div>\n<div style=\"font-size: 21px; line-height: 1.45; font-weight: 600; color: #244650; margin-bottom: 12px;\">Sliding can increase the real contact area \u2014 even as friction decreases.<\/div>\n<p style=\"margin: 0; font-size: 16px; line-height: 1.7;\">Using high-resolution fluorescence microscopy, we observed that the real contact area between surfaces can grow during sliding. Since friction nevertheless decreases, this reveals a reduction in the average interfacial shear strength, challenging the idea of a constant friction force per unit contact area.<\/p>\n<\/div>\n\n<!-- RESEARCH THEMES -->\n<h3 style=\"color: #10708a; font-size: 22px; font-weight: 600; margin: 32px 0 16px;\">Understanding frictional interfaces<\/h3>\n<div style=\"display: flex; flex-wrap: wrap; gap: 16px; margin-bottom: 28px;\"><!-- THEME 1 -->\n<div style=\"flex: 1 1 230px; min-width: 0; background: #F6F8F9; border: 1px solid #E1E8EA; border-radius: 9px; padding: 20px;\">\n<div style=\"font-size: 24px; color: #10708a; margin-bottom: 8px;\">\u23f1<\/div>\n<div style=\"font-size: 17px; font-weight: 600; color: #294b55; margin-bottom: 8px;\">Contact aging<\/div>\n<p style=\"font-size: 15px; line-height: 1.65; margin: 0;\">Stationary interfaces evolve over time, changing the friction force needed to initiate sliding. This behaviour connects frictional contacts to the physics of glassy and jammed materials.<\/p>\n<\/div>\n<!-- THEME 2 -->\n<div style=\"flex: 1 1 230px; min-width: 0; background: #F6F8F9; border: 1px solid #E1E8EA; border-radius: 9px; padding: 20px;\">\n<div style=\"font-size: 24px; color: #10708a; margin-bottom: 8px;\">\u25ce<\/div>\n<div style=\"font-size: 17px; font-weight: 600; color: #294b55; margin-bottom: 8px;\">Microscopic contact mechanics<\/div>\n<p style=\"font-size: 15px; line-height: 1.65; margin: 0;\">By combining surface profilometry, contact imaging and friction measurements, we investigate how microscopic asperities deform and evolve during sliding.<\/p>\n<\/div>\n<\/div>\n<!-- PUBLICATION -->\n<h3 style=\"color: #10708a; font-size: 22px; font-weight: 600; margin: 32px 0 14px;\">Explore the research<\/h3>\n<p style=\"margin-bottom: 16px;\">Discover the experimental findings and underlying physics in our publication.<\/p>\n<a style=\"display: block; background: #F3F7F8; border: 1px solid #E1E8EA; border-left: 3px solid #10708A; border-radius: 8px; padding: 20px 22px; margin-bottom: 30px; text-decoration: none;\" href=\"https:\/\/doi.org\/10.1126\/sciadv.aav7603\" target=\"_blank\" rel=\"noopener noreferrer\"> <span style=\"display: block; font-size: 12px; color: #10708a; font-weight: 600; letter-spacing: 0.6px; margin-bottom: 8px;\"> SCIENCE ADVANCES \u00b7 2019 <\/span> <span style=\"display: block; font-size: 18px; font-weight: 600; color: #263f47; line-height: 1.45; margin-bottom: 8px;\"> Frictional weakening of slip interfaces <\/span> <span style=\"display: block; font-size: 14px; color: #6b7c85; line-height: 1.6;\"> Weber et al. <\/span> <span style=\"display: block; font-size: 13px; color: #10708a; font-weight: 600; margin-top: 12px;\"> Read publication \u2197 <\/span> <\/a> <!-- CONTACT -->\n<p style=\"font-size: 14px; color: #6b7c85; border-top: 1px solid #E1E8EA; padding-top: 16px; margin-bottom: 0;\">Research contact: Kasra Farain \u00a0\u00b7\u00a0 <a style=\"color: #10708a; text-decoration: none;\" href=\"mailto:k.farain@uva.nl\"> k.farain@uva.nl <\/a><\/p>\n<\/div>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>What happens at the microscopic level when two surfaces begin to slide? The transition from static to dynamic friction plays a crucial role in everything from earthquake dynamics to the stability and wear of mechanical systems. Yet a fundamental question remains: why is the force needed to initiate sliding often greater than the force required [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":1669,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[17],"tags":[],"_links":{"self":[{"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/posts\/1535"}],"collection":[{"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/comments?post=1535"}],"version-history":[{"count":7,"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/posts\/1535\/revisions"}],"predecessor-version":[{"id":3998,"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/posts\/1535\/revisions\/3998"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/media\/1669"}],"wp:attachment":[{"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/media?parent=1535"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/categories?post=1535"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/iop.fnwi.uva.nl\/scm\/index.php\/wp-json\/wp\/v2\/tags?post=1535"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}