{"id":4694,"date":"2019-01-14T02:32:54","date_gmt":"2019-01-14T07:32:54","guid":{"rendered":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/?page_id=4694"},"modified":"2019-01-14T07:40:44","modified_gmt":"2019-01-14T12:40:44","slug":"two-dof-string-model","status":"publish","type":"page","link":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/chapter-ii-animations\/two-dof-string-model\/","title":{"rendered":"Two-DOF string model"},"content":{"rendered":"<p><!--This file created 3\/26\/04 7:45 AM by Claris Home Page version 2.0-->\u00a0As we have seen from this lecture, the qualitative nature of the free response of a system will depend on the particular initial conditions given to the system. For example, for a two-DOF system released <i>from<\/i> <i>rest<\/i> (a zero initial velocity for all points in the system):<\/p>\n<p>&nbsp;<\/p>\n<table border=\"1\" width=\"852\" cellpadding=\"6\">\n<tbody>\n<tr>\n<td width=\"81\"><center><b><i><span style=\"font-family: Arial;\">FIRST MODE<\/span><\/i><\/b><\/center><center>\u00a0<\/center><\/td>\n<td width=\"307\"><span style=\"font-family: Arial;\">If the initial conditions are in the <\/span><i><span style=\"font-family: Arial;\">first<\/span><\/i><span style=\"font-family: Arial;\"> mode<\/span><\/p>\n<blockquote><p><img decoding=\"async\" src=\"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-content\/uploads\/sites\/18\/2019\/01\/eqn_01.gif\" \/><\/p><\/blockquote>\n<p><span style=\"font-family: Arial;\">the then response will be <\/span><span style=\"color: #af0000; font-family: Arial;\">HARMONIC<\/span><span style=\"font-family: Arial;\"> having a frequency of the <\/span><i><span style=\"color: #af0000; font-family: Arial;\">first natural frequency<\/span><\/i><span style=\"font-family: Arial;\"> and the shape of the <\/span><i><span style=\"font-family: Arial;\">response will remain in the first mode<\/span><\/i><span style=\"font-family: Arial;\">.<\/span><\/td>\n<\/tr>\n<tr>\n<td width=\"81\"><center><b><i><span style=\"font-family: Arial;\">SECOND MODE<\/span><\/i><\/b><\/center><center>\u00a0<\/center><\/td>\n<td width=\"307\"><span style=\"font-family: Arial;\">If the initial conditions are in the <\/span><i><span style=\"font-family: Arial;\">second<\/span><\/i><span style=\"font-family: Arial;\"> mode<\/span><\/p>\n<blockquote><p><img decoding=\"async\" src=\"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-content\/uploads\/sites\/18\/2019\/01\/eqn_02.gif\" \/><\/p><\/blockquote>\n<p><span style=\"font-family: Arial;\">then the response will be <\/span><span style=\"color: #af0000; font-family: Arial;\">HARMONIC<\/span><span style=\"font-family: Arial;\"> having a frequency of the <\/span><i><span style=\"color: #af0000; font-family: Arial;\">second natural frequency<\/span><\/i><span style=\"font-family: Arial;\"> and the shape of the <\/span><i><span style=\"font-family: Arial;\">response will remain in the second mode<\/span><\/i><\/td>\n<\/tr>\n<tr>\n<td width=\"81\"><center><b><i><span style=\"font-family: Arial;\">NON-MODAL RESPONSE<\/span><\/i><\/b><\/center><\/td>\n<td width=\"307\">F<span style=\"font-family: Arial;\">or ANY initial conditions other than those in a) and b), the response will be (generally) <\/span><span style=\"color: #af0000; font-family: Arial;\">NON-HARMONIC<\/span><span style=\"font-family: Arial;\"> and will be a <\/span><span style=\"color: #af0000; font-family: Arial;\">LINEAR COMBINATION<\/span><span style=\"font-family: Arial;\"> of the two modes.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&nbsp;<\/p>\n<table style=\"border-collapse: collapse; width: 159.8430907172996%; height: 499px;\" border=\"1\">\n<tbody>\n<tr style=\"height: 499px;\">\n<td style=\"width: 80%; height: 499px;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-content\/uploads\/sites\/18\/2019\/01\/response.gif\" width=\"636\" height=\"402\" \/><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<p style=\"text-align: center;\">\n","protected":false},"excerpt":{"rendered":"<p>\u00a0As we have seen from this lecture, the qualitative nature of the free response of a system will depend on the particular initial conditions given to the system. For example, for a two-DOF system released from rest (a zero initial velocity for all points in the system): &nbsp; FIRST MODE\u00a0 If the initial conditions are &hellip; <a href=\"https:\/\/www.purdue.edu\/freeform\/ervibrations\/chapter-ii-animations\/two-dof-string-model\/\" class=\"more-link\">Continue reading <span class=\"screen-reader-text\">Two-DOF string model<\/span> <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":10,"featured_media":0,"parent":4682,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"class_list":["post-4694","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-json\/wp\/v2\/pages\/4694","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-json\/wp\/v2\/users\/10"}],"replies":[{"embeddable":true,"href":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-json\/wp\/v2\/comments?post=4694"}],"version-history":[{"count":9,"href":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-json\/wp\/v2\/pages\/4694\/revisions"}],"predecessor-version":[{"id":4740,"href":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-json\/wp\/v2\/pages\/4694\/revisions\/4740"}],"up":[{"embeddable":true,"href":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-json\/wp\/v2\/pages\/4682"}],"wp:attachment":[{"href":"https:\/\/www.purdue.edu\/freeform\/ervibrations\/wp-json\/wp\/v2\/media?parent=4694"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}