{"id":249091,"date":"2023-02-08T10:36:03","date_gmt":"2023-02-08T10:36:03","guid":{"rendered":"\/forum\/forums\/topic\/need-help-troubleshooting-free-free-modal-analysis-with-non-zero-frequencies\/"},"modified":"2024-02-29T15:11:57","modified_gmt":"2024-02-29T15:11:57","slug":"need-help-troubleshooting-free-free-modal-analysis-with-non-zero-frequencies","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/need-help-troubleshooting-free-free-modal-analysis-with-non-zero-frequencies\/","title":{"rendered":"Need help troubleshooting free free modal analysis with non-zero frequencies"},"content":{"rendered":"<p class=\"_1qeIAgB0cPwnLhDF9XSiJM\">I have a model of a box with a point mass inside. The box is made up of 6 individual components (sides) and they&#8217;re all connected using bonded contacts. The geometry of the box is made up of midsurfaces (shell elements). Each side of the box has a chassis slide attached using bonded contacts. The chassis slides are solid elements.<\/p>\n<p class=\"_1qeIAgB0cPwnLhDF9XSiJM\">My ultimate goal is to determine the resonant frequency and I&#8217;ve already gotten some results but I wasn&#8217;t convinced. So I suppressed the boundary conditions and the point mass to check the rigid body modes.<\/p>\n<p class=\"_1qeIAgB0cPwnLhDF9XSiJM\">1-3 translation modes are 0 Hz but 4-6 rotation modes are non-zero, in fact they&#8217;re in the single digit frequency range. So I extracted equivalent total strain and notice non-zero values for strain at each corner of the box. Can anyone shed some light on possible causes? I appreciate any help.<\/p>\n<p class=\"_1qeIAgB0cPwnLhDF9XSiJM\">I checked my contacts using the contact tool and don&#8217;t have any open contacts. There are some that are statused orange.<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/02\/08-02-2023-1675852265-mceclip0.png\"><\/p>\n","protected":false},"template":"","class_list":["post-249091","topic","type-topic","status-closed","hentry","topic-tag-Modal_Analysis-1","topic-tag-equivalent-strain"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["274526","240","20905"],"_bbp_author_ip":["23.192.164.18"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["2196"],"_bbp_topic_status":["answered"],"_bbp_topic_id":["249091"],"_bbp_forum_id":["27791"],"_bbp_engagement":["240","20905","274526"],"_bbp_voice_count":["3"],"_bbp_reply_count":["5"],"_bbp_last_reply_id":["249267"],"_bbp_last_active_id":["249267"],"_bbp_last_active_time":["2023-02-09 14:57:16"]},"test":"michael-r-yousseflmco-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/249091","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":1,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/249091\/revisions"}],"predecessor-version":[{"id":354583,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/249091\/revisions\/354583"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=249091"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}