{"id":158152,"date":"2022-06-06T09:58:49","date_gmt":"2022-06-06T09:58:49","guid":{"rendered":"\/knowledge\/forums\/topic\/why-dont-mode-shape-deformations-for-the-first-3-rigid-body-modes-translate-along-global-xy-and-z-directions\/"},"modified":"2022-06-06T09:58:49","modified_gmt":"2022-06-06T09:58:49","slug":"why-dont-mode-shape-deformations-for-the-first-3-rigid-body-modes-translate-along-global-xy-and-z-directions","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/why-dont-mode-shape-deformations-for-the-first-3-rigid-body-modes-translate-along-global-xy-and-z-directions\/","title":{"rendered":"Why don&#8217;t mode shape deformations for the first 3 rigid body modes translate along global x,y and z directions?"},"content":{"rendered":"<p>There is no guarantee or restriction to require that the rigid-body modes are parallel to the global Cartesian coordinate system.  Consequently, if the calculated rigid-body modes aren&#8217;t aligned with global Cartesian, they may look strange. What matters is only that the rigid-body modes (eigenvectors) are orthogonal to each other.  Hence, there should be a linear combination of modes 1 through 6 to equate rigid-body translation along the global X direction, for example. Rigid-body motion has no unique solution. The basis taken is not orthogonal to the global CS doesn&#8217;t mean that it&#8217;s incorrect.<\/p>\n","protected":false},"template":"","class_list":["post-158152","topic","type-topic","status-publish","hentry","topic-tag-mode-shape","topic-tag-rigid-body-motion"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_wp_page_template":["default"],"_bbp_last_active_time":["06-06-2022 20:20"],"_bbp_forum_id":["27792"],"_btv_view_count":["587"],"_bbp_likes_count":["0"]},"test":"articlesansys-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/topics\/158152","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/topics\/158152\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/media?parent=158152"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}