{"id":165603,"date":"2023-03-17T09:00:46","date_gmt":"2023-03-17T09:00:46","guid":{"rendered":"\/knowledge\/forums\/topic\/is-the-usum-value-from-a-psd-analysis-correct-i-know-there-are-certain-derived-quantities-that-should-not-be-computed-from-the-1-sigma-components-for-example-s1\/"},"modified":"2023-07-31T12:31:35","modified_gmt":"2023-07-31T12:31:35","slug":"is-the-usum-value-from-a-psd-analysis-correct-i-know-there-are-certain-derived-quantities-that-should-not-be-computed-from-the-1-sigma-components-for-example-s1","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/is-the-usum-value-from-a-psd-analysis-correct-i-know-there-are-certain-derived-quantities-that-should-not-be-computed-from-the-1-sigma-components-for-example-s1\/","title":{"rendered":"Is the USUM value from a PSD analysis correct?  I know there are certain derived quantities that should not be computed from the 1-sigma components (for example, s1)."},"content":{"rendered":"<p>USUM is calculated from the 1-sigma components of displacement. It should be reasonably accurate because the calculation of USUM doesn&#8217;t dependent on the sign of the components.  It is still somewhat conservative as it assumes the components are in-phase.  A check on the calculation could be done in \/POST26 by computing an RPSD of USUM for some location using a variable which was the SRSS combination of the component displacements.  The square root of the integral of the USUM RPSD should match the \/POST1 1-sigma value.<\/p>\n","protected":false},"template":"","class_list":["post-165603","topic","type-topic","status-publish","hentry","topic-tag-4663","topic-tag-apdl","topic-tag-mechanical-apdl","topic-tag-random-vibration","topic-tag-structural-dynamics","topic-tag-structural-mechanics"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_wp_page_template":["default"],"_bbp_last_active_time":["3\/15\/2023 20:20"],"_bbp_forum_id":["27792"],"_bbp_author_ip":["23.56.168.180"],"_btv_view_count":["841"],"siebel_km_number":["698441"],"product_version":["12"],"km_published_date":["2007-12-29T00:00:00.000Z"],"family":["Structural Mechanics"],"application_name":["Mechanical APDL"]},"test":"articlesansys-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/topics\/165603","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\/165603\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/media?parent=165603"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}