{"id":40079,"date":"2020-01-11T11:17:23","date_gmt":"2020-01-11T11:17:23","guid":{"rendered":"\/forum\/forums\/topic\/modal-analysis-boundary-conditions-for-simply-supported-beam\/"},"modified":"2020-01-11T11:17:23","modified_gmt":"2020-01-11T11:17:23","slug":"modal-analysis-boundary-conditions-for-simply-supported-beam","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/modal-analysis-boundary-conditions-for-simply-supported-beam\/","title":{"rendered":"Modal Analysis &#8211; Boundary Conditions for Simply Supported Beam"},"content":{"rendered":"<p>Hello<\/p>\n<p><\/p>\n<p>I am facing a problem in workbench modal analysis results. I had models a simple steel beam of length 1.044 m and cross sectional dimension 0.023 x 0.005 m. E = 2.05E+11 N\/m^2 and poisons ratio = 0.3. Density = 7830 kg\/m^3.&nbsp;<\/p>\n<p><\/p>\n<p>Theoretically i have calculated its first three bending modes and their frequencies are f1=10.65, f2=42.58 &amp; f3=95.81 Hz respectively.&nbsp;<\/p>\n<p><\/p>\n<p>In FE Model, beam length is along the x-axis while its width (0.023m) is along z-axis and depth (0.005m) along y-axis. I had applied boundary conditions at both extreme ends as follows to let the beam behave as simply-supported:&nbsp;<\/p>\n<p><\/p>\n<p>UX=UY=UZ= 0 &amp; RX=RY=0 , RZ= Free&nbsp;<\/p>\n<p><\/p>\n<p>With all these conditions i am getting first three modes as:<\/p>\n<p><\/p>\n<p>f1=16.283, f2=44.887 &amp; f3=98.13 Hz<\/p>\n<p><\/p>\n<p>Why the Theoretical and Numerical values are not equal or at least there should be very less difference between them?<\/p>\n<p><\/p>\n<p>Is there any problem with the boundary conditions or something else?<\/p>\n<p><\/p>\n<p>Looking for the solution.<\/p>\n<p><\/p>\n<p>Thanks<\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"template":"","class_list":["post-40079","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["12258"],"_bbp_old_topic_author_name_id":["Anonymous"],"_bbp_old_is_topic_anonymous_id":["false"],"_bbp_old_closed_status_id":["publish"],"_bbp_author_ip":[null],"_bbp_old_sticky_status_id":["normal"],"_bbp_likes_count":["0"],"_btv_view_count":["4436"],"_bbp_subscription":["245980"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["40079"],"_bbp_forum_id":["27791"],"_bbp_engagement":["166004","171645"],"_bbp_voice_count":["2"],"_bbp_reply_count":["3"],"_bbp_last_reply_id":["102912"],"_bbp_last_active_id":["102912"],"_bbp_last_active_time":["2020-01-20 07:46:53"]},"test":"smehboob"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/40079","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":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/40079\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=40079"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}