{"id":360378,"date":"2024-04-03T20:30:58","date_gmt":"2024-04-03T20:30:58","guid":{"rendered":"\/forum\/forums\/topic\/dimensions-of-the-mass-and-stiffness-matrices-exported-from-apdl\/"},"modified":"2024-04-03T20:30:58","modified_gmt":"2024-04-03T20:30:58","slug":"dimensions-of-the-mass-and-stiffness-matrices-exported-from-apdl","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/dimensions-of-the-mass-and-stiffness-matrices-exported-from-apdl\/","title":{"rendered":"Dimensions of the mass and stiffness matrices exported from APDL"},"content":{"rendered":"<p style=\"text-align: justify\">I am conducting a <strong>modal analysis<\/strong> of a clamped-clamped beam using Ansys APDL. The beam mesh contains 200 elements and 201 nodes, and I am using <strong>BEAM188<\/strong>, which has <strong>6 degrees<\/strong> of freedom at each node.<\/p>\n<p style=\"text-align: justify\">I expected that the extracted mass and stiffness matrices would have dimensions of <strong>1206&#215;1206<\/strong>, since each node has 6 DOF, thus 201*6 = 1206.<\/p>\n<p style=\"text-align: justify\">The extracted matrices have dimensions of <strong>1194&#215;1194<\/strong>, apparently, the DOF from the fixed ends (12 DOF) are removed. I would like to know if it is possible to extract the mass and stiffness matrices including the fixed ends, that is, to extract the matrices with dimensions of 1206&#215;1206.<\/p>\n<p style=\"text-align: justify\">To <strong>extract the matrices<\/strong>, I use the following commands:<\/p>\n<p>&nbsp;<\/p>\n<p style=\"text-align: left\">! Stiffness<\/p>\n<p style=\"text-align: left\">*DMAT,MatKD,D,IMPORT,FULL,beam_apdl.full,STIFF&nbsp;<br \/>*PRINT,MatKD,Kdense.matrix<\/p>\n<p style=\"text-align: left\">! Mass<\/p>\n<p style=\"text-align: left\">*DMAT,MatMD,D,IMPORT,FULL,beam_apdl.full,MASS<br \/>*PRINT,MatMD,Mdense.matrix<\/p>\n<p style=\"text-align: left\">! below the commands create sperse matrix<\/p>\n<p style=\"text-align: left\">*SMAT,MatKS,D,IMPORT,FULL,beam_apdl.full,STIFF&nbsp;<br \/>*PRINT,MatKS,Ksparse.matrix<\/p>\n<p style=\"text-align: left\">*SMAT,MatMS,D,IMPORT,FULL,beam_apdl.full,MASS<br \/>*PRINT,MatMS,Msparse.matrix<\/p>\n<p>&nbsp;<\/p>\n<p>I thank you in advance for your attention!<\/p>\n","protected":false},"template":"","class_list":["post-360378","topic","type-topic","status-closed","hentry","topic-tag-Modal_Analysis-1","topic-tag-apdl","topic-tag-mass-matrix-1","topic-tag-stiffness-matrix"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["342866","20905"],"_bbp_author_ip":["96.7.218.223"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["626"],"_bbp_topic_status":["unanswered"],"_bbp_topic_id":["360378"],"_bbp_forum_id":["27791"],"_bbp_engagement":["20905","342866"],"_bbp_voice_count":["2"],"_bbp_reply_count":["2"],"_bbp_last_reply_id":["361617"],"_bbp_last_active_id":["361617"],"_bbp_last_active_time":["2024-04-10 20:35:27"]},"test":"aerospace-gabrielgmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/360378","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\/360378\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=360378"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}