{"id":390222,"date":"2024-10-17T10:49:09","date_gmt":"2024-10-17T10:49:09","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ansys-substructuring-and-extract-stiffness-matrix\/"},"modified":"2024-10-30T13:42:24","modified_gmt":"2024-10-30T13:42:24","slug":"ansys-substructuring-and-extract-stiffness-matrix","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ansys-substructuring-and-extract-stiffness-matrix\/","title":{"rendered":"ANSYS Substructuring and extract Stiffness Matrix"},"content":{"rendered":"<p>&lt;p&gt;&lt;p&gt;&lt;p&gt;Hello,&nbsp;&lt;\/p&gt;&lt;p&gt;my problem is a bit complicated to explain. I try to sketch my workflow below:&lt;\/p&gt;&lt;\/p&gt;&lt;\/p&gt;<\/p>\n<ol>\n<li>I model a shaft in ANSYS Workbench\/Mechanical and mesh it.<\/li>\n<li>Boundary conditions are defined with the ANSYS option cylindrical bearings. The shaft is free in circumferential direction. Other BC are used to get a fully constrained model. The picture below shows them left and right of the gearing:&lt;br&gt;<\/li>\n<li>After meshing, I create a substructuring model and define some points at the gearing as masterpoints.&nbsp;<\/li>\n<li>Forces are defined at a tooth<\/li>\n<li>The substructured stiffness matrix and the Load vector are extracted via the HB-Format (command HBMAT in an APDL script).<\/li>\n<li>Stiffness Matrix and Load vector are imported in Matlab and the System K*u=f is solved.&nbsp;<\/li>\n<\/ol>\n<p>&lt;p&gt;&lt;p&gt;&lt;p&gt;To test my workflow, I did the calculation in Matlab and ANSYS directly. Results for u should be the same in both cases.&nbsp;&lt;\/p&gt;&lt;p&gt;Now to my problem:&lt;\/p&gt;&lt;\/p&gt;&lt;\/p&gt;<\/p>\n<ul>\n<li>For the configuration with the cylindrical bearing boundary condition, the deformation u from Matlab (derived with the load vector and stiffness matrix from Ansys) differs from the deformation calculated with ANSYS directly .<\/li>\n<li>Changing the cylindrical bearing boundary condition to fully constrained boundary condition (u = 0 at the cylindrical surfaces in the picture above), the solution from ANSYS directly and Matlab are the same.<\/li>\n<\/ul>\n<p>&lt;p&gt;&lt;p&gt;&lt;p&gt;So it can be assumend, that in my model with the cylindrical bearing boundary conditions, something is wrong with the exported stiffness matrix. Maybe I have some commands missing?&lt;\/p&gt;&lt;p&gt;It would be nice if someone has done something like this before or has an idea of what to look out for to solve the problem.&lt;\/p&gt;&lt;p&gt;Best,&lt;\/p&gt;&lt;p&gt;Jonas&lt;\/p&gt;&lt;\/p&gt;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-390222","topic","type-topic","status-publish","hentry","topic-tag-boundary-condition","topic-tag-cylindricaljoint-1","topic-tag-cylindrical-support","topic-tag-mechanical","topic-tag-stiffness-matrix","topic-tag-substructuring-2"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["471374","20905"],"_bbp_author_ip":["2001:4ca0:2323:1:518:bb93:e4cc:47ec"],"_btv_view_count":["527"],"_bbp_topic_status":["unanswered"],"_edit_last":["471374"],"_bbp_revision_log":["a:2:{i:390223;a:2:{s:6:\"author\";i:471374;s:6:\"reason\";s:0:\"\";}i:392014;a:2:{s:6:\"author\";i:471374;s:6:\"reason\";s:0:\"\";}}"],"_bbp_topic_id":["390222"],"_bbp_forum_id":["27791"],"_bbp_engagement":["20905","471374"],"_bbp_voice_count":["2"],"_bbp_reply_count":["2"],"_bbp_last_reply_id":["392016"],"_bbp_last_active_id":["392016"],"_bbp_last_active_time":["2024-10-30 13:44:52"]},"test":"jonas-f-bergertum-de"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/390222","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":2,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/390222\/revisions"}],"predecessor-version":[{"id":392014,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/390222\/revisions\/392014"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=390222"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}