{"id":166507,"date":"2023-03-17T13:12:04","date_gmt":"2023-03-17T13:12:04","guid":{"rendered":"\/knowledge\/forums\/topic\/what-are-the-different-ways-to-excite-a-base-with-displacement-or-acceleration-in-harmonic-analysis-mapdl\/"},"modified":"2023-07-31T12:31:57","modified_gmt":"2023-07-31T12:31:57","slug":"what-are-the-different-ways-to-excite-a-base-with-displacement-or-acceleration-in-harmonic-analysis-mapdl","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/what-are-the-different-ways-to-excite-a-base-with-displacement-or-acceleration-in-harmonic-analysis-mapdl\/","title":{"rendered":"What are the different ways to excite a base (with displacement or acceleration) in harmonic analysis? (MAPDL)"},"content":{"rendered":"<p>In the attached example, 3 methods are presented for a base excitation in a harmonic analysis  &#8211; The Large Mass method: used for several years, the acceleration is replaced by a force applied to a large mass fixed to the base of the model. This mass is a lot heavier than the total mass of the structure (>10^3). To replace the A0 acceleration, an equivalent force F = ML*A0 is applied.   &#8211; The Enforced Motion method: available since R13 for MSUP harmonic. This method create a loadvector in the modal basis which allow to apply an acceleration or a displacement  &#8211; The Full harmonic method: more accurate but also more time consuming. The displacement (or the acceleration) is directly applied threw an imposed displacement (using D command)  Nota : In harmonic, displacement and acceleration are linked by the following equation :  A = w\u00b2.U (w is the pulsation) <\/p>\n<p>Attachments:<br \/>\n1. <a href=https:\/\/ansys13.ansys.com\/KnowledgeArticles\/Phase-1\/2040083\/2040083.pdf>2040083.pdf<\/a><br \/>\n2. <a href= https:\/\/ansys13.ansys.com\/KnowledgeArticles\/Phase-1\/2040083\/2040083.zip>2040083.zip<\/a><\/p>\n","protected":false},"template":"","class_list":["post-166507","topic","type-topic","status-publish","hentry","topic-tag-mechanical-apdl","topic-tag-modal-harmonic-response","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":["4966"],"siebel_km_number":["2040083"],"product_version":[""],"km_published_date":["2015-08-19T20:12:19.000Z"],"family":["Structural Mechanics"],"application_name":["Mechanical APDL"]},"test":"solution"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/topics\/166507","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\/166507\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/media?parent=166507"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}