{"id":455503,"date":"2026-03-31T23:04:44","date_gmt":"2026-03-31T23:04:44","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/constraints-and-eliminating-degrees-of-freedom\/"},"modified":"2026-03-31T23:04:44","modified_gmt":"2026-03-31T23:04:44","slug":"constraints-and-eliminating-degrees-of-freedom","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/constraints-and-eliminating-degrees-of-freedom\/","title":{"rendered":"Constraints and Eliminating Degrees of Freedom"},"content":{"rendered":"<p>&lt;p&gt;Hi Everyone, this is my first post, and I&#8217;m new to FEA so please have some patience with my elementary questions \ud83d\ude42&nbsp;&lt;\/p&gt;&lt;p&gt;I am trying to replicate an as built condition for a fixture we have. I have a 4 piece assembly thats bolted to a flat plane with a significant amount of fasteners. I am using a frictionless constraint, paired with cylindrical constraints on each of my bolt locations. I believe the frictionless constraint will eliminate 1 translation, and 2 rotational degrees of freedom. My fasteners (since i have more than 1) eliminate 2 more translational, and one rotational dof.&nbsp;&lt;\/p&gt;&lt;p&gt;However when i run a modal analysis, my responses are 0,0,0 and then basically zero and my mode shapes show rigid body motion.&lt;\/p&gt;&lt;p&gt;Is there a better way to approach this?&lt;\/p&gt;&lt;p&gt;Thank you,&lt;\/p&gt;&lt;p&gt;e&nbsp;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-455503","topic","type-topic","status-publish","hentry","topic-tag-mechanical"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27791"],"_bbp_topic_id":["455503"],"_bbp_subscription":["449342","240"],"_bbp_author_ip":["173.59.5.174"],"_bbp_last_reply_id":["455652"],"_bbp_last_active_id":["455652"],"_bbp_last_active_time":["2026-04-02 11:29:24"],"_bbp_reply_count":["2"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["449342","240"],"_btv_view_count":["18"],"_bbp_topic_status":["unanswered"]},"test":"eric-soringlmco-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/455503","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\/455503\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=455503"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}