{"id":397893,"date":"2024-12-18T17:29:37","date_gmt":"2024-12-18T17:29:37","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/"},"modified":"2024-12-18T17:29:37","modified_gmt":"2024-12-18T17:29:37","slug":"397893","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/","title":{"rendered":"Reply To: Cross-coupled stiffness elements in LS-DYNA"},"content":{"rendered":"<p>&lt;p&gt;Hello Simon,&lt;\/p&gt;&lt;p&gt;I found the following in our knowledge database:&lt;\/p&gt;&lt;p&gt;&#8221;&lt;\/p&gt;<\/p>\n<pre>Superelements are not appropriate for bodies undergoing finite rotations.  \nFor that case, one could employ flexible rigid bodies (*part_modes)\"&lt;br&gt;&lt;br&gt;One developer told me: \"&lt;span data-teams=\"true\"&gt;We are working on extending it to large rotations, underway.\"&lt;br&gt;&lt;br&gt;And here is more information from our knowledge database:&lt;br&gt;&lt;br&gt;\"A \"flexible rigid body\" saves cpu time by approximating response using mode superposition.\nThe basic procedure is to first compute normal modes (*control_implicit_eigenvalue) and\/or\nconstraint or attachment modes (*control_implicit_modes) of a deformable body.\nThen in a subsequent explicit analysis, you approximate that deformable body as a\n\"flexible rigid body\" via the command *part_modes.\n\nHere are links to papers describing the procedure and examples:\nhttp:\/\/ftp.lstc.com\/anonymous\/outgoing\/jday\/Session_12-1.pdf\nhttp:\/\/ftp.lstc.com\/anonymous\/outgoing\/jday\/flexrb.pdf\nhttp:\/\/ftp.lstc.com\/anonymous\/outgoing\/jday\/Bitzenbauer.pdf\nThe first two are essentially the same paper.\n\nExample input (rather old, I'm afraid) is in http:\/\/ftp.lstc.com\/anonymous\/outgoing\/jday\/flexrb_example.tar\"&lt;br&gt;&lt;br&gt;You will find a regular super element example here:&lt;br&gt;&lt;br&gt;http:\/\/ftp.lstc.com\/anonymous\/outgoing\/support\/EXAMPLES\/superel_inertia_matrix.tar&lt;br&gt;&lt;br&gt;&lt;br&gt;Let me know if this helps or not.&lt;br&gt;&lt;br&gt;&lt;br&gt;Reno.&lt;\/span&gt;<\/pre>\n","protected":false},"template":"","class_list":["post-397893","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Hello Simon,I found the following in our knowledge database:&quot;Superelements are not appropriate for bodies undergoing finite rotations. For that case, one could employ flexible rigid bodies (*part_modes)&quot;One developer told me: &quot;We are working on extending it to large rotations, underway.&quot;And here is more information from our knowledge database:&quot;A &quot;flexible rigid body&quot; saves cpu time\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<link rel=\"canonical\" href=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/\" \/>\n\t<meta name=\"generator\" content=\"All in One SEO (AIOSEO) 4.9.10\" \/>\n\t\t<meta property=\"og:locale\" content=\"en_US\" \/>\n\t\t<meta property=\"og:site_name\" content=\"Ansys Learning Forum | Ansys Innovation Space\" \/>\n\t\t<meta property=\"og:type\" content=\"article\" \/>\n\t\t<meta property=\"og:title\" content=\"Reply To: Cross-coupled stiffness elements in LS-DYNA | Ansys Learning Forum\" \/>\n\t\t<meta property=\"og:description\" content=\"Hello Simon,I found the following in our knowledge database:&quot;Superelements are not appropriate for bodies undergoing finite rotations. For that case, one could employ flexible rigid bodies (*part_modes)&quot;One developer told me: &quot;We are working on extending it to large rotations, underway.&quot;And here is more information from our knowledge database:&quot;A &quot;flexible rigid body&quot; saves cpu time\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2024-12-18T17:29:37+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2024-12-18T17:29:37+00:00\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n\t\t<meta name=\"twitter:title\" content=\"Reply To: Cross-coupled stiffness elements in LS-DYNA | Ansys Learning Forum\" \/>\n\t\t<meta name=\"twitter:description\" content=\"Hello Simon,I found the following in our knowledge database:&quot;Superelements are not appropriate for bodies undergoing finite rotations. For that case, one could employ flexible rigid bodies (*part_modes)&quot;One developer told me: &quot;We are working on extending it to large rotations, underway.&quot;And here is more information from our knowledge database:&quot;A &quot;flexible rigid body&quot; saves cpu time\" \/>\n\t\t<script type=\"application\/ld+json\" class=\"aioseo-schema\">\n\t\t\t{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/397893\\\/#breadcrumblist\",\"itemListElement\":[{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum#listItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\",\"nextItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/397893\\\/#listItem\",\"name\":\"Reply To: Cross-coupled stiffness elements in LS-DYNA\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/397893\\\/#listItem\",\"position\":2,\"name\":\"Reply To: Cross-coupled stiffness elements in LS-DYNA\",\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum#listItem\",\"name\":\"Home\"}}]},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#organization\",\"name\":\"Ansys Learning Forum\",\"description\":\"Ansys Innovation Space\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/397893\\\/#webpage\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/397893\\\/\",\"name\":\"Reply To: Cross-coupled stiffness elements in LS-DYNA | Ansys Learning Forum\",\"description\":\"Hello Simon,I found the following in our knowledge database:\\\"Superelements are not appropriate for bodies undergoing finite rotations. For that case, one could employ flexible rigid bodies (*part_modes)\\\"One developer told me: \\\"We are working on extending it to large rotations, underway.\\\"And here is more information from our knowledge database:\\\"A \\\"flexible rigid body\\\" saves cpu time\",\"inLanguage\":\"en-US\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#website\"},\"breadcrumb\":{\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/397893\\\/#breadcrumblist\"},\"datePublished\":\"2024-12-18T17:29:37+00:00\",\"dateModified\":\"2024-12-18T17:29:37+00:00\"},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#website\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/\",\"name\":\"Ansys Learning Forum\",\"description\":\"Ansys Innovation Space\",\"inLanguage\":\"en-US\",\"publisher\":{\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#organization\"}}]}\n\t\t<\/script>\n\t\t<!-- All in One SEO -->\n\n","aioseo_head_json":{"title":"Reply To: Cross-coupled stiffness elements in LS-DYNA | Ansys Learning Forum","description":"Hello Simon,I found the following in our knowledge database:\"Superelements are not appropriate for bodies undergoing finite rotations. For that case, one could employ flexible rigid bodies (*part_modes)\"One developer told me: \"We are working on extending it to large rotations, underway.\"And here is more information from our knowledge database:\"A \"flexible rigid body\" saves cpu time","canonical_url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"BreadcrumbList","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/#breadcrumblist","itemListElement":[{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum#listItem","position":1,"name":"Home","item":"https:\/\/innovationspace.ansys.com\/forum","nextItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/#listItem","name":"Reply To: Cross-coupled stiffness elements in LS-DYNA"}},{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/#listItem","position":2,"name":"Reply To: Cross-coupled stiffness elements in LS-DYNA","previousItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum#listItem","name":"Home"}}]},{"@type":"Organization","@id":"https:\/\/innovationspace.ansys.com\/forum\/#organization","name":"Ansys Learning Forum","description":"Ansys Innovation Space","url":"https:\/\/innovationspace.ansys.com\/forum\/"},{"@type":"WebPage","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/#webpage","url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/","name":"Reply To: Cross-coupled stiffness elements in LS-DYNA | Ansys Learning Forum","description":"Hello Simon,I found the following in our knowledge database:\"Superelements are not appropriate for bodies undergoing finite rotations. For that case, one could employ flexible rigid bodies (*part_modes)\"One developer told me: \"We are working on extending it to large rotations, underway.\"And here is more information from our knowledge database:\"A \"flexible rigid body\" saves cpu time","inLanguage":"en-US","isPartOf":{"@id":"https:\/\/innovationspace.ansys.com\/forum\/#website"},"breadcrumb":{"@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/#breadcrumblist"},"datePublished":"2024-12-18T17:29:37+00:00","dateModified":"2024-12-18T17:29:37+00:00"},{"@type":"WebSite","@id":"https:\/\/innovationspace.ansys.com\/forum\/#website","url":"https:\/\/innovationspace.ansys.com\/forum\/","name":"Ansys Learning Forum","description":"Ansys Innovation Space","inLanguage":"en-US","publisher":{"@id":"https:\/\/innovationspace.ansys.com\/forum\/#organization"}}]},"og:locale":"en_US","og:site_name":"Ansys Learning Forum | Ansys Innovation Space","og:type":"article","og:title":"Reply To: Cross-coupled stiffness elements in LS-DYNA | Ansys Learning Forum","og:description":"Hello Simon,I found the following in our knowledge database:&quot;Superelements are not appropriate for bodies undergoing finite rotations. For that case, one could employ flexible rigid bodies (*part_modes)&quot;One developer told me: &quot;We are working on extending it to large rotations, underway.&quot;And here is more information from our knowledge database:&quot;A &quot;flexible rigid body&quot; saves cpu time","og:url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/","article:published_time":"2024-12-18T17:29:37+00:00","article:modified_time":"2024-12-18T17:29:37+00:00","twitter:card":"summary_large_image","twitter:title":"Reply To: Cross-coupled stiffness elements in LS-DYNA | Ansys Learning Forum","twitter:description":"Hello Simon,I found the following in our knowledge database:&quot;Superelements are not appropriate for bodies undergoing finite rotations. For that case, one could employ flexible rigid bodies (*part_modes)&quot;One developer told me: &quot;We are working on extending it to large rotations, underway.&quot;And here is more information from our knowledge database:&quot;A &quot;flexible rigid body&quot; saves cpu time"},"aioseo_meta_data":{"post_id":"397893","title":null,"description":null,"keywords":null,"keyphrases":null,"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"default","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":null,"og_custom_url":null,"og_article_section":null,"og_article_tags":null,"twitter_use_og":false,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":"default","schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":null,"robots_max_videopreview":null,"robots_max_imagepreview":"large","priority":null,"frequency":null,"local_seo":null,"limit_modified_date":false,"created":"2025-10-17 21:42:06","updated":"2026-08-14 17:21:34","ai":null,"breadcrumb_settings":null,"seo_analyzer_scan_date":null},"aioseo_breadcrumb":"<div class=\"aioseo-breadcrumbs\"><span class=\"aioseo-breadcrumb\">\n\t\t\t<a href=\"https:\/\/innovationspace.ansys.com\/forum\" title=\"Home\">Home<\/a>\n\t\t<\/span><span class=\"aioseo-breadcrumb-separator\">&raquo;<\/span><span class=\"aioseo-breadcrumb\">\n\t\t\tReply To: Cross-coupled stiffness elements in LS-DYNA\n\t\t<\/span><\/div>","aioseo_breadcrumb_json":[{"label":"Home","link":"https:\/\/innovationspace.ansys.com\/forum"},{"label":"Reply To: Cross-coupled stiffness elements in LS-DYNA","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/397893\/"}],"acf":[],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/397893","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/reply"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/397893\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=397893"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}