{"id":302013,"date":"2023-08-18T04:27:49","date_gmt":"2023-08-18T04:27:49","guid":{"rendered":"\/forum\/forums\/topic\/a-question-about-using-shell-and-solid-elements-together\/"},"modified":"2023-08-18T04:27:49","modified_gmt":"2023-08-18T04:27:49","slug":"a-question-about-using-shell-and-solid-elements-together","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/a-question-about-using-shell-and-solid-elements-together\/","title":{"rendered":"A question about using shell and solid elements together"},"content":{"rendered":"<p>Hello,<\/p>\n<p>A summary about the origin of my questions&#8230;. Trabecular bone and cortical bone usually have the following layout in long bones:<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/08\/18-08-2023-1692331504-mceclip0.png\"><\/p>\n<p>Since trabecular bone is a major part of the bone it is normally modelled using solid elements. Cortical bone is a relatively thin layer on top of trabecular bone so it&#8217;s possible to model them using solid elements as well with certain care.<\/p>\n<p><strong>However<\/strong>, I&#8217;ve noticed a particular modelling technique for cortical bone in lumbar spine FEA models involving using shell elements on top of solid elements so I guess they share nodes (Bowden et al. 2007 10.1016\/j.clinbiomech.2007.12.010). I am aware that there is certain interaction between solid and shell elements in mesh transitions that is well documented like this one \/forum\/forums\/topic\/interface-between-solid-and-shell-elements\/)<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/08\/18-08-2023-1692331991-mceclip1.png\" width=\"410\" height=\"487\"><\/p>\n<p>But what happens exactly when you build shell elements on top of solid ones? Is this recommended or not?<\/p>\n<p>I couldn&#8217;t find much information apart from skins or membrane elements in other software, so I have some questions I hope someone has some experience with:<\/p>\n<ul>\n<li>From what I understand, solid elements don&#8217;t have rotational DOF so only translational DOF are shared, right? If both elements have default LS DYNA element formulations is it okay to use nodal averages for the surface?<\/li>\n<li>The nodes used to construct a shell element are placed in the shell midplane, so what would happen with the half thickness being projected inside the solid element? Is there a way to project the thickness completely in one direction rather than half and half?<\/li>\n<li>Does this technique have any implications with regards to contact (basically frictionless automatic surface to surface with SOFT=0)? The difference in young&#8217;s modulus between trabecular-solid (E=300 MPa) and cortical-shell is significant (E=12 000 MPa).<\/li>\n<\/ul>\n<p>Thanks,<\/p>\n<p>Andres<\/p>\n","protected":false},"template":"","class_list":["post-302013","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["280671","200","88","3136"],"_bbp_author_ip":["104.102.248.196"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["2932"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["302013"],"_bbp_forum_id":["27814"],"_bbp_engagement":["88","200","3136","280671"],"_bbp_voice_count":["4"],"_bbp_reply_count":["13"],"_bbp_last_reply_id":["303708"],"_bbp_last_active_id":["303708"],"_bbp_last_active_time":["2023-08-28 18:06:19"]},"test":"andres-menattu-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/302013","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\/302013\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=302013"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}