{"id":31420,"date":"2018-11-09T03:25:19","date_gmt":"2018-11-09T03:25:19","guid":{"rendered":"\/forum\/forums\/topic\/nonlinear-material-with-reduced-integration-tubing-convergence\/"},"modified":"2018-11-09T03:25:19","modified_gmt":"2018-11-09T03:25:19","slug":"nonlinear-material-with-reduced-integration-tubing-convergence","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/nonlinear-material-with-reduced-integration-tubing-convergence\/","title":{"rendered":"Nonlinear Material with Reduced Integration &#8211; Tubing Convergence"},"content":{"rendered":"<p>Hi all,<\/p>\n<p><\/p>\n<p>I&#8217;m working on trying to get a nonlinear 4 layered tubing to be 1. pressurized, 2. bent, and 3. subsequently advanced through an inner rigid tubing and hit a wall and slide past a fixed support:<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/2ddaa98d-0a7d-4941-88e6-a96f0013fdfa\/5f85ed58-7194-488e-8200-a99101795e40_schematic.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n<p><\/p>\n<p>I have available to me uniaxial, biaxial, and planar shear stress data for 3 out of the 4 materials (Silicone Rubber, PU80A, PU55D). The PU&#8217;s fit well with a Rooney Mivlin 2 parameter model:<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/2ddaa98d-0a7d-4941-88e6-a96f0013fdfa\/7d964fd5-8adb-425b-800f-a991017af9b0_pu80a.jpg?width=690&amp;upscale=false\" alt=\"\"><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/2ddaa98d-0a7d-4941-88e6-a96f0013fdfa\/dded6852-da05-4e94-83ff-a991017b0b15_pu55d.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n<p><\/p>\n<p>Using the incompressibility parameter of <img decoding=\"async\" src=\"\/angry.gif\" width=\"\" height=\"\" alt=\"D=\" title=\"D=\" class=\"bbcode_smiley\" \/> 2\/K. The Silicone rubber, however, fits best with a Mooney-Rivlin 9 Parameter:<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/2ddaa98d-0a7d-4941-88e6-a96f0013fdfa\/3c7229f0-9d00-4033-a38e-a991017b65e7_rubber.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n<p><\/p>\n<p>I, however, do not know how to exactly calculate the Incompressibility Parameter for a 9 parameter model&#8230; If anyone knows details on how to obtain based on the data I have it would be great. Not confident on how important it is to have this value, I was only provided the data, not the D1 value&#8230;<\/p>\n<p><\/p>\n<p>I&#8217;ve also included keyopt, matid,2,1 to introduce Uniform Reduced Integration to all of the nonlinear materials (excluding PET) (To my understanding, this is applied to SOLID185). As it stands, I&#8217;m using Linear ordered elements (perhaps quadtratic would elicit better behavior? Unsure) with 200 divisions of sweeps, 2 elements through thickness of the tubes, and 35 divisions around the perimeter, totaling 59,533 elements.<\/p>\n<p><\/p>\n<p>I also decided to bend it halfway (15 degrees) while increasing the pressure in the first substep, as it appeared that my convergence troubles came in the 2nd load step of 30 degrees near the very end. The thought being that I&#8217;ve increased the number of steps over which this load is applied, although not sure if it matters as it appears it&#8217;s just starting to buckle or becoming unstable near the end.<\/p>\n<p><\/p>\n<p>I&#8217;ve gotten through the bend, but ran into trouble getting it to hit the wall and sliding past the fixed support:<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/2ddaa98d-0a7d-4941-88e6-a96f0013fdfa\/355405a5-730f-4c0a-8970-a9930037c2fe_convergence.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n<p><\/p>\n<p>Are there any thoughts on how to get full convergence? Does missing the incompressibility parameter mean a lot in terms of convergence assistance?<\/p>\n<p><\/p>\n<p>Regards,<\/p>\n<p><\/p>\n<p>Zach<\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n<p><\/p>\n<p>&nbsp;<\/p>\n","protected":false},"template":"","class_list":["post-31420","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["3592"],"_bbp_old_topic_author_name_id":["Anonymous"],"_bbp_old_is_topic_anonymous_id":["false"],"_bbp_old_closed_status_id":["publish"],"_bbp_author_ip":[null],"_bbp_old_sticky_status_id":["normal"],"_bbp_likes_count":["0","0","0","0","0"],"_btv_view_count":["1098"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["31420"],"_bbp_forum_id":["27791"],"_bbp_engagement":["897","159194"],"_bbp_voice_count":["2"],"_bbp_reply_count":["3"],"_bbp_last_reply_id":["68960"],"_bbp_last_active_id":["68960"],"_bbp_last_active_time":["2018-11-09 16:34:24"]},"test":"zjuv9021"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/31420","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\/31420\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=31420"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}