{"id":460927,"date":"2026-07-06T22:40:09","date_gmt":"2026-07-06T22:40:09","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/using-the-deformation-gradient-and-storing-history-variables-at-the-same-time\/"},"modified":"2026-07-06T22:40:09","modified_gmt":"2026-07-06T22:40:09","slug":"using-the-deformation-gradient-and-storing-history-variables-at-the-same-time","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/using-the-deformation-gradient-and-storing-history-variables-at-the-same-time\/","title":{"rendered":"Using the deformation gradient and storing history variables at the same time"},"content":{"rendered":"<p>&lt;p&gt;Hello all,&lt;\/p&gt;&lt;p&gt;I am trying to write a UMAT that requires the total strain from the previous cycle as well as needing to store internal stress modes for the material model I am trying to implement. Setting IHYPER = 1 and LHV = (some number) in the keyword seems to wipe hsv(1) &#8211; hsv(9) at the beginning of every cycle.&lt;\/p&gt;&lt;p&gt;How do I make use of the deformation gradient and save internal stress modes at the same time?&lt;\/p&gt;&lt;p&gt;Many thanks,&lt;\/p&gt;&lt;p&gt;K&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-460927","topic","type-topic","status-publish","hentry","topic-tag-ansys-ls-dyna-1","topic-tag-hyperelastic","topic-tag-ls-dyna","topic-tag-UMAT-1"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27814"],"_bbp_topic_id":["460927"],"_bbp_subscription":["659990","275204"],"_bbp_author_ip":["50.222.127.226"],"_bbp_last_reply_id":["460985"],"_bbp_last_active_id":["460985"],"_bbp_last_active_time":["2026-07-07 13:02:54"],"_bbp_reply_count":["1"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["659990","275204"],"_btv_view_count":["78"],"_bbp_topic_status":["unanswered"]},"test":"kshi84gatech-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/460927","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\/460927\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=460927"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}