{"id":367631,"date":"2024-05-20T13:37:42","date_gmt":"2024-05-20T13:37:42","guid":{"rendered":"\/forum\/forums\/topic\/how-can-i-calculate-strain-at-integration-point\/"},"modified":"2024-05-20T13:39:43","modified_gmt":"2024-05-20T13:39:43","slug":"how-can-i-calculate-strain-at-integration-point","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/how-can-i-calculate-strain-at-integration-point\/","title":{"rendered":"How can I calculate strain at integration point?"},"content":{"rendered":"

Hi,<\/p>\n

Im trying to calculate the nodal stress for a single 10-node tetrahedral element composed of SOLID187, based on nodal displacement using MATLAB. <\/p>\n

 I first constructed the strain-displacement matrix B based on the shape function formula for 10 node tetrahedron in the ANSYS theory reference.<\/p>\n

<\/p>\n

 \"59\"<\/a>\"50\"<\/a>Size of B matrix is 6×30, and Nodal displacement is 30×1 <\/p>\n

Since shape function of solid 187 is linear, I simply inserted the respective coefficients of shape function into the B matrix <\/p>\n

<\/a><\/p>\n

Since these values are from the integration points, I used the ANSYS command ERESX,NO to transfer the values from the integration points to the nodes. According to the reference, solid 187 has 4 integration points. Each vertex receives the value of the integration point directly, and the midpoints are the average of the two nearest integration points’ values.<\/p>\n

By multiplying the displacement vector with the B matrix, I obtained the strain epsilon and I compared those value to ANSYS. However, the strain values I calculated using MATLAB do not match the strain values obtained from ANSYS.<\/p>\n

 <\/p>\n

I suspect that the error might be due to an incorrect calculation of the B matrix, or perhaps the data at each vertex in ANSYS does not actually match the values at the integration points exactly. I have followed the node ordering exactly as it is presented in the ANSYS reference.<\/p>\n

Could you please help me understand if there is a mistake or misunderstanding in my approach?<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n","protected":false},"template":"","class_list":["post-367631","topic","type-topic","status-closed","hentry","topic-tag-apdl","topic-tag-elasticstrain-1","topic-tag-integration-point"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["80516","18229"],"_bbp_author_ip":["23.11.229.223"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["928"],"_bbp_topic_status":["unanswered"],"_edit_lock":["1716212340:294145"],"_bbp_topic_id":["367631"],"_bbp_forum_id":["27791"],"_bbp_engagement":["18229","80516"],"_bbp_voice_count":["2"],"_bbp_reply_count":["4"],"_bbp_last_reply_id":["369781"],"_bbp_last_active_id":["369781"],"_bbp_last_active_time":["2024-06-04 14:03:13"]},"test":"dhjang4522gmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/367631","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":1,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/367631\/revisions"}],"predecessor-version":[{"id":367632,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/367631\/revisions\/367632"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=367631"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}