{"id":162060,"date":"2023-01-25T07:34:10","date_gmt":"2023-01-25T07:34:10","guid":{"rendered":"\/knowledge\/forums\/topic\/why-arent-nonlinear-results-extrapolated-from-integration-points-to-nodes\/"},"modified":"2023-07-31T12:36:48","modified_gmt":"2023-07-31T12:36:48","slug":"why-arent-nonlinear-results-extrapolated-from-integration-points-to-nodes","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/why-arent-nonlinear-results-extrapolated-from-integration-points-to-nodes\/","title":{"rendered":"Why aren&#8217;t nonlinear results extrapolated from integration points to nodes?"},"content":{"rendered":"<p>Nonlinear results cannot be linearly extrapolated because they are *nonlinear*.  To linearly extrapolate a result, such as stress or strain, would mean that the quantity deviates from the constitutive model.  For example, SEQV and EPPL,EQV, if linearly extrapolated when plasticity is active, would mean SEQV and EPTO,EQV would no longer lie on the stress-strain curve.  A similar situation would exist for hyperelasticity or with other nonlinear constitutive models being active.  Hence, linear extrapolation of nonlinear results is meaningless, and the best we can do is copy from integration points to node.  (Of course, the reason why we have calculations of stresses, strains, etc. at the integration points is that although we solve DOF solution at nodes, element quantities are over the volume, so the integration points provide the best locations of evaluation of those quantities rather than at the nodes.)  Note that ERESX does not apply to BEAM188\/189 nor to the through-thickness results for SHELL elements (ERESX affects in-plane results only for SHELLs).<\/p>\n","protected":false},"template":"","class_list":["post-162060","topic","type-topic","status-publish","hentry","topic-tag-4431","topic-tag-extrapolation-of-results","topic-tag-general","topic-tag-integration-points","topic-tag-mechanical-apdl","topic-tag-structural-mechanics"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Nonlinear results cannot be linearly extrapolated because they are *nonlinear*. To linearly extrapolate a result, such as stress or strain, would mean that the quantity deviates from the constitutive model. For example, SEQV and EPPL,EQV, if linearly extrapolated when plasticity is active, would mean SEQV and EPTO,EQV would no longer lie on the stress-strain curve.\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<link rel=\"canonical\" href=\"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/why-arent-nonlinear-results-extrapolated-from-integration-points-to-nodes\/\" \/>\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 Knowledge | Ansys Innovation Space\" \/>\n\t\t<meta property=\"og:type\" content=\"article\" \/>\n\t\t<meta property=\"og:title\" content=\"Why aren\u2019t nonlinear results extrapolated from integration points to nodes? | Ansys Knowledge\" \/>\n\t\t<meta property=\"og:description\" content=\"Nonlinear results cannot be linearly extrapolated because they are *nonlinear*. To linearly extrapolate a result, such as stress or strain, would mean that the quantity deviates from the constitutive model. For example, SEQV and EPPL,EQV, if linearly extrapolated when plasticity is active, would mean SEQV and EPTO,EQV would no longer lie on the stress-strain curve.\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/why-arent-nonlinear-results-extrapolated-from-integration-points-to-nodes\/\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2023-01-25T07:34:10+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2023-07-31T12:36:48+00:00\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n\t\t<meta name=\"twitter:title\" content=\"Why aren\u2019t nonlinear results extrapolated from integration points to nodes? | Ansys Knowledge\" \/>\n\t\t<meta name=\"twitter:description\" content=\"Nonlinear results cannot be linearly extrapolated because they are *nonlinear*. To linearly extrapolate a result, such as stress or strain, would mean that the quantity deviates from the constitutive model. 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To linearly extrapolate a result, such as stress or strain, would mean that the quantity deviates from the constitutive model. For example, SEQV and EPPL,EQV, if linearly extrapolated when plasticity is active, would mean SEQV and EPTO,EQV would no longer lie on the stress-strain curve.","og:url":"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/why-arent-nonlinear-results-extrapolated-from-integration-points-to-nodes\/","article:published_time":"2023-01-25T07:34:10+00:00","article:modified_time":"2023-07-31T12:36:48+00:00","twitter:card":"summary_large_image","twitter:title":"Why aren\u2019t nonlinear results extrapolated from integration points to nodes? | Ansys Knowledge","twitter:description":"Nonlinear results cannot be linearly extrapolated because they are *nonlinear*. To linearly extrapolate a result, such as stress or strain, would mean that the quantity deviates from the constitutive model. 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