{"id":392493,"date":"2024-11-03T14:21:44","date_gmt":"2024-11-03T14:21:44","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ls-opt-polynomial-accuracy-problem\/"},"modified":"2024-11-03T14:21:44","modified_gmt":"2024-11-03T14:21:44","slug":"ls-opt-polynomial-accuracy-problem","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ls-opt-polynomial-accuracy-problem\/","title":{"rendered":"Ls-Opt Polynomial Accuracy Problem"},"content":{"rendered":"<p>&lt;p&gt;Hello, I&acute;m new to Ls-Opt and i want to make an Optimization for a Buckling Simulation of a sandwich panel.&lt;\/p&gt;&lt;p&gt;As a start i want to detemin the sensitivities of the parameters with an DOE study. However even with a quadric order the accuracy of the polynomial metamodell for the force output is at 46% (RMS Error). I used the D-Optimal point selection with default settings and 150 points on 9 variables for this. In the accuracy plot i can see that many experiments are being predicted with positiv force values which leaves me questioning if it is possible to set the model so the maximum value can only be 0 ? I find it also interesting that the positive input forces on the other end of the panel which are introduced by a prescribed motion are being predicted very well with only 7-10% RMS Error. Togehther their sum equals the force otput. If anyone has ideas on this please let me know.&nbsp;&lt;\/p&gt;&lt;p&gt;&nbsp;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/11\/03-11-2024-1730642104-mceclip0.png\" \/>&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-392493","topic","type-topic","status-publish","hentry","topic-tag-design-optimization","topic-tag-implicit","topic-tag-ls-dyna","topic-tag-ls-opt-1"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Hello, I\u00b4m new to Ls-Opt and i want to make an Optimization for a Buckling Simulation of a sandwich panel.As a start i want to detemin the sensitivities of the parameters with an DOE study. 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